Jeffrey J. Legos

Dabrafenib and trametinib versus dabrafenib and placebo for Val600 BRAF-mutant melanoma: a multicentre, double-blind, phase 3 randomised controlled trial

BACKGROUND Previously, a study of ours showed that the combination of dabrafenib and trametinib improves progression-free survival compared with dabrafenib and placebo in patients with BRAF Val600Lys/Glu mutation-positive metastatic melanoma. The study was continued to assess the secondary endpoint of overall survival, which we report in this Article. METHODS We did this double-blind phase 3 study at 113 sites in 14 countries. We enrolled previously untreated patients with BRAF Val600Glu or Val600Lys mutation-positive unresectable stage IIIC or stage IV melanoma. Participants were computer-randomised (1:1) to receive a combination of dabrafenib (150 mg orally twice daily) and trametinib (2 mg orally once daily), or dabrafenib and placebo. The primary endpoint was progression-free survival and overall survival was a secondary endpoint. This study is registered with ClinicalTrials.gov, number NCT01584648. FINDINGS Between May 4, 2012, and Nov 30, 2012, we screened 947 patients for eligibility, of whom 423 were randomly assigned to receive dabrafenib and trametinib (n=211) or dabrafenib only (n=212). The final data cutoff was Jan 12, 2015, at which time 222 patients had died. Median overall survival was 25·1 months (95% CI 19·2-not reached) in the dabrafenib and trametinib group versus 18·7 months (15·2-23·7) in the dabrafenib only group (hazard ratio [HR] 0·71, 95% CI 0·55-0·92; p=0·0107). Overall survival was 74% at 1 year and 51% at 2 years in the dabrafenib and trametinib group versus 68% and 42%, respectively, in the dabrafenib only group. Based on 301 events, median progression-free survival was 11·0 months (95% CI 8·0-13·9) in the dabrafenib and trametinib group and 8·8 months (5·9-9·3) in the dabrafenib only group (HR 0·67, 95% CI 0·53-0·84; p=0·0004; unadjusted for multiple testing). Treatment-related adverse events occurred in 181 (87%) of 209 patients in the dabrafenib and trametinib group and 189 (90%) of 211 patients in the dabrafenib only group; the most common was pyrexia (108 patients, 52%) in the dabrafenib and trametinib group, and hyperkeratosis (70 patients, 33%) in the dabrafenib only group. Grade 3 or 4 adverse events occurred in 67 (32%) patients in the dabrafenib and trametinib group and 66 (31%) patients in the dabrafenib only group. INTERPRETATION The improvement in overall survival establishes the combination of dabrafenib and trametinib as the standard targeted treatment for BRAF Val600 mutation-positive melanoma. Studies assessing dabrafenib and trametinib in combination with immunotherapies are ongoing. FUNDING GlaxoSmithKline.

Caspase 3 activation is essential for neuroprotection in preconditioning

Sublethal insults can induce tolerance to subsequent stressors in neurons. As cell death activators such as ROS generation and decreased ATP can initiate tolerance, we tested whether other cellular elements normally associated with neuronal injury could add to this process. In an in vivo model of ischemic tolerance, we were surprised to observe widespread caspase 3 cleavage, without cell death, in preconditioned tissue. To dissect the preconditioning pathways activating caspases, and the mechanisms by which these proteases are held in check, we developed an in vitro model of excitotoxic tolerance. In this model, antioxidants and caspase inhibitors blocked ischemia-induced protection against N-methyl-d-aspartate toxicity. Moreover, agents that blocked preconditioning also attenuated induction of HSP 70; transient overexpression of a constitutive form of this protein prevented HSP 70 up-regulation and blocked tolerance. We outline a neuroprotective pathway where events normally associated with apoptotic cell death are critical for cell survival.

Inhibition of p38 mitogen-activated protein kinase provides neuroprotection in cerebral focal ischemia

