A platform for research and endeavour

Welcome to Volume 5, Issue 1 of the Australian Medical Student Journal (AMSJ). The latest issue continues to showcase the vast breadth of medical student and junior doctor research, reviews, and opinions in a wide range of relevant and compelling articles.

This issue includes the latest trends in laboratory-based cancer research, covered in an editorial by Alison Browning, and provides a timely overview of this rapidly growing field. Grace Leo’s editorial shifts our attention to the waning practice of compassion during patient care and ways in which this can be addressed.

Key guest articles include a piece by Professor Patrick McGorry which builds on the momentum placed on medical student mental health and wellbeing this year, offering new insights in this area in the wake of a 2013 beyondblue survey which highlighted some stark statistics on medical student and junior doctor mental health. Professor Stephen Leeder, the Editor-in-Chief of the Medical Journal of Australia (MJA) which is celebrating its centenary this year, navigates the overload of medical information that faces us now and into the future. The Australian Indigenous Doctor’s Association provide an informative view into the future of Indigenous health in Australia, and draws on the need to train culturally competent doctors to make inroads in this area.

Additionally, this issue has attracted an unprecedented number of original research submissions, testament to the growing popularity of research amongst students and the AMSJ’s ongoing drive to publish early career research. Stephanie Barnes suggests a technique to anatomically localise functionally defined cortical areas using MRI, while a second research article in the field of radiology compares two key methods of identifying adrenal glands on computed tomography (CT). Public health measures to prevent skin cancers amongst men and women are assessed in a study of rural Australians, and the findings suggest that the measures are still not being heeded by some.

The review and feature articles again cover a diverse array of topics, with a spotlight on penicillin allergies, an overview of the history of modern anaesthesia, and reviews of cancer and psychiatric treatments.

The growing calibre of research submissions, as well as our staple review and feature articles, reflect the variety of interests and undertakings of Australian medical students and junior doctors. The AMSJ is currently in the midst of exploring potential partnerships with the Australian Medical Students’ Association (AMSA) and the MJA to bring more opportunities to students, encourage research, and promote medical editing and journalism. Keep an eye out on our website for more announcements. Furthermore, our presence on social media continues to strengthen and has played a strong role in increasing our readership, including to an emerging international audience.

The AMSJ is produced by an expanding team of volunteer staff of medical students which is now well and truly established across all states and medical schools in Australia. This year has been a time of transition at the AMSJ with many staff members completing their terms with us and handing over the reigns to a new team of enthusiastic editors, proof-readers, and other internal staff positions who bring with them a wealth of experience. I would like to thank past executive members and editors who have overseen the development of the AMSJ and to current staff who have worked tirelessly to publish this issue. I would also like to extend our thanks to the peer-reviewers who have provided us with invaluable feedback on articles and are central to the quality and success of the AMSJ.
Finally, I would like to thank our readers, authors and sponsors who continue to support the AMSJ. On behalf of the staff at the AMSJ, we hope you enjoy this issue.

Thank you to AMSJ Peer Reviewers:

  • Dr Karl Friston
  • Dr Shuli Futeran
  • Dr Craig Lewis
  • Dr Saxon Smith
  • Dr Susan Ireland
  • Professor Philip Hazell
  • Dr Matthew Links
  • Dr Himanshu Popat
  • Professor Jennifer Reath
  • Dr Shaun Roman
  • Dr Wai Kit Lee
  • Professor Graham Johnston
  • Dr Tracy Putoczki
  • Dr Joanne Lewohl
  • Professor David Robertson
  • Dr Michael Hornberger
  • Dr Joseph Moxon
  • Dr Tony Lamont
  • Dr Susan Smith
  • Dr Shane Brun
  • Dr Ryan Shum
  • Dr Martin Kroslak
  • Professor Saxby Pridmore
  • Dr Stephen Adelstein
  • Professor Gregory Peterson
  • Mrs Lisa Gilroy
  • Ms Miranda Stephens
  • Dr Andrew Chang
  • Dr William Glasson
  • Professor Philip Mitchell
  • Professor Anthony Harris
  • Dr Matthew Fasnacht
  • Associate Professor Ute Vollmer-Conna
  • Associate Professor Julian Trollor

Appraising laboratory-based cancer research for the medical student

Increasingly clinicians are being asked to participate in translational research–working closely with laboratory scientists to help guide research goals and projects. The work that is done in the laboratory setting can sometimes fall outside the scientific grounding that most medical students and clinicians receive at university, making it difficult to assess the quality of techniques described in journal articles. This article aims to explore some of the most frequently utilised models and technologies in laboratory-based cancer research to ease the appraisal of such scientific papers for the budding clinician.

Statistical significance and biological significance

A recent publication in Nature demonstrating the limitations of the p value has highlighted how research results can be unintentionally misleading, [1] yet many studies still rely simply on this measure. Beyond the limitations of statistics, it is important to consider what a meaningful outcome is in the context of cancer treatment. A treatment may lead to a significant reduction in the levels of a certain protein or RNA transcript, but it is more important to measure how this ultimately affects an in situ tumour. Depending on the way these levels are measured, a small reduction in expression levels can appear statistically significant, but may not represent a large enough change to actually alter the behaviour of tumour cells. Small quantities of stimuli such as cytokines can sometimes have no effect on cancer cells. [2] Similarly, systems can reach an optimal concentration at which point even increasing doses by 10-fold will have no additional effect on cell growth. [2] It is therefore pertinent to consider not only whether a change can pass statistical tests, but also whether this change is altering the tumour environment through more functional experiments that can quantify proliferation, angiogenesis, cell death or apoptosis.

Culturing cancer cells

Many studies utilise in vitro cell culture work. It is a convenient way to look closely at the behaviour of cancer cells in response to various stimuli and treatments. There are, however, a number of limitations to this model. Human cancer cell lines originate from human tumours (the most famous being the HeLa cell lines – isolated from Henrietta Lacks, a cervical cancer patient from the 1950s [3]). Many are not sourced from primary tumours, but rather originate from metastases, commonly from surrounding lymph nodes, but sometimes from such unusual and distal sites as a brachial muscle metastasis. [4] Cancer cells that metastasise are known to have different properties to primary tumours, [5] and although studying metastasis themselves is a valuable pursuit, applying the properties of these cells to a whole disease is flawed.

Furthermore, in order to culture cancer cells, an immortalisation process must be undertaken to allow continued growth outside of the body. [6] Although many cancer cells have already developed a way to avoid normal cell cycle regulation, this process inevitably introduces more oncogenic mutations that may not have been present originally. [7] It is also clear that over time in culture, these cells develop further mutations, leading to variability in results. The product of this is conflicting scientific articles: for example, eight years later and in a different laboratory, pancreatic cancer cells showed the opposite expression of a key oncogenic transcription factor. [8, 9]

Despite allowing scientists to look closely at the behaviour of cancer cells, in vitro studies have limited application to in vivo disease, demonstrating the need for in vitro studies to be confirmed with compelling disease models.

Models of disease

As a way of contextualising results seen in cells cultured in the laboratory, animal models of cancer are widely used to examine pathogenesis and management options.

Mice with genetic mutations

Specific augmentation of genes can lead to spontaneous development of tumours without other stimuli. [10] These models can be excellent for studying a range of disease processes, looking at specific oncogenes and other events (such as inflammation) that may result in the development of tumours. [10] Their relevance can sometimes be limited by this single mutation, as very rarely do endogenous or naturally occurring human tumours result from one single mutation. Additionally, tumours do not always mimic the disease course in humans, with atypical metastatic processes. [11]

Mice with inducible cancers

As gene modulation developed, a number of systems that allows organ- or cell-type-specific genetic mutation have allowed more detailed study into the roles of specific proteins in the development of tumours.

A common inducible model is the Kras model. Kras is a gene that is mutated in approximately 90% of lung cancers. [12] This gene can be utilised to generate lung tumours in mice. Removal of a stop codon in the K-ras gene allows for expression and development of tumours, which can be done by administering a viral effector, AdenoCre. [12] Similar to mice with specific genetic mutations, this sort of targeted induction of mutation is not wholly representative of human disease.

Other forms of treatment can also be used to provoke dysplasia in animal models. An extremely widely used model for mimicking inflammation-associated colorectal cancer is the DSS-AOM model. This model has been highly variable, especially in regards to the role of the immune system in worsening or alleviating disease. [13-18] Much of this variation has been attributed to resident gut flora variation, highlighting its role in the development of inflammation-associated cancer, [16] but not assisting in providing a robust answer to the scientific questions posed in these individual studies.


An alternative to endogenous cancers, animals can be used to investigate the response of human tumours to therapies. The process of removing a tumour from a patient, and inserting it into an immunocompromised mouse is called xenografting. These can be very effective models for assessing, in vivo, the penetrance and effects of cancer therapy. [19-22] Unfortunately, these too have limitations. Many studies insert tumours in the subcutaneous tissue of the mouse flank – making tumour size easy to measure, both for ethical and research outcomes. However, the limitations of this location are clear, as the tumour is not located in a place it would usually physiologically be able to access. Recently, an effort to establish xenografts in a most physiologically appropriate location has been made. [23, 24] This may yield more accurate results and improve the efficiency of translated treatments in clinical trials.

Xenografts could also potentially play a role in advancing personalised medicine. Studies have implanted an individual patient’s tumour into a colony of mice, who are then administered a range of chemotherapeutic agents to determine which regime leads to the greatest reduction in tumour burden. [25] This is an exciting frontier in personalised medicine that will hopefully lead to more effective treatment in the future.


Despite limitations in laboratory research, the future for cancer therapy lies, at least partially, in these laboratories. When paired with a clear clinical goal and active attempts to translate ideas both from the bed to the bench and back again, promising breakthroughs can be made that will be valuable for researcher, clinician and most importantly, patient.

Conflict of interest

None declared.


A Browning:


[1] Nuzzo R. Scientific method: statistical errors. Nature 2014;506(7487):150-2. Epub 2014/02/14.

[2] Beales IL. Effect of interlukin-1beta on proliferation of gastric epithelial cells in culture. BMC gastroenterology 2002;2:7. Epub 2002/04/09.

[3] Callaway E. Deal done over HeLa cell line. Nature 2013;500(7461):132-3. Epub 2013/08/09.

[4] Akiyama S, Amo H, Watanabe T, Matsuyama M,Sakamoto J, Imaizumi M, et al. Characteristics of three human gastric cancer cell lines, NU-GC-2, NU-GC-3 and NUGC-4. The Japanese journal of surgery 1988;18(4):438-46. Epub 1988/07/01.

[5] Bidwell BN, Slaney CY, Withana NP, Forster S, Cao Y, Loi S, et al. Silencing of Irf7 pathways in breast cancer cells promotes bone metastasis through immune escape. Nature medicine 2012;18(8):1224-31. Epub 2012/07/24.

[6] Maqsood MI, Matin MM, Bahrami AR, Ghasroldasht MM. Immortality of cell lines: challenges and advantages of establishment. Cell biology international 2013;37(10):1038- 45. Epub 2013/06/01.

[7] Lehman TA, Modali R, Boukamp P, Stanek J, Bennett WP, Welsh JA, et al. P53 mutations in human immortalized epithelial cell lines. Carcinogenesis 1993;14(5):833-9. Epub 1993/05/01.

[8] Corcoran RB, Contino G, Deshpande V, Tzatsos A, Conrad C, Benes CH, et al. STAT3 plays a critical role in KRAS-induced pancreatic tumorigenesis. Cancer research 2011;71(14):5020-9. Epub 2011/05/19.

[9] Scholz A, Heinze S, Detjen KM, Peters M, Welzel M, Hauff P, et al. Activated signal transducer and activator of transcription 3 [STAT3] supports the malignant phenotype of human pancreatic cancer. Gastroenterology 2003;125(3):891-905. Epub 2003/09/02.

[10] Judd LM, Bredin K, Kalantzis A, Jenkins BJ, Ernst M, Giraud AS. STAT3 activation regulates growth, inflammation, and vascularization in a mouse model of gastric tumorigenesis. Gastroenterology 2006;131(4):1073-85. Epub 2006/10/13.

[11] Judd LM, Alderman BM, Howlett M, Shulkes A, Dow C, Moverley J, et al. Gastric cancer development in mice lacking the SHP2 binding site on the IL-6 family co-receptor gp130. Gastroenterology 2004;126(1):196-207. Epub 2003/12/31.

[12] Jackson EL, Willis N, Mercer K, Bronson RT, Crowley D, Montoya R, et al. Analysis of lung tumor initiation and progression using conditional expression of oncogenic K-ras. Genes & development 2001;15(24):3243-8. Epub 2001/12/26.

[13] Allen IC, TeKippe EM, Woodford RM, Uronis JM, Holl EK, Rogers AB, et al. The NLRP3 inflammasome functions as a negative regulator of tumorigenesis during colitisassociated cancer. J Exp Med 2010;207(5):1045-56. Epub 2010/04/14.

[14] Bauer C, Duewell P, Mayer C, Lehr HA, Fitzgerald KA, Dauer M, et al. Colitis induced in mice with dextran sulphate sodium [DSS] is mediated by the NLRP3 inflammasome. Gut 2010;59(9):1192-9. Epub 2010/05/06.

[15] Dupaul-Chicoine J, Yeretssian G, Doiron K, Bergstrom KS, McIntire CR, LeBlanc PM, et al. Control of intestinal homeostasis, colitis, and colitis-associated colorectal cancer by the inflammatory caspases. Immunity 2010;32(3):367-78. Epub 2010/03/17.

[16] Elinav E, Strowig T, Kau AL, Henao-Mejia J, Thaiss CA, Booth CJ, et al. NLRP6 inflammasome regulates colonic microbial ecology and risk for colitis. Cell 2011;145(5):745-57. Epub 2011/05/14.

[17] Takagi H, Kanai T, Okazawa A, Kishi Y, Sato T, Takaishi H, et al. Contrasting action of IL-12 and IL-18 in the development of dextran sodium sulphate colitis in mice. Scand J Gastroenterol 2003;38(8):837-44. Epub 2003/08/28.

[18] Zaki MH, Boyd KL, Vogel P, Kastan MB, Lamkanfi M, Kanneganti TD. The NLRP3 inflammasome protects against loss of epithelial integrity and mortality during experimental colitis. Immunity 2010;32(3):379-91. Epub 2010/03/23.
[19] Yagi Y, Fushida S, Harada S, Tsukada T, Kinoshita J, Oyama K, et al. Biodistribution of humanized anti-VEGF monoclonal antibody/bevacizumab on peritoneal metastatic models with subcutaneous xenograft of gastric cancer in mice. Cancer chemotherapy and pharmacology 2010;66(4):745-53. Epub 2009/12/25.

[20] Stoeltzing O, McCarty MF, Wey JS, Fan F, Liu W, Belcheva A, et al. Role of hypoxia-inducible factor 1alpha in gastric cancer cell growth, angiogenesis, and vessel maturation. Journal of the National Cancer Institute 2004;96(12):946- 56. Epub 2004/06/17.

[21] Fujimoto-Ouchi K, Sekiguchi F, Yasuno H, Moriya Y, Mori K, Tanaka Y. Antitumor activity of trastuzumab in combination with chemotherapy in human gastric cancer xenograft models. Cancer chemotherapy and pharmacology 2007;59(6):795-805. Epub 2006/10/13. [22] Min Y, Adachi Y, Yamamoto H, Imsumran A, Arimura Y, Endo T, et al. Insulin-like growth factor I receptor blockade enhances chemotherapy and radiation responses and inhibits tumour growth in human gastric cancer xenografts. Gut 2005;54(5):591-600. Epub 2005/04/16.

