Showing papers by "Novartis published in 2016"

Ribociclib as First-Line Therapy for HR-Positive, Advanced Breast Cancer

Abstract: BackgroundThe inhibition of cyclin-dependent kinases 4 and 6 (CDK4/6) could potentially overcome or delay resistance to endocrine therapy in advanced breast cancer that is positive for hormone receptor (HR) and negative for human epidermal growth factor receptor 2 (HER2). MethodsIn this randomized, placebo-controlled, phase 3 trial, we evaluated the efficacy and safety of the selective CDK4/6 inhibitor ribociclib combined with letrozole for first-line treatment in 668 postmenopausal women with HR-positive, HER2-negative recurrent or metastatic breast cancer who had not received previous systemic therapy for advanced disease. We randomly assigned the patients to receive either ribociclib (600 mg per day on a 3-weeks-on, 1-week-off schedule) plus letrozole (2.5 mg per day) or placebo plus letrozole. The primary end point was investigator-assessed progression-free survival. Secondary end points included overall survival, overall response rate, and safety. A preplanned interim analysis was performed on Januar...

Dabrafenib plus trametinib in patients with previously untreated BRAFV600E-mutant metastatic non-small-cell lung cancer: an open-label, phase 2 trial

Abstract: Summary Background BRAF mutations act as an oncogenic driver via the mitogen-activated protein kinase (MAPK) pathway in non-small cell lung cancer (NSCLC). BRAF inhibition has shown antitumour activity in patients with BRAF V600E -mutant NSCLC. Dual MAPK pathway inhibition with BRAF and MEK inhibitors in BRAF V600E -mutant NSCLC might improve efficacy over BRAF inhibitor monotherapy based on observations in BRAF V600 -mutant melanoma. We aimed to assess the antitumour activity and safety of dabrafenib plus trametinib in patients with BRAF V600E -mutant NSCLC. Methods In this phase 2, multicentre, non-randomised, open-label study, we enrolled adult patients (aged ≥18 years) with pretreated metastatic stage IV BRAF V600E -mutant NSCLC who had documented tumour progression after at least one previous platinum-based chemotherapy and had had no more than three previous systemic anticancer therapies. Patients with previous BRAF or MEK inhibitor treatment were ineligible. Patients with brain metastases were allowed to enrol only if the lesions were asymptomatic, untreated (or stable more than 3 weeks after local therapy if treated), and measured less than 1 cm. Enrolled patients received oral dabrafenib (150 mg twice daily) plus oral trametinib (2 mg once daily) in continuous 21-day cycles until disease progression, unacceptable adverse events, withdrawal of consent, or death. The primary endpoint was investigator-assessed overall response, which was assessed by intention to treat in the protocol-defined population (patients who received second-line or later treatment); safety was also assessed in this population and was assessed at least once every 3 weeks, with adverse events, laboratory values, and vital signs graded according to the Common Terminology Criteria for Adverse Events version 4.0. The study is ongoing but no longer recruiting patients. This trial is registered with ClinicalTrials.gov, number NCT01336634. Findings Between Dec 20, 2013, and Jan 14, 2015, 59 patients from 30 centres in nine countries across North America, Europe, and Asia met eligibility criteria. Two patients who had previously been untreated due to protocol deviation were excluded; thus, 57 eligible patients were enrolled. 36 patients (63·2% [95% CI 49·3–75·6]) achieved an investigator-assessed overall response. Serious adverse events were reported in 32 (56%) of 57 patients and included pyrexia in nine (16%), anaemia in three (5%), confusional state in two (4%), decreased appetite in two (4%), haemoptysis in two (4%), hypercalcaemia in two (4%), nausea in two (4%), and cutaneous squamous cell carcinoma in two (4%). The most common grade 3–4 adverse events were neutropenia in five patients (9%), hyponatraemia in four (7%), and anaemia in three (5%). Four patients died during the study from fatal adverse events judged to be unrelated to treatment (one retroperitoneal haemorrhage, one subarachnoid haemorrhage, one respiratory distress, and one from disease progression that was more severe than typical progression, as assessed by the investigator). Interpretation Dabrafenib plus trametinib could represent a new targeted therapy with robust antitumour activity and a manageable safety profile in patients with BRAF V600E -mutant NSCLC. Funding GlaxoSmithKline.

