Dabrafenib In Patients Research Articles

A Phase 2 Clinical Trial of Trametinib and Low-Dose Dabrafenib in Patients with Advanced Pretreated NRASQ61R/K/L Mutant Melanoma (TraMel-WT).

Simple SummaryMEK-inhibitor monotherapy has activity in advanced NRASQ61R/K/L mutant melanoma but is associated with dose-limiting cutaneous toxicity. The combination of a BRAF- with a MEK-inhibitor at their full dose (as in BRAFV600E/K mutant melanoma) has low cutaneous toxicity. We hypothesized that a low dose of the BRAF-inhibitor dabrafenib can mitigate the skin toxicity associated with a full dose of the MEK-inhibitor trametinib in patients with advanced NRASQ61R/K/L mutant melanoma who progressed after treatment with immune checkpoint inhibitors. The results of this two-stage phase 2 trial show that addition of a low dose of dabrafenib effectively mitigates the skin toxicity associated with trametinib. This combination is, however, insufficiently active in patients with advanced NRASQ61R/K/L mutant melanoma. The combination of low-dose dabrafenib plus full-dose trametinib can be of further interest for the treatment of MEK-inhibitor-sensitive tumors.Background: MEK-inhibitor monotherapy has activity in advanced NRASQ61R/K/L mutant melanoma but is associated with dose-limiting cutaneous toxicity. The combination of a BRAF- with a MEK-inhibitor at their full dose (as in BRAFV600E/K mutant melanoma) has low cutaneous toxicity. It is unknown whether a low dose of BRAF-inhibitor can mitigate the skin toxicity associated with full-dose MEK-inhibitor treatment in patients with advanced NRASQ61R/K/L mutant melanoma. Methods: This two-stage phase 2 clinical trial investigated trametinib 2 mg once daily in patients with advanced NRASQ61R/K/L mutant melanoma who were pretreated with immune checkpoint inhibitors. In case of trametinib-related cutaneous toxicity, low-dose dabrafenib (50 mg twice daily) was added to prevent recurrent cutaneous toxicity (pre-amendment). Following an amendment, trametinib was combined upfront with low-dose dabrafenib (post-amendment). Objective response rate (ORR) served as the primary endpoint. Results: All 6 patients enrolled pre-amendment developed trametinib-related cutaneous toxicity, necessitating treatment interruption. Combining trametinib with low-dose dabrafenib prevented recurrent skin toxicity thereafter. Trametinib-related skin toxicity was effectively mitigated in all 10 patients post-amendment. In all 16 included patients, the ORR and disease control rate was 6.3% (1 partial response) and 50.0%, respectively. The trial was halted after the first stage. Conclusions: Combining full-dose trametinib with low-dose dabrafenib can mitigate MEK-inhibitor-related skin toxicity but was insufficiently active in this patient population. This combination can be of further interest for the treatment of MEK-inhibitor-sensitive tumors.

Correlation between initial tumour volume and treatment duration on Dabrafenib: observation study of subjects with BRAF mutant melanoma on the BRF112680 trial

BackgroundPlanar-based measurements of lesions in metastatic melanoma have limitations in estimating tumor burden of a patient and in predicting response to treatment. Volumetric imaging might add predictive value to Response criteria in Solid Tumor (RECIST)-measurement. Based on clinical observations, we explored the association between baseline tumor volume (TV) and duration of treatment with dabrafenib in patients with metastatic melanoma. We have also explored the prognostic value of TV for overall survival (OS) and progression free survival (PFS).MethodsThis is a retrospective, chart-review of primary source documents and medical imaging of a cohort of patients participating in the BRF112680 phase 1 clinical trial at the Prince of Wales Hospital. TV was quantified by contouring all the measurable baseline target lesions in the standard manner for radiation planning using Voxxar™ software. We used Cox regression models to analyse associations between TV and duration of treatment with dabrafenib and between TV, PFS and OS.ResultsAmong 13 patients of BRAF 112680 trial, 10 were included in the retrospective analysis. Target lesion sum volume ranged from 0.3 to 1065.5 cm3 (cc), with a median of 27.5 cc. The median PFS and OS were 420 days (range 109–1765) and 1680 days (range 390–2940), respectively. The initial TV was inversely correlated with duration of treatment with dabrafenib (rho − 0.6; P 0.03). In multivariate analysis, TV was a predictor for OS (HR 2.81 CI 1.06–6.19) and PFS (8.76 (CI 1.05–43.58). Patients with tumour volume above the median had significantly lower OS of 6-months compared to 56-months survival for patients with smaller volumes; P = 0.019.ConclusionsTV is a predictor for treatment duration and is prognostic of OS and PFS in patients with metastatic melanoma. These findings need to be validated prospectively in clinical trials.