[23] Jones-Bolin S, Ruggeri B. Orthotopic models of human gastric carcinoma in nude mice: applications for study of tumor growth and progression. Curr Protoc Pharmacol 2007;Chapter 14:Unit 14 4. Epub 2007/06/01.

[24] Bhullar JS, Makarawo T, Subhas G, Alomari A, Silberberg B, Tilak J, et al. A true orthotopic gastric cancer murine model using electrocoagulation. Journal of the American College of Surgeons 2013;217(1):64-70; discussion -1. Epub 2013/04/16.

[25] Villarroel MC, Rajeshkumar NV, Garrido-Laguna I, De Jesus-Acosta A, Jones S, Maitra A, et al. Personalizing cancer treatment in the age of global genomic analyses: PALB2 gene mutations and the response to DNA damaging agents in pancreatic cancer. Molecular cancer therapeutics 2011;10(1):3-8. Epub 2010/12/08.


Recapturing compassion

Recapturing compassionJohn was wheeled into hospital on a Friday of a long weekend. He was elderly and frail, with severe Parkinson’s disease. Many
hospital staff attended to him – prescribing medications, delivering meals, and changing his sheets. Unfortunately, no one realised that John’s limited mobility meant that he could not reach his drinking cup. Although the staff had performed their duties, the absence of compassion led John to become dehydrated and develop acute kidney injury.

When we first entered medicine, we pledged ourselves as model medical students. We spoke of our compassion for the sick and a
dedication to helping our community. But as we progress through our studies into full time clinical work, putting such aspirations into actions becomes more challenging.

There are checklists for assessing practical skills – be it history taking and examination, inserting cannulas, or writing discharge summaries. Medical schools are honed to teach us to be competent; but do they teach us how to be compassionate?

Why should we care about compassion?

Compassion is derived from the Latin, ‘compati’, meaning ‘to suffer with’ other people. It also involves an active concern for
and effort to alleviate that suffering.

Whilst as students we may initially see the best way to alleviate suffering is to ‘cure’ our patients with medicine, we soon come to realise that we cannot ‘cure’ all our patients. Indeed, over 7 million Australians suffer from chronic disease, which cannot be ‘cured’ completely. [1] But it is not just for these patients that the ‘care’ is just as, if not more important than the ‘cure’. As Sir William Osler explains, ‘The good physician treats the disease; the great physician treats the patient
who has the disease.’

Patients want compassionate doctors. [2] Being compassionate can improve patient wellbeing and care. Compassionate doctors
also help reduce patient anxiety. [3] A positive patient mindset is important, as several studies have linked optimism with better health outcomes. [4] When compassion enters the patient-physician relationship, it builds trust, aiding more accurate diagnosis and understanding of patient problems. [5] Through compassion, care is optimised. It transforms healthcare from being a system to a service.

Why do we struggle with being compassionate?

Although we may begin work with a good understanding of the necessity of compassion, stressors such as heavy workloads and limited time can harden our hearts towards our patients. [6] Bureaucracy and red tape takes time away from direct patient contact. We start to become wary as the list of people needing attention expands. It is possible to let faces blur and details melt away until we are treating ‘the man with the ankle fracture’ or ‘bed 5’s dehydration’. While we never intend to lack compassion, the current reality of medicine means that we are often preoccupied with treating the patient, rather than caring for them.

In many instances, acting with compassion to a patient can be a challenge. In medicine, we see humanity at its best, but also at its worst. Patients are not always polite or easily satisfied. Sometimes, the most difficult keep coming back again and again. ‘Frequent flyers’ is a term applied to patients who commonly represent to hospital. Last year, 1,200 of these patients accounted for over 22,000 presentations to Victorian casualty wards between them. [7] One patient managed to visit Royal Melbourne Hospital 144 times alone. [7] Whilst some of these patients have legitimate health problems, others may be drug seeking, homeless, or hypochondriacs.

It is not surprising then that doctors are at high risk of ‘compassion fatigue’, resulting from the constant demand of caring for others. Compassion fatigue can lead to burn-out and compromise our ability to provide safe and effective patient care. It is concerning to look at the results of the 2008 Australian Health and Wellbeing Survey of junior doctors which found that 54 percent of respondents were at risk of secondary trauma or ‘compassion fatigue’. [8]

How can we recapture compassion?

Perhaps we must begin by remembering to treat ourselves with compassion.

Having enough time for oneself is important in continuing to be a kind and functioning human being capable of showing others
compassion. This includes addressing basic needs such as getting enough sleep, eating regular meals, and making time to refresh our bodies and souls. Unfortunately, it is common to see doctors neglecting on these things and more. There are doctors who have abstained from drinking water to avoid bathroom breaks, and others who have even performed ward rounds with drips in their arms. Such exploits have been boasted about as personal achievements or as self-sacrifice for the sake of having more time with patients. But this is a misperception that is likely to do more harm to ourselves and our patients, as we are prone to make mistakes when tired and stressed. [9]

In fact, being compassionate does not necessarily require large amounts of time. One study compared two interviews in which
the diagnosis of breast cancer was presented. In the second interview, the doctor was more compassionate and added two statements, which acknowledged the patient’s difficulty of receiving such a diagnosis and expressing support. [3] Study participants evaluated the doctor as significantly more compassionate and they also had a reduced anxiety state compared to those exposed to the standard interview. Interestingly, the time difference between the two interviews was only 40 seconds. In the time that we might wait for a lift, it is possible to improve patient wellbeing by showing compassion.

Sometimes it seems difficult to know where we should start with being compassionate to our patients. It does not have to be a
dramatic act, but may begin with pulling up a chair and four simple words, “Hello my name is…”. This is the potent thought that Dr Kate Granger triggered across the world in her viral hashtag #hellomynameis. It was a call to address what she saw as an important gap in communication and patient care within the healthcare system. [10]

Dr Granger is a geriatrician. She is also a longterm patient diagnosed with sarcoma in 2011. During her illness she was startled to find that many of the healthcare workers examining, treating, and looking after her went about nameless. They had missed an essential step to building relationship and trust – the introduction. [10] These experiences inspired her to start sharing her stories and encouraged reforms in Britain’s National Health Service (NHS).

At the end of the day, we do not always need to feel compassionate or have vast time or strength for it. Instead, we choose
compassion in the little things and persevere in the remembrance that everyone has intrinsic worth. That is when we discover
the simple truth – that what makes a compassionate doctor is the same as what makes a compassionate human being.

At the Australian Medical Student Journal, we provide a stepping-stone for medical student research and writing. We also hope to inspire not only more competent clinicians, but more compassionate ones too.


I would like to thank May Whitbourn, Peggy Kuo, Linda Wu, Dr Michelle Johnston, Dr Natalie May and Dr Matthew Leung for their
invaluable feedback and encouragement.

Conflict of Interest

None declared.


G Leo:


[1] Australian Institute of Health and Welfare. Chronic Diseases. Accessed online August 2014:

[2] Puchalski CM. The Role of Spirituality in Health Care. Proc (Bayl Univ Med Cent). 2001. 14(4) 352-7.

[3] Fogarty LA, Curbow BA, Wingard JR, McDonnell K, Somerfield MR. Can 40 Seconds of Compassion Reduce Patient Anxiety? American Society of Clinical Oncology. 1999. 17(1) p371.

[4] Diener E, Chan MY. Happy People Live Longer: Subjective Well-Being Contributes to Health and Longevity. Applied Psychology: Health and Well-Being. 3(1) p1-43.

[5] Post SG. Compassionate care enhancement: benefits and outcomes. The International Journal of Person Centred Medicine. 1(4) pp808-13

[6] Ahrweiler F, Neumann M, Goldblatt H, Hahn EG, Scheffer C. Determinants of physician empathy during medical education: hypothetical conclusions from an exploratory qualitative survey of practicing physicians. BMC Med Educ. 2014 Jun 22;14:122. doi: 10.1186/1472-6920-14-122.

[7] Mickelburough P. Frequent Flyer Patients Clog Hospital Queues by Visiting Up to Twice a Week. Herald Sun. June 8th 2014. Accessed online August 2014:

[8] Australian Medical Association. AMA Survey Report on Junior Doctor Health and Wellbeing. 2008. Accessed online August 2014:

[9] Helmreich RL, Merritt AC. Culture at work: national, organizational and professional influences. Aldershot: Ashgate, 1998.

[10] Granger K. #hellomynameis. Accessed online July 2014:


Psychopathy: A disorder or an evolutionary strategy?

Psychopathy: A disorder or an evolutionary strategy?I am writing to discuss an interesting construct in psychiatry often referred to as ‘psychopathy’. In psychiatry there is often
lively debate about how we should classify and define psychopathology, influenced by cultural factors as much as scientific
advances. In this letter I wish to explore the somewhat controversial idea that, instead of being a disease or pathology, psychopathy can be viewed as a natural variant in human personality. In other words, psychopathy may be a phenotype resulting from various adaptive strategies occurring throughout evolution.

Psychopathy is a term describing a particular constellation of personality traits and behaviours, sometimes viewed by the medical community and society as a disorder or pathology. The Hare Psychopathy Checklist, Revised (PCL-R) is the traditional measure used to define and assess psychopathy.

Factor 1 traits
Lack of guilt/remorse
Lack of empathy
Factor 2 traits
High impulsivity
Poor behavioural control
Criminal versatility

Box 1. The Hare PCL-R defines psychopathy as a combination of key interpersonal and affective deficits (Factor 1) and socially deviant behaviours (Factor 2) [1]

Although psychopathy is sometimes perceived as being synonymous with the DSM-5 diagnosis of antisocial personality disorder,
this is largely incorrect. Antisocial personality disorder focuses more on outwardly observable criminal behaviours, whereas
psychopathy takes into account personality traits that are less readily observable. These differences have been discussed elsewhere.[3]

The concept of psychopathy as an adaptive strategy is well discussed by Glenn et al. [4] Unlike schizophrenia and other mental
disorders that are clearly harmful or maladaptive for the individual, psychopathy is not so clear-cut. One can even argue
that the greatest danger of psychopathy is harm to society, rather than harm to the affected individual. Certain traits associated with psychopathy (such as fearlessness and superficial charm) may have been beneficial to the individual in the ancestral environment, existing as a social strategy to increase survival and reproductive success.[4] Even in today’s society, it seems that traits such as fearlessness and low stress reactivity may sometimes help a person to perform well in high-stress occupations (e.g. executive management, politics, military).

Psychopathy may be more common than we expect. The idea of ‘successful’ and ‘unsuccessful’ psychopaths further complicates the pathology vs. strategy debate. Most studies have been unable to find a clear correlation between psychopathy and intelligence. [5] According to Hare, ‘successful’ psychopaths are commonly described as intelligent, successful and high-functioning
individuals, with no criminal convictions and variable integration into society. These individuals are usually more difficult
to identify and study. [6] ‘Unsuccessful’ psychopaths typically describe the cohort encountered in forensic settings, individuals who regularly run into trouble with the law (and are hence easier to identify and study). [6] Consequently, it is this population from whom we derive the bulk of our knowledge and research on psychopathy. If we are only identifying a subset of psychopaths, psychopathy on the whole may be more ubiquitous in society than we think.

Further research is still required into many aspects of psychopathy. Whether the traits associated with psychopathy represent true pathology is still open to debate. Although a diagnosis of psychopathy has the practical benefit of directing treatment in the forensic setting (e.g. towards behavioural change and control therapies instead of empathy and social skills training), [7] the psychopath label carries considerable stigma and possible social, psychological and legal consequences for the individual. An example is the difference in criminal sentencing in certain countries. [8] For personality traits to constitute a disorder
in the DSM-5, there must be significant distress or functional impairment caused to the individual. Although psychopathy
is not a personality disorder in the DSM-5, it is interesting to note that ‘successful’ psychopaths may experience neither of these.

In conclusion, the aim of this article was to put forth an alternative view on psychopathy. Rather than to comment on management or the correctness of any particular viewpoint, I hope to have highlighted some of the complexities surrounding human personality and behaviour through this brief discussion on psychopathy.

Conflict of interest

None declared.


K Cheng:


[1] Hare RD. Manual for the Hare Psychopathy Checklist-Revised. 2nd ed. Toronto, ON: Multi-Health Systems; 2003.

[2] American Psychiatric Association. Diagnostic and statistical manual of mental disorders, fifth edition.

[Internet] 5th ed. Arlington, VA: American Psychiatric Association; 2013 [cited 2014 April 5]. Available from:

[3] Ogloff JRP. Psychopathy/antisocial personality disorder conundrum. Aust N Z J Psychiatry. 2006 Jun;40(6-7):519-28.

[4] Glenn AL, Kurzban R, Raine A. Evolutionary theory and psychopathy. Aggress Violent Behav. 2011 Sep;16:371-80.

[5] Blair J, Mitchell D, Blair K. The psychopath: emotion and the brain. Oxford, UK: Blackwell Publishing; 2005.

[6] Babiak P, Hare RD. Snakes in suits: when psychopaths go to work. New York: Harper Collins Publishers; 2006.

[7] McMurran M. Motivating offenders to change: a guide to enhancing engagement in therapy. UK: John Wiley & Sons; 2002.

[8] Kiehl KA, Sinnott-Armstrong WP. Handbook on psychopathy and law. USA: Oxford University Press; 2013.


About Helen Caldicott’s guest article

About Helen Caldicott’s guest articleAs a university academic whose professional interests include the chemistry of serious reactor accidents I disagree with many of
the statements made by Helen Caldicott in her recent article “The impact of the nuclear crisis on global health”. While she is an iconic figure for many people it is important that her statements are critically assessed, in the interests of public health neither statements made by the opponents or supporters of any technology should be accepted blindly. For reasons of brevity I am unable to address all my concerns about her article, so I will focus on a few of the errors I believe she has made. Helen claims that the low level exposure that the general public experienced caused symptoms of “radiation sickness”. This claim is at odds with what I have been taught during the radiological health and safety training I have had and I would like to point out that
to induce the acute radiation syndrome in humans a dose of at least 1 to 2 Gy needs to be delivered over a short time. The doses which the public had during the accident were far too small. If radiation is as able as she claims to induce the acute effects (blood and GI disturbances) then surely these effects would be commonly seen after moderate medical exposures such as CT scans and diagnostic nuclear medical procedures.

I would like to challenge her claim that all radioactive elements bioconcentrate as they pass through a food chain. While some
radionuclides can pass through food chains with ease, others do not do so, for example, the human digestive system is unable to
absorb into the blood more than a small fraction of any plutonium that is swallowed. A classic test to determine if a worker has
inhaled plutonium dust is to measure the plutonium content of their faeces. If the digestive system were a good absorber of this element then this test would be impossible.

It is noteworthy that the biokinetics of tritium and cesium are not compatible with the idea that it will bioconcentrate in all food chains; the biological half-life of cesium in humans and farmyard animals is in the range of one to three months. As a result, after a short exposure to cesium most of it will be gone in less than one year. During a protracted constant exposure to cesium-134 or 137 an equilibrium will be set up within months which will prevent the further accumulation of cesium; the majority of the cesium ingested will be excreted before it is able to undergo radioactive decay. The common form of tritium (HTO) has an even shorter biological half-life in humans, as a result it is one of the least toxic radioisotopes.