GSDMD membrane pore formation constitutes the mechanism of pyroptotic cell death

Abstract: Pyroptosis is a lytic type of cell death that is initiated by inflammatory caspases. These caspases are activated within multi-protein inflammasome complexes that assemble in response to pathogens and endogenous danger signals. Pyroptotic cell death has been proposed to proceed via the formation of a plasma membrane pore, but the underlying molecular mechanism has remained unclear. Recently, gasdermin D (GSDMD), a member of the ill-characterized gasdermin protein family, was identified as a caspase substrate and an essential mediator of pyroptosis. GSDMD is thus a candidate for pyroptotic pore formation. Here, we characterize GSDMD function in live cells and in vitro We show that the N-terminal fragment of caspase-1-cleaved GSDMD rapidly targets the membrane fraction of macrophages and that it induces the formation of a plasma membrane pore. In vitro, the N-terminal fragment of caspase-1-cleaved recombinant GSDMD tightly binds liposomes and forms large permeability pores. Visualization of liposome-inserted GSDMD at nanometer resolution by cryo-electron and atomic force microscopy shows circular pores with variable ring diameters around 20 nm. Overall, these data demonstrate that GSDMD is the direct and final executor of pyroptotic cell death.

Tumor cells can follow distinct evolutionary paths to become resistant to epidermal growth factor receptor inhibition

Abstract: Although mechanisms of acquired resistance of epidermal growth factor receptor (EGFR)-mutant non-small-cell lung cancers to EGFR inhibitors have been identified, little is known about how resistant clones evolve during drug therapy. Here we observe that acquired resistance caused by the EGFR(T790M) gatekeeper mutation can occur either by selection of pre-existing EGFR(T790M)-positive clones or via genetic evolution of initially EGFR(T790M)-negative drug-tolerant cells. The path to resistance impacts the biology of the resistant clone, as those that evolved from drug-tolerant cells had a diminished apoptotic response to third-generation EGFR inhibitors that target EGFR(T790M); treatment with navitoclax, an inhibitor of the anti-apoptotic factors BCL-xL and BCL-2 restored sensitivity. We corroborated these findings using cultures derived directly from EGFR inhibitor-resistant patient tumors. These findings provide evidence that clinically relevant drug-resistant cancer cells can both pre-exist and evolve from drug-tolerant cells, and they point to therapeutic opportunities to prevent or overcome resistance in the clinic.

Visualizing Genomic Data Using Gviz and Bioconductor.

Abstract: The Gviz package offers a flexible framework to visualize genomic data in the context of a variety of different genome annotation features. Being tightly embedded in the Bioconductor genomics landscape, it nicely integrates with the existing infrastructure, but also provides direct data retrieval from external sources like Ensembl and UCSC and supports most of the commonly used annotation file types. Through carefully chosen default settings the package greatly facilitates the production of publication-ready figures of genomic loci, while still maintaining high flexibility due to its ample customization options.

Indacaterol–Glycopyrronium versus Salmeterol–Fluticasone for COPD

Abstract: BackgroundMost guidelines recommend either a long-acting beta-agonist (LABA) plus an inhaled glucocorticoid or a long-acting muscarinic antagonist (LAMA) as the first-choice treatment for patients with chronic obstructive pulmonary disease (COPD) who have a high risk of exacerbations The role of treatment with a LABA–LAMA regimen in these patients is unclear MethodsWe conducted a 52-week, randomized, double-blind, double-dummy, noninferiority trial Patients who had COPD with a history of at least one exacerbation during the previous year were randomly assigned to receive, by inhalation, either the LABA indacaterol (110 μg) plus the LAMA glycopyrronium (50 μg) once daily or the LABA salmeterol (50 μg) plus the inhaled glucocorticoid fluticasone (500 μg) twice daily The primary outcome was the annual rate of all COPD exacerbations ResultsA total of 1680 patients were assigned to the indacaterol–glycopyrronium group, and 1682 to the salmeterol–fluticasone group Indacaterol–glycopyrronium showed not onl

Coinhibitory Pathways in Immunotherapy for Cancer.

