NKTR-214 therapy study in patients with RCC

Early this year at the ASCO Genitourinary Cancers 2017 meeting, Hurwitz et al. (2017) presented clinical data from a Phase I clinical trial of the oncology agent NKTR-214 in patients with renal cell carcinoma (RCC) showing encouraging evidence of anti-tumour activity, and a favourable safety and tolerability profile. NKTR-214 was developed by Nektar Therapeutics to expand specific cancer-fighting immune cells in the tumour environment and increase expression of the cell surface receptor PD-1 on these immune cells.

NKTR-214 is a CD122-biased cytokine agonist conjugated with multiple releasable chains of polyethylene glycol and designed to provide sustained signalling through the heterodimeric IL-2 receptor pathway (IL-2Rβγ) to preferentially activate and expand effector CD8+ T and natural killer (NK) cells – usually cancer-fighting immune cells – over T regulatory cells (Tregs) – immunosuppressive cells that usually limit anti-tumour response.

A dose escalation trial of NKTR-214 was initiated to assess the safety, tolerability and explore immune changes in the blood and tumour microenvironment in patients with RCC. NKTR-214 was administered IV every 2 or 3 weeks. Pre and post treatment blood and tumour samples were collected and analysed for immune phenotyping, gene expression and changes in the tumour microenvironment by immunohistochemistry.

Among 25 patients dosed, 15 had RCC. Treatment with single-agent NKTR-214 was well tolerated and the maximum tolerated dose (MTD) was not reached. There were no autoimmune-related adverse events or organ related inflammation. 6 out of the 15 RCC patients, with prior tyrosine kinase inhibitor (TKI) treatments, experienced tumour shrinkage. Analysis of the tumour microenvironment revealed several significant immunological changes post treatment, including increase in total and proliferating NK, CD8+, and CD4+ T cells. There was good correlation between increase in activated CD4+ and CD8+ T cells in peripheral blood with an increase in T cell infiltrates within the tumour tissue. There was a greater abundance of CD8+ T cell compared to Treg immune suppressive cells accumulating in the tumour tissue. NKTR-214 also increased cell-surface expression of PD-1 on CD4+ and CD8+ T cells.

NKTR-214 increased immune infiltration in the tumour and anti-tumour activity in patients who previously progressed on TKIs, with a favourable safety profile. The ability to alter the immune environment and increase PD-1 expression on effectors T cells may improve the effectiveness of anti-PD-1 blockade. A trial combination of NKTR-214 and nivolumab is being evaluated. The Phase 1/2 clinical program will enrol up to 260 patients and will evaluate the potential for the combination of Opdivo (nivolumab) and NKTR-214 to show improved and sustained efficacy and tolerability above the current standard of care in melanoma, kidney, triple-negative breast cancer, bladder and non-small cell lung cancer patients.

The NKTR-214 clinical trial is currently recruiting participants, you can find more information here.

Findacure – Medical Research Explained: Clinical research

Following last week’s blog about pre-clinical research, this week we introduce the second part of Findacure’s webinar explaining clinical research.

The subject of clinical research was presented by Sarah Venugopal from Raremark, a company connecting families affected by rare diseases with information on the latest research and treatments in the field.

Clinical research, also known as clinical trials, clinical studies or human trials, are conducted to collect data about the safety and effectiveness of a potential new test, drug or device before it is approved and widely used.

The key players in clinical research are:

  • The sponsor – organization that funds the clinical trial, can be a pharma company, a charity, a hospital or even an individual
  • The ethics review boards – independent groups responsible for the protection of the rights, safety and well-being of people taking part in a trial
  • The principal investigator (PI) – person who leads the trial, usually a specialist doctor or researcher
  • The study coordinator – person who supports the PI and is in charge of the day-to-day running of the trial, there can be more than one
  • The participants – the patients or healthy volunteers taking part in the trial

People take part in clinical trials to help speed up the approval process for new drugs for themselves or others, to access specialist care, to potentially access an experimental treatment and to be monitored closely.

Main types of clinical trial:

  • Diagnostic trials – new tests or procedures for diagnosing diseases
  • Natural history studies – often done for rare diseases, they generate insights into how diseases might progress naturally over time
  • Observational studies – monitor participants without intervening for example whilst they are already on an existing treatment or after surgery
  • Screening trials – evaluate new tests, test the best way to detect certain diseases or medical conditions
  • Treatment trials – the one people are more familiar with, they evaluate the effectiveness and safety of potential new treatments

Four phases of Clinical trials:

Phase I – Typically a small study (5-100) with healthy volunteers assessing safety usually with a very low dose of the drug. This phase usually lasts months to a year. In rare diseases, sometimes this phase is with patients with the condition so that the drug can be approved faster. 70% of the drugs tested on phase I make it to phase II.

Phase II – Assessing safety and efficacy, larger study with people with the condition, can include a placebo. 33% of the drugs tested on phase II make it to phase III.

Phase III – Larger studies, randomized and controlled, people with the condition, lead to a potential approval, looks at dosing. 70-90% of the drugs tested on phase III make it to phase IV.

Phase IV – Drug is approved for use, monitor long-term safety and effectiveness in the real world.

Usually the entire process lasts about 6 to 10 years.

What happens during a trial?

