Tumor microenvironment helps skin cancer cells resist drug treatment .

Neighboring non-cancer cells may contribute to drug resistance

One of cancer’s most frightening characteristics is its ability to return after treatment. In the case of many forms of cancer, including the skin cancer known as melanoma, tailored drugs can eradicate cancer cells in the lab, but often produce only partial, temporary responses in patients. One of the burning questions in the field of cancer research has been and remains: how does cancer evade drug treatment?

New research by a team from Dana-Farber Cancer Institute, the Broad Institute and Massachusetts General Hospital suggests that some of the answers to this question do not lie in cancer cells themselves. To find the answers, scientists are looking beyond tumor cells, studying the interplay between cancer cells and their healthy counterparts. The research team has found that normal cells that reside within the tumor, part of the tumor microenvironment, may supply factors that help cancer cells grow and survive despite the presence of anti-cancer drugs. These findings appear online this week in a paper published in Nature.

“Historically, researchers would go to great lengths to pluck out tumor cells from a sample and discard the rest of the tissue,” said senior author Todd Golub, MD, the Charles A. Dana Investigator in Human Cancer Genetics at Dana-Farber Cancer Institute, pediatric oncologist at Dana-Farber/Children’s Hospital Cancer Center, and director of the Broad’s Cancer Program. Golub is also a professor at Harvard Medical School and an investigator at Howard Hughes Medical Institute. “But what we’re finding now is that those non-tumor cells that make up the microenvironment may be an important source of drug resistance.”

To investigate how the tumor microenvironment may contribute to drug resistance, the researchers designed experiments in which cancer cells were grown in the same wells (miniscule test tubes no larger than a pencil eraser) along with normal cells. These co-cultured cells were then treated with anti-cancer drugs. When grown alone, such cancer cells died in the presence of many of these targeted agents, but when grown together with normal cells, cancer cells developed resistance to more than half of the 23 agents tested.

These observations reflect what clinicians often see in patients with cancers such as melanoma. In the case of melanoma, targeted therapies have been developed against a specific, common mutation in a gene known as BRAF. While some patients’ tumors show an overwhelming response to BRAF inhibitors and seem to disappear, other patients’ tumors only respond by slightly decreasing in size. The failure to shrink tumors at the outset suggests that those tumors possess some level of innate resistance — the ability to evade drugs from the beginning of treatment.

“Even though recent advanced in targeted therapy have caused tremendous excitement in melanoma, the fact remains that drug resistance eventually develops in nearly all metastatic melanomas treated with RAF inhibitors, and in some cases is present at the outset of treatment,” said Levi A. Garraway, MD, PhD, an associate professor at Dana-Farber and Harvard Medical School and a senior associate member of the Broad Institute. “There are many different types of mechanisms that tumors may hijack to circumvent the effects of therapy…no single experimental approach can capture all of these potential mechanisms. Thus, the application of complementary approaches can offer considerable synergy in terms of discovering the full spectrum of clinically relevant resistance mechanisms.”

Scientists have uncovered resistance mechanisms that cancer cells develop over time – genetic changes in specific genes that may give cancer the ability to overcome the effects of a drug with time – but these acquired resistance mechanisms do not explain the innate resistance seen in many tumors.

“We can take cancer cells out of a melanoma patient, put them on a dish, and most times they will turn out to be extremely sensitive to the targeted agents, but that’s not what we see in patients,” said Ravid Straussman, MD, PhD, a postdoctoral fellow at the Broad Institute and first author of the Nature paper. “Why do we get just a partial response in most patients? We set out to dissect this question, and the next logical step was to think beyond cancer cells.”

After completing systematic, high-throughput screens of more than 40 cancer cell lines, the researchers chose to focus on melanoma, looking at whether factors normal cells secrete help cancer cells resist treatment. They measured more than 500 secreted factors and found that the factor most closely linked to BRAF inhibitor drug resistance was hepatocyte growth factor (HGF). HGF interacts with the MET receptor, abnormal activation of which has been tied to tumor growth in previous studies but never to drug resistance in melanoma.