Abstract: The immune system is capable of recognizing tumors and eliminates many early malignant cells. However, tumors evolve to evade immune attack, and the tumor microenvironment is immunosuppressive. Immune responses are regulated by a number of immunological checkpoints that promote protective immunity and maintain tolerance. T cell coinhibitory pathways restrict the strength and duration of immune responses, thereby limiting immune-mediated tissue damage, controlling resolution of inflammation, and maintaining tolerance to prevent autoimmunity. Tumors exploit these coinhibitory pathways to evade immune eradication. Blockade of the PD-1 and CTLA-4 checkpoints is proving to be an effective and durable cancer immunotherapy in a subset of patients with a variety of tumor types, and additional combinations are further improving response rates. In this review we discuss the immunoregulatory functions of coinhibitory pathways and their translation to effective immunotherapies for cancer.

Twenty years on: the impact of fragments on drug discovery.

Abstract: Fragment-based methods have made substantial contributions to drug discovery in the past 20 years, particularly for challenging targets. Erlanson and colleagues discuss progress in the field, key aspects such as the design of fragment libraries and the choice of screening technique, and how current challenges in fragment-based drug discovery might be overcome.

Allosteric inhibition of SHP2 phosphatase inhibits cancers driven by receptor tyrosine kinases

Abstract: SHP099, a selective inhibitor of signalling meditator SHP2 with drug-like properties, has an allosteric mechanism of action whereby it stabilizes SHP2 in an auto-inhibited conformation, and suppresses RAS–ERK signalling and proliferation in receptor-tyrosine-kinase-driven cancer cell lines and mouse tumour xenograft models. The tyrosine phosphatase SHP2 is a key mediator of receptor tyrosine kinase (RTK) signalling, as well as being important in immune checkpoint pathways. Reduction of SHP2 activity suppresses tumour cell growth, and SHP2 is a potential, but so far elusive, therapeutic target in cancer. Pascal Fortin and colleagues report the development of a selective SHP2 inhibitor with drug-like properties. The inhibitor, SHP099, has an allosteric mechanism of action whereby it stabilizes SHP2 in an auto-inhibited conformation. It also suppresses RAS–ERK signalling to inhibit RTK-driven proliferation in human cancer cell lines and mouse tumour xenograft models. The non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, has an important role in signal transduction downstream of growth factor receptor signalling and was the first reported oncogenic tyrosine phosphatase1. Activating mutations of SHP2 have been associated with developmental pathologies such as Noonan syndrome and are found in multiple cancer types, including leukaemia, lung and breast cancer and neuroblastoma1,2,3,4,5. SHP2 is ubiquitously expressed and regulates cell survival and proliferation primarily through activation of the RAS–ERK signalling pathway2,3. It is also a key mediator of the programmed cell death 1 (PD-1) and B- and T-lymphocyte attenuator (BTLA) immune checkpoint pathways6,7. Reduction of SHP2 activity suppresses tumour cell growth and is a potential target of cancer therapy8,9. Here we report the discovery of a highly potent (IC50 = 0.071 μM), selective and orally bioavailable small-molecule SHP2 inhibitor, SHP099, that stabilizes SHP2 in an auto-inhibited conformation. SHP099 concurrently binds to the interface of the N-terminal SH2, C-terminal SH2, and protein tyrosine phosphatase domains, thus inhibiting SHP2 activity through an allosteric mechanism. SHP099 suppresses RAS–ERK signalling to inhibit the proliferation of receptor-tyrosine-kinase-driven human cancer cells in vitro and is efficacious in mouse tumour xenograft models. Together, these data demonstrate that pharmacological inhibition of SHP2 is a valid therapeutic approach for the treatment of cancers.

Long-term benefits and risks of frontline nilotinib vs imatinib for chronic myeloid leukemia in chronic phase: 5-year update of the randomized ENESTnd trial.

Abstract: Long-term benefits and risks of frontline nilotinib vs imatinib for chronic myeloid leukemia in chronic phase: 5-year update of the randomized ENESTnd trial

The tumor microenvironment underlies acquired resistance to CSF-1R inhibition in gliomas

Abstract: Macrophages accumulate with glioblastoma multiforme (GBM) progression and can be targeted via inhibition of colony-stimulating factor-1 receptor (CSF-1R) to regress high-grade tumors in animal models of this cancer. However, whether and how resistance emerges in response to sustained CSF-1R blockade is unknown. We show that although overall survival is significantly prolonged, tumors recur in >50% of mice. Gliomas reestablish sensitivity to CSF-1R inhibition upon transplantation, indicating that resistance is tumor microenvironment-driven. Phosphatidylinositol 3-kinase (PI3K) pathway activity was elevated in recurrent GBM, driven by macrophage-derived insulin-like growth factor-1 (IGF-1) and tumor cell IGF-1 receptor (IGF-1R). Combining IGF-1R or PI3K blockade with CSF-1R inhibition in recurrent tumors significantly prolonged overall survival. Our findings thus reveal a potential therapeutic approach for treating resistance to CSF-1R inhibitors.