It starts with the sponsor designing the trial with doctors/investigators, then investigators see patients and collected data, the data is entered into a database, the data is analysed and presented in a report and finally the report is used to support approval.

Most large clinical trials are randomized, double-blind placebo-controlled trials. This is a common way to design a trial as it ensures the data is robust, reliable and reduces bias.

Placebo-controlled – a placebo contains no active ingredients and is given to some of the participants in a trial so that the effectiveness of the drug can be accurately seen

Randomized – participants are randomly assigned to either take the active drug or the placebo

Double-blind – to reduce bias, neither the researchers nor the patients know who is taking the experimental drug or the placebo

What happens after a trial?

If the drug is shown to be safe the results are submitted for approval to regulatory bodies (FDA or EMA), this process takes a very long time and the data is reviewed to make sure is reliable, cost-effective and has a positive impact. Additional data might be needed and it important to continue to monitor drug in real world. Usually there is publication of results on PubMed or clinicaltrials.gov but unfortunately, not all sponsors publish their results.

You can watch the entire Findacure webinar here and learn about BHD Syndrome clinical trials here.

Findacure – Medical Research Explained: Pre-clinical research

Last week Findacure hosted a webinar explaining the complex medical research field that introduced the different stages of pre-clinical and clinical research necessary to get a treatment available to patients.

The first talk focused on pre-clinical research and was presented by Oliver Timmis from the AKU Society, a charity that supports patients with the rare condition alkaptonuria.

Oliver explained that assessing a potential treatment of a condition by a drug starts with pre-clinical research. Pre-clinical research in drug development aims to show that a drug is safe and effective in a non-human model before human research is initiated. The drug development timeline is time consuming, taking 16 years on average from the discovery of a drug to having it as an available treatment for patients. The timeline starts with several years of pre-clinical testing and then clinical testing in different phases. Pre-clinical testing is quite variable, compounds are narrowed down at this phase with just a few going to clinical trials – this has very high costs (~$1 billion net cost invested over 15 years).

Pre-clinical development was defined as the testing of promising candidate compounds to ensure that they are:

  • Likely to be effective
  • Safe
  • Sufficiently stable
  • Excreted safely from the body

Around the world there are regulatory guidelines by agencies such as the FDA and the EMA that help in the development of effective pre-clinical and clinical research.

Animal studies are widely used in pre-clinical research, in fact, they are a legal requirement for any human drug developed in Europe.  Animal studies are a standard procedure but controversial, therefore, ethical guidance for appropriate use is in place with systems such as the principles of the 3Rs.

Research can be divided into two categories – Basic and Applied/Clinical. Basic research aims to discover facts about how and why things occur without any relation to clinical outcome; applied research uses information generated by basic research to treat and prevent illness.

You can find BHD-specific basic and clinical research in the BHD Article Library.

Before pre-clinical research there is a period of “pre-pre-clinical research” to establish a target, to choose a molecule that is likely to work, act on symptoms/pathways most important to patients, and work out how to measure if this molecule is having the expected effect.

A classic type of pre-clinical studies is toxicology studies. These studies are usually performed in animals to support human studies. Important considerations are which species and how many animals to use.  It has to be practical and the duration of studies should not be too long since the idea is to get to clinical studies quickly.

Toxicology studies are conducted to assess:

  • Toxic effects following single and multiple dosing
  • Effects on reproduction
  • Potential for teratogenicity
  • Peri/postnatal effects
  • Potential to cause cancer and genetic abnormalities
  • Effects in the immune system
  • Potential to cause skin and eye problems

There are acute/short term toxicity studies which look for effects over short periods using the route of administration intended for humans. Usually, animals are observed for 30 days for eating/drinking habits, weight change, toxic effects and psychomotor changes. Subacute/subchronic studies, uses repeat dosing aligned to intended human usage. Testing over 90-180 days is required to support human administration for 1 week. For a chronic human illness testing over 1 year is required in animals

Definitive animal studies define the No Observable Adverse Effect Level (NOAEL) – the highest amount of drug used with lowest side effects. There is the need to use most sensitive species available and to consider the treatment regime.

An important tool used in medical research is the biomarker. Biomarkers are surrogates for problems in the human body, changes in biological systems that are related to exposure to a toxin. To be useful in pre-clinical studies biomarkers should be chemical specific, quantifiable at low levels, and the ability to be monitored in a non-invasive way is an advantage. Different types of biomarkers include biomarkers of exposure, of response effects and of susceptibility.

In summary, preclinical studies are undertaken to ensure that medicines are safe and effective.  Success in preclinical studies means that a drug has been demonstrated to be probably effective, safe, sufficiently stable, and excreted safely from the body.  Then agreement from the regulators is needed before moving on to clinical research (testing in humans).

Clinical research, the second part of this webinar will be discussed in a future blog.

You can watch the entire webinar here.