Helen claims that iodine-131 is a potent carcinogen in humans, while I advocate exercising great care when working with any radioactive substance I note that a Swedish medical scientist (L.E. Holm) was unable to find any evidence that this radionuclide is able to cause thyroid cancer in humans. He could see no excess of thyroid cancer in a population of people exposed during diagnostic medical procedures. However data associated with Chernobyl and atom bomb tests strongly indicates that radioactive iodine causes thyroid cancer. L.E. Holm suggested that the shorter lived higher beta energy iodine radioisotopes from bombs / Chernobyl may have been the main carcinogen. While I do not know if L.E. Holm’s short-lived iodine hypothesis is right, based on the current evidence it is not a certainty that iodine-131 is a potent carcinogen.

I hold the view that people are equally entitled to hold antinuclear or pronuclear views. However, any scientific argument either for or against nuclear power should be correct and good quality science.

Conflict of interest

None declared.


M Foreman:

Review Articles

The α-5 subunit-containing GABA-A receptor: a target for the treatment of cognitive defects

Amnesic effects of benzodiazepines are in part the result of the activity of α5-subunit containing GABAA receptors (GABRA5). Negative modulators at this receptor could improve cognition. In order to explore this beneficial effect, this article reviews the evidence on the effects of GABRA5 negative modulators and searches potential uses for such drugs. A literature search found a number of GABRA5 negative modulators. These drugs generally improve hippocampal-dependant learning via an increase in longterm potentiation (LTP) in the hippocampus. Passive avoidance learning was also improved. In addition, the compounds examined demonstrated minimal side effects partly due to lack of binding to different alpha subunit-containing GABAA types. Due to its beneficial properties, there is potential for such a drug in treating Alzheimer’s, alcohol-related amnesia and Down syndrome. Despite the myriad animal studies that utilised GABRA5 negative modulators, only three human studies were found. Due to its cognitive enhancing properties and minimal side effects, further human trials should be conducted in order to ascertain the potential of such drugs in treating cognitive deficits.

The α5 subunit-containing GABAA receptor: a target for the treatment of cognitive defectsγ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain and is responsible for regulating neuronal excitability. There are at least three different receptors that it targets — GABAA, GABAB and GABAC. [1] The GABAA receptor is the main target for the popular class of drugs, the benzodiazepines. This receptor is an ionotropic membrane receptor, which facilitates the movement of chloride into cells. In neurons, this increases the threshold needed to excite them.[2] Benzodiazepines are positive modulators at this receptor and exert their effects by binding to the interface between the γ2 and α subunits on the GABAA receptor. [3] Since they are modulators and not agonists, they do not work in the absence of GABA. [4] They only bind to the receptors containing the α5, α3, α2, and α1 subunits. [5] Each of these subunits mediates different effects. In knockout mice, the α1 subunit has shown hypnotic/sedative effects, whilst the α3, α2 and α5 subunits have anti-anxiolytic effects and these have been exploited for therapeutic use.[6]

Despite their uses in treating various conditions, traditional benzodiazepines have numerous side effects. The main side effects associated with therapeutic use are amnesia, confusion, impaired coordination and dizziness. There may be tolerance due to rapid escalation in the dose needed to provide the required effect. There are also long-term issues with dependence. In acute overdose the most life-threatening effect is respiratory depression, especially when combined with alcohol. [7]

Interestingly, it is thought that positive modulators at the α5 subunit-containing GABAA receptors (GABRA5) produce the anterograde amnesia associated with benzodiazepine use. [7] Most of these receptors are found in the hippocampus (a brain region associated with memory) and provide tonic inhibition in this region. [8] The exploitation of this receptor has led to the increasing use of the infamous ‘date rape’ drug flunitrazepam, which is a positive modulator at the GABRA5 in addition to its other functions. Because of its amnestic effects, victims are unable to recall events following intoxication and this provides a major challenge for prosecutors. [7] Despite these negative properties, by using a GABRA5 negative modulator the opposite effect might The α5 subunit-containing GABAA receptor: a target for the treatment of cognitive defects be achieved and cognition improved. The use of such a drug could potentially improve the quality of life for those living with cognitive defects and could also counteract drug-induced amnesia (for example, alcoholic ‘blackout’). However, this must be balanced with the inverse activity of non-selective negative modulators which could produce
convulsant or anxiogenic effects. [4]

Based on the premise that a GABRA5 negative modulator could improve cognition, the aim of this literature review was to review the evidence on (1) the effects of GABRA5 negative modulators on cognition; and (2) investigate the potential of GABRA5 negative modulators in managing conditions involving cognitive defects.

Effects of GABRA5 selective negative modulators

A number of GABRA5 negative modulator compounds were examined. Many of the studies used animals as subjects. Studies in animals provide a solid starting platform for understanding the various physiological changes that a drug induces. [9] Of particular importance is the avoidance of potential side effects as a result of non-selective actions at other GABAA receptors. Side effects could include an increase in anxiety, aggressiveness, motor impairment, inability to sleep and proconvulsant effects. [7] Ultimately, the knowledge gained from animal experimentation can be used to conduct safe and effective clinical trials.

Dawson et al. [10] examined a compound named α51A (3-(5-Methylisoxazol-3-yl)-6-[(1-methyl-1,2,3-triazol-4-yl)methyloxy]-1,2,4-triazolo[3,4-a]phthalazine), which has selective negative modulator effects at GABRA5. The authors found that α51A reversed the inhibiting effects of GABRA5 in the hippocampus in rats and mice. This resulted in an increase in performance in a memory test named the “delayed matching-to-position version of the Morris water maze”, which is a hippocampus-dependant cognitive test. [11] In addition, ‘long-term potentiation’ (LTP), which is thought to underlie the synaptic changes that take place during memory formation, was found to be enhanced in the hippocampus. [11,12] Benzodiazepine (agonist) effects and non-selective GABAA negative modulator effects were also examined. The authors found no anxiogenic, convulsant, withdrawal or motor-impairing effects from the drug. [10]

Only certain components of memory have shown to be improved by GABRA5 negative modulators. Collinson et al. [13] extrapolated on the results obtained by Dawson et al. [10] and looked at the effect of a modified version of α51A, α51A-II. They separated memory into three components — encoding, consolidation (conversion into long-term memory) and recall. Results were obtained by measuring performance in the delayed matching-to-position (DMTP) version of the Morris water maze in rats. The authors found that the compound improved encoding and recall but not consolidation in this hippocampaldependant memory test. [13]

The effect on cognition by another selective GABRA5 negative modulator was examined by Ballard et al. [14] This was done by the use of an imidazo-triazolo-benzodiazepine compound named RO4938581. The effect of this compound on cognition was examined in rats. [15] This compound demonstrated similar effects to those found by Dawson et al. [10] in that they found no convulsant or anxiogenic effects. In addition, similar to Dawson et al. [10], there was an increase in hippocampal LTP. The authors also found that working memory was enhanced since RO493881 reversed scopolamine-induced working memory impairment. [14] This was shown by an increase in performance in the DMTP task, which is used to assess spatial working memory. [14,15] It also reversed diazepam-induced spatial impairment. This was demonstrated by an increase in performance in the Morris water maze task. [14]

‘Moderate’ GABRA5 negative modulators improve passive avoidance learning but generally have no effect on active learning. [16] This was shown by an experiment conducted by Savic et al. [16] in which they examined effects of PWZ-029 (a ‘moderate’ GABRA5 negative modulator) on passive and active learning avoidance in rats. The result was obtained through various shuttle-box based behavioural experiments. This experiment proved that even at ‘moderate’ efficacy a GABRA5 negative modulator can induce memory formation. The compound also had no effect on muscle tension and anxiety (nonselective side effects). [16] Although promising, this study was limited by the fact that the compound only had ‘moderate’ negative modulator activity at GABRA5 so using a more efficient compound may display different effects on avoidance learning. Despite this limitation, this shows that the use of a ‘moderate’ GABRA5 negative modulator would be beneficial in the treatment of disease due to its limited side effects and its memory-enhancing properties. [16]

Application in management

The compounds examined in this review show that selective GABRA5 negative modulators have nootropic effects without any serious side effects, which are seen in non-selective negative modulators at the alpha subunit of the GABAA receptor. [17] Thus, there is strong potential for the use of GABRA5 negative modulators in healthcare settings. One major limitation is that most of the data obtained for this review was from animals. Further human trials need to be conducted to ascertain the potential of this drug. Drawing on the literature, possible future uses for a GABRA5 negative modulator are detailed below.

GABRA5 negative modulators could be used to treat Alzheimer’s disease since GABRA5 is preserved in Alzheimer’s disease patients.
[18] Alzheimer’s disease is commonly characterised by the gradual worsening of ability to remember new information. [19] Administration of a GABRA5 negative modulator could help with the ‘encoding’ and ‘recall’ of this information. [8] It could also be used to treat mild cognitive impairment (MCI), which is a risk factor for later developing the disease. [20] Administration of such a drug to patients may provide relief to older caregivers, who often show signs of sleep detriment. [21]

A review by Attack [22] in 2010 found two human trials on the GABRA5 negative modulator α5Ia and one trial on MRK-016. Since then no human trials were found and this could be an area of future research. The first study found that a potential application of GABRA5 negative modulators is the treatment of alcohol-induced amnesia. Nutt et al. [23] found that pre-treatment reduces alcohol’s amnestic effects in humans. This was measured by word list learning which is linked to hippocampal processing. Alcohol-induced amnesia has been shown to predict future alcohol-related injury. [24] Therefore, the use of a GABRA5 negative modulator may help in reducing this risk. In addition, it may also reduce alcohol-related stress since it has been found that amnestic episodes related to alcohol have resulted in moderate psychological stress. [25]

Unfortunately, GABRA5 does not improve age-related cognitive defects. In fact it has been found that α5IA significantly impairs cognition in the elderly despite having positive effects on the young. Attack [22] found that young subjects (mean age 22 years) performed much better than older subjects (mean age 72 years) on the paired associates learning test, which is sensitive to age-related cognitive decline. Therefore, this trial showed no potential in reversing age-related cognitive decline. This demonstrates that careful consideration based on age should be taken in to account when using this drug.

MRK-016 (3-tert-butyl-7-(5-methylisoxazol-3-yl)-2-(1-methyl-1H-1,2,4-triazol-5-ylmethoxy)-pyrazolo[1,5-d]-[1,2,4]triazine) is another negative modulator and showed greater LTP in rat hippocampal slices than α51A. It also enhanced performance in the DMTP and Morris water maze tasks, which are used to test spatial memory. In humans, it was well tolerated in young adults with a maximum tolerated dose of 5 mg with 75% occupancy. In elderly subjects, however, it was poorly tolerated even at 10% of the maximum dosage in young adult males. Therefore, this particular drug has been precluded for development. [26]

Recent trials of GABRA5 agonists, in particular L-655,708 and MRK-016, have focused on restoring post-anaesthetic cognitive deficits. Lecker et al. [27] found that L-655,708 and MRK-016 reduced the potentiation of GABRA5 post-inhalation of isoflurane and sevoflurane. A further study by Zureck et al. [28] found that short-term memory assessed by the novel object recognition task was fully reversed by L-655,708 after isoflurane anaesthesia. This demonstrates the potential use of L-655,708 in reducing post-anaesthetic amnesia. However, further studies which include those performed on humans are needed to validate the potential of MRK-016 and other GABRA5 negative modulators in reducing post-anaesthetic amnesia.

The use of GABRA5 negative modulators could help with treating cognitive deficits related to Down syndrome. A recent review by Martínez-Cué et al. [29] investigated this specific application. It identified two studies that examined the effects of a GABRA5 inverse modulator on a Down syndrome mouse model (Ts65Dn). Braudeau et al. [30] found that acute treatment with the GABRA negative modulator α5IA improved learning deficits in the Morris water maze task. The second study also showed that chronic administration of a similar drug, RO4938581 has also been shown to have memory-promoting effects in the Morris water maze task on Ts65Dn mice. [31] In a practical sense, administration of such a drug could improve performance in learning a wide range of functional skills in those living with Down syndrome. For example, in children this may include learning how to use the toilet and administering self-care. [32]


The literature supporting the use of a GABRA5 negative modulator in the treatment of cognitive deficits is promising. GABRA5 negative modulators exert their actions by enhancing hippocampal dependant memory formation. There are minimal side effects as no withdrawal symptoms, convulsant, anxiogenic or motor-impairing effects were found. There is great potential for the use of GABRA5 negative modulators as they have been shown to reduce alcohol-related amnesia and may have potential in the treatment of Alzheimer’s disease. They could also treat cognitive deficits in Down syndrome patients, increasing the speed at which they learn functional skills. Due to these favourable findings, there is an increased need for human clinical trials in order to validate the potential for this important receptor target.


A/Prof Zoltan Sarnyai, for reviewing this article when I submitted it as an assignment.

Conflict of interest

None declared.


A Bhandari:


[1] Lonstein JS, Maguire J, Meinlschmidt G, Neumann ID. Emotion and mood adaptations in the peripartum female: complementary contributions of gamma-aminobutyric acid and oxytocin. J Neuroendocrinol. Forthcoming 2014. DOI: 10.1111/jne.12188.

[2] D’Hulst C, Atack JR, Kooy RF. The complexity of the GABAA receptor shapes unique pharmacological profiles. Drug Discov Today. 2009;14(17-18):866-75.

[3] Sigel E, Buhr A. The benzodiazepine binding site of GABAA receptors. Trends Pharmacol Sci. 1997;18(11):425-9.

[4] Rudolph U, Knoflach F. Beyond classical benzodiazepines: novel therapeutic potential of GABAA receptor subtypes. Nat Rev Drug Discov. 2011;10(9):685-97.

[5] Atack JR. GABAA receptor subtype-selective modulators. II. α5-selective inverse agonists for cognition enhancement. Curr Top Med Chem. 2011;11(9):1203-14.

[6] Mohler H. GABAA receptor diversity and pharmacology. Cell Tissue Res. 2006;326(2):505-16.

[7] Rang HP, Dale M. Rang and Dale’s Pharmacology: Churchill Livingstone; 2007.

[8] Collinson N, Atack JR, Laughton P, Dawson GR, Stephens DN. An inverse agonist selective for α5 subunit-containing GABAA receptors improves encoding and recall but not consolidation in the Morris water maze. Psychopharmacology (Berl). 2006;188(4):619-28.

[9] Ferreira LM, Hochman B, Barbosa MVJ. Modelos experimentais em pesquisa. Acta Cirurgica Brasileira. 2005;20:28-34.

[10] Dawson GR, Maubach KA, Collinson N, Cobain M, Everitt BJ, MacLeod AM, et al. An inverse agonist selective for α5 subunit-containing GABAA receptors enhances cognition. J Pharmacol Exp Ther. 2006;316(3):1335-45.

[11] Nakazawa K, Sun LD, Quirk MC, Rondi-Reig L, Wilson MA, Tonegawa S. Hippocampal CA3 NMDA receptors are crucial for memory acquisition of one-time experience. Neuron. 2003;38(2):305-15.

[12] Cooke SF, Bliss TV. Plasticity in the human central nervous system. Brain. 2006;129(Pt 7):1659-73.

[13] Collinson N, Kuenzi FM, Jarolimek W, Maubach KA, Cothliff R, Sur C, et al. Enhanced learning and memory and altered GABAergic synaptic transmission in mice lacking the alpha 5 subunit of the GABAA receptor. J Neuro Sci. 2002;22(13):5572-80.

[14] Ballard TM, Knoflach F, Prinssen E, Borroni E, Vivian JA, Basile J, et al. RO4938581, a novel cognitive enhancer acting at GABAA α5 subunit-containing receptors. Psychopharmacology (Berl). 2009;202(1-3):207-23.