In addition to studying cells in the lab, the research team sought to replicate their findings in samples from cancer patients. Keith Flaherty, MD, director of developmental therapeutics at Massachusetts General Hospital Cancer Center and an associate professor at Harvard Medical School, and his lab provided 34 patient samples for study. The team measured levels of HGF in these samples and saw a relationship between how much HGF was present and the amount of tumor shrinkage patients experienced. For example, tumors in patients with high levels of HGF shrank less than those in patients with low HGF levels.

“To try to explore in patient samples what factors in the microenvironment are not only present but functionally important in drug resistance would have been largely impossible. Coming up with candidates in the lab and then exploring relevance in humans in a targeted way is the only tractable approach,” said Flaherty. “By taking this high-throughput screening, hypothesis-generating approach, we could then follow up by looking at patient samples. In a case like melanoma, where you already have a targeted therapy available, it puts you on good footing to narrow in on specific factors that may be at play in drug resistance.”

Several HGF/MET inhibitors are in clinical development or are FDA-approved for other indications, making clinical trials combining these inhibitors with BRAF inhibitors feasible in the future. In addition, researchers could follow the same approach taken by the team to screen other drugs currently in development, identifying mechanisms of resistance and ways to counter them even before treatment begins.

“Drug resistance should no longer surprise us,” said Golub. “We’re thinking about how to do this – how to systematically dissect resistance – much earlier in the drug development process so that by the time a new drug enters the clinic, we have a good sense of what the likely mechanisms of resistance will be and have a strategy to combat them.”

Source: Dana Faber cancer Institute.


HIV Treatment as Prevention: Principles of Good HIV Epidemiology Modelling for Public Health Decision-Making in All Modes of Prevention and Evaluation.

Public health responses to HIV epidemics have long relied on epidemiological modelling analyses to help prospectively project and retrospectively estimate the impact, cost-effectiveness, affordability, and investment returns of interventions, and to help plan the design of evaluations. But translating model output into policy decisions and implementation on the ground is challenged by the differences in background and expectations of modellers and decision-makers. As part of the PLoS Medicine Collection “Investigating the Impact of Treatment on New HIV Infections”—which focuses on the contribution of modelling to current issues in HIV prevention—we present here principles of “best practice” for the construction, reporting, and interpretation of HIV epidemiological models for public health decision-making on all aspects of HIV. Aimed at both those who conduct modelling research and those who use modelling results, we hope that the principles described here will become a shared resource that facilitates constructive discussions about the policy implications that emerge from HIV epidemiology modelling results, and that promotes joint understanding between modellers and decision-makers about when modelling is useful as a tool in quantifying HIV epidemiological outcomes and improving prevention programming.

Source: PLOS.


Pandemic (H1N1) 2009: a clinical spectrum in the general paediatric population.

This retrospective case series describes the clinical spectrum of 43 children with pandemic (H1N1) 2009 admitted to a single hospital in Australia during the peak winter flu season. Clinical features, diagnoses, length of hospitalisation and complications were reviewed in children up to 17 years of age with proven pandemic (H1N1) 2009 by RT-PCR. The median age was 6 years, 42% had a pre-existing medical condition. The most common presentation was fever and cough, and 88% of patients met our criteria for flu-like illness. Consolidation on chest x ray was the most common diagnosis (n=20, 46%), followed by dehydration (n=13, 30%). Three (7%) had encephalopathy and two (5%) had diabetic ketoacidosis. There were two intensive care admissions and no deaths. Pandemic (H1N1) 2009 flu has a wide range of presentation in the paediatric population. The diagnosis should be considered during the current pandemic in any child with fever, or who is unwell.


Since being identified in Mexico in April 2009, human influenza A (H1N1) virus has spread across the world and has widespread community transmission in many countries. The World Health Organization escalated the pandemic to alert phase 6 in early June 2009.1 The outbreak coincided with Australia’s flu season resulting in 35 579 confirmed cases of pandemic (H1N1) 2009 and 161 deaths, in Australia as of 7 September 2009.2 An early report of 18 hospitalised patients of the initial outbreak in Mexico showed that the pandemic (H1N1) 2009 virus caused severe illness and death in previously healthy young to middle-aged persons.3 Despite this, it has been found that the majority of patients continue to experience mild illness.