STK11/LKB1 deficiency promotes neutrophil recruitment and proinflammatory cytokine production to suppress T cell activity in the lung tumor microenvironment

Abstract: STK11/LKB1 is among the most commonly inactivated tumor suppressors in non-small cell lung cancer (NSCLC), especially in tumors harboring KRAS mutations. Many oncogenes promote immune escape, undermining the effectiveness of immunotherapies, but it is unclear whether the inactivation of tumor suppressor genes, such as STK11/LKB1, exerts similar effects. In this study, we investigated the consequences of STK11/LKB1 loss on the immune microenvironment in a mouse model of KRAS-driven NSCLC. Genetic ablation of STK11/LKB1 resulted in accumulation of neutrophils with T-cell-suppressive effects, along with a corresponding increase in the expression of T-cell exhaustion markers and tumor-promoting cytokines. The number of tumor-infiltrating lymphocytes was also reduced in LKB1-deficient mouse and human tumors. Furthermore, STK11/LKB1-inactivating mutations were associated with reduced expression of PD-1 ligand PD-L1 in mouse and patient tumors as well as in tumor-derived cell lines. Consistent with these results, PD-1-targeting antibodies were ineffective against Lkb1-deficient tumors. In contrast, treating Lkb1-deficient mice with an IL6-neutralizing antibody or a neutrophil-depleting antibody yielded therapeutic benefits associated with reduced neutrophil accumulation and proinflammatory cytokine expression. Our findings illustrate how tumor suppressor mutations can modulate the immune milieu of the tumor microenvironment, and they offer specific implications for addressing STK11/LKB1-mutated tumors with PD-1-targeting antibody therapies.

Activity and safety of ceritinib in patients with ALK-rearranged non-small-cell lung cancer (ASCEND-1): updated results from the multicentre, open-label, phase 1 trial

Abstract: Summary Background ALK -rearranged non-small-cell lung cancer (NSCLC) is sensitive to ALK tyrosine kinase inhibitors (ALK inhibitors) such as crizotinib, but resistance invariably develops, often with progression in the brain. Ceritinib is a more potent ALK inhibitor than crizotinib in vitro, crosses the blood–brain barrier in vivo, and shows clinical responses in patients with crizotinib-resistant disease. We aimed to assess whole-body activity of ceritinib in both ALK inhibitor-pretreated and ALK inhibitor-naive patients with ALK -rearranged NSCLC. Methods ASCEND-1 was an open-label, phase 1 trial that recruited patients from 20 academic hospitals or cancer centres in 11 countries in Europe, North America, and Asia-Pacific. Eligible patients were aged 18 years or older with ALK -rearranged locally advanced or metastatic cancer that had progressed despite standard therapy (or for which no effective standard therapy existed), who had at least one measurable lesion at baseline. The primary objective (to determine the maximum tolerated dose) has been reported previously. This updated analysis includes all patients with ALK -rearranged NSCLC given oral ceritinib at the recommended dose of 750 mg/day in the dose-escalation and expansion phases. Here we report the secondary outcomes of overall response, duration of response, and progression-free survival, analysed in all patients who received at least one 750 mg dose of ceritinib. Exploratory analyses included retrospective analysis of intracranial activity by independent neuroradiologists, in patients with untreated or locally treated neurologically stable brain metastases at baseline. Safety was assessed in all patients who received at least one dose of ceritinib. This study is no longer recruiting patients; however, treatment and follow-up are ongoing. This study is registered with ClinicalTrials.gov, number NCT01283516. Findings Between Jan 24, 2011, and July 31, 2013, 255 patients were enrolled and received at least one dose of ceritinib 750 mg/day, of whom 246 had ALK -rearranged NSCLC. At data cutoff (April 14, 2014), median follow-up was 11·1 months (IQR 6·7–15·2) and 147 (60%) patients had discontinued treatment, 98 (40%) as a result of disease progression. An overall response was reported in 60 (72% [95% CI 61–82]) of 83 ALK inhibitor-naive patients and 92 (56% [49–64]) of 163 ALK inhibitor-pretreated patients. Median duration of response was 17·0 months (95% CI 11·3–non-estimable [NE]) in ALK inhibitor-naive patients and 8·3 months (6·8–9·7) in ALK inhibitor-pretreated patients. Median progression-free survival was 18·4 months (95% CI 11·1–NE) in ALK inhibitor-naive patients and 6·9 months (5·6–8·7) in ALK inhibitor-pretreated patients. Of 94 patients with retrospectively confirmed brain metastases and at least one post-baseline MRI or CT tumour assessment, intracranial disease control was reported in 15 (79% [95% CI 54–94]) of 19 ALK inhibitor-naive patients and in 49 (65% [54–76]) of 75 ALK inhibitor-pretreated patients. Of these 94 patients, 11 had measurable brain lesions and no previous radiotherapy to the brain, six of whom achieved a partial intracranial response. Serious adverse events were recorded in 117 (48%) of 246 patients. The most common grade 3–4 laboratory abnormalities were increased alanine aminotransferase (73 [30%] patients) and increased aspartate aminotransferase (25 [10%]). The most common grade 3–4 non-laboratory adverse events were diarrhoea and nausea, both of which occurred in 15 (6%) patients. Two on-treatment deaths during the study were deemed to be related to study drug by the investigators, one due to interstitial lung disease and one as a result of multiorgan failure that occurred in the context of infection and ischaemic hepatitis. Interpretation The durable whole-body responses reported, together with the intracranial activity, support a clinical benefit for treatment with ceritinib in patients with ALK -rearranged NSCLC who have received crizotinib, or as an alternative to crizotinib. A confirmatory phase 2 clinical trial is ongoing to assess ceritinib activity in patients with ALK -rearranged NSCLC and brain or leptomeningeal metastases. Funding Novartis Pharmaceuticals Corporation.