20P Interim safety and efficacy results of a phase II clinical trial on trametinib and low-dose dabrafenib in patients with advanced BRAFV600 wild-type melanoma

20P Interim safety and efficacy results of a phase II clinical trial on trametinib and low-dose dabrafenib in patients with advanced BRAFV600 wild-type melanoma

Effectiveness of dabrafenib in the treatment of patients with BRAF V600-mutated metastatic melanoma in a Named Patient Program.

Given the approval of dabrafenib in patients with BRAF-mutant metastatic melanoma, a better understanding of treatment patterns and clinical outcomes with dabrafenib in a clinical setting is warranted. We performed a retrospective chart review of patients who received dabrafenib in a compassionate use setting through the Named Patient Program (DESCRIBE I study) during December 2010-August 2013 in Europe, New Zealand and Australia. Of the 331 Named Patient Program patients included, the majority (95.8%) had stage IV disease at dabrafenib initiation and 39.9% had brain metastases (BMs). Dabrafenib was used first line in 67.7% of patients, and median treatment duration was 6.4 months. Dabrafenib was well tolerated. Common grade 2/3 adverse events were hyperkeratosis (7.6%), pyrexia/fever (6.6%), fatigue (5.1%), hand-foot syndrome (5.4%) and nausea (3.6%). Overall response rate was 45.9%, median progression-free survival was 5.2 months (95% confidence interval, 4.2-6.1 months), and median overall survival was 12.4 months (95% confidence interval, 10.2-15.0 months). In patients with known brain metastases (n = 132) versus patients without (n = 199), overall response rate was 42.4% versus 48.2%, progression-free survival was 3.9 months (95% confidence interval, 3.8-5.5 months) versus 5.9 months (95% confidence interval, 4.8-7.8 months) and overall survival was 9.5 months (95% confidence interval, 6.7-12.4 months) versus 15 months (95% confidence interval, 11.1-20.5 months), respectively. Safety and effectiveness of dabrafenib in patients with unresectable advanced BRAF V600-mutant melanoma treated in an Named Patient Program was similar to the clinical trial experience, demonstrating effectiveness of dabrafenib in a nontrial setting.

1332P - An open-label, non-randomized, phase IIIb study of trametinib in combination with dabrafenib for patients with unresectable advanced BRAFV600-mutant melanoma: A subgroup analysis of patients with brain metastasis