DHM attenuates obesity-induced slow-twitch-fiber decrease via FLCN/FNIP1/AMPK pathway

Obesity is often associated with decreases in the proportion of skeletal muscle slow-twitch fibers and insulin sensitivity. Slow-twitch fibers are rich in mitochondria and utilize fatty acid oxidative phosphorylation for energy production. In their new study, Zhou et al. (2017) explore the role of the FLCN/FNIP1/AMPK signalling pathway in obesity-induced reductions in slow-twitch fibers and insulin sensitivity in skeletal muscle using high-fat-diet-induced (HFD) obese mice, ob/ob mutant mice, and palmitate-treated C2C12 myotubes. The authors also assess the effects of dihydromyricetin (DHM) on the obesity-induced decrease in slow-twitch fibers, and the molecular mechanisms responsible for this effect.

AMP-activated protein kinase (AMPK) plays a central role in skeletal muscle oxidative metabolism and fiber-type specification. AMPK activation in skeletal muscle induces expression of its downstream transcriptional regulator PGC-1α. FLCN, responsible for Birt-Hogg Dubé syndrome, interacts with the AMPK signalling pathway by binding to folliculin-interacting protein 1 (FNIP1) (Baba et al., 2006). Folliculin (FLCN) and FNIP1 may regulate skeletal muscle-fiber-type specification through the AMPK/PGC-1α pathway (Hasumi et al., 2012). Although the interaction between FLCN/FNIP1 and AMPK appears to play an important role in skeletal muscle adaptations, its involvement in the obesity-induced decrease in slow-twitch fibers and insulin resistance remains unclear.

Exercise is commonly prescribed for obesity and metabolic diseases, including insulin resistance and diabetes, since it increases AMPK activity, promoting slow-twitch fibers and increasing the use of fatty acids in skeletal muscle (Lantier et al., 2014). The authors have previously reported that the flavonoid DHM enhanced exercise performance (Zou et al., 2014), and improved skeletal muscle insulin resistance by autophagy induction via AMPK (Shi et al., 2015). However, the ability of DHM to increase the proportion of skeletal muscle slow-twitch fibers via the AMPK signalling pathway remains unclear.

In the HFD-fed and ob/ob mice the proportions of slow-twitch fibers, insulin sensitivity (detected by the markers of insulin sensitivity, insulin-stimulated Akt and insulin receptor substrate 1 (IRS-1) phosphorylation) and oxidative metabolism in skeletal muscle were decreased compared with control mice, and this effect was prevented by DHM treatment.

Increased non-esterified fatty acids (NEFA) levels are closely associated with insulin resistance in obesity and type 2 diabetes. In line with these results, the authors found that plasma NEFA levels were significantly increased in HFD-fed and ob/ob mice compared with controls and they negatively correlated with slow-twitch-fiber proportion.

To verify the results obtained in mice, in vitro experiments with C2C12 myotubes were performed. Palmitate, one of the most elevated plasma NEFA in obesity, was used to induce insulin resistance in C2C12 myotubes and shown to decrease expression of slow-fiber specification Myh7 protein, this was inhibited by DHM.

Western blot analysis show decreased phosphorylation of AMPK in both HFD-fed and ob/ob mice, and in palmitate-treated C2C12 myotubes. The similar trends in AMPK activity and changes in slow-twitch fibers and insulin resistance suggest that AMPK might be involved in these obesity-induced changes. FNIP1 and FLCN expression levels were significantly increased in skeletal muscle in HFD-fed and ob/ob mice, and in palmitate-treated C2C12 myotubes and negatively correlated with AMPK activity. These results implicated FNIP1/FLCN in obesity-induced AMPK inactivation, and the subsequent decreases in slow-twitch fibers and insulin sensitivity in skeletal muscle.

The role of the FLCN/FNIP1/AMPK signalling pathway in obesity-induced insulin resistance and the decrease in slow-twitch fibers was further clarified using over-expression and knock-down of FNIP1 and FLCN. Transfection of C2C12 myotubes with FNIP1 resulted in a corresponding increase in FLCN levels. AMPK phosphorylation levels increased following FLCN or FNIP1 knock-down, and decreased following their over-expressions. mRNA levels of the PGC-1α encoding gene were assessed and results showed that its expression was negatively related to FNIP1/FLCN expression, and consistent with AMPK activity.

DHM ameliorated the obesity-induced decrease in slow-twitch-fiber proportion, insulin sensitivity, and AMPK activity. However, it was necessary to verify if these effects of DHM were mediated by FNIP1 and FLCN. FNIP1 and FLCN expression levels were significantly decreased following DHM administration in HFD-fed and ob/ob mice, and in palmitate-induced C2C12 models. Also, the preventive effects of DHM on the palmitate-induced decrease in slow-twitch fibers, AMPK activation, p-Akt and p-IRS-1 expression, were blocked by FLCN over-expression. These results demonstrated that the effects of DHM were mediated by the FNIP1/FLCN/AMPK signalling pathway.


Obtained from Zhou et al. (2017)

Yan et al. recently reported FLCN/AMPK as a novel molecular pathway involved in regulating mitochondrial function and browning of white adipocytes, this was discussed on a previous blog. Here, the results of the study demonstrate that the FNIP1/FLCN complex might play an important role in AMPK/PGC-1α signalling in the obesity-induced decreases in slow-twitch-fibers and insulin sensitivity. Furthermore, DHM acts as a potential exercise mimetic by attenuating these obesity-induced effects via the FNIP1/FLCN/AMPK signalling pathway. These results provide new insights into the FNIP1/FLCN/AMPK signalling pathway, key in BHD research, and novel mechanisms and potential targets for treatments of insulin resistance and type 2 diabetes.