Mitogen‐activated protein kinases (MAPKs) are involved in many cellular processes. The stress‐activated MAPK, p38, has been linked to inflammatory cytokine production and cell death following cellular stress. Here, we demonstrate focal ischemic stroke‐induced p38 enzyme activation (i.e., phosphorylation) in the brain. The second generation p38 MAPK inhibitor SB 239063 was identified to exhibit increased kinase selectivity and improved cellular and in vivo activity profiles, and thus was selected for evaluation in two rat models of permanent focal ischemic stroke. SB 239063 was administered orally pre‐ and post‐stroke and intravenously post‐stroke. Plasma concentration levels were achieved in excess of those that effectively inhibit p38 activity. In both moderate and severe stroke, SB 239063 reduced infarct size by 28–41%, and neurological deficits by 25–35%. In addition, neuroprotective plasma concentrations of SB 239063 that reduced p38 activity following stroke also reduced the stroke‐induced expression of IL‐1β and TNFα (i.e., cytokines known to contribute to stroke‐induced brain injury). SB 239063 also provided direct protection of cultured brain tissue to in vitro ischemia. This robust SB 239063‐induced neuroprotection emphasizes a significant opportunity for targeting MAPK pathways in ischemic stroke injury, and also suggests that p38 inhibition be evaluated for protective effects in other experimental models of nervous system injury and neurodegeneration.

Adjuvant Dabrafenib plus Trametinib in Stage III BRAF-Mutated Melanoma

BACKGROUND Combination therapy with the BRAF inhibitor dabrafenib plus the MEK inhibitor trametinib improved survival in patients with advanced melanoma with BRAF V600 mutations. We sought to determine whether adjuvant dabrafenib plus trametinib would improve outcomes in patients with resected, stage III melanoma with BRAF V600 mutations. METHODS In this double‐blind, placebo‐controlled, phase 3 trial, we randomly assigned 870 patients with completely resected, stage III melanoma with BRAF V600E or V600K mutations to receive oral dabrafenib at a dose of 150 mg twice daily plus trametinib at a dose of 2 mg once daily (combination therapy, 438 patients) or two matched placebo tablets (432 patients) for 12 months. The primary end point was relapse‐free survival. Secondary end points included overall survival, distant metastasis–free survival, freedom from relapse, and safety. RESULTS At a median follow‐up of 2.8 years, the estimated 3‐year rate of relapse‐free survival was 58% in the combination‐therapy group and 39% in the placebo group (hazard ratio for relapse or death, 0.47; 95% confidence interval [CI], 0.39 to 0.58; P<0.001). The 3‐year overall survival rate was 86% in the combination‐therapy group and 77% in the placebo group (hazard ratio for death, 0.57; 95% CI, 0.42 to 0.79; P=0.0006), but this level of improvement did not cross the prespecified interim analysis boundary of P=0.000019. Rates of distant metastasis–free survival and freedom from relapse were also higher in the combination‐therapy group than in the placebo group. The safety profile of dabrafenib plus trametinib was consistent with that observed with the combination in patients with metastatic melanoma. CONCLUSIONS Adjuvant use of combination therapy with dabrafenib plus trametinib resulted in a significantly lower risk of recurrence in patients with stage III melanoma with BRAF V600E or V600K mutations than the adjuvant use of placebo and was not associated with new toxic effects. (Funded by GlaxoSmithKline and Novartis; COMBI‐AD ClinicalTrials.gov, NCT01682083; EudraCT number, 2012‐001266‐15.)

SB 239063, a novel p38 inhibitor, attenuates early neuronal injury following ischemia.

The aim of the present study was to evaluate p38 MAPK activation following focal stroke and determine whether SB 239063, a novel second generation p38 inhibitor, would directly attenuate early neuronal injury. Following permanent middle cerebral artery occlusion (MCAO), brains were dissected into ischemic and non-ischemic cortices and Western blots were employed to measure p38 MAPK activation. Neurologic deficit and MR imaging were utilized at various time points following MCAO to monitor the development and resolution of brain injury. Following MCAO, there was an early (15 min) activation of p38 MAPK (2.3-fold) which remained elevated up to 1 h (1.8-fold) post injury compared to non-ischemic and sham operated tissue. Oral SB 239063 (5, 15, 30, 60 mg/kg) administered to each animal 1 h pre- and 6 h post MCAO provided significant (P<0.05) dose-related neuroprotection reducing infarct size by 42, 48, 29 and 14%, respectively. The most effective dose (15 mg/kg) was further evaluated in detail and SB 239063 significantly (P<0.05) reduced neurologic deficit and infarct size by at least 30% from 24 h through at least 1 week. Early (i.e. observed within 2 h) reductions in diffusion weighted imaging (DWI) intensity following treatment with SB 239063 correlated (r=0.74, P<0.01) to neuroprotection seen up to 7 days post stroke. Since increased protein levels for various pro-inflammatory cytokines cannot be detected prior to 2 h in this stroke model, the early improvements due to p38 inhibition, observed using DWI, demonstrate that p38 inhibition can be neuroprotective through direct effects on ischemic brain cells, in addition to effects on inflammation.