BackgroundThirty to 60% of stage unresectable AJCC III and IV melanoma patients (pts) develop brain metastases (BM). This population has been excluded from most clinical trials. Using a large prospective trial including pts with advanced BRAFV600-mutant melanoma and allowing for BM, we assessed in the BM population factors associated with disease progression and stratified the population into risk groups using regression tree analysis (RTA). MethodsThis phase IIIb single arm, open label, multicenter, non randomized French study included pts with unresectable stage IIIc or IV BRAFV600-mutant melanoma. Selection criteria allowed for BM, ECOG ≤2, previous advanced melanoma treatments. Pts received dabrafenib (D) + trametinib (T) until progression. Progression-free survival (PFS) was estimated using the Kaplan Meier analysis and modeled with a multivariate Cox regression model. Risk subgroups were identified using an exponential RTA. Significance was set at p<0.05. ResultsBetween March 2015 and November 2016, 856 pts were included and 275 (32%) had BM. Median PFS was 5.68 months (95% CI, 5.29-6.87) in the BM population. Significant independent factors associated with lower PFS were ECOG ≥1, elevated serum LDH, ≥3 metastatic sites, and non naïve status (Table). Pts with ECOG 0, <3 metastatic sites, LDH <ULN, no prior treatment had the highest probability of PFS at 6 months (65% [95% CI, 52-76]).Table: 1332PMultivariate Cox proportional hazards analysis of PFS by prognostic factorsTable: 1332PN (%)HR95% CIp valueLDH at baseline*<1 ULN115 (41.8)1 (=reference)--[1 - 2[ ULN50 (18.2)1.30[0.83 - 2.04]0.2473≥2 ULN21 (7.6)2.50[1.37 - 4.58]0.0030Missing89 (32.4)1.44[0.99 - 2.10]0.0571ECOG PS*O144 (52.4)1 (=reference)--191 (33.1)1.36[0.94 - 1.96]0.0995≥240 (14.6)2.17[1.37 - 3.44]0.0010Metastatic sites*<384 (30.6)1 (=reference)--≥3191 (69.5)1.58[1.10 - 2.28]0.0142StatusNaïve121 (44.0)1 (=reference)--Non naïve154 (56.0)1.60[1.14 - 2.25]0.0061*Factors included in the RTA. ConclusionsTo our knowledge, this is the first analysis from the largest prospective study in BRAF-mutated melanoma pts with BM. The study was carried out in difficult-to-treat pts and in conditions that were close to the real-world setting. ECOG >1, ≥3 metastatic sites and elevated LDH were associated with shorter PFS, a finding previously demonstrated only in pts without BM. Regression trees will be presented. Editorial acknowledgementJone Iriondo-Alberdi (PhD) from ITEC Services. Legal entity responsible for the studyNovartis Pharma S.A.S. (France). FundingNovartis Pharma S.A.S. (France). DisclosureC. Dutriaux: Honoraria (self), Advisory / Consultancy: Novartis. C. Robert: Advisory / Consultancy: Roche; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Merck Sharp & Dohme ; Advisory / Consultancy: Sanofi; Advisory / Consultancy: Novartis; Advisory / Consultancy: Amgen; Advisory / Consultancy, Participation to Boards and Steering Committees: Pierre Fabre. J.J. Grob: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Bristol-Myers Squibb; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Merck Sharp & Dohme ; Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Roche; Honoraria (self), Advisory / Consultancy: Novartis; Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy: Merck; Honoraria (self), Advisory / Consultancy: Pierre Fabre; Honoraria (self), Advisory / Consultancy: Pfizer; Honoraria (self), Advisory / Consultancy: Incyte. L. Mortier: Honoraria (self), Advisory / Consultancy: Amgen; Honoraria (self), Advisory / Consultancy: Bristol-Myers Squibb; Honoraria (self), Advisory / Consultancy: Roche; Honoraria (self), Advisory / Consultancy: GSK/Novartis; Honoraria (self), Advisory / Consultancy: MSD; Honoraria (self), Advisory / Consultancy: Leo; Honoraria (self): Sanofi; Honoraria (self): Novartis; Honoraria (self): Pierre Fabre; Honoraria (self): Merck Serono. C. Lebbe: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Bristol-Myers Squibb; Honoraria (self), Travel / Accommodation / Expenses: Merck Sharp & Dohme ; Honoraria (self): Roche; Honoraria (self): Novartis; Honoraria (self): Amgen; Honoraria (self): Merck; Honoraria (self): Pierre Fabre; Honoraria (self): Pfizer; Honoraria (self): Incyte. S. Mansard: Advisory / Consultancy: Novartis. F. Grange: Advisory / Consultancy: Novartis. E. Neidhardt: Honoraria (self): BMS. T. Lesimple: Advisory / Consultancy: Novartis; Advisory / Consultancy: MSD; Advisory / Consultancy: Incyte; Advisory / Consultancy: Pierre Fabre; Research grant / Funding (self): Roche. C. Bedane: Advisory / Consultancy: Novartis. S. Dalac-Rat: Advisory / Consultancy: Novartis; Advisory / Consultancy: Roche; Advisory / Consultancy: BMS; Advisory / Consultancy: Pierre Fabre. C. Nardin: Advisory / Consultancy: Novartis; Advisory / Consultancy: Bristol-Myers Squibb; Advisory / Consultancy: Merck Sharp & Dohme . A. Szenik: Full / Part-time employment: Novartis. A. Denden: Full / Part-time employment: Novartis. P. Saiag: Travel / Accommodation / Expenses: Amgen; Travel / Accommodation / Expenses, Non-remunerated activity/ies: Bristol-Myers Squibb; Travel / Accommodation / Expenses, Non-remunerated activity/ies: Merck Sharp & Dohme ; Travel / Accommodation / Expenses: Merck Serono; Travel / Accommodation / Expenses: Pfizer; Research grant / Funding (self), Travel / Accommodation / Expenses, Non-remunerated activity/ies: Roche-Genentech; Travel / Accommodation / Expenses: Pierre Fabre; Travel / Accommodation / Expenses: Novartis. All other authors have declared no conflicts of interest.