[15] Goto K, Kurashima R, Watanabe S. Delayed matching-to-position performance in C57BL/6N mice. Behav Process. 2010;84(2):591-7.

[16] Savic MM, Clayton T, Furtmuller R, Gavrilovic I, Samardzic J, Savic S, et al. PWZ-029, a compound with moderate inverse agonist functional selectivity at GABAA receptors containing α5 subunits, improves passive, but not active, avoidance learning in rats. Brain Res. 2008;1208:150-9.

[17] Navarro JF, Buron E, Martin-Lopez M. Anxiogenic-like activity of L-655,708, a selective ligand for the benzodiazepine site of GABAA receptors which contain the α5 subunit, in the elevated plus-maze test. Prog Neuropsychopharmacol Biol Psychiatry. 2002;26(7-8):1389-92.

[18] Howell O, Atack JR, Dewar D, McKernan RM, Sur C. Density and pharmacology of α5 subunit-containing GABAA receptors are preserved in hippocampus of Alzheimer’s disease patients. Neuroscience. 2000;98(4):669-75.

[19] Daulatzai MA. Early stages of pathogenesis in memory impairment during normal senescence and Alzheimer’s disease. J Alzheimers Dis: JAD. 2010;20(2):355-67.

[20] Grundman M, Petersen RC, Ferris SH, Thomas RG, Aisen PS, Bennett DA, et al. Mild cognitive impairment can be distinguished from Alzheimer disease and normal aging for clinical trials. Arch Neurol. 2004;61(1):59-66.

[21] Rowe MA, McCrae CS, Campbell JM, Benito AP, Cheng J. Sleep pattern differences between older adult dementia caregivers and older adult noncaregivers using objective and subjective measures. J Clin Sleep Med. 2008;4(4):362-9.

[22] Atack JR. Preclinical and clinical pharmacology of the GABAA receptor α5 subtypeselective inverse agonist α5IA. Pharmacol Ther. 2010;125(1):11-26.

[23] Nutt DJ, Besson M, Wilson SJ, Dawson GR, Lingford-Hughes AR. Blockade of alcohol’s amnestic activity in humans by an α5 subtype benzodiazepine receptor inverse agonist. Neuropharmacology. 2007;53(7):810-20.

[24] Mundt MP, Zakletskaia LI, Brown DD, Fleming MF. Alcohol-induced memory blackouts as an indicator of injury risk among college drinkers. Inj Prev. 2012;18(1):44-9.

[25] Buelow G, Koeppel J. Psychological consequences of alcohol induced blackout among college students. J Alcohol Drug Educ. 1995.

[26] Atack JR, Maubach KA, Wafford KA, O’Connor D, Rodrigues AD, Evans DC, et al. In vitro and in vivo properties of 3-tert-butyl-7-(5-methylisoxazol-3-yl)-2-(1-methyl-1H-1,2,4-triazol-5-ylmethoxy)- pyrazolo[1,5-d]-[1,2,4]triazine (MRK-016), a GABAA receptor α5 subtype-selective inverse agonist. J Pharmacol Exp Ther. 2009;331(2):470-84.

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Review Articles

A review of early intervention in youth psychosis

Early intervention in youth psychosis has been a topic of contentious discussion. In particular, there is a lack of consensus regarding how early to treat patients with a psychotic disorder. There has been a recent push to provide treatment early in the development of psychosis, specifically to patients in an ultra-high risk or prodromal stage. There is also debate about the types of interventions that should be used, such as psychoeducation, psychotherapy and pharmacotherapy. In Australia, these uncertainties have been reflected by the production of conflicting guidelines by key stakeholders in this area. There are significant arguments both for and against the practice of early intervention. This article explores these arguments and reviews current practices in Australia. A number of updated recommendations are also set out in accordance with the findings of this article.


A review of early intervention in youth psychosisPsychotic disorders are characterised by the presence of symptoms that reflect an excess or distortion of normal functions. For example, hallucinations, delusions, thought disorder and disorganised behaviour are symptoms characteristic of psychosis. Patients diagnosed with schizophrenia must demonstrate positive symptoms or severe negative symptoms (e.g. flattened affect, social withdrawal) in addition to deterioration in their social and vocational functioning. [1] Hence, the diagnosis is typically made after the onset of significant symptomology.

McGorry et al. [2] argue that late-stage diagnosis of a psychotic illness leads to delayed and inconsistent management of these patients. The concept of “early intervention” refers to appropriately managing patients in the early stages of psychotic disease, to minimise long-term negative social and psychological outcomes. As such, it represents a secondary prevention strategy and a paradigm shift in the way schizophrenia and other psychotic disorders are viewed; rather than being seen as illnesses with an inevitably poor social and functional outcome, they are viewed as conditions whose course can be altered
by recognition of the early warning signs and application of timely intervention. [2] The proponents of early intervention argue that many of the recognised risk factors for the development and progression of a psychotic disorder (e.g. disrupted peer and family networks, substance A review of early intervention in youth psychosis use, depression) are recognisable in advance and can be acted upon. [2]

The clinical staging model [3] proposes that psychiatric illnesses should be viewed as a sequence of stages that increase in disease severity. Employing the appropriate treatment modality at a particular stage would allow regression of the disease to an earlier stage. The clinical stages of early psychosis include the ‘ultra-high risk’ stage, the ‘first psychotic episode’ stage and the ‘first 5 years after diagnosis’ stage. [2]

The ‘ultra-high risk’ stage is the stage preceding the first psychotic episode. Although the first psychotic episode is often the first recognised sign of a psychotic illness, retrospective analysis reveals many changes occur in an individual’s thoughts and behaviour in the period preceding the psychotic episode. This is known as the ‘prodromal phase’. To intervene at this stage, it is clearly necessary to be able to identify this period in advance, and a considerable research effort is being focused on developing prospective criteria for this purpose. Two tools currently in use are the Positive and Negative Syndrome Scale (PANSS) or Attenuated Positive Symptoms (APS) approach and the Basic Symptoms (BS) approach. [4] The PANSS is a 30-point questionnaire with a 7-point rating for each question. It covers positive symptoms (e.g. delusions, hallucinations), negative symptoms (e.g. social withdrawal, blunted affect) and general symptoms of psychopathology (e.g. depression, poor insight, feelings of tension). [5] The Basic Symptoms approach focuses on subtler, self-experienced subclinical symptoms such as thought interference, disturbance of receptive language, inability to divide attention between tasks and derealisation. [6]

Intervention at the ‘first psychotic episode’ stage is largely aimed at reducing the duration of untreated psychosis (DUP), as a high DUP has been shown to result in poorer outcomes. Some authors have argued that untreated psychosis can lead to irreversible brain damage. [7,8] Although this theory has yet to receive widespread support, the personal, social and societal consequences of untreated psychosis can have a tremendous impact on the patient’s ability to recover from the episode. [2] Functional MRI brain imaging studies have shown decreased memory encoding in patients with schizophrenia and interestingly, decreased posterior cingulate activity in patients with ongoing first-episode psychosis compared to those showing remission at one year. [9] Such alterations in brain activity in patients more likely to proceed to a significant psychotic illness has exciting implications for the use of fMRI as a tool in screening for patients most likely to benefit from early intervention.

The ‘first 5 years after diagnosis’ stage is a crucial period that determines a patient’s long-term outcome. It is the time most likely to result in suicide, disengagement, relapse, [2] long-term treatment resistance and the break down and accumulation of disabilities in personal, social and occupational settings. [10] Mason et al. [11] suggest that the level of disability accumulated in the first 2 years of psychosis may in fact ‘set a ceiling for recovery in the long term’. Hence, intervention at this period is important. Maintaining a steady support structure especially tailored towards young people receiving a diagnosis of psychosis is likely to maximise chances of engagement with mental health care, life-style modifications, and adequate family involvement. [2]

Current Practice
There are currently a number of different practices/guidelines in Australia relating to early intervention in youth psychosis. The Royal Australian and New Zealand College of Psychiatrists (RANZCP) has produced clinical practice guidelines for schizophrenia, which include recommendations for patients at ultra-high risk (UHR). [12] Orygen Youth Health and headspace have also developed guidelines, called ‘The Australian Clinical Guidelines for Early Psychosis’, which are now in the second edition. [13]

Australia has established the first clinical and research clinic in the world for individuals considered to be at imminent risk of psychosis. The Personal Assessment and Crisis Evaluation (PACE) clinic was established by Orygen in Melbourne in 1994. [14] The clinic receives referrals from general practice, school counsellors and various health services. [14] They facilitate case management and provide a variety of in-house support services to families and carers including group programs, vocational and educational assistance, and occupational therapy. [15] Orygen, in conjunction with the Australian General Practice Network, the Australian Psychological Society and the Brain and Mind Research Institute also established headspace, which is a national youth mental health foundation. [16] The aim of headspace was to facilitate early intervention by increasing community awareness, clinician training and taking a youth-specific approach to management, as well as utilising multidisciplinary care. [16,17] Another service available is the Early Psychosis Prevention and Intervention Centres (EPPIC). In the 2010-11 and 2011-12 budgets, the Federal Government allocated $247m to the establishment of a network of 16 of these centres across Australia, modelled upon Orygen’s EPPIC centre in Melbourne. [18] A more detailed summary of the current guidelines/practices existing in Australia for youth psychosis is listed in Table 1.

Table 1. Current practice (guidelines and health services) in Australia for youth psychosis.

RANZCP Clinical Practice Guidelines for the Treatment of Schizophrenia and Related Disorders (2005) [12] Assessment and close monitoring every 2-4 weeks along with the provision of information to the patient and their family about the risk and likelihood of progression. Other techniques such as cognitive behavioural therapy (CBT), stress management and vocational rehabilitation should be employed depending on any concurrent psychosocial difficulties. Antipsychotics are only to be prescribed when the patient has been frankly psychotic for over a week, or in cases when milder symptoms are associated with a risk of self-harm or aggression (however, patients without such a history are often treated regularly with antipsychotics and the primary concern here is that they may have a delirium or physical illness, which should be excluded first). [12]
The Australian Clinical Guidelines for Early Psychosis [13] Commencement of CBT for all patients identified as being at ultra-high risk is recommended. Family, vocational, educational and accommodation support should also be provided as required in a low stigma setting. Antipsychotic medication should only be considered once full threshold psychotic symptoms have been sustained for over a week, or if there is rapid deterioration accompanied by psychotic-like symptoms. [13]
Health Service
Nature of service provided
The Personal Assessment and Crisis Evaluation (PACE) clinic PACE provides information to individuals and their families about what it means to be at risk of psychosis. [14] They facilitate case management and provide a variety of in-house support services to families and carers including group programs, vocational and educational assistance and occupational therapy. [15] Specific treatment is largely in the form of voluntary participation in clinical trials, such as those looking at antipsychotic use or CBT in ultra-high risk individuals. [14]
Headspace These centres for 12-25 year olds combine specialist mental health, drug and alcohol and primary care services, vocational services and training, and employment support within a youth and family-friendly environment. [16,17] Headspace centres are also tasked with developing awareness campaigns for their local community and providing training for primary care and other workers using an evidence-based approach. [16]
Early Psychosis Prevention and Intervention Centres (EPPIC) Provide comprehensive in-patient and mobile components and aim to identify patients as early as possible and deliver phase-specific bestpractice interventions to psychotic individuals between the ages of 15 to 24. [19] This model has also been adopted widely around the world, including in the UK [20] and the US. [21]


The early intervention model has also been subject to some criticism. The major basis for this is a lack of evidence, especially with regard to the use of anti-psychotics in the prodromal stages of psychotic illness and the significant cost associated with creating a clinical infrastructure for patients who may never proceed to a long-term psychotic illness.

Results and Discussion

Evidence for early intervention

There is evidence from several small studies that psychotherapy such as CBT [22] and pharmacotherapy [3,23] can reduce the progression of ultra-high risk individuals to first episode psychosis.

Wyatt et al. [8] reviewed 22 studies, of varying study designs, which included contemporaneous control group studies, cohort studies, mirror image studies and early intervention studies. In these studies, patients with schizophrenia were either given or not given neuroleptics at a specific time during the course of their illness. 19 of the studies, in particular, looked at patients who were experiencing their first psychotic episode. After re-analysing the data, Wyatt et al. [8] showed that early intervention with a neuroleptic in first-break schizophrenic patients improved the long-term course of the illness, commonly assessed based on re-hospitalisation and relapse rates. It was also shown that with the use of neuroleptics, the length of the initial psychotic period was reduced. In addition, when neuroleptics were discontinued, it resulted in poorer outcomes as the patients were not able to return to their previous level of functioning and relapses occurred more frequently. Neuroleptic medication has the strongest support for relapse prevention in schizophrenia and is the basis of most interventions.

It has been suggested that the duration of untreated psychotic episodes directly correlates with less complete recovery, a higher rate of relapse and increased levels of compromised functioning, since these episodes have a toxic effect on the brain. [7,8,24-26] These studies, both retrospective and prospective, suggest that a longer DUP in the early stage of schizophrenia is associated with a longer time to remission, a lower level of recovery, a greater likelihood of relapse and a worse overall outcome.

Studies have shown that raising public awareness and using mobile outreach detection teams to identify candidate patients [27] has significantly reduced DUP, leading to beneficial outcomes. In particular there has been a reduction in negative symptoms in schizophrenic patients.

Arguments against early intervention

There are certain groups who are against early intervention. One of the arguments against early intervention relates to whether it is cost effective, as resources may be diverted from treatment programs for patients who already have an established diagnosis of psychosis. In addition, they argue that the great majority of high-risk patients do not in fact progress to frank psychosis. There is also the argument that some patients seeking early intervention may not have ‘true prodromal’ features, thus inflating the numbers of those who actually require early intervention. These arguments are discussed in more detail below.

Economic cost of early intervention may be infeasible

Those against early intervention believe the increased attention and funding given to early intervention diverts funding away from treatment in those with established psychosis. [28-30] They also argue that proponents of early intervention have touted the cost-effectiveness of early intervention as such programs utilise more outpatient resources compared to inpatient resources, thus reducing overall healthcare costs (with outpatient services being much cheaper than inpatient treatment). However, critics of early intervention have pointed out that implementation of a cost-effective treatment actually increases total costs [31,32] since cheaper treatment would have a much higher uptake compared to an expensive alternative, thus raising the total cost of treatment. In addition, Amos argues that total healthcare costs are further increased since in-patient costs are not reduced with early intervention. [33] This is because 80% or more of hospital costs are fixed costs and by shifting psychosis treatment to largely outpatient settings in the community, community costs increase but hospital costs are not reduced. [33] This is corroborated by previous studies, which show an increase in total costs when hospitalisation rates had been reduced. [34,35]

Most high-risk patients do not progress to frank psychosis

One possible explanation for this is that a subset of adolescents whom are identified as being UHR may just be odd adolescents that become odd adults with few progressing to a frank psychosis. The prominent child psychiatrist Sula Wolff was the first to describe these odd adolescents in her book, Loners: The Life Path of Unusual Children. [36] Her research has shown that while odd qualities such as those found in schizoid and schizotypal disorders are found pre-morbidly in patients with schizophrenia, very few children with such personality traits/disorders go on to develop schizophrenia. For example, in 1995 Wolff undertook a records survey of all psychiatric hospital admissions in Scotland. Overall, 5% of schizoid young people were affected by schizophrenia in adulthood compared to a population prevalence rate in the UK of 0.31-0.49%. [36] These numbers suggest that while the risk for schizophrenia in schizoid children is higher than that of the general population, it is still low. To reiterate, there may be a proportion of patients who are flagged as being prodromal but whom actually have qualities consistent with schizoid personality disorder that will never progress to psychosis.