Stroke Genomics: Approaches to Identify, Validate, and Understand Ischemic Stroke Gene Expression

Sequencing of the human genome is nearing completion and biologists, molecular biologists, and bioinformatics specialists have teamed up to develop global genomic technologies to help decipher the complex nature of pathophysiologic gene function. This review will focus on differential gene expression in ischemic stroke. It will discuss inheritance in the broader stroke population, how experimental models of spontaneous stroke might be applied to humans to identify chromosomal loci of increased risk and ischemic sensitivity, and also how the gene expression induced by stroke is related to the poststroke processes of brain injury, repair, and recovery. In addition, we discuss and summarise the literature of experimental stroke genomics and compare several approaches of differential gene expression analyzes. These include a comparison of representational difference analysis we have provided using an experimental stroke model that is representative of stroke evolution observed most often in man, and a summary of available data on stroke differential gene expression. Issues regarding validation of potential genes as stroke targets, the verification of message translation to protein products, the relevance of the expression of neuroprotective and neurodestructive genes and their specific timings, and the emerging problems of handling novel genes that may be discovered during differential gene expression analyses will also be addressed.

Comparison of dabrafenib and trametinib combination therapy with vemurafenib monotherapy on health-related quality of life in patients with unresectable or metastatic cutaneous BRAF Val600-mutation-positive melanoma (COMBI-v): results of a phase 3, open-label, randomised trial.

BACKGROUND In the COMBI-v trial, patients with previously untreated BRAF Val600Glu or Val600Lys mutant unresectable or metastatic melanoma who were treated with the combination of dabrafenib and trametinib had significantly longer overall and progression-free survival than those treated with vemurafenib alone. Here, we present the effects of treatments on health-related quality of life (HRQoL), an exploratory endpoint in the COMBI-v study. METHODS COMBI-v was an open-label, randomised phase 3 study in which 704 patients with metastatic melanoma with a BRAF Val600 mutation were randomly assigned (1:1) by an interactive voice response system to receive either a combination of dabrafenib (150 mg twice-daily) and trametinib (2 mg once-daily) or vemurafenib monotherapy (960 mg twice-daily) orally as first-line therapy. The primary endpoint was overall survival. In this pre-specified exploratory analysis, we prospectively assessed HRQoL in the intention-to-treat population with the European Organisation for Research and Treatment of Cancer quality of life (EORTC QLQ-C30), EuroQoL-5D (EQ-5D), and Melanoma Subscale of the Functional Assessment of Cancer Therapy-Melanoma (FACT-M), completed at baseline, during study treatment, at disease progression, and after progression. We used a mixed-model, repeated measures ANCOVA to assess differences in mean scores between groups with baseline score as covariate; all p-values are descriptive. The COMBI-v trial is registered with ClinicalTrials.gov, number NCT01597908, and is ongoing for the primary endpoint, but is not recruiting patients. FINDINGS From June 4, 2012, to Oct 7, 2013, 1645 patients at 193 centres worldwide were screened for eligibility, and 704 patients were randomly assigned to dabrafenib plus trametinib (n=352) or vemurafenib (n=352). Questionnaire completion rates for both groups were high (>95% at baseline, >80% at follow-up assessments, and >70% at disease progression) with similar HRQoL and symptom scores reported at baseline in both treatment groups for all questionnaires. Differences in mean scores between treatment groups were significant and clinically meaningful in favour of the combination compared with vemurafenib monotherapy for most domains across all three questionnaires during study treatment and at disease progression, including EORTC QLQ-C30 global health (7·92, 7·62, 6·86, 7·47, 5·16, 7·56, and 7·57 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; p<0·001 for all assessments except p=0·005 at week 40), EORTC QLQ-C30 pain (-13·20, -8·05, -8·82, -12·69, -12·46, -11·41, and -10·57 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; all p<0·001), EQ-5D thermometer scores (7·96, 8·05, 6·83, 11·53, 7·41, 9·08, and 10·51 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; p<0·001 for all assessments except p=0·006 at week 32), and FACT-M Melanoma Subscale score (3·62, 2·93, 2·45, 3·39, 2·85, 3·00, and 3·68 at weeks 8, 16, 24, 32, 40, 48, and disease progression, respectively; all p<0·001). INTERPRETATION From the patients perspective, which integrates not only survival advantage but also disease-associated and adverse-event-associated symptoms, treatment with the combination of a BRAF inhibitor plus a MEK inhibitor (dabrafenib plus trametinib) adds a clear benefit over monotherapy with the BRAF inhibitor vemurafenib and supports the combination therapy as standard of care in this population.