Open Source Drug Discovery with the Malaria Box Compound Collection for Neglected Diseases and Beyond.

Abstract: A major cause of the paucity of new starting points for drug discovery is the lack of interaction between academia and industry. Much of the global resource in biology is present in universities, whereas the focus of medicinal chemistry is still largely within industry. Open source drug discovery, with sharing of information, is clearly a first step towards overcoming this gap. But the interface could especially be bridged through a scale-up of open sharing of physical compounds, which would accelerate the finding of new starting points for drug discovery. The Medicines for Malaria Venture Malaria Box is a collection of over 400 compounds representing families of structures identified in phenotypic screens of pharmaceutical and academic libraries against the Plasmodium falciparum malaria parasite. The set has now been distributed to almost 200 research groups globally in the last two years, with the only stipulation that information from the screens is deposited in the public domain. This paper reports for the first time on 236 screens that have been carried out against the Malaria Box and compares these results with 55 assays that were previously published, in a format that allows a meta-analysis of the combined dataset. The combined biochemical and cellular assays presented here suggest mechanisms of action for 135 (34%) of the compounds active in killing multiple life-cycle stages of the malaria parasite, including asexual blood, liver, gametocyte, gametes and insect ookinete stages. In addition, many compounds demonstrated activity against other pathogens, showing hits in assays with 16 protozoa, 7 helminths, 9 bacterial and mycobacterial species, the dengue fever mosquito vector, and the NCI60 human cancer cell line panel of 60 human tumor cell lines. Toxicological, pharmacokinetic and metabolic properties were collected on all the compounds, assisting in the selection of the most promising candidates for murine proof-of-concept experiments and medicinal chemistry programs. The data for all of these assays are presented and analyzed to show how outstanding leads for many indications can be selected. These results reveal the immense potential for translating the dispersed expertise in biological assays involving human pathogens into drug discovery starting points, by providing open access to new families of molecules, and emphasize how a small additional investment made to help acquire and distribute compounds, and sharing the data, can catalyze drug discovery for dozens of different indications. Another lesson is that when multiple screens from different groups are run on the same library, results can be integrated quickly to select the most valuable starting points for subsequent medicinal chemistry efforts.