Recently, there has been a decline in the proportion of patients at high risk of psychosis actually progressing to frank psychosis

This decline has important ramifications for the practice of early intervention. A decline in the transition rate of patients identified as UHR has been reported within the PACE clinic (Melbourne, Australia) and in other UHR clinics as well. [37,38] As an example, The PACE clinic has reported that each successive year between 1995-2000 had a rate equal to 0.8 of the previous year. [38] The reported decline in transition rate was not due to differing patient characteristics across the years, such as gender, age, family history, baseline functioning and degree of psychopathology and psychiatric symptoms. [38] Additionally, the UHR criteria remained unchanged in the PACE clinic between 1995-2000. [38]

There are a number of possible explanations for the declining transition rate to psychosis. Firstly, UHR patients are being detected more quickly than in the past (the duration of symptoms prior to detection is getting shorter). [38] However, it is unclear whether the resulting decline in transition rate is due to earlier treatment (which may be more effective than delayed treatment), the identification of increased numbers of false positives (those who are not going to progress to psychosis) or a combination of both. [38] There may also be an effect from clinicians becoming better at managing UHR patients. [38] Additionally, it has been noted that the decline in transition rate was more prominent for patients who met two of the UHR inclusion criteria simultaneously compared to those who met only one of the criteria. [38] This could have been due to the increased emphasis which was placed on detection of patients who met both criteria, both in the UHR clinic and from referrers, thereby leading to earlier detection and treatment. [38] This is also in keeping with the wider community shift and preoccupation towards early psychosis and its recognition, and the increase in available referral pathways.

The decline in transition rate also raises questions about the validity of intervention approaches, such as pharmacotherapy and psychosocial treatment, on patients who may not ultimately transition to psychosis. [38] Such intervention may be harmful and therefore unjustified in this context. The UHR concept, which is used extensively in psychosis research, may also have to be re-visited if many of the identified patients are not transitioning. [38]

Due to the uncertainties regarding the basis for the declining transition rate, a review of the role of UHR clinics may be warranted. [38] It may be necessary to initially monitor patients and treat conditions such as depression, substance use problems and anxiety disorders while withholding antipsychotic treatment until features suggestive of transition occur, such as worsening of sub-threshold psychotic symptoms. [38] This may be prudent in the context of detecting increasing numbers of patients who were never destined to transition to psychosis. In any case, further research is needed to clarify the ongoing uncertainties in this area.

Bias in patient selection

Specialised teams set up to treat early psychosis engage with anyone who is seeking help. However, Castle [39] believes that this would skew the treatment group, as it would engage those with help-seeking behaviours rather than prodromal psychosis. Furthermore, it also raises the issue that those seeking help may have signs and symptoms of what is a normal developmental process or a ‘psychosis proneness’, which is part of a normal distribution within the general population. [40] Thus, these individuals may not require treatment for psychosis at all as they would either grow out of ‘psychotic proneness’ or would
stabilise and never develop psychosis.

Prescribing anti-psychotics to a population that is not psychotic: An ethical implication

The potential dangers of psychotropic drugs on young people are outlined in the United Nations Convention on the Rights of the Child, where children are recognised as being particularly deserving of protection from unnecessary exposure to psychotropic substances. [41] However, much of the research into early intervention includes administration of a low dose of antipsychotics as a crucial and efficacious treatment option. [42] Furthermore, antipsychotics are known to have serious side effects including sedation, weight gain, mild sexual dysfunction and disconcerting extrapyramidal symptoms (EPS) such as pseudoparkinsonism, akathisia, acute dystonia, and tardive dyskinesia. [43] While these effects have a stronger association with first generation antipsychotics, there is increasing evidence suggesting that second generation antipsychotics (SGA) are associated with significant side effects such as weight gain, hyperprolactinemia and EPS in the adolescent population.

Summary and recommendations

In view of the currently available literature, the authors make the following summary and recommendations with regards to early intervention in psychosis.

  • Psychosis is a highly disabling condition with detrimental impacts on patients’ relationships and occupational and social functioning
  • Possible interventions that delay or prevent transition from the prodromal period to psychosis are important, both clinically and economically
  • A systematic review by the Cochrane Database found limited evidence about interventions to prevent psychosis. Despite this, early intervention facilities such as headspace are widespread in Australia

Our recommendations

  1. We do not recommend the use of antipsychotics in children and adolescents who have been identified as at increased risk but who have not yet progressed to frank psychosis. Exposing children and adolescents to the serious side effects of antipsychotics is both unethical and inappropriate considering a proportion of these patients will not progress to psychosis.
  2. We recommend more research into safer, less harmful interventions such as omega-3 fatty acids and psychotherapy. For omega-3 fatty acids, evidence suggests a beneficial effect on transition rates compared to placebo. [44] However, this evidence comes from a single trial with few participants. A replication study with a larger sample size is needed to more definitively ascertain the merit of this intervention
  3. As previously discussed, preliminary evidence shows that CBT may reduce the transition rate to psychosis. Further research should be undertaken to conclusively establish the benefit of psychotherapy in high-risk individuals. Further research should
    include investigation of the cost-effectiveness of psychotherapy as an early intervention for youth psychosis. In addition, research should aim to identify any detrimental effects associated with providing psychotherapy to patients who do not progress to psychosis.
  4. Patients identified as being at risk of developing psychosis should be monitored closely by a multi-disciplinary team. Team members may include a general practitioner, social worker, psychiatrist and psychologist. By closely monitoring at-risk patients, their progression into frank psychosis can be detected earlier and appropriate treatment given in a timely manner. Prompt detection and treatment of psychosis is crucial, as delayed untreated psychosis has been shown to result in poorer outcomes.

Table 2. Summary of the evidence supporting and arguments against early intervention in psychosis.

Evidence supporting early intervention Evidence from small studies showing psychotherapy such as CBT and pharmacotherapy can reduce the progression
of ultra-high risk individuals to first episode psychosis.Studies show that raising public awareness and using mobile outreach detection teams to identify candidate patients significantly reduces the duration of psychosis.
Arguments not in favour of early intervention The economic cost of early intervention may be infeasible.Most patients identified as being high risk do not progress to frank psychosis.Treatment teams for early psychosis may disproportionately target patients with “help
seeking behaviour” and thereby treat more patients who simply display signs and symptoms of a normal developmental process or “psychosis proneness”.The negative ethical implications associated with prescribing antipsychotics to a population that is not psychotic.


The authors would like to thank Professor Jeff Cubis and Professor David Harley for their guidance and expert opinion on the matter.

Conflict of interest

None declared.


H C Y Yu:


Insights into the application of evolutionary and ecological concepts to cancer treatment via modelling approaches

Therapeutic resistance has been shown to result in poorer clinical outcomes in cancer treatment. It has been proposed that evolutionary adaptations of cancer cells to therapy result in the development of resistance with the rate of adaptive change correlating with the heterogeneity of the tumour. These concepts can help overcome therapeutic resistance and have been exploited by Gatenby and others in promising evolutionary double-bind simulations. It was further suggested that tumour vasculature contributes to intra-tumoural heterogeneity through the development of substrate gradients. Increasing analogy between natural ecosystems such as riparian habitats and the tumour environment may allow us to devise novel treatment strategies. This review will briefly examine some of these evolutionary and ecological concepts and how they can be applied to cancer treatment.


a7_0Carcinogenesis is the process by which normal cells in the body acquire mutations and form tumours. In the 1970s, Peter Nowell characterized this transformation in terms of evolutionary change and this concept has been well accepted by the scientific community. [1] He proposed that genetic instability and mutations form the basis for heritable changes required for natural selection and clonal growth of single cancer cells. Cells are selected for desirable characteristics such as survival and proliferation in response to changes in their immediate environment. [1] Surprisingly, evolutionary principles have seldom been used in the treatment of cancer. Aktipis and colleagues did an analysis of over 6000 papers focusing on therapeutic resistance and cancer relapse and revealed that ‘evolution’ has been used in only 1% of all papers. [2]

As evolution is influenced by changes in the environment, it is possible to view the tumour microenvironment as an ecosystem consisting of heterogeneous populations of cancer cells interacting with one another, and with other cells of the microenvironment. These complex interactions have much in common with ecosystems in nature and consist of analogous abiotic and biotic components which provide novel treatment targets to circumvent therapeutic failure.

Failure of chemotherapy can be attributed to cancer resistance which can be inherent or acquired. Inherent resistance may occur due to over-expression of drug metabolism pathways such as the excision repair cross-complementing 1 gene (ERCC1 — a nucleoside excision repair gene) in resistance against platinum agents while acquired resistance can be caused by altered membrane transport as in the case of the P-glycoprotein transport protein encoded by the multi-drug resistance-1 gene (MDR-1). [3]

Evolutionary game theory

Hypoxia and acidosis within the tumour can exert selective pressures on individual cancer cell populations. These populations may adapt to these conditions through different phenotypic strategies arising from genetic instability and genotypic variations. Gilles and colleagues proposed that these interactions can be understood through the evolutionary game theory. In this theory, the evolutionary rate of a phenotypic strategy is dependent on the amount of phenotypic diversity and the fitness of cancer cell populations. [4] Cancer cell populations will evolve rapidly in the presence of a harsh tumour environment or when cell populations are phenotypically diverse. Selective pressures originating from perturbations outside the tumour microenvironment can also promote further phenotypic diversity. [4,5] Alteration of the tumor environment by chemotherapy can potentially encourage cancer cell populations to diversify and become heterogeneous via de novo mutations arising from therapy or selection of existing chemotherapy-resistant cells in the tumour. [5]

The evolutionary game theory therefore predicts that the probability of the existence and/or emergence of resistant cells correlates with the level of tumour heterogeneity. It also suggests that chemotherapy will inadvertently lead to resistance if chemo-resistant cells (such as cancer stem cells) are already present in the tumour. [4,5] These predictions appear to correlate with clinical findings as advanced cancers which are less responsive to therapies usually exhibit high levels of heterogeneity while the use of high-dose chemotherapy improves survival but seldom cures epithelial cancers. [6]

High-dose chemotherapy regimens were first conceptualized mathematically through the Norton-Simon model. It is hypothesised that administering the maximum tolerated dose (MTD) over a short time period would achieve a high cancer cell kill rate and a low probability of therapy-induced evolution of resistant clones. [7] This model, however, does not account for pre-existing chemo-resistant cells which clonally proliferate and result in cancer relapse after initial treatment. By recognising that resistant cells potentially pre-exist in tumours and that they correlate positively with tumour heterogeneity, certain strategies can be devised. These include controlling the heterogeneity of the tumour to prevent the occurrence of chemo-resistance and, exploiting our ability to predictably alter the adaptive strategies of cancer cells through various treatment modalities.

Controlling tumour heterogeneity: induction of evolutionary bottlenecks and achieving an evolutionary ‘double-bind’

Intra-tumoural heterogeneity is minimal in early neoplasms and the use of low-dose chemotherapy may be sufficient to eliminate early cancers with less risk of resistance. [7] This formed the basis of metronomic chemotherapy where low doses of chemo-drugs were given in frequent intervals. [8] However, intricate strategies involving circumvention of therapeutic resistance would be required as a cancer progresses.

Resistant cells favour tumour progression in a treatment setting but many forms of resistance incur phenotypic costs. If the phenotypic cost is low, for example, due to the ability of the cancer cell to adapt to therapy through up-regulation of xenobiotic mechanisms or usage of a redundant signaling pathway, control of cancer cell proliferation will be less effective. [9] Conversely, if the phenotypic cost is high, for example, due to competition from co-existing cancer cell populations with different proliferative characteristics and biological therapies, robust and long-lasting control may be achieved because cancer cells can only survive by diverting resources away from proliferation. The latter creates an evolutionary double-bind where the only way tumour cells can evade the deleterious effects of treatment is by compromising its fitness attributes, thereby inhibiting its proliferation or ability to develop resistance. [9]

An evolutionary double-bind in a combination therapy setting would require anticipating the adaptation of cancer cell populations to a specific treatment and then targeting the adapted phenotype by a follow-up treatment. [4] In a study by Hunter et al., treatment of glioblastoma multiforme tumours with the alkylating agent temozolomide (TMZ) resulted in hypermutations in the MSH6 mismatch repair gene. [5,10] These mutations were not present in untreated tumours and suggest that chemotherapy selected for MSH6-mutant cells. A clonal selection process was thought to create an evolutionary bottleneck where the majority of the cells were MSH-6 mutants while cancer cells with the wild-type MSH6 gene were eliminated. [5,11]

The transient decrease in genetic heterogeneity following TMZ administration provides a therapeutic window when cancer cells are most susceptible to a secondary treatment. [5] An in vivo study investigating the effects of the oral poly(ADP-ribose) polymerase (PARP) inhibitor ABT-888 on xenograft models of human tumours found that this PARP inhibitor not only synergistically maintains and potentiates the cytotoxic effects of TMZ on different tumours but also overcomes TMZ resistance. [12] ABT-888 and other similar PARP inhibitors may therefore have a role as a secondary treatment in combination therapies as they can eliminate most of the residual chemo-resistant cell populations. A schematic diagram of a two-step evolutionary double-bind is shown in Figure 1.

Insights into the application of evolutionary and ecological concepts to cancer treatment via modelling approaches

Figure 1. Evolutionary double-bind. For simplicity, tumour cells can be sensitive (neutral or susceptible) or resistant to a treatment. A two-step setup would involve the first treatment reducing heterogeneity of the tumour by imposing a high phenotypic cost on tumour cells. The second treatment works synergistically with the first treatment, such as in the case of PARP inhibitors and TMZ, to eradicate initially resistant cell populations.

Chemotherapy-based combination therapies

The widespread use of chemotherapy necessitates a scrutinisation of its synergistic and antagonistic effects in cancer treatment. Basanta and colleagues examined the use of an evolutionary double-bind in a combination therapy consisting of the p53 vaccine and chemotherapy. [13] Using a mathematical framework derived from the evolutionary game theory, they found that the p53 vaccine and chemotherapy work synergistically to exert robust anti-tumour effects. Interestingly, depending on whether the p53 vaccine or chemotherapy was used as the first treatment, different effects were observed.

Application of chemotherapy before the p53 vaccine was found to be more effective than using the p53 vaccine initially followed by chemotherapy. [13] This was attributed to a commensalistic relationship between vaccine-resistant cells and other cell populations. Eliminating vaccine-resistant cells in the first instance disrupts the protective effect and results in other cell populations (e.g. chemo-resistant and fully susceptible) being susceptible to immune mechanisms mediated by the p53 vaccine. In other words, ecological interactions between different cell populations of a tumour appear to determine the effectiveness of an evolutionary double-bind.

Although application of the p53 vaccine before chemotherapy had a diminished anti-tumour effect, the effectiveness of this approach can be increased with longer exposure to the p53 vaccine. [13] Indeed, both approaches appeared to be most effective when the first treatment was applied for a longer period. This reflects the importance of the first treatment as a limiting factor in combination therapy. Prolonged exposure to the first treatment widened the therapeutic window and acted as a barrier against therapeutic resistance most likely by reducing tumour heterogeneity through the creation of an evolutionary bottleneck.