The selective p38 inhibitor SB-239063 protects primary neurons from mild to moderate excitotoxic injury

Inhibition of the p38 mitogen-activated protein kinase (MAP Kinase) pathway reduces acute ischemic injury in vivo, suggesting a direct role for this signaling pathway in a number of neurodegenerative processes. The present study was designed to evaluate further the role of p38 MAP Kinase in acute excitotoxic neuronal injury using the selective p38 inhibitor SB-239063 (trans-1-(4hydroxycyclohexyl)-4-(fluorophenyl)-5-(2-methoxy-pyrimidin-4-yl) imidazole). Unlike the widely used p38 inhibitor, SB-203580 (4-(4-Fluorophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)1H-imidazole), this second generation p38 inhibitor more selectively inhibits p38 MAP Kinase without affecting the activity of other MAP Kinase signaling pathways and provides a more accurate means to selectively assess the role of p38 in excitotoxicity that has not been previously possible. SB-239063 provided substantial protection against cell death induced by either oxygen glucose deprivation (OGD) or magnesium deprivation in cultured neurons. The ability of this compound to block excitotoxicity was not due to direct inhibition of N-methyl-D-aspartate (NMDA) receptor-mediated currents as SB-239063 did not alter NMDA electrophysiological responses. SB-239063 did not protect against a severe excitotoxic insult induced by 60-min exposure to NMDA. However, when tested against a less severe, brief (5 min) NMDA exposure, p38 inhibition provided substantial protection. These data demonstrate that inhibition of p38 MAP Kinase can confer neuroprotection in vitro against mild but not severe excitotoxic exposure, and suggests that other additional pathways/mechanism(s) may be involved in severe excitotoxic cell death.

Pharmacological interventions for stroke: failures and future

Given the few options currently available for patients following ischaemic stroke, the recent disappointing failures of several large-scale Phase III clinical trials has made the search for novel therapeutic approaches even more critical. Experimental evidence has suggested that the majority of stroke patients have a slow evolution of brain injury which can occur over several hours. Progressive microcirculatory failure following the initial onset of ischaemia may contribute to the expansion of brain injury. Included among the pathophysiological changes that are speculated to occur as a secondary response to the initial ischaemia are free radical production, excitotoxicity (for example, glutamate) disruption of ionic homeostasis (for example, sodium and calcium influx), enzymatic changes, stimulation of the inflammatory process, endothelin release, activation of platelets and leukocytes, delayed coagulation and endothelial dysfunction. All of these pathophysiological reactions could contribute to an increase in local vascular resistance and therefore cause progressive hypoperfusion of the brain following the onset of stroke. The scope of this review will focus on recent clinical failures in addition to agents currently in clinical development, comparing vascular targets to the common neuroprotective strategies.

Correlation of BRAF Mutation Status in Circulating-Free DNA and Tumor and Association with Clinical Outcome across Four BRAFi and MEKi Clinical Trials

Purpose: Tumor-derived circulating cell–free DNA (cfDNA) is a potential alternative source from which to derive tumor mutation status. cfDNA data from four clinical studies of the BRAF inhibitor (BRAFi) dabrafenib or the MEK inhibitor (MEKi) trametinib were analyzed to determine the association between BRAF mutation status in cfDNA and tumor tissue, and the association of BRAF cfDNA mutation status with baseline factors and clinical outcome. Experimental Design: Patients with BRAF V600 mutation–positive melanoma were enrolled in each study after central confirmation of BRAF status in tumor using a PCR-based assay. BRAF mutation status in cfDNA from patient plasma collected at baseline, 732 of 836 (88%) enrolled patients in total, was determined. Results: BRAF mutations were detectable in cfDNA in 76% and 81% of patients with BRAF V600E/V600K–positive tumors, respectively. Patients negative for BRAF mutations in cfDNA had longer progression-free survival (PFS) and overall survival in each of the four studies, compared with patients with detectable cfDNA BRAF mutations. The presence of BRAF-mutant cfDNA was an independent prognostic factor for PFS after multivariate adjustment for baseline factors in three of four studies. Patients negative for BRAF mutation–positive cfDNA in plasma had higher response rates to dabrafenib and trametinib. Conclusions: BRAF mutations in cfDNA are detectable in >75% of late-stage melanoma patients with BRAF mutation–positive tumors. The lack of circulating, BRAF mutation–positive cfDNA is clinically significant for metastatic melanoma patients, and may be a prognostic marker for better disease outcome. Clin Cancer Res; 22(3); 567–74. ©2015 AACR.