Long-term findings from COMFORT-II, a phase 3 study of ruxolitinib vs best available therapy for myelofibrosis

Abstract: Ruxolitinib is a Janus kinase (JAK) (JAK1/JAK2) inhibitor that has demonstrated superiority over placebo and best available therapy (BAT) in the Controlled Myelofibrosis Study with Oral JAK Inhibitor Treatment (COMFORT) studies. COMFORT-II was a randomized (2:1), open-label phase 3 study in patients with myelofibrosis; patients randomized to BAT could crossover to ruxolitinib upon protocol-defined disease progression or after the primary end point, confounding long-term comparisons. At week 48, 28% (41/146) of patients randomized to ruxolitinib achieved ⩾35% decrease in spleen volume (primary end point) compared with no patients on BAT (P<0.001). Among the 78 patients (53.4%) in the ruxolitinib arm who achieved ⩾35% reductions in spleen volume at any time, the probability of maintaining response was 0.48 (95% confidence interval (CI), 0.35-0.60) at 5 years (median, 3.2 years). Median overall survival was not reached in the ruxolitinib arm and was 4.1 years in the BAT arm. There was a 33% reduction in risk of death with ruxolitinib compared with BAT by intent-to-treat analysis (hazard ratio (HR)=0.67; 95% CI, 0.44-1.02; P=0.06); the crossover-corrected HR was 0.44 (95% CI, 0.18-1.04; P=0.06). There was no unexpected increased incidence of adverse events with longer exposure. This final analysis showed that spleen volume reductions with ruxolitinib were maintained with continued therapy and may be associated with survival benefits.

Prevalence of ESR1 Mutations in Cell-Free DNA and Outcomes in Metastatic Breast Cancer: A Secondary Analysis of the BOLERO-2 Clinical Trial.

Abstract: Importance Estrogen receptor α ( ESR1 ) mutations found in metastatic breast cancer (MBC) promote ligand-independent receptor activation and resistance to estrogen-deprivation therapy in laboratory models. The prevalence of these mutations and their potential impact on clinical outcomes has not been established. Objective To determine the prevalence of ESR1 mutations (Y537S and D538G) in estrogen receptor (ER)-positive MBC and determine whether mutation is associated with inferior outcomes. Design, Setting, and Participants From December 16, 2014, to August 26, 2015, we analyzed cell-free DNA (cfDNA) from baseline plasma samples from participants in the BOLERO-2 double-blind phase 3 study that randomized patients from 189 centers in 24 countries with MBC to exemestane plus placebo or exemestane plus everolimus. The study enrolled postmenopausal women with a diagnosis of MBC and prior exposure to an aromatase inhibitor. Baseline plasma samples were available from 541 of 724 patients (74.7%). We assessed the effect of mutation on overall survival of the population and the effect of mutation on progression-free survival (PFS) by treatment arm. Interventions Patients were randomized to treatment with exemestane (25 mg oral daily) together with everolimus (10 mg oral daily) or with placebo. Main Outcomes and Measures The 2 most frequent mutations in ESR1 (Y537S and D538G) were analyzed from cfDNA using droplet digital polymerase chain reaction and samples scored as wild-type, D538G, Y537S, or double mutant. Cox-proportional hazards model was used to assess PFS in patient subgroups defined by mutations, and the effect of each mutation on overall survival. Results Of 541 evaluable patients, 156 (28.8%) had ESR1 mutation D538G (21.1%) and/or Y537S (13.3%), and 30 had both. These mutations were associated with shorter overall survival (wild-type, 32.1 months [95% CI, 28.09-36.40 months]; D538G, 25.99 months [95% CI, 19.19-32.36 months]; Y537S, 19.98 months [13.01-29.31 months]; both mutations, 15.15 months [95% CI, 10.87-27.43 months]). The D538G group (hazard ratio, 0.34 [95% CI, 0.02-0.57]) derived a similar PFS benefit as wild type from addition of everolimus to exemestane. Conclusions and Relevance ESR1 mutations are prevalent in ER-positive aromatase inhibitor-treated MBC. Both Y537S and D538G mutations are associated with more aggressive disease biology. Trial Registration clinicaltrials.gov Identifier:NCT00863655