  • Zhou Q, Gu Y, Lang H, Wang X, Chen K, Gong X, Zhou M, Ran L, Zhu J, & Mi M (2017). Dihydromyricetin prevents obesity-induced slow-twitch-fiber reduction partially via FLCN/FNIP1/AMPK pathway. Biochimica et biophysica acta PMID: 28363698

Novel FLCN mutations in Chinese patients

The gene FLCN is inactivated in individuals with BHD syndrome. The FLCN gene encodes the protein Folliculin, which is a putative tumour suppressor. Over 150 different FLCN mutations have been identified, most of which are likely to be pathogenic (LOVD-hosted FLCN mutation database). The majority of these mutations are frameshift, nonsense, insertion/deletion, or splice site mutations, resulting in truncation and inactivation of the encoded protein folliculin. FLCN consists of 14 exons spanning approximately 20 kb of genomic DNA (Nickerson et al., 2002).

Novel FLCN mutations are still being identified and here we discuss two case studies with novel mutations found in patients in China:

Li et al. (2017) report two Chinese BHD patients with novel FLCN mutations. The first case was a 54-year-old man with renal cell carcinoma (RCC), spontaneous pneumothorax (and spontaneous pneumothorax in his family history) and no apparent skin lesions. Genetic testing revealed a novel frameshift mutation (c.946-947delAG) of the FLCN gene. The second case was very similar, a 37-year-old man with chromophobe RCC, no cutaneous lesions, history of spontaneous pneumothorax and family history of pneumothorax. Genetic testing revealed the novel mutation c.770-772delCCT.

Hao et al. (2017) report the case of a 56-year-old Chinese woman who presented with multiple skin papules, pneumothorax and multiple bilateral pulmonary cysts. The patient underwent a tube thoracostomy and had a family history of spontaneous pneumothorax, of pulmonary bullae and of renal cell carcinoma (RCC). The patient’s pneumothorax recurred after 12 years and then she developed another pneumothorax at age 50 years. The patient then underwent surgical intervention. A chest computed tomography (CT) scan showed multiple cystic lesions. Ultrasound examination showed that the patient did not develop RCC, but multiple thyroid nodules were spotted (read previous blog about BHD and thyroid conditions). Genetic testing identified four FLCN mutations. An unreported mutation (c.2297 T > C) in exon 14, and three other mutations that were previously reported to have a minimal correlation to the onset of BHD (Cho et al., 2008) – a mutation in exon 1 (c.-299C > T), a mutation in intron 8 (c.871 + 36G > A) and a mutation in intron 9 (c.1062 + 6C > T).

To date, around 90% of the reported BHD patients are from Europe and the United States. The incidence of skin symptoms seems to be lower among Asian BHD patients (~30%) compared with the higher incidence reported among patients from western countries (~90%) (Murakami et al., 2014Toro et al., 2008Furuya et al., 2013). On the other hand, recurrent pneumothorax is observed in approximately 90% of Asian patients compared to the lower percentage among Western countries patients (Kunogi et al., 2010).

In patients with RCC and pulmonary cysts but without cutaneous lesions, screening for mutations in the FLCN gene should be performed, especially for those with a family history of RCC or pneumothorax. Novel FLCN mutations are still being identified all over the world, to add to those already listed in LOVD-hosted FLCN mutation database. Further studies using large cohorts are still needed to clarify possible genotype–phenotype correlations in BHD syndrome.

  • Li T, Ning X, He Q, & Gong K (2017). Novel germline mutations in FLCN gene identified in two Chinese patients with Birt-Hogg-Dubé syndrome. Chinese journal of cancer, 36 (1) PMID: 28069055
  • Hao S, Long F, Sun F, Liu T, Li D, & Jiang S (2017). Birt-Hogg-Dubé syndrome: a literature review and case study of a Chinese woman presenting a novel FLCN mutation. BMC pulmonary medicine, 17 (1) PMID: 28222720

BHD syndrome: a new case report and a review

Birt-Hogg-Dubé syndrome (BHD), also known as Hornstein–Knickenberg syndrome is an inherited disease associated with skin lesions, lung cysts, pneumothorax and kidney cancer.

Jensen et al. (2017) present a new case report of BHD and a review of the literature. This is a great opportunity to review the genetics, clinical manifestations, diagnosis, treatment, prognosis and follow-up strategies and to draw attention to BHD, unknown to many physicians. Early diagnosis is crucial so that patients can have access to systematic screening for kidney cancer.

The new case report is of a 29-year old female presenting with a spontaneous pneumothorax (SP) two days after running a marathon. The patient also had 11 relatives with cases of SP, therefore she was referred for follow-up. A high-resolution computed tomography (HRCT) scan showed multiple cysts in the lungs, which led to the suspicion of BHD. Genetic testing revealed a mutation (c.1285delC) in the FLCN gene which confirmed the diagnosis of BHD. Family members were offered genetic counselling and 11 family members were diagnosed. The patient and her affected family members were offered a follow-up program with MRI of the kidneys and pulmonary function tests.

Obtained from Jensen et al. (2017)

A search on PubMed and Embase with the terms ‘Birt-Hogg-Dubé syndrome’ and ‘Hornstein-Knickenberg syndrome’ identified 330 papers. Additional articles were identified from reference lists of the already identified papers (snow ball search).