Ecological interactions (e.g. commensalism or competition) between cancer cell populations are important and we can further characterize these interactions by considering the fitness of different cancer cell populations through phenotypic costs. [4] In the absence of treatment, resistant cells are likely to be less fit and have a slower rate of proliferation as compared to sensitive cells since they have to devote more resources to surviving. [4] These cells are most often found in the inner regions of a solid tumour where harsh conditions such as hypoxia and acidosis cause necrosis of tumour cells but favour the selection of resistant clones. Conversely, sensitive cells will be located at the outer rim of the tumour where a close proximity to the vasculature and expression of pro-survival proteins allow them to proliferate easily. [14] We can therefore predict that sensitive cells will be more susceptible to chemotherapy due to their proximity to the blood supply whereas resistant cells are highly affected by metabolic changes.

Silva and Gatenby proposed an evolutionary double-bind strategy consisting of the glucose competitor 2-deoxyglucose (2-DG) and chemotherapy. This was an attempt to reduce the fitness of both sensitive and resistant cell populations as well as stabilize tumour growth through competition via in silico simulations. [15] Different combinations of 2-DG and chemotherapy were modeled mathematically and the combination of 2-DG→chemotherapy was suggested to have the most potent anti-tumour effect. Efficacy was predicted to be lower in chemotherapy→2-DG and lowest in the synchronous administration of 2-DG and chemotherapy. The results become intuitive when we consider tumour cell populations in terms of inner region and outer rim populations. For the 2-DG→chemotherapy approach, the inner region populations are ‘pulverized’ by 2-DG due to their sensitivity to glucose depletion and this increases the surface area for chemotherapy to eliminate the outer rim cells. [15] Furthermore, 2-DG created a ‘pulverized’ morphology where a barrier of cells exists between the outer rim and inner region cells. This potentiates glucose depletion because glucose cannot diffuse effectively from the outer rim to inner region.

Interestingly, 2DG→chemotherapy mirrors the effectiveness of the p53 vaccine→chemotherapy approach. [13] This is probably attributed to the initial targeting of chemo-resistant cells and also the maintenance of a higher proportion of sensitive (and presumably fitter) cells as compared to resistant cells. The latter implies that sensitive cells can impede proliferation of resistant cells via competition for resources. Indeed, the chemotherapy→2-DG approach most likely had a better anti-tumour effect than synchronous administration because, even though the chemo-sensitive outer rim cells were targeted first, the introduction of a break or ‘drug holiday’ between chemotherapy sessions in the study’s protocol allowed the sensitive cells to recover and maintain a sizeable numerical advantage over resistant cells. [16] A similar effect was also noted in previous studies with different treatments. The chemotherapy→2-DG approach fared worse than 2-DG→chemotherapy as glucose can readily diffuse from the outer rim to inner (i.e. allowing chemo-resistant cells to survive) while the synchronous approach was least effective as the outer-rim was readily destroyed by chemotherapy; therefore reducing competition between sensitive cells and resistant cells. [15] Moreover, poor diffusion of chemotherapeutic drugs to areas deeper within the tumour meant that the inner region cells only received sub-lethal doses which favour the development of chemo-resistance.

Out of the three strategies, only the 2DG→chemotherapy approach managed to achieve an almost complete eradication of cancer cells when a bolus of MTD chemotherapy was applied while the other two strategies resulted in chemo-resistance. This result has two implications: firstly, it reflects the point that eradication of tumour cells is possible if tumour heterogeneity is targeted in the first instance and, specifically here, the chemo-resistant population. Secondly, it also implies that delineation of tumour cell populations into sub-groups based on location and proximity to key tumour structures such as the vasculature may be therapeutically significant. In fact, there is evidence that populations of tumour cells often exhibit a convergent phenotype despite genotypic differences between individual cells. [17] Thus, targeting this phenotype may be a more practical option since natural selection acts on phenotypes rather than genotypes.

Riparian ecosystems as an ecological framework for human tumours

Tumour vasculature can contribute to intra-tumoural heterogeneity by creating disparities in substrates such as oxygen and glucose through blood flow gradients, which then select for different populations of cancer cells. [17,18] Alfarouk and colleagues proposed that growth of cancer cell populations can be understood in the context of plant species in a riparian habitat. [18] A riparian habitat is the interface between land and a river stream and two distinct regions of plants can be identified depending on their distance from a river. The mesic region contains lush, tall vegetation which are adjacent to and well nourished by the nutrients from the river. This is followed by an abrupt transition to a xeric region containing sparse, short vegetation which, due to their relatively long distance away from the river, develop adaptations that allow them to conserve water and survive in arid conditions. [19] The rivers and regions of vegetation in a riparian habit are analogous to the vasculature and cancer cells in a tumour respectively.

Tumour cell populations can be broadly separated into ‘mesic’ and ‘xeric’ cells depending if they are adjacent or distal to a blood vessel. [18] Mesic tumour cells and their proximity to blood vessels would render them highly susceptible to angiogenesis inhibitors by systemic administration. Since the ‘lush’ mesic region is expected to contain many tumor cells, a drastic reduction in tumour volume can be achieved. [18] However, the elimination of mesic tumour cells favours unprohibited proliferation of xeric tumour cells and an early treatment directed against the xeric region would be necessary. Phase I and II trials have shown that pro-drug carriers (containing chemotherapeutic drugs) based on 2-nitromidazoles can target hypoxic regions of a tumor and have shown strong anti-tumour effects. [20,21] Combining pro-drug carriers with an intra-tumoural route of administration may improve the accuracy of this approach. Considering the scarcity of xeric tumour cells, prolonged early treatment may be extremely effective. A summary of the different strategies described above is shown in Figure 2.

Insights into the application of evolutionary and ecological concepts to cancer treatment via modelling approaches

Figure 2. Best predicted outcomes in evolutionarily and ecologically enlightened strategies. (i) In silico studies suggest that p53-resistant cells and p53-sensitive cells exist in a state of commensalism. The initial introduction of p53 eliminates vaccine-resistant cells and predisposes all remaining cells to destruction by chemotherapy. A greater effect is seen with prolonged p53 administration. (ii) 2DG targets and ‘pulverizes’ resistant cells, creating physical barrier between resistant cells but retains an outer-rim chemo-sensitive cells that inhibits cancer spread. (iii) Riparian-based therapy may achieve maximal tumour cell death through a localized targeting of mesic cells by hypoxia-based strategies followed by targeting of xeric cells by angiogenesis inhibitors.

Discussion and conclusion

Tumours are resilient in nature because they consist of a heterogeneous system of cells locked in a constant state of feedback. [22] Any perturbations in the environment of these cells may simply reinforce tumourigenic processes which restore overall tumour fitness. Although all therapies inherently disturb this fragile equilibrium, in silico studies have demonstrated proof of principle that a well-designed strategy such as an evolutionary double-bind can control and potentially eradicate most tumour cells. While modelling methods may not translate to immediate clinical benefits, they are an inexpensive way of exploring theoretical concepts in a controlled situation and provide a sound framework for further in vivo studies and clinical trials. The models described here can also readily be modified to study other forms of combination therapy, illustrating their flexibility and broad applicability to the clinical environment. One limitation, though, is that the parameters used in models have to be as realistic as possible and this can only occur through close cooperation between experimentalists and clinicians.

Key features highlighted here such as the need for prolonged initial treatment to reduce intra-tumoural heterogeneity, enhancing competition between resistant and sensitive cells and combining systemic and localized approaches are intuitive and feasible options that can be readily applied to existing treatment protocols. High-dose chemotherapy is no longer considered as a first-line approach except occasionally as salvage treatment for relapsed disease. This is not surprising in light of possible selection for chemo-resistance and increasing preference for low-dose maintenance and adaptive regimens. [6] The examples discussed in this review focused primarily on solid tumours due to easy visualisation and amenability to mathematical modelling. However, treatment of haematological malignancies would also benefit from a double-bind approach as evident from the restoration of drug sensitivity by second-generation tyrosine kinase inhibitors in treatment-resistant chronic myelogenous leukemia. [23]

There are several potential areas for further research. Firstly, we need to understand why natural selection appears to control cancers but does not eliminate them. In fact, a parallel exists with infectious diseases and high fitness costs and the tendency for organisms to evolve tolerance mechanisms may account for this phenomenon. Secondly, we should consider maximising the potential of new treatment modalities such as immunotherapy in evolutionary double-binds. [24] The limited efficacy of immunotherapy appears to contradict observations in natural ecosystems which indicate that biological control incurs higher phenotypic costs and achieves robust control of pests. This implies that inappropriate immune targets are being selected and, therefore, a true double-bind cannot be achieved. [4,23]

In conclusion, therapeutic resistance is a major obstacle to the optimisation of cancer treatment. Evolutionary and ecological principles may appear far-fetched concepts with little direct relevance to oncology but a closer inspection of the evolutionary origins and the spatial organisation of cancer cells reveal strategies that can improve clinical outcomes. Under-utilisation of these concepts is most likely a reflection of an inability to change our mindset rather than an issue of practicality. These encouraging modelling results provide a sound foundation for further translational research.

Conflict of interest

None declared.




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Review Articles

Glibenclamide therapy as tertiary prevention of melioidosis for Type 2 diabetics.

Background: Melioidosis is a relatively high-incidence, high-mortality tropical infectious disease caused by Burkholderia pseudomallei. To date, the few prevention and management strategies in practice have failed to reduce mortality from septic shock in patients with severe melioidosis. Up to 60.9% of patients also have pre-existing type 2 diabetes mellitus (T2DM), the most significant risk factor for melioidosis. An effective tertiary prevention strategy against melioidosis for these diabetic individuals would impact significantly on the burden of disease. Glibenclamide, a drug belonging to the sulfonylurea class and commonly used as an antidiabetic, may have the potential to be one such strategy.

Aim: To examine the underlying inflammatory cause of morbidity and mortality in melioidosis and to assess the potential for glibenclamide to ameliorate these causes.

Results: Bacteraemia with B. pseudomallei leads to widespread infection. Multi-organ damage and loss of function results from both direct bacterial damage and an excessive inflammatory response, the latter of which also causes potentially fatal septic shock in 21% of cases. Massive cellular infiltration of the lungs is particularly damaging. The immunomodulatory effects of T2DM further exacerbate the deleterious immune response into a dysregulated, hyperinflammatory state. On the other hand, the several anti-inflammatory effects of glibenclamide have been demonstrated to significantly reduce mortality from septic shock in melioidosis.

Conclusion: For diabetics living in regions where melioidosis is endemic, choosing glibenclamide over other sulfonylureas and metformin for antidiabetic treatment could be a promising tertiary prevention measure against melioidosis.


Glibenclamide therapy as tertiary prevention of melioidosis for Type 2 diabeticsMelioidosis, a tropical infectious disease, is a significant cause of death and illness in northern Australia and Southeast Asia. Its non-specific prodrome and clinical presentation makes early detection difficult.[1] Yet, timely diagnosis is critical because responsiveness to treatment declines with progression of the disease over time.[2] Morbidity and mortality remains high despite aggressive antibiotic treatment. As of yet, no vaccine is available for primary prevention and novel developments such as granulocyte colony-stimulating factor (G-CSF) and corticosteroid therapy lack evidence as good measures of tertiary prevention. Considering the significant population health threat, any effective prevention strategy would be of value. This article suggests the potential use of glibenclamide, an antidiabetic sulfonylurea, for tertiary prevention of melioidosis in diabetics. Because diabetics are approximately 13 times more likely to contract melioidosis,[3,4] this strategy may have widespread application.

One of the major and dangerous end-stage complications of melioidosis is septic shock. Especially in settings such as Northeast (NE) Thailand where melioidosis is endemic but intensive care is unavailable, morbidity and mortality from septic shock are unacceptably high. Systemically-spread B. pseudomallei stimulates massive release of cytokines into the blood, this event being instrumental in the immunopathogenesis of septic systemic vasodilation, hypotension, vascular hyperpermeability, and disseminated intravascular coagulation (DIC). Furthermore, poor glycaemic control in diabetics increases the risk and severity of these events by precipitating a compensatory, dysregulated, and hyperinflammatory response to bacterial immunogenic stimuli. Demanding particular attention is the stimulated production of cytokine IL-1β because it promotes excessive neutrophilic recruitment to the lungs and bacterial persistence inside cells. Fortunately, there is strong evidence that glibenclamide acts protectively against IL-1β-mediated damage by targeting IL-1β production directly as well as multiple upstream components in the IL-1β production pathway. The result of glibenclamide use for diabetics is a significantly reduced morbidity and mortality from melioidosis septic shock compared with diabetics not taking the drug.

Epidemiology of Melioidosis

Melioidosis is endemic in Southeast Asia, northern Australia, India, Hong Kong, southern China and Taiwan.[5,6] Isolated sporadic cases have also appeared in Central America, the Caribbean, New Caledonia, Mauritius, Africa, and the Middle East.[7] Of particular concern are the hyperendemic hotspots – NE Thailand and the Top End of the Northern Territory of Australia. A 2006 NE Thailand study that gathered results from four large hospitals reported the region experienced an estimated minimum annual incidence of 21.3 cases per 100,000 people and case fatality rate of 40.5%, melioidosis locally being the third highest infectious cause of death and second most common pathogenic cause of community-acquired bacteraemia.[8,3] From 2004 to 2009, according to data collected at Royal Darwin Hospital (RDH), the annual incidence in the Top End was 21.6 per 100,000 people and average case fatality rate plateaued at 9% having decreased from 30% since 1989. The lower fatality rate in Darwin is attributed to greater access to intensive care unit (ICU) supportive care and early sepsis management that prolongs life in the event of fatal septic shock, a complication that develops in at least 21% of cases.[9]

Type 2 diabetes mellitus (T2DM) is the largest risk factor for melioidosis. 48% and 60.9% of individuals with melioidosis were confirmed to have T2DM at RDH and in NE Thailand respectively.[10,11] The 2006 Thai study reported that the relative risk (RR) of melioidosis in adult diabetics compared with non-diabetics was 12.4.[3] In the Top End region, combining diabetes with the additional risk factor of Indigenous ethnicity raised the RR from 13.1 to 20.6. Other notable risk factors associated with a significant RR are chronic lung disease (RR 4.3), age ≥ 45 years (RR 4.0), chronic renal disease (RR 3.2), Indigenous ethnicity (RR 3.0), male sex (RR 2.4) and hazardous alcohol consumption (RR 2.1).[6]

The presence of any of these risk factors in infected individuals also dramatically increases their chance of developing septic shock (RR 4.5) and death (RR 9.2), the risk factors with highest independent association with death being age ≥ 50 years (RR 2.1) and chronic lung disease (RR 1.5). Malignancy (RR 1.9) and rheumatic heart disease and/or congestive cardiac failure (RR 1.7) are statistically insignificant risk factors for death. Clinical presentations most likely to result in death are septic shock (RR 11.2) and, out of the non-septic shock cases, the presence of neurological infection foci (RR 4.7).[9] Additionally, case fatality during the peak rainfall months of December through February is 1.6 times greater than it is during other months.[9]

Immunopathogenesis and pathophysiology

Melioidosis is caused by Gram-negative bacterium B. pseudomallei. Bacteria, found in contaminated soil, rodents, food, water, and excretions, are transmitted via inhalation, ingestion, or percutaneous inoculation – usually direct contact with open skin lesions.[12,13] Post-inoculation, B. pseudomallei can invade most human cell types. Employing Type 3 Secretion System (TTSS) clusters, bacteria enter non-phagocytic cells. If bacteria are phagocytosed, TTSS enables exit from intracellular phagocytic endosomes such that degradation is evaded. Once escaped into the cytoplasm of cells both phagocytic and non-phagocytic, bacteria replicate and self-induce polarised actin filamentation that confers motility, facilitating spread to neighbouring cells by forcing host-cell membrane protrusion and fusion.[14]

B. pseudomallei possesses highly immunogenic factors that trigger a strong host immune reaction essential to the host for early bacterial containment.[15] B. pseudomallei expresses pathogen-associated molecular patterns including lipopeptides, peptidoglycan, lipopolysaccharide, flagellin, TTSS, and DNA. They are recognised by host cell toll-like receptors (TLR) and NOD-like receptors (NLR). TLRs and NLRs are expressed by immune cells both professional – macrophages and dendritic cells – and non-professional – epithelial cells, endothelial cells, and fibroblasts.[16]

Activation of NLRC4 or NLRP3 induces binding of caspase-1, Asc (apoptosis-associated speck-like protein containing CARD) and NLRC4 or NLRP3 to form an inflammasome. The NLRC4 inflammasome in infected macrophages triggers pyroptosis, serving to limit intracellular B. pseudomallei growth and proliferation, while the NLRP3 inflammasome performs proteolytic activation of pro-IL-1β and pro-IL-18 into their mature forms for secretion.[17] IL-1β recruits neutrophils to infection site(s). However, excessive recruitment is often deleterious because neutrophils, lacking NLRC4, fail to pyroptose and instead provide a favourable intracellular environment that sustains chronic bacterial persistence. In the lungs, persistence leads to damaging pulmonary abscess formation and acute respiratory distress syndrome.[17,18] In contrast, elevated IL-18 production correlates with survival and immunoprotection because IL-18 induces IFN-γ production.[17,19] IFN-γ activates macrophages, stimulating their direct antimicrobial processes – phagolysosomal fusion and toxic reactive nitrogen species synthesis that produces nitrosative stress.[20] The cytokine also facilitates macrophage antigen processing and presentation, recruits leukocytes to infection site(s), upregulates Th1 CD4+ cell population, enhances natural killer cell function, regulates B cell anti-lipopolysaccharide antibody production and isotype switching.[21]

Glibenclamide therapy as tertiary prevention of melioidosis for Type 2 diabetics
Figure 1. NLRC4 inflammasome leads to immunoprotective effects while NLRP3 inflammasome produces both protective and deleterious responses. Glibenclamide works by inhibiting NLRP3 inflammasome formation and its deleterious effects.