Efficacy and Safety of Midostaurin in Advanced Systemic Mastocytosis

Abstract: BackgroundAdvanced systemic mastocytosis comprises rare hematologic neoplasms that are associated with a poor prognosis and lack effective treatment options. The multikinase inhibitor midostaurin inhibits KIT D816V, a primary driver of disease pathogenesis. MethodsWe conducted an open-label study of oral midostaurin at a dose of 100 mg twice daily in 116 patients, of whom 89 with mastocytosis-related organ damage were eligible for inclusion in the primary efficacy population; 16 had aggressive systemic mastocytosis, 57 had systemic mastocytosis with an associated hematologic neoplasm, and 16 had mast-cell leukemia. The primary outcome was the best overall response. ResultsThe overall response rate was 60% (95% confidence interval [CI], 49 to 70); 45% of the patients had a major response, which was defined as complete resolution of at least one type of mastocytosis-related organ damage. Response rates were similar regardless of the subtype of advanced systemic mastocytosis, KIT mutation status, or exposure...

Exosomes surf on filopodia to enter cells at endocytic hot spots, traffic within endosomes, and are targeted to the ER

Abstract: Exosomes are nanovesicles released by virtually all cells, which act as intercellular messengers by transfer of protein, lipid, and RNA cargo. Their quantitative efficiency, routes of cell uptake, and subcellular fate within recipient cells remain elusive. We quantitatively characterize exosome cell uptake, which saturates with dose and time and reaches near 100% transduction efficiency at picomolar concentrations. Highly reminiscent of pathogenic bacteria and viruses, exosomes are recruited as single vesicles to the cell body by surfing on filopodia as well as filopodia grabbing and pulling motions to reach endocytic hot spots at the filopodial base. After internalization, exosomes shuttle within endocytic vesicles to scan the endoplasmic reticulum before being sorted into the lysosome as their final intracellular destination. Our data quantify and explain the efficiency of exosome internalization by recipient cells, establish a new parallel between exosome and virus host cell interaction, and suggest unanticipated routes of subcellular cargo delivery.

Dabrafenib in patients with BRAF(V600E)-positive advanced non-small-cell lung cancer: a single-arm, multicentre, open-label, phase 2 trial

Abstract: Summary Background Activating BRAF V600E (Val600Glu) mutations are found in about 1–2% of lung adenocarcinomas, which might provide an opportunity for targeted treatment in these patients. Dabrafenib is an oral selective inhibitor of BRAF kinase. We did a trial to assess the clinical activity of dabrafenib in patients with advanced non-small-cell lung cancer (NSCLC) positive for the BRAF V600E mutation. Methods In this phase 2, multicentre, non-randomised, open-label study, we enrolled previously treated and untreated patients with stage IV metastatic BRAF V600E -positive NSCLC. Patients received oral dabrafenib 150 mg twice daily. The primary endpoint was investigator-assessed overall response, which was assessed in patients who had received at least one dose of dabrafenib; safety was also assessed in this population. The study is ongoing but not enrolling patients in this cohort. This trial is registered with ClinicalTrials.gov, number NCT01336634. Findings Between Aug 3, 2011, and Feb 25, 2014, 84 patients were enrolled, six of whom had not previously received systemic treatment for NSCLC. 26 of the 78 previously treated patients achieved an investigator-assessed overall response (33% [95% CI 23–45]). Four of the six previously untreated patients had an objective response. One patient died from an intracranial haemorrhage that was judged by the investigator to be due to the study drug. Serious adverse events were reported in 35 (42%) of 84 patients. The most frequent grade 3 or worse adverse events were cutaneous squamous-cell carcinoma in ten (12%), asthenia in four (5%), and basal-cell carcinoma in four (5%). Interpretation Dabrafenib showed clinical activity in BRAF V600E -positive NSCLC. Our findings suggest that dabrafenib could represent a treatment option for a population of patients with limited therapeutic options. Funding GlaxoSmithKline.

Disordered methionine metabolism in MTAP/CDKN2A-deleted cancers leads to dependence on PRMT5.

Abstract: 5-Methylthioadenosine phosphorylase (MTAP) is a key enzyme in the methionine salvage pathway. The MTAP gene is frequently deleted in human cancers because of its chromosomal proximity to the tumor suppressor gene CDKN2A. By interrogating data from a large-scale short hairpin RNA–mediated screen across 390 cancer cell line models, we found that the viability of MTAP-deficient cancer cells is impaired by depletion of the protein arginine methyltransferase PRMT5. MTAP-deleted cells accumulate the metabolite methylthioadenosine (MTA), which we found to inhibit PRMT5 methyltransferase activity. Deletion of MTAP in MTAP-proficient cells rendered them sensitive to PRMT5 depletion. Conversely, reconstitution of MTAP in an MTAP-deficient cell line rescued PRMT5 dependence. Thus, MTA accumulation in MTAP–deleted cancers creates a hypomorphic PRMT5 state that is selectively sensitized toward further PRMT5 inhibition. Inhibitors of PRMT5 that leverage this dysregulated metabolic state merit further investigation as a potential therapy for MTAP/CDKN2A-deleted tumors.