The authors then reviewed what is known about BHD based on these publications, some of which we highlight here:

  • BHD is named after 3 Canadian doctors, who described the syndrome in 1977. They reported a family of 70 members with 15 family members who developed skin lesions on the face, neck, and torso.
  • The autosomal dominant inheritance of the combination of skin manifestations and renal cell carcinoma (RCC) in BHD was first described by Toro et al. in 1999. In this study, lung manifestations were also noticed.
  • In 2001, Schmidt et al. and Khoo et al. located the gene locus of BHD to be on the short arm of chromosome 17 and in 2002 Nickerson et al. linked BHD to the FLCN gene on chromosome 17, which encodes the protein folliculin.
  • Zbar et al. (2002) reported that patients with BHD had a 50-fold risk of SP and a 7-fold increased risk of developing RCC. The histology of renal tumours in BHD is diverse.
  • Several FLCN interacting proteins including FNIP1 and FNIP2 have been identified (Baba et al., 2005; Hasumi et al., 2008).
  • FLCN regulates numerous signalling pathways, including the mammalian target of rapamycin (mTOR) pathway.
  • Neither gender, nor smoking, nor other risk factors have been reported as predictors of the development of cysts or SP. Lung function is rarely affected.
  • Almoosa et al. (2006) found that pleurodesis decreases the pneumothorax recurrence rate, and pleurodesis after the first SP in BHD has been recommended.
  • Skin manifestations are common in BHD and are seen in approximately 58–90% of patients. Fibrofolliculomas are the most frequent, but also trichodiscomas and acrochordons have been described. Fibrofolliculomas present as multiple, pale yellow or white, slightly elevated, dome-shaped, and smooth tumours with a diameter of 2–4 mm. Fibrofolliculomas are predominantly located in the face, neck, and upper torso.
  • A recent double-blind placebo-controlled randomized clinical trial showed no effect of the topical mTOR inhibitor rapamycin on fibrofolliculomas in BHD patients.
  • Since 2008, six BHD symposia have been held where researchers, clinicians, and patients meet and discuss the progress in the BHD field.
  • Currently, the BHD foundation is aware of over 600 BHD families worldwide.
  • Due to its rarity and to the variable presentation of the symptoms, the diagnosis of BHD is often delayed for years. The European BHD consortium has proposed a set of criteria for the diagnosis of BHD. Upon diagnosis of BHD, the patients should undergo examination of the skin, CT imaging of the chest, abdominal MR or CT imaging for renal tumours as well as genetic screening for pathogenic FLCN mutations.

In summary, knowledge in the BHD field is still limited. The variable clinical manifestations of BHD and the fact that no genotype-phenotype correlations have been found, makes early diagnosis and management of BHD complex. Further research is needed to investigate the exact mechanisms of pathogenesis and to optimize the management of BHD patients.

  • Jensen, D., Villumsen, A., Skytte, A., Madsen, M., Sommerlund, M., & Bendstrup, E. (2017). Birt–Hogg–Dubé syndrome: a case report and a review of the literature European Clinical Respiratory Journal, 4 (1) DOI: 10.1080/20018525.2017.1292378

Ammonium regulates mTOR signalling

mTORC1 and mTORC2 are two distinct mammalian TOR (target of rapamycin) complexes that regulate cell growth and metabolism. In cancer, genetic alterations lead to activation of mTOR signalling impacting tumour metabolism. Upregulated glutaminolysis is part of the metabolic reaction occurring in cancer that liberates high levels of ammonium, a toxic waste product. Although the importance of glutamine as a tumour nutrient is recognized, little is known about the potential effects of ammonium produced by glutaminolysis in tumours. In their new study,  Merhi et al., 2017 identify ammonium as a dose-dependent regulator of mTORC2, mTORC1 and of proliferation in cancer cells.

To study potential signalling pathways responding to ammonium, the authors performed a kinase array with lysates of MCF-7 breast cancer cells and detected an increase in the phosphorylation of the kinases AKT-S473 and ERK1/2 upon ammonium addition in a time and dose dependent manner. This was confirmed by western blot. Similarly, the authors observed AKT phosphorylation in other cancer and fibroblast cell lines. The upstream pathway leading to the induction of AKT phosphorylation was investigated. Pre-treatment of MCF-7 cells with a PI3K inhibitor impaired AKT phosphorylation and prevented its induction by ammonium supplementation. mTORC2 has been shown to promote cell proliferation and survival by phosphorylation and activation of the AKT and SGK and the phosphorylation of AKT-S473 is a good readout for mTORC2 activity (Oh et al., 2011). Merhi et al. show that siRNA-mediated knockdown of RICTOR (a subunit of mTORC2), leads to reduction of basal and ammonium-induced AKT-S473 phosphorylation. In addition, ammonium also induced NDRG1-T346 phosphorylation, another readout of mTORC2 activity. Knockdown of YES1 kinase and pharmacological inhibition of the focal adhesion kinase (FAK) decreased ammonium-induced AKT-S473 and NDRG1-T346 phosphorylation. The authors also addressed if integrins, known regulators of FAK signalling, was involved in the ammonium-induced AKT-S473 phosphorylation. Results showed that knockdown of ITGβ1 decreased the basal and the ammonium-induced AKT-S473 phosphorylation. Collectively the data indicates that ammonium-induced activation of mTORC2 involves ITGβ1, FAK, YES1, and PI3K signalling.