TLR activation upregulates secretion of principal inflammatory mediators including type 1 interferon, chemokines, antimicrobial proteins, and pro-inflammatory cytokines.[22] Elevated expression of TLR1, TLR2, TLR3, TLR4, TLR5, TLR8, and TLR10 has been demonstrated in patients with septic melioidosis.[16] In particular, stimulation of the TLR2-mediated signalling pathway is a principal step in recognising the immune challenge of B. pseudomallei and initiating early inflammatory processes.[23] TNF-α and IL-6, along with IL-1β, increase vascular permeability, induce acute phase protein production, and recruit leukocytes to the site of infection.[24] TNF-α and IL-6 also activate the complement and coagulation cascades that are key defense mechanisms of the innate response.[25] However, excessive inflammatory cytokine production induced by widespread bacteraemia often leads to septic shock characterised by systemic vasodilatory hypotension, vascular hyperpermeability causing major cellular and fluid leakage from the intravascular to extravascular compartments, DIC, and death in the absence of immediate treatment.[26]

Through the establishment of bacteraemia, B. pseudomallei spreads from primary foci of infection to other body tissues, usually the lungs, genitourinary tract, skin, joints, bones, liver, spleen, skeletal muscles, prostate, parotid gland, and nervous system. Multi-organ spread leading to impaired organ function and failure is the main source of morbidity and mortality in melioidosis.[27] Thus, a rapid but non-deleterious inflammatory response is critical before B. pseudomallei establishes an intracellular niche that enables its persistence and protection against eradication by a subsequent immune attack. Paradoxically, subsequent immune attacks may cause further damage to the host.

Effect of type 2 diabetic state on host response

Diabetics, due to their generally immunosuppressed state, compared with non-diabetics, are more susceptible to developing sepsis from most organisms,[28] with the most common source of systemic spread being respiratory, followed by urinary and abdominal.[29] Gram-positive bacteria have become the leading cause of sepsis since the 1980s, and sepsis due to causes other than B. pseudomallei actually affects diabetics more commonly than melioidosis.[29,30] However, it is still of significance that diabetics are particularly vulnerable to pathogens such as B. pseudomallei and Mycobacterium tuberculosis because immune defence against these intracellular bacteria is highly macrophage-mediated – a function that is critically impaired in poorly-controlled T2DM.[31]

T2DM, especially if poorly controlled, causes marked immunomodulation that produces B. pseudomallei-induced immune responses that are damaging and yet insufficient to offer host protection. Morris et al. created an ex vivo whole-blood assay using human peripheral blood to compare inflammatory responses to B. pseudomallei between diabetics and non-diabetics. Immune insufficiency was worst in poorly controlled diabetics, the assay detecting: elevated serum IL-10 (an anti-inflammatory cytokine); reduced CD11b on polymorphonuclear leukocytes (PMNs) leading to decreased PMN function with reduced activation, adhesion, transmigration, and migratory capacity towards IL-8; reduced endotoxaemia-induced upregulation of ICAM-1; and defects in phagocytic detection and response to the bacteria.[32] In vivo and in vitro models using streptozotocin (STZ)-induced, leptin deficiency, leptin receptor deficiency, and diet-induced diabetic mice found similar immune impairments.[31,33-35] Transcriptional analysis of STZ-diabetic mice responses over the first 42 hours of B. pseudomallei exposure attributed delayed defence and splenic dysfunction (permitting uncontrolled bacterial replication intracellularly causing susceptibility to sepsis) to diminished TLR2 recognition of the bacterium.[34]

Incompetence of the early inflammatory response to contain an initial infection precipitates a compensatory, dysregulated, hyperinflammatory response to the spreading infection. The intensity of this ensuing reaction is exacerbated by chronic low-grade inflammation and increased oxidative stress, both characteristic of T2DM. Morris et al. found poorly controlled diabetics to have the most elevated levels of pro-inflammatory markers ESR, CRP, TNF-α, IL-1β, IL-6, IL-8, IL-12p70, MCP-1, and MPO (which indicates increased oxidative burst activity in PMNs). At focal infection sites, there was extensive infiltration with PMNs and greater risk of tissue damage, as well as generalised endothelial dysfunction and vascular inflammation.[32]

Hyperglycaemia is a major link between T2DM, immune derangement, and susceptibility to sepsis. The supra-physiological hyperosmolarity of hyperglycaemic blood directly potentiates TLR4-mediated cytokine production, as well as dampening phagocytic responses and granulocyte oxidative burst.[36] Activation of the RAGE pathway by advanced glycation end-products formed secondary to hyperglycaemia perpetuates inflammation and worsens survival in septic mice.[37] Furthermore, in the event of sepsis, poor glycaemic control allowing for periods of hyperglycaemia in both diabetics and non-diabetics correlates with longer hospital stay, greater morbidity, and possibly decreased survival.[38] In addition to immunomodulatory effects, hyperglycaemia exacerbates hypotension in septic shock by promoting glycosuric diuresis and cardiac hyperresponsiveness to cholinergic stimulation and the baroreflex.[39] Elevated risk of myocardial infarction, stroke, and venous thromboembolism is associated with the prothrombotic effect of acute hyperglycaemia that is further potentiated by hyperinsulinaemia or an inflammatory stress state.[40]

Prevention and management

No human vaccine is available.[41] CDC prevention guidelines recommend avoiding contact with soil and stagnant water in endemic regions.[42] High-risk individuals should stay indoors during heavy wind and rain in endemic regions due to possible bacterial aerosolisation that greatly facilitates transmission.[43]

Treatment involves two weeks of intravenous antibiotics – ceftazidime, meropenem, or imipenem, in combination with trimethoprim-sulfamethoxazole – followed by 3 months of oral eradication therapy to prevent recrudescence.[44] However, even with early antibiotic administration, case fatality from septicaemia remains at 37% in Thailand.[45] The development of septic shock is an indication for ICU supportive care usually involving invasive monitoring, fluid resuscitation, renal replacement therapy, and vasopressor, inotropic, and mechanical ventilatory support.[46,47]

Adjunctive use of recombinant G-CSF holds no clinical utility for improving sepsis from melioidosis and other aetiologies. Both animal and human trials – including prospective, multicentre, randomised, double-blind, and placebo-controlled studies – confirm this.[47-49] In fact, G-CSF may cause increased hepatic dysfunction and higher peak troponin I levels.[50] Other immunomodulatory adjuncts such as corticosteroids do not improve survival.[46] In light of the paucity of effective evidence-based prevention strategies and adjunct therapies for underserved populations, we turn to a novel potential for tertiary prevention.

Glibenclamide and its protective effect

Glibenclamide is a sulfonylurea used in the management of diabetes. It antagonises ATP-dependent potassium (KATP) channels in pancreatic β-cells, stimulating insulin release. The salient risk associated with glibenclamide is accidentally developing hypoglycaemia, an event of varying seriousness in patients who are not critically ill but a great predictor of mortality in acute sepsis. Furthermore, recent studies comparing glibenclamide with metformin and other sulfonylureas elucidated its significant adverse effects in addition to severe hypoglycaemia, such as increased risk of malignancy and mortality from cardiovascular disease due to interference with ischaemic preconditioning.[51,52] Despite glibenclamide still being a popular choice, a trend in medical opinion has arisen against its use in favour of alternative sulfonylureas.[53,54]

However, for T2DM individuals living in regions endemic with melioidosis, choosing glibenclamide over other antidiabetic drugs has an additional benefit that clinicians must consider. In a 5-year prospective cohort study from 2002 to 2006, Koh et al. followed 1160 adult patients with culture-confirmed melioidosis for 28 days during and after their admission to a major NE Thailand hospital. 71.3% of diabetic individuals taking glibenclamide survived from melioidosis after 28 days, while only 50.7% of diabetics not taking glibenclamide and 47.0% of non-diabetics survived (survival of patients discharged from hospital within 28 days were assumed to have survived). Using a logistics regression model, glibenclamide treatment reduced case fatality with an adjusted odds ratio (AOR) of 0.34 when compared to diabetics not taking glibenclamide and an AOR of 0.47 compared to non-diabetics. Incidences of hypotension (AOR 0.48) and respiratory failure (AOR 0.50) were also reduced in these patients.[55] Therefore, this protective effect must be factored into the drug’s risk-benefit comparison with metformin and with other sulfonylureas. If it informs clinicians’ drug choices for glycaemic control in management of T2DM, glibenclamide can contribute to tertiary prevention of melioidosis.

Although preventing hyperglycaemia in sepsis improves patient outcomes, glibenclamide does not rely on its glucose-lowering effect.[56] Using a mouse model, Koh et al. attributed the mechanism of glibenclamide’s protective effect to two main anti-inflammatory pathways. Firstly, glibenclamide reduces IL-1β secretion, attenuating IL-8 production and neutrophilic and monocytic influx into the lungs (without completely ablating the neutrophilic response).[55,57] In vitro evidence suggests that glibenclamide does this by partially blocking NLRP3 inflammasome formation and/or by directly inhibiting the secretion of mature IL-1β (Figure 1).[57-59] Glibenclamide may also attenuate transcription and translation of caspase-1, NLRP3, and IL-1β genes.[57] Secondly, by reducing systemic vasodilation and maintaining normal peripheral vascular resistance, glibenclamide restores systemic mean arterial pressure in the event of septic shock. KATP channels in vascular smooth muscle preferentially open during sepsis.[60] When they do, they hyperpolarise the cell, inhibiting Ca2+ influx (via voltage-dependent Ca2+ channels) and causing muscular relaxation. Glibenclamide opposes this effect by blocking the KATP channels. However, the only evidence for this is found in animal models.[61,62]


Melioidosis remains a significant public health concern due to its high incidence, mortality and case fatality rates particularly in the Top End of Northern Territory and NE Thailand. T2DM is the largest risk factor for melioidosis. The antidiabetic drug, glibenclamide, reduces morbidity and mortality from melioidosis-induced septic shock and so plays a potential role in tertiary prevention of melioidosis. In the debate over glibenclamide use, consideration of the drug’s protective effect for diabetics living in melioidosis-endemic regions, particularly those that are resource-limited, is critical.



Conflict of Interests

None declared


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Review Articles

Resistance to epidermal growth factor receptor inhibitors in non-small cell lung cancer and strategies to overcome it

The War on Cancer has been a particularly long, drawn-out one ever since the National Cancer Act was put into legislation by then U.S. President Richard Nixon. While we attempt to reveal the mechanisms that sustain the uncontrolled growth of cancer cells, the biology of cancer constantly changes and adapts to evade our treatment modalities. The discovery of imatinib, which is a tyrosine kinase inhibitor (TKI) and treats a subset of chronic myelogenous leukaemia, heralded a new generation of drugs that would specifically target cancer cells and reduce toxicity to normal cells. Erlotinib and gefitinib are two epidermal growth factor receptor (EGFR) TKI’s that have been developed for the treatment of patients with EGFR-mutation-expressing non-small cell lung carcinoma. However, in recent years, resistance to EGFR TKIs has been described in the literature. While the promise of a new treatment modality has been short-lived, this has also sparked interest and research efforts to understand the mechanisms of resistance to EGFR TKIs in a bid to discover strategies to overcome them and to further drug development. Well studied mechanisms include T790M mutation, loss of balance in the PI3K/Akt/mTOR pathway and MET amplification amongst many others. This article reviews the current literature regarding various mechanisms of resistance to EGFR TKIs and their potential for translation into new therapeutic agents and treatment strategies.


Resistance to epidermal growth factor receptor inhibitors in non-small cell lung cancer and strategies to overcome itOne famous discovery of a targeted drug treatment is imatinib, a tyrosine kinase inhibitor (TKI) used to treat a subset of chronic myelogenous leukaemia expressing the Philadelphia chromosome. This discovery has triggered a series of research efforts, shedding light on topics such as tumourigenesis and cell signaling pathways, leading to the development of many new drugs which target these specific mechanisms. However, it has been documented that resistance to these drugs can develop, therefore reducing their treatment potential [1,2] This is also true for a similar group of TKIs known as epidermal growth factor receptor (EGFR) inhibitors, which have been used as part of the treatment regime for a subgroup of lung cancer patients with non-small cell lung carcinoma. This article will review the mechanisms of intrinsic and acquired resistance to EGFR inhibitors and strategies to overcome them.