CRISPR screens provide a comprehensive assessment of cancer vulnerabilities but generate false-positive hits for highly amplified genomic regions

Abstract: CRISPR/Cas9 has emerged as a powerful new tool to systematically probe gene function. In this study, we compare the performance of CRISPR to RNAi-based loss-of-function screens for the identification of cancer dependencies by performing parallel deep-coverage shRNA and CRISPR screens targeting 2722 genes across several cancer cell lines. CRISPR-based dropout screens identified more lethal genes compared to RNAi in all five cancer models, indicating that the identification of many cellular dependencies may require full gene inactivation, as induced by CRISPR but not RNAi. However, in two aneuploid cancer models we found that all genes within highly amplified regions, including non-expressed genes, scored as lethal by CRISPR, revealing an unanticipated class of false-positive hits in CRISPR-based screens. Using a CRISPR tiling array that encompassed all possible sgRNAs against the coding regions of 139 genes, we found that sgRNAs targeting essential domains provide the most robust dropout phenotypes, suggesting that this approach might be used to define the protein domains that are required for cancer dependence. Collectively, these findings demonstrate the utility of CRISPR-based screens in the identification of cancer-dependent genes, but also reveal the need to carefully control for false-positive results especially in chromosomally unstable cancer lines.

Multicenter Phase II Study of Whole-Body and Intracranial Activity With Ceritinib in Patients With ALK-Rearranged Non–Small-Cell Lung Cancer Previously Treated With Chemotherapy and Crizotinib: Results From ASCEND-2

Abstract: PURPOSE Phase I data (ASCEND-1) showed ceritinib efficacy in patients with ALK-rearranged non-small-cell lung cancer (NSCLC), regardless of brain metastases status and with or without prior therapy with an inhibitor of the ALK protein. Data are presented from a phase II trial (ASCEND-2) in which ceritinib efficacy and safety were evaluated in patients who had ALK-rearranged NSCLC previously treated with at least one platinum-based chemotherapy and who had experienced progression during crizotinib treatment as their last prior therapy. PATIENTS AND METHODS Patients with advanced ALK-rearranged NSCLC, including those with asymptomatic or neurologically stable baseline brain metastases, received oral ceritinib 750 mg/d. Whole-body and intracranial responses were investigator assessed (according to RECIST version 1.1). Patient-reported outcomes were evaluated with the Lung Cancer Symptom Scale and European Organisation for Research and Treatment of Cancer surveys (the core-30 and the 13-item lung cancer-specific quality-of-life questionnaires). RESULTS All 140 patients enrolled had received two or more previous treatment regimens, and all patients had received crizotinib. The median duration of exposure and the follow-up time with ceritinib were 8.8 months (range, 0.1 to 19.4 months) and 11.3 months (range, 0.1 to 18.9 months), respectively. Investigator-assessed overall response rate was 38.6% (95% CI, 30.5% to 47.2%). Secondary end points, all investigator assessed, included disease control rate (77.1%; 95% CI, 69.3% to 83.8%), time to response (median, 1.8 months; range, 1.6 to 5.6 months), duration of response (median, 9.7 months; 95% CI, 7.1 to 11.1 months), and progression-free survival (median, 5.7 months; 95% CI, 5.4 to 7.6 months). Of 100 patients with baseline brain metastases, 20 had active target lesions at baseline; investigator-assessed intracranial overall response rate was 45.0% (95% CI, 23.1% to 68.5%). The most common adverse events (majority, grade 1 or 2) for all treated patients were nausea (81.4%), diarrhea (80.0%), and vomiting (62.9%). Patient-reported outcomes showed a trend toward improved symptom burden. The global quality-of-life score was maintained during treatment. CONCLUSION Consistent with its activity in ASCEND-1, ceritinib treatment provided clinically meaningful and durable responses with manageable tolerability in chemotherapy- and crizotinib-pretreated patients, including those with brain metastases.