The purpose of this study was to describe the clinical spectrum of pandemic (H1N1) 2009 virus in the general paediatric population. The Gold Coast Hospital serves a population of over 455 000 people. Our case series describes the epidemiological characteristics, clinical features, range of diagnoses and length of hospitalisation in 43 children positive for pandemic (H1N1) 2009 admitted to the Gold Coast Hospital.


This retrospective study was conducted by review of medical charts, laboratory and radiological findings of all children admitted to the Gold Coast Hospital with confirmed pandemic (H1N1) 2009. The study period was from the 25 May 2009 to the 16 August 2009, coinciding with Australia’s flu season. During this period, all children admitted into hospital with a febrile or respiratory illness were tested for pandemic (H1N1) 2009 by two Taqman based real-time RT-PCR methods, designed locally in Australia. The two assays, H1-PCR and N1-PCR, were designed targeting the pandemic (H1N1) 2009 virus haemagglutinin and neuraminidase genes, respectively. These RT-PCR methods are found to be sensitive and specific for pandemic (H1N1) 2009 RNA.4 The tests were done at the closest tertiary centre 1 h away and took 2 h to complete. In the peak of the pandemic, due to the overwhelming number of samples, it took 48 h for results to return. Specimens were collected from nasal pharyngeal aspirates or nasal pharyngeal swabs. These specimens were also tested with a multiplex PCR assay for a select respiratory viral panel including influenza A, influenza B, respiratory syncytial virus, parainfluenza types 1, 2 and 3, adenovirus and human metapneumovirus.

Epidemiological characteristics observed were age, gender and pre-existing medical conditions. Pre-existing medical conditions were obtained from the initial history and chart review. These were then categorised according to physiological system. Asthmatic patients were included if they were, at the time of admission, on preventive treatment for asthma. Due to variable documentation of obesity or indigenous background in the medical charts, these factors were not examined in our study.

Clinical features were obtained from findings documented by the treating physician. Based on Queensland Health’s pandemic (H1N1) 2009 case definition, children had flu-like illness if they presented with a fever of at least 38°C, or a history of fever, with one symptom of cough, sore throat or rhinorrhoea.5

Diagnosis was based on history and examination findings documented by the admitting physician, laboratory and radiological findings. In our study, respiratory diagnoses were divided into three groups namely, asthma, bronchiolitis and consolidation on chest x ray. Asthma was defined as the presence of wheezing and/or chest retraction in those with a past history of asthma, without evidence of consolidation on chest x ray. Bronchiolitis was defined as the presence of wheezing and/or chest retraction in those <1 year of age without evidence of consolidation on chest x ray. Due to the difficulty in differentiating consolidation caused by pneumonia or asthma, those with bilateral or unilateral consolidation on chest x ray were analysed in one group called consolidation. Febrile convulsion was defined as a seizure associated with a fever, or history of recent fever, with no previous history of afebrile seizures or evidence of central nervous infection or metabolic abnormality. Dehydration was defined according to the admitting physician’s initial assessment based on history of fluid loss, or poor oral intake, clinical signs including tachycardia, dry mucous membranes, poor central capillary refill, poor urine output and laboratory findings. Encephalopathy was defined as altered mental status lasting greater than 24 h. Diabetic ketoacidosis was defined by biochemical criteria of a blood glucose greater than 11 mmol/litre and evidence of metabolic acidosis (venous pH <7.3 and/or plasma bicarbonate <15 mmol/litre).