Introduction to EGFR inhibitors

The work of Stanley Cohen and Rita Levi-Montalcini in Epidermal Growth Factors has revolutionized cancer research and treatment, having been awarded the 1986 Nobel Prize for Medicine. [3] Their work has triggered further research, eventuating into the approval of gefitinib in 2003 and erlotinib in 2010 by the Food and Drug Administration (FDA) for use in patients with NSCLC. [4-6]

The overexpression and over-activation of EGFR (independent of any ligands) has been found to be involved in the tumour progression of many different types of cancers. [7] Aberrant activation of this oncogene leads to a cascade of complex downstream signaling that contributes to tumourigenesis. [8] The understanding of EGFR’s role in tumourigenesis assisted in the development of gefitinib and erlotinib as first generation TKIs to target and block EGFR activity to retard cancer growth. They bind reversibly to the ATP binding pocket of EGFR, preventing receptor phosphorylation and subsequent downstream intracellular signaling. [6,8] There is evidence to suggest that EGFR TKIs have led to significant extension of progression-free survival as a second or third line treatment in patients with advanced NSCLC with positive EGFR status. [6,9,10] Promising results have also emerged in recent years for the use of EGFR TKIs as first line treatment for NSCLC patients exhibiting EGFR mutations in Phase III trials. [10-13]
Lung cancer is the 5th most commonly diagnosed cancer in Australia with poor 5-year survival rates of around 14%. [14] Specifically, NSCLC accounts for 60% of all cases of lung cancer. [15] According to the guidelines for lung cancer treatment in Australia, the role of EGFR TKIs (erlotinib), remains primarily in the treatment of Stage IV inoperable NSCLC. [16] It is not recommended for first-generation EGFR TKIs like gefitinib or erlotinib to be used in combination with standard chemotherapy regimens. Erlotinib plays more of a role as a first-line maintenance therapy after standard chemotherapy, as a second-line therapy instead of chemotherapy or as a third-line therapy after having failed two lines of treatment and for patients with poor performance status.
In 2010, Jackman et al. proposed a definition of acquired resistance to EGFR inhibitors to help standardize investigations into this topic. [17] They have found that about 70% of NSCLC patients with positive EGFR mutation status will experience tumour regressions whilst on either gefitinib or erlotinib. However, most initial responders develop acquired resistance to EGFR TKIs, [6] usually occurring about after 12 months of treatment. [18,19] Therefore, much effort has been dedicated to understanding and rediscovering the different mechanisms of EGFR inhibitor resistance-both intrinsic and acquired-in order to develop strategies to overcome them.

Areas of interest

There are numerous hypotheses as to how NSCLC patients develop resistance to EGFR TKIs. However, mechanisms of EGFR TKI resistance that have been more extensively studied and show the most potential for translation into clinical practice will be highlighted in this article.

T790M – The ‘gatekeeper mutation’

The mechanism of resistance that is most commonly identified in recent work is an acquired mutation in the EGFR gene at position 790 (T790M) in exon 20. This involves a threonine to methionine substitution and it is present in 50% of patients with acquired resistance to EGFR TKIs. [6,7,9,20] This substitution mutation causes steric interference with the binding of EGFR TKIs to the ATP binding site. [21] It is also hypothesized that this mutation leads to increased ATP affinity, conferring drug resistance. [6,21] This allows for phosphorylation of EGFR despite the administration of TKIs due to its restored affinity for ATP, allowing the cancer cell to grow unchecked once again with the restoration of EGFR activation. Of interest, some studies have found T790M mutations occurring at low frequency in the germ line of TKI-naive patients, [6,22,23] indicating potential intrinsic resistance. This mutation can also be found in NSCLC patients expressing wild-type EGFR before treatment, possibly explaining that the T790M mutation may be a contributing factor to intrinsic resistance to TKIs. [7]

Figure 1. T790M driven drug resistance and mechanism of action of different generations of EGFR TKIs.
Figure 1. T790M driven drug resistance and mechanism of action of different generations of EGFR TKIs.

Loss of PTEN expression and PIK3CA mutation in the PI3K/Akt/mTOR pathway

A complex network of signaling pathways interacting via various molecules are involved in cancer cell growth independent of EGFR activity. These signaling pathways are usually downstream of an EGFR and can potentially bypass loss of EGFR activation due to administration of TKIs such as gefitinib and erlotinib. One important pathway is the PI3K/Akt/mTOR signaling pathway. Sustained activation of Akt can potentiate resistance to chemotherapy and radiotherapy in general. [24,25] For EGFR-expressing NSCLC patients, Akt is strongly activated to maintain the survival of cancer cells. Activation of Akt always involves membrane recruitment for phosphate transfer. This is regulated positively by phosphoinositol-3-kinase (PI3K) and negatively by phosphatase and tensin homologue (PTEN), a tumour suppressor gene product. Therefore, loss of PTEN expression, via a deletion on chromosome 10, leads to uncontrolled phosphate transfer and activation of Akt, which is commonly observed in NSCLC patients with EGFR TKI resistance. [7,26] On the other hand, a PI3K catalytic alpha (PIK3CA) oncogene mutation is also observed in a small minority of advanced NSCLC patients. [27] This mutation enhances the positive regulation of the pathway via PI3K, thereby leading to heightened activation of Akt. As it is noted that PIK3CA mutations are commonly found in treatment naive lung adenocarcinoma [6] with concurrent driver mutations in EGFR, KRAS or BRAF, PIK3CA mutation is likely to be a secondary, acquired mutation contributing to resistance. [28] By targeting these mechanisms, a patient’s response to EGFR TKIs can potentially be restored.

Insulin-like growth factor 1 Receptor – Parallel EGFR independent pathway

Like EGFR, Insulin-like growth factor 1 receptor (IGF-1R) is a tyrosine kinase that can trigger similar downstream signaling events. Blockade of EGFR pathways with TKI administration has led to compensatory or adaptive upregulation of downstream signaling via the IGF-1R pathway which eventually leads to sustained activation of the PI3K/Akt/mTOR pathway. [29] Gefitinib-resistant cancer cells are also found to have reduced expression of IGF binding proteins, [8] which modulates the activity of IGF-1R by binding to IGF ligands such as IGF-1 and IGF-2. Loss of these binding proteins leads to higher levels of IGF-1 and IGF-2, which increases constitutive activation of the IGF-1R tyrosine kinase and its downstream targets.

Figure 2. PI3K/Akt/mTOR pathway.
Figure 2. PI3K/Akt/mTOR pathway.

MET pathway amplification

EGFR is an important member of a class of four ErbB receptor tyrosine kinases – EGFR/HER1/ErbB1, HER2/ErbB2, HER3/ErbB3 and HER4/ErbB4. Dimerization of any two of this class of receptors (homodimerization or heterodimerization) will lead to phosphorylation and eventual downstream signal cascade. MET (Mesenchymal- Epithelial Transition) is a receptor tyrosine kinase that binds to hepatocyte growth factor (HGF) and is found to undergo amplification in the presence of TKIs. The extensive crosstalk between the HGF/ MET pathway and the PI3K/Akt/mTOR pathway strongly reactivates downstream signals through HER3/ErbB3 phosphorylation, resulting in similar downstream events as EGFR phosphorylation, despite TKI administration. [6,9,18,30] Another interesting observation is that both MET and EGFR have loci on chromosome 7 and EGFR mutation positive NSCLC patients commonly have polysomy of chromosome 7. [19,31] This could be a contributing factor to the presence of intrinsic resistance to EGFR TKIs as targeting EGFRs does not negate the effect of co-existing MET amplification on the PI3K/Akt pathway.

Figure 3. MET amplification.
Figure 3. MET amplification.


The vascular endothelial growth factor (VEGF) pathway, which plays a key role in angiogenesis, is another signaling pathway that can be targeted. This is based on the principle that multiple oncogenic targets can contribute to the malignant phenotype. By targeting multiple oncogenic targets, such as inhibition of both EGFR and VEGF, it is hoped that this would circumvent development of resistance to EGFR TKIs, maintaining treatment efficacy. [32]

Sequist et al. observed that a histological transformation from NSCLC to small cell lung cancer (SCLC) can occur with TKI treatment. [33] This was found in 14% of EGFR-expressing NSCLC patients who have acquired EGFR TKI resistance. The significance of this is that the histological transformation has now given the patient a chance of a good response with standard SCLC chemotherapy regimens. More investigations regarding this are necessary to understand the mechanism of the transformation as it can potentially be a novel strategy for the treatment of NSCLC patients.

Novel Therapies being investigated to overcome EGFR TKI resistance

2nd Generation Irreversible Tyrosine Kinase Inhibitors

Through understanding how the T790M mutation changes binding of first generation TKIs to EGFR, second generation irreversible TKIs have been developed and are being investigated in various trials. These second generation TKIs such as neratinib and afatinib bind irreversibly to the ATP binding site of EGFR via the formation of a covalent bond. They have been shown to be able to overcome T790M driven acquired resistance. [6,34,35] Also, these TKIs can target not only EGFR/HER1 tyrosine kinase receptors, but also other members of the same class that potentiate similar downstream signaling. For example, afatinib targets EGFR/ErbB1 and ErbB2 tyrosine kinase receptors. [35] Dacomitinib is shown to be a pan-HER TKI, targeting all members of the same class, and is found to be effective against tumours harbouring T790M mutations, however, phase III trials have yet to be completed. [20,36] There are also concerns regarding the higher toxicity profile of these drugs with a narrower therapeutic window. Work on third generation EGFR TKIs are also in progress, binding covalently to the ATP site of mutant EGFR with particular specificity to the T790M mutant. [6,37]

Specific T790M inhibitors

A new class of drug that specifically targets and inhibits the T790M mutant has also been developed. [38] It is thought that targeting cancer cells which have the mutation would spare cells without the mutation and therefore remain susceptible to TKIs. Hence, mutated cancer cells with acquired resistance to TKIs can now be targeted, and the efficacy of TKIs on TKI-susceptible cancer cells is maintained.

Altering the PI3K/Akt/mTOR pathway

There is great promise in creating drugs to target this pathway as we know that levels of molecules involved in signal transduction are tightly regulated by multiple factors via many interactions. However, because this pathway is present in both cancer cells and many normal cells as well, there are concerns that drugs which alter its activity would result in pharmacological toxicities. PI3K (LY294002) and Akt inhibitors are currently being studied both as a monotherapy and as a concurrent treatment with EGFR TKIs. [39]

Another drug that has been used with great experience as an immunosuppressive agent, everolimus, is being studied for its effect on advanced NSCLC. [40] Another PI3K/mTOR inhibitor, XL765, is currently undergoing early phase trials against erlotinib alone and in combination with erlotinib. [41]

MET receptor – inhibiting amplification

Observation of the crosstalk between the HGF/MET and PI3K/AKT/ mTOR pathways has led to the hypothesis that co-administration of MET inhibitors can restore sensitivity to EGFR TKIs in resistant tumours displaying MET amplification. [42,43] In a phase II randomized trial, progression free survival (PFS) was higher when erlotinib was given with tivantinib (an agent targeting the MET receptor) as compared to erlotinib given with placebo. [44] Although this finding was not statistically significant, phase III trials are currently ongoing to explore its efficacy and related toxicities. [45]

Onartuzumab, an anti-MET receptor monoclonal antibody has shown increased PFS and overall survival when given with Erlotinib as compared to placebo. [46]

A phase I study of cabozantinib (XL184), a drug which targets both VEGF and MET receptors, has shown promise after preliminary analysis. [9]


Multiple targets with great potential are currently being investigated. Blockade of IGF-1R receptors with antibodies or molecular substrates can potentially alter downstream signaling that promotes cancer growth. [29] This can also be achieved by administration of recombinant IGF binding proteins to reduce circulating levels of IGF-1R ligands. Inhibition of the nuclear factor κB pathway is also of particular interest.

Different approaches to the treatment of EGFR positive NSCLC patients


With the observation of histological transformation as a mechanism of acquired resistance to overcome EGFR inhibition, [37] it is hypothesized that under the therapeutic stress of EGFR TKIs, the cancer cells can be encouraged to adopt this resistance mechanism and transform from a NSCLC to SCLC. Administration of EGFR TKIs can then ‘sensitize’ the cancer cells to be susceptible to platinum and etoposide based chemotherapy (standard regimen for SCLC), that would otherwise be ineffective for NSCLC.

Alternating Treatment/Different Dosing

A review by Oxnard [37] has found that although some cancer cells can acquire the T790M mutation in the presence of a EGFR TKI, this mutation becomes undetectable after a period of discontinued EGFR TKI therapy. It is explained that the T790M mutation causes suboptimal growth profile in the absence of EGFR TKIs and therefore through the notion of ‘survival of the fittest’, they are removed from the cancer population when EGFR TKIs are discontinued. This dynamic change in cancer cell profile now allows the cancer to once again be susceptible to EGFR TKI treatment. Thus, there is a biological rationale to create a dosing schedule with intervals of EGFR TKI treatment and intervals without. This would hopefully maximize cancer cell kill and improve patient outcomes.


There is a lot of potential in targeting specific parts of the complex signaling network in cancer treatment, but this runs the risk of the development of acquired resistance via compensatory pathways. Therefore, a different approach of combining multiple drugs targeting different receptors and different parts of the signaling pathway at the same time may provide a synergistic effect in limiting cancer cell growth. This can be achieved with various classes of drugs such as TKIs, downstream signal molecule inhibitors, monoclonal antibodies targeting receptors involved, immunosuppresants such as everolimus and even chemotherapy. However, trials do require adequate time, participants and investments. More effort and investigation must be performed before the best combination can be identified.

Selection of Patients

Demographically, it has been found in many articles that patients who are most likely to respond to EGFR TKIs are of Asian background (mainly Japanese), female, never-smokers and have NSCLC of the adenocarcinoma histology. [6,8,19,20,39] Presence of mutant KRAS is also found to be a strong predictor of lack of response to EGFR TKIs in NSCLC patients. [6,47,48] It is also discovered that low expression of nuclear factor κB inhibitor was predictive of poor clinical outcome for patients receiving erlotinib without a T790M mutation, indicating its potential in predicting response to EGFR TKI therapy. [18] PTEN inactivation is also a predictor of resistance to EGFR-family antagonists, implying that this subset of patients would not be amenable to long term EGFR TKI therapy. [39] These predictors not only enable us to select patients who are more likely to benefit from EGFR TKI therapy, but also help to prevent exposure of unnecessary toxicities to poor responders. With further validation of these predictors through studies, it might be even possible to develop a nomogram or scoring system to predict the success of EGFR TKIs in NSCLC patients.

Future Directions

As investigative techniques such as genotypic assessments, new assays, cell lineage tracing, chemical genomic profiling studies, next generation sequencing and proteomics develop, more information regarding tumorigenesis will be revealed. Ongoing research in other cancers may also provide insight to the pathogenesis of NSCLC. As more drugs are being released for clinical use, further research must be done to determine the short and long term side effect profiles of these drugs, whether used on their own or in combination. The fundamental principles of beneficence and non-maleficence should not be forgotten. No matter how novel or promising a drug can prove to be, its value for clinical application becomes limited when its toxicity profile causes more harm than good to patients.

It is also interesting to note that tumour signaling profiles are in a dynamic rather than static state. Mutations can be gained and lost, depending on patient’s biology, genetics and treatment received. This could mean that gathering information regarding the cancer may have to be a continuous activity rather than just prior to treatment. Patients may have to be regularly biopsied at different stages of chemotherapy or EGFR TKI treatment.

Knowing that every patient with NSCLC can have subtle differences in the biology of the cancer, future research may warrant the need to create a tumour bank where cancer cells are profiled and sequenced, both before and after treatment. This information will then be stored in a database where researchers can retrieve information from, and possibly access cell samples if required.

With the development of deep analytic systems such as the IBM supercomputer Watson, who is ‘learning’ about lung cancer at the Memorial Sloane-Kettering Cancer Centre, information from the tumour bank can be rapidly processed to generate meaningful data. Such information sharing will require an international effort, enhancing the development of targeted, higher-powered and multi-centred trials. This can drive down the high costs of drug discovery, reducing wastage of precious resources into unfruitful studies that seek to answer poorly formulated clinical questions.


The idealistic imagination of cancer cure will come in the form of personalized medicine where cancer cells are analyzed through a machine which puts together a concoction of molecules to create a single, simple tablet that will destroy the tumour entirely without side effects. As research becomes more focused into the little details of each signaling molecule in every pathway, the cumulative understanding of cancer will be heightened tremendously. The content and amount of research done is no doubt exciting and promising, but, as a clinician, our focus remains ultimately on the patient and not merely on the cancer.

Conflict of interest

None declared.


B Chua:


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