Dabrafenib in patients with recurrent, BRAF V600E mutated malignant glioma and leptomeningeal disease.

BRAF V600E mutations occur frequently in malignant melanoma, but are rare in most malignant glioma subtypes. Besides, more benign brain tumors such as ganglioglioma, dysembryoblastic neuroepithelial tumours and supratentorial pilocytic astrocytomas, only pleomorphic xanthoastrocytomas (50–78%) and epitheloid glioblastoma (50%) regularly exhibit BRAF mutations. In the present study, we report on three patients with recurrent malignant gliomas harbouring a BRAF V600E mutation. All patients presented with markedly disseminated leptomeningeal disease at recurrence and had progressed after radiotherapy and alkylating chemotherapy. Therefore, estimated life expectancy at recurrence was a few weeks. All three patients received dabrafenib as a single agent and all showed a complete or nearly complete response. Treatment is ongoing and patients are stable for 27 months, 7 months and 3 months, respectively. One patient showed a dramatic radiologic and clinical response after one week of treatment. We were able to generate an ex vivo tumor cell culture from CSF in one patient. Treatment of this cell culture with dabrafenib resulted in reduced cell density and inhibition of ERK phosphorylation in vitro. To date, this is the first series on adult patients with BRAF-mutated malignant glioma and leptomeningeal dissemination treated with dabrafenib monotherapy. All patients showed a dramatic response with one patient showing an ongoing response for more than two years.

Four-month course of adjuvant dabrafenib in patients with surgically resected stage IIIC melanoma characterized by a BRAFV600E/K mutation.

BackgroundWe tested the hypothesis that a 4-month course of adjuvant dabrafenib in stage IIIC BRAF-mutated melanoma would improve 2 year RFS from 24% to 51%, and that tumor-derived cell free DNA (cfDNA) in plasma would correlate with and predict recurrence.MethodsPatients with stage IIIC BRAF V600E/K mutated melanoma who were free of disease after surgical resection received 4 months of adjuvant dabrafenib. Patients were evaluated with imaging at baseline, at the end of cycles 2, 4, 6, then every 3 months until disease relapse or 2 years, whichever came first. Serial blood samples were collected for evaluation of cfDNA at the same time.Results21/23 patients enrolled were evaluable; 2 patients withdrew consent during the first week of treatment. The 2 year RFS was 28.6% (95% CI 12-48%). The estimated overall survival at 2 years was 78% (95% CI 51-91%). cfDNA detection had a 53% sensitivity in relapsing patients but cfDNA detection did not provide lead-time advantage over CT scanning.ConclusionA 4-month course of adjuvant dabrafenib did not result in a detectable improvement in 2-year RFS. cfDNA was less sensitive than standard CT imaging and did not provide a lead-time advantage in detecting relapse.