Patients were treated with the antiviral, oseltamivir, at the discretion of the admitting physician. Factors considered when commencing treatment were based on the joint position statement published by the Australasian Society for Infectious Diseases (ASID) and the Thoracic Society of Australia and New Zealand (TSANZ).6 These recommendations included treatment for children with risk factors for severe disease, particularly children <5 years of age, those with immunosuppression or chronic disease like asthma, cardiorespiratory disease, diabetes and renal failure. In children with no risk factors for severe disease, oseltamivir was recommended in those who presented within 48 h of onset of symptoms. Oseltamivir was not recommended in those <1 year of age due to limited safety data. Oseltamivir was given to those hospitalised with severe flu infection even after 48 h of symptom onset.


In the period from the end of May to mid-August 2009, a total of 683 children were admitted to hospital. Of these 130 children were screened, via nasopharyngeal swab or aspirate, for pandemic (H1N1) 2009 influenza virus and other common respiratory viruses on our respiratory viral PCR panel. Forty-three children were proven to have pandemic (H1N1) 2009. The characteristics of the patients with pandemic (H1N1) 2009 are listed in table 1.

Fever was the most common presenting symptom (n=41, 95%) followed by cough (n=40, 93%). Other common symptoms were vomiting (n=21, 49%), rhinorrhoea (n=19, 44%) and respiratory distress (n=16, 37%). Headache, myalgia, sore throat, lethargy, abdominal pain, diarrhoea, confusion and seizures were other symptoms reported at presentation. Two (5%) patients did not have a fever or history of fever. Both had pre-existing medical conditions. Thirty-eight (88%) patients fulfilled our criteria for flu-like illness.

The most common diagnosis was consolidation on chest x-ray, with a total of 20 (46%) patients. Thirteen (30%) patients were clinically dehydrated, and four (9%) patients had an exacerbation of asthma. Encephalopathy was diagnosed in three (7%) patients and two (5%) were admitted with diabetic ketoacidosis. Febrile convulsion, bronchiolitis and abdominal pain each occurred in one (2%) patient.

Overall, the median length of stay was 2 days. Those with consolidation had a median length of stay of 2 days while asthma, bronchiolitis, clinical dehydration and febrile convulsion had a median length of 1 day. Patients with encephalopathy and diabetic ketoacidosis had a median length of stay of 4 and 5 days, respectively. Those who were previously healthy had a median stay of 1 day while those who had a pre-existing medical condition had a median stay of 2 days. Twenty-nine (67.4%) patients were treated with oseltamivir.

Of the 43 patients, there were no deaths. Two patients (4.6%) required intensive care; both had pre-existing disorders. One patient had severe bilateral pneumonia and respiratory distress requiring non-invasive ventilation with a background of Retts syndrome. The other patient was admitted to intensive care in severe diabetic ketoacidosis. Five patients (11.6%) were readmitted with complications, including secondary pneumonia, ongoing confusion and exacerbation of asthma. Three of these patients had been treated initially with oseltamivir.


Our case series of 43 paediatric patients with proven pandemic (H1N1) 2009 admitted to hospital during the peak of Australia’s flu season demonstrates the wide range of presentations in the paediatric population. All paediatric age groups were affected and almost half of those admitted had an underlying medical problem.

During this study period, there was a low clinical threshold to obtain pandemic (H1N1) 2009 identification. It became apparent that children were being admitted with a wide range of presentations. Fever and cough were present in almost all our cases. Screening only with our criteria for flu-like illness would have missed 12% of children with pandemic (H1N1) 2009 in contrast to a similar report in the UK which found it would have missed 40% of cases using their case definition which required fever and two other symptoms.7 This same report found that 19% of cases did not have a temperature of at least 38ºC or history of fever in contrast to our study which found only 5%. A full screening study of all admissions may be warranted in the future. This was unable to be done due to the significant impact it would have on the testing laboratory during a pandemic.

Consolidation on chest x ray was the most common diagnosis followed by clinical dehydration requiring rehydration in hospital. Interestingly three patients had encephalopathy. Similar neurological complications have been documented in patients with pandemic (H1N1) 2009 in Dallas, Texas as well as in other seasonal flu epidemics.8 In one case, a 16-year-old boy with no previous medical or psychological disorder, had hallucinations and paranoid delusions for 7 days. The other two cases, 2 and 9 years of age, had seizures and altered mental status. Two patients were admitted with diabetic ketoacidosis, one with known diabetes and the other their first presentation.