Ammonium treatment has been shown to induce a transient increase in calcium in cultured astrocytes (Rose et al., 2005). To explore this, the authors assessed the role of calcium in ammonium-induced mTORC2 activation. Pre-treatment of cells with a calcium chelator decreased basal and ammonium-induced AKT-S473 and NDRG1-T346 phosphorylation. In addition, an increase in cytoplasmic calcium concentration induced a rapid increase in AKT-S473 phosphorylation in a mTORC2- dependent way, suggesting that ammonium-induced mTORC2-dependent AKT phosphorylation is modulated by intracellular calcium mobilization.

The impact of ammonium on the activity of mTORC1 remains unclear. The kinase array revealed a decreased phosphorylation of p70S6K-T389, an mTORC1 readout, after treatment with ammonium, suggesting ammonium potentially inhibits mTORC1. Western blot analysis confirmed this mild decrease in phosphorylation. However, this weak dephosphorylation appeared transient, suggesting that the inhibition of mTORC1 was quickly compensated by a reactivation. AKT activation has been shown to promote mTORC1 by inhibiting the TSC complex. In addition, AKT-mediated phosphorylation of another negative regulator of mTORC1, PRAS40, prevents its inhibitory role (Dibble et al., 2015). Merhi et al. found that ammonium induced the rapid phosphorylation of TSC2-T1462, PRAS40-T246 and of 4EBP1 – another readout of mTORC1 activity – suggesting consequent rapid mTORC1 activation. This shows an additional regulatory process upon ammonium addition that transiently counteracts the mTORC1-mediated stimulation of p70S6K-T389 phosphorylation. Treatment with an inhibitor of AKT, not only prevented the ammonium-induced phosphorylation of AKT, but also reduced the phosphorylation of TSC2, PRAS40 and 4EBP1, consistent with ammonium-induced activation of mTORC1 being AKT-dependent.

The impact of ammonium on the proliferation of MCF-7 cells was also assessed. Adding high concentrations of ammonium (~15 mM) resulted in significant cell growth inhibition while low concentrations stimulated growth both in the presence or absence of glutamine supplementation.

In summary, the authors show that ammonium triggers mTORC2-dependent phosphorylation of AKT-S473 in cancer cells. The mTORC2 activation occurs via the PI3K pathway and relies on YES1 and FAK kinases, on integrin ITGβ1 and on intracellular calcium stores mobilization. In addition, ammonium also leads to an AKT-dependent stimulation of mTORC1 signalling and to a dose-dependent stimulation of proliferation. This study identifies that ammonium, a waste product of cancer cells, impacts both mTORC2 and mTORC1 signalling and brings insights into the molecular mechanism of the ammonium-mediated regulation and tumour growth.

FLCN, the gene responsible for BHD Syndrome, has been shown to regulate mTOR signalling. Our interactive folliculin signalling diagram illustrates the relationship between Folliculin (FLCN) and several proteins and signalling pathways including mTORC1 and mTORC2.

  • Merhi A, Delrée P, & Marini AM (2017). The metabolic waste ammonium regulates mTORC2 and mTORC1 signaling. Scientific reports, 7 PMID: 28303961

Shire Rare Disease Summit

In the field of rare diseases one of the key points of progress is to ensure that rare disease patients benefit from advances in medical sciences. To promote this, the global biotechnology company Shire hosted a Rare Disease Summit yesterday in London, which focused on the policy environment for patient access to orphan drugs and how this can be improved. The Summit was also marked by the launch of a report: “Equity and Access – Making the UK a Rare Disease Leader”, funded by Shire and developed by an expert steering group which includes recommendations to improve access to orphan drugs in the UK.

Segolene Ayme from the French Institute of Health and Medical Research (Inserm) and Bertram Haussler from the IGES Institute presented French and German policy developments in improving the quality of care and access to orphan drugs for rare disease patients.

Josie Godfrey, a former NICE director, talked about the creation of the Advisory Group for National Specialised Services (AGNSS) in the UK and how before there had been no systematic approach to look into rare and ultra rare diseases. Josie focused on the point that everyone should get access to the health system with the same prices and same effectiveness.

Christine Lavery from the MPS Society discussed issues with funding for rare diseases, mentioning that it is important to recognise affordability and budget impact but that the Pharmaceutical Price Regulation Scheme (PPRS) in the UK does not put any money into rare diseases and shows no benefits for these patients.

Trevor Cole from Birmingham Women’s Hospital talked about the “perceived difficulties” in the rare disease field such as the small numbers of patients, the surrogate end points, the fact that there is often no possibility of comparison with other conditions and the high variability between diseases and discussed how we can benefit from these difficulties. For example, small numbers keep the costs down, patients can be followed in a smaller number of centres, there is more detailed observation and therefore it is easier to pick up more nuanced changes in each patient. The endpoints can be considered more critically with expertly designed and run studies and a better understanding of the disease process allowing the identification of better surrogate markers.