BRAF-MEK inhibition in melanoma brain metastases: a new hope

About 30% of patients with stage IV melanoma manifest clinically apparent melanoma brain metastasis at some point in their disease course. Until about 5 years ago, few patients with melanoma brain metastasis were eligible for clinical trials, and survival rates were dismal. The development of brain metastases is a complex process that involves tumour cells escaping from the primary or other metastatic sites, intravasating into the systemic circulation, and arresting in and extravasating from intracranial capillary beds, ultimately resulting in the establishment of new and progressive tumours. Although the biology of melanoma brain metastasis remains poorly understood, a number of signalling pathways have been implicated. STAT3 signalling is involved in extravasation, angiogenesis, and prevention of anoikis (death due to inadequate attachment to extracellular matrix). Increased PI3K/AKT signalling, often caused by loss of the negative regulator PTEN, has been reported in melanoma brain metastasis compared with matched extracranial lesions. 1 Chen G Chakravarti N Aardalen K et al. Molecular profiling of patient-matched brain and extracranial melanoma metastases implicates the PI3K pathway as a therapeutic target. Clin Cancer Res. 2014; 20: 5537-5546 Crossref PubMed Scopus (126) Google Scholar Preclinical evidence also shows that the brain microenvironment contributes to melanoma growth and treatment resistance. 2 Niessner H Forschner A Klumpp B et al. Targeting hyperactivation of the AKT survival pathway to overcome therapy resistance of melanoma brain metastases. Cancer Med. 2013; 2: 76-85 Crossref PubMed Google Scholar Although the blood–brain barrier prevents most drugs from accessing normal brain, it is compromised in brain metastases, so therapeutics with extracranial activity frequently show intracranial activity. BRAF inhibitors have potent activity against extracranial BRAFV600-mutant metastatic melanoma; a trial 3 Long VB Trefzer U Davies MA et al. Dabrafenib in patients with Val600Glu or Val600Lys BRAF-mutant melanoma metastatic to the brain (BREAK-MB): a multicentre, open-label, phase 2 trial. Lancet Oncol. 2012; 13: 1087-1095 Summary Full Text Full Text PDF PubMed Scopus (734) Google Scholar of dabrafenib monotherapy showed that 39% of patients with melanoma brain metastases responded, despite little or no penetration through the intact blood–brain barrier. Dabrafenib plus trametinib in patients with BRAFV600-mutant melanoma brain metastases (COMBI-MB): a multicentre, multicohort, open-label, phase 2 trialDabrafenib plus trametinib was active with a manageable safety profile in this melanoma population that was consistent with previous dabrafenib plus trametinib studies in patients with BRAFV600-mutant melanoma without brain metastases, but the median duration of response was relatively short. These results provide evidence of clinical benefit with dabrafenib plus trametinib and support the need for additional research to further improve outcomes in patients with melanoma brain metastases. Full-Text PDF

SC05.03 Novel Tyrosine Kinase Inhibitors in Lung Cancer

SC05.03 Novel Tyrosine Kinase Inhibitors in Lung Cancer

Dabrafenib in patients with BRAF-mutated non-small cell lung cancer

Dabrafenib in patients with BRAF-mutated non-small cell lung cancer

A case of vitiligo-like depigmentation induced by dabrafenib in patients with metastatic melanoma

A case of vitiligo-like depigmentation induced by dabrafenib in patients with metastatic melanoma

Dabrafenib in patients with BRAFV600E-positive advanced non-small-cell lung cancer: a single-arm, multicentre, open-label, phase 2 trial

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. 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. 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%). 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. GlaxoSmithKline.

Combination therapy with BRAF and MEK inhibitors for melanoma: latest evidence and place in therapy.