Pandemic (H1N1) 2009 in the general paediatric population can have a wide range of presentation. Respiratory illness was the most common presentation, there were however, less typical presentations like encephalopathy and diabetic ketoacidosis. There were no deaths and two admissions to intensive care in which both patients had pre-existing medical conditions. Pandemic (H1N1) 2009 should be considered as a diagnosis in any child with fever or who is unwell, even without fever.


World Health Organization. New influenza A (H1N1) virus: global epidemiological situation June 2009. Wkly Epidemiol Rec 2009;84:24960.


Australian Government Department of Health and Ageing. Pandemic (H1N1) 2009 update bulletin. www.healthemergency.gov.au/ (Accessed September 2009).

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Source: BMJ.






Docosahexaenoic acid supplementation decreases liver fat content in children with non-alcoholic fatty liver disease: double-blind randomised controlled clinical trial.

To investigate whether dietary supplementation with docosahexaenoic acid (DHA) decreases liver fat content in children with non-alcoholic fatty liver disease (NAFLD).

Design, setting and patients We performed a randomised controlled trial of DHA supplementation (250 and 500 mg/day) versus placebo in 60 children with biopsy-proven NAFLD (20 children per group).

Main outcome measures The main outcome was the change in liver fat content as detected by ultrasonography after 6 months of treatment. Secondary outcomes were the changes in insulin sensitivity index, alanine transaminase, triglycerides and body mass index after 6 months of treatment.

Results Blood DHA increased in children supplemented with DHA (0.65%, 95% CI 0.30% to 1.10% for the DHA 250 mg group and 1.15%, 0.87% to 1.43% for the DHA 500 mg group). The odds of more severe versus less severe liver steatosis after treatment was lower in children treated with DHA 250 mg/day (OR = 0.01, 0.002 to 0.11, p <0.001) and DHA 500 mg/day (OR = 0.04, 0.002 to 0.46, p = 0.01) as compared to placebo but there was no difference between the DHA groups (p = 0.4). Insulin sensitivity index increased and triglycerides decreased to a similar degree in both DHA groups as compared to placebo but there was no effect on alanine transaminase and body mass index.

Conclusion DHA supplementation improves liver steatosis and insulin sensitivity in children with NAFLD.

Source: BMJ.

Limbic encephalitis in children and adolescents.

Limbic encephalitis is rare in people <18 years of age and rarely given a formal diagnosis.

Design Retrospective study on presentation and outcome of children and adolescents with the clinico-radiological syndrome of limbic encephalitis tested for specific neuronal autoantibodies (Abs) over 3.5 years.

Setting Assessment, diagnosis, treatment and follow-up at 12 neuropaediatric and neurological departments in Europe, with Abs determined in Bonn, Germany and Oxford, UK.

Patients Ten patients <18 years of age who presented with a disorder mainly affecting the limbic areas of <5 years’ duration with MRI evidence of mediotemporal encephalitis (hyperintense T2/FLAIR signal, resolving over time).

Results Median age at disease onset was 14 years (range 3–17). Eight patients had defined Abs: one each with Hu or Ma1/2 Abs, four with high titre glutamic acid decarboxylase (GAD) Abs, two of whom had low voltage-gated potassium channel (VGKC) Abs and two with only low titre VGKC Abs. A tumour was only found in the patient with Hu Abs (a neuroblastoma). After a median follow-up of 15 months with corticosteroid or intravenous immunoglobulin treatment, starting after a median of 4 months, two patients recovered, eight remained impaired and one died.

Conclusions Limbic encephalitis is a disease that can occur in childhood or adolescence with many of the hallmarks of the adult disorder, suggesting that both result from similar pathogenic processes. Since most of the cases were non-paraneoplastic, as now also recognised in adults, more systematic and aggressive immunotherapies should be evaluated in order to improve outcomes.

Source: BMJ.