Ulf Staginnus from Shire gave an industry perspective mentioning that alternative pricing is needed along with engaging with a broader perspective – thinking about how can rare disease research and drug discovery benefit society – and finding alternative models.

Virginia Acha from the Association of the British Pharmaceutical Industry (ABPI) talked about the importance of raising public consciousness of  rare diseases and how partnerships are key since most innovations in rare disease drugs or devices happen by combining different fields such as biology, engineering and nanotechnology.

Neil Churchill from NHS England shared his experience as director of patient experience dealing with the difficulties patients have with the system such as lack of involvement and poor communication between patients and physicians. Neil emphasised that good experience of care makes patients safer and gives them better outcomes.

Nick Meade from Genetic Alliance UK gave a talk about the patient voice in rare disease decision making and how patients should play a role as policy makers, decision makers, information providers and how they should be able to make informed, private and individual choices about personal care provision. Nick discussed how NHS England is failing to bring the patients into policymaking and the lack of transparency and communication that exists around patients as decision makers as members of Clinical Reference Groups.

Tom Fowler from Genomics England discussed the 100,000 Genomes project that has been discussed in a previous blog. He highlighted the impressive amount of data gathered – 21 petabytes – and how this will bring benefits for NHS England patients.

The meeting ended with some discussion and closing remarks and all delegates left with the idea that there is a long way to go to ensure that rare disease patients receive the care they deserve and how debate and collaboration between all stakeholders in the UK, in Europe and worldwide is essential.

Spontaneous Pneumothorax and air travel in BHD Syndrome

Previous studies show that BHD syndrome causes spontaneous pneumothorax (SP) in 24-38% of patients, with a recurrence rate of up to 75% (Toro et al., 2007; Toro et al., 2008; Houweling et al., 2011). A common preventative strategy used following an initial SP in patients with BHD is pleurodesis, however, its efficacy in preventing recurrent episodes is not well known. Due to the pressure changes during air travel, cystic air spaces expand and compress in the thorax possibly leading to cyst rupture and pneumothorax. In their new study, Gupta et al. (2017) evaluate the risk of pneumothorax, the efficacy of pleurodesis, and the safety of air travel in patients with BHD.

104 BHD patients were recruited from the Rare Lung Diseases Clinic Network and the BHD Foundation, and surveyed about pneumothorax and air travel experiences. This study classified any pneumothorax occurring either during a flight or within 24 hours after as a flight related pneumothorax. Differently, considering symptom delay, a recent study discussed on a previous blog classified any pneumothorax that happened within one month of air travel as flight related pneumothorax (Johannesma et al., 2016). Here, the limit to 24 hours meant to distinguish between a flight related SP and an unrelated SP that happened to occur after a flight.

 The survey results showed that the average age at diagnosis of BHD was 47 years, with an average delay from first symptoms of 13 years. Pulmonary cysts were the most frequent phenotypic manifestation of BHD, in 85% of patients. Spontaneous pneumothorax was the presenting manifestation that led to the diagnosis in 65% of patients, typically after the second episode. Mild symptomatic dyspnea was reported by 50% of the patients. 76% of patients had at least one spontaneous pneumothorax during their lifetime, and 82% had multiple. Of the patients with a sentinel pneumothorax, 73% had an ipsilateral recurrence. The mean age at first and second pneumothorax was 36.5 and 37 years, respectively and the average number of recurrent episodes was 3.6.

Spontaneous pneumothorax was mainly diagnosed by chest radiograph, with computed tomographic imaging used as a diagnostic modality for the first episode in only 8 patients. 62% of patients had at least one pleurodesis to prevent recurrent pneumothoraces. Pleurodesis was generally performed after the second pneumothorax and reduced the recurrence by half – 63% of recurrence rate of SP managed without pleurodesis compared to 33% following pleurodesis. Similar conclusions regarding efficacy of pleurodesis have been previously published (Johannesma et al., 2014).

Air travel

96% of the patients in the study had flown at least once in their lifetime and the average number of flights per patient was 25. There was no difference in the average number of flights taken by patients with a history of SP versus patients without a SP. Patients frequently experienced adverse effects during air travel, including chest pressure, anxiety, headache, shortness of breath and chest pain. 11 episodes of spontaneous pneumothorax occurred in 8 patients either during or within 24 hours of air travel. The authors calculated a flight related pneumothorax risk of 8% per patient, and 0.12% per flight. 8 of these 11 episodes represented recurrent SP and the majority had not undergone prior pleurodesis. Prior pleurodesis reduced the occurrence of a subsequent flight-related pneumothorax.

24% of patients changed their flight frequency after the diagnosis of BHD was established, either by avoiding or reducing air travel. The recommendations that patients were given by physicians regarding the safety of air travel after spontaneous pneumothorax were variable and more than half of the patients were given no specific recommendations. Clear recommendations are currently not available but studies emphasize that patients with a current closed pneumothorax should avoid air travel and recommend flight restrictions between 1 and 4 weeks after resolution of pneumothorax (Hu et al., 2014, Ahmedzai et al., 2011).

A significant proportion of the patients were recruited from pulmonary clinics, representing an ascertainment bias, perhaps causing the higher prevalence of spontaneous pneumothorax (76%) observed in this study compared with the 24-38% previously reported in the literature.