Treatment with BRAF inhibitors such as vemurafenib or dabrafenib in patients with advanced BRAFV600 mutated melanoma has shown objective tumor responses in approximately half of the patients. However, the duration of responses is limited in a majority of these patients, with progression-free survival rates around 6 months due to tumor progression from development of acquired resistance. Preclinical studies have suggested that concurrent inhibition of the BRAF kinases and MEK of the mitogen-activated protein kinase (MAPK) pathway could decrease MAPK-driven acquired resistance, resulting in longer duration of responses, higher rate of tumor responses, and a decrease in the cutaneous toxicities observed from paradoxical MAPK pathway activation with BRAF inhibitor monotherapy. This review provides an overview of the currently available clinical trial data on BRAF and MEK inhibitors together and in combinations with other therapeutic agents.

Dabrafenib for Treating Unresectable, Advanced or Metastatic BRAF V600 Mutation-Positive Melanoma: An Evidence Review Group Perspective.

The National Institute for Health and Care Excellence (NICE) invited GlaxoSmithKline, the manufacturer of dabrafenib, to submit evidence for the clinical and cost effectiveness of dabrafenib for the treatment of unresectable, advanced or metastatic BRAF V600 mutation-positive melanoma in accordance with the Institute's Single Technology Appraisal (STA) process. The Liverpool Reviews and Implementation Group (LRiG) at the University of Liverpool was commissioned to act as the Evidence Review Group (ERG). This article summarizes the ERG's review of the evidence submitted by the company and provides a summary of the Appraisal Committee's (AC) final decision in October 2014. The clinical evidence for dabrafenib was derived from an ongoing phase III, randomized, double-blind, placebo-controlled, international, multicentre clinical trial (BREAK-3) involving 230 patients randomized 2:1 to receive either dabrafenib or dacarbazine. A significant improvement in median progression-free survival (PFS) but not overall survival (OS) was reported in the dabrafenib arm compared with dacarbazine. Vemurafenib is considered a more appropriate comparator than is dacarbazine. The clinical evidence for vemurafenib was derived from a completed phase III, randomized, double-blind, placebo-controlled, international, multicentre clinical trial (BRIM-3) involving 675 patients randomized 1:1 to receive either vemurafenib or dacarbazine. A significant improvement in median PFS and OS was reported in the vemurafenib arm compared with dacarbazine. As there is no direct evidence comparing dabrafenib versus vemurafenib, the company presented an indirect treatment comparison (ITC) that demonstrated no statistical differences between dabrafenib and vemurafenib for PFS or OS. The ERG expressed concerns with the ITC, mainly in relation to the validity of the assumptions underpinning the methodology; the ERG concluded this resulted in findings that are unlikely to be robust or reliable. Dabrafenib and vemurafenib are both available to patients treated by the National Health Service (NHS) in England via a Patient Access Scheme (PAS) in which the costs of the drugs are discounted. Using these discounted costs, the incremental cost-effectiveness ratios (ICERs) generated by the company were £60,980 per quality-adjusted life-year (QALY) for dabrafenib versus dacarbazine and £11,046 per QALY gained for dabrafenib versus vemurafenib. The ERG considered the economic model structure developed by the company to derive the ICERs to be overly complex and based on unsubstantiated assumptions, most importantly in relation to the projection of OS. Applying the latest OS data from BREAK-3 to a less complex model structure increased the estimated ICER for dabrafenib compared with dacarbazine from £60,980 to £112,727 per QALY gained. Since the results from the ITC were considered by the ERG to be neither reliable nor robust, the ERG also considered a cost-effectiveness comparison to be inappropriate due to a lack of meaningful or reliable data. In spite of limitations in the data, the AC took the view that dabrafenib and vemurafenib were "likely" of similar clinical effectiveness. Since the overall costs of these two drugs were similar, the AC recommended the use of dabrafenib in patients with unresectable, advanced or metastatic BRAF V600 mutation-positive melanoma.

BRAF Inhibitor Dabrafenib in Patients with Metastatic BRAF-Mutant Thyroid Cancer

Mutations of v-raf murine sarcoma viral oncogene homolog B (BRAF) are commonly identified in papillary and anaplastic thyroid carcinoma and are associated with worse prognosis compared with the wild type. BRAF inhibition in papillary thyroid