Similarly to Johannesma et al., 2016, the present study indicates that patients with BHD have a risk of spontaneous pneumothorax during flight that is most likely less than 1%, and even lower for patients with a history of pleurodesis. Patients with BHD should be advised about the risks of pneumothorax and benefits of pleurodesis and get medical advice regarding air travel.

  • Gupta N, Kopras EJ, Henske EP, James LE, El-Chemaly S, Veeraraghavan S, Drake MG, & McCormack FX (2017). Spontaneous Pneumothoraces in Patients with Birt-Hogg-Dubé Syndrome. Annals of the American Thoracic Society PMID: 28248571

Rare Disease Day – Findacure Scientific Conference: Drug Repurposing for Rare Diseases

This year’s Findacure Scientific Conference took place in London on Rare Disease Day and was again focused on Drug Repurposing for Rare Diseases. The conference brought together over 100 representatives from patient groups, researchers and members of the healthcare industry to discuss the importance and the latest developments in drug repurposing for rare diseases.

Rick Thompson from Findacure started the conference with an introduction to drug repurposing for rare diseases and its advantages. Currently from the ~7000 rare diseases only 400 have treatments. Finding new uses for existing drugs to treat a new population offers several advantages such as being faster and cheaper, the known safety profile, side effects and pathways of action of the drug and the reduction in early phase trials. To support drug repurposing Findacure is creating a Social Impact Bond (SIB) program to enable investment in drug repurposing projects for rare diseases that have high costs for the NHS by reducing the burden of the current care costs, generating returns from healthcare savings. If this model is successful this will be a new way to quickly develop new treatments for rare diseases. Findacure is promoting an open call for new repurposing ideas.

Tim Barrett from the University of Birmingham introduced drug repurposing for Wolfram syndrome, a very rare disease with no cure, no treatment and little research. p21cip1 was identified as a drug target and a drug screen for repurposed drugs took place. The screening identified sodium valproate, a drug used for epilepsy, as a potential candidate. The hypothesis was that sodium valproate administration would slow the rate of progression of neurodegeneration in Wolfram syndrome compared with current standard of care. Funding for a phase II efficacy study was awarded to pursue this idea. Tim ended his talk suggesting the possibility of having several arms in a clinical trial with different diseases with similar mechanisms or phenotypes being tested with a same drug.

Bev and Georgia Hart talked about their experience as a family affected by Friedreich’s ataxia. They specifically focused on their experience participating in an IFNγ clinical trial in the US highlighting how being able to act is so important for patients and how patients should be involved in deciding the outcomes of clinical trials.

Richard Wyse from The Cure Parkinson’s Trust (CPT) presented Parkinson’s as a series of rare diseases, unique to each patient. Drug repositioning represents one of CPT’s major therapeutic initiatives. They are currently promoting a Linked Clinical Trials initiative to evaluate, prioritise and repurpose existing regulatory-approved medications that may also have direct therapeutic benefits for patients with Parkinson’s.

Christine Charman from the company Takeda presented the TAK-celerator, a new business model to accelerate development of therapies in rare diseases. The TAK-celerator focus is to establish the capacity to execute rare diseases projects with external partners, to bridge the gap between academia and industry providing a mechanism to accelerate early stage programs to preclinical development and to reposition assets from the Takeda pipeline in addition to de novo opportunities

Daniel O’Connor from the MHRA and Jonathan Underhill from NICE talked about regulation, implementation and optimisation in drug repurposing. Daniel mentioned the regulatory incentives to support repurposing such as a new therapeutic indication for a well-established substance, Paediatric use marketing authorisation and Orphan drug designation. Jonathan presented the medicines optimisation approach, a person-centred approach to ensure people obtain the best possible outcomes from their medicines. This approach sees shared decision-making as an essential part of evidence-based medicine and is seeking to use the best available evidence to guide decisions about the care of the individual patient, considering their needs, preferences and values. Jonathan remembered that NICE offers guidelines not tramlines and that informed, shared decision making is key in drug repurposing for rare diseases.

This was followed by six lightning talks with five minutes presentations on mobilising information resources for rare diseases, on bringing the clinical trials to the patients in an in-home service, and on cases studies of drug repurposing in polyglucosan body disease, MdDS and mast cell and on accelerating the UK drug repurposing pipeline.

The last talk was given by Pan Pantziarka from the Anticancer Fund who shared their projects on repurposing non-cancer drugs for new indications in oncology in rare cancers.

BHD is a rare disease with no cure or preventative treatments available.  Greater understanding of the molecular pathways in BHD and their roles in pathology will enable researchers to identify drug target candidates since the BHD clinical trial with Rapamycin, an mTOR inhibitor, did not show promising results (Gijezan et al., 2014). Repositioning of known drugs could then be useful in discovering treatments for BHD and other rare diseases faster and more cost effectively than conventional drug development.

  • Gijezen LM, Vernooij M, Martens H, Oduber CE, Henquet CJ, Starink TM, Prins MH, Menko FH, Nelemans PJ, & van Steensel MA (2014). Topical rapamycin as a treatment for fibrofolliculomas in Birt-Hogg-Dubé syndrome: a double-blind placebo-controlled randomized split-face trial. PloS one, 9 (6) PMID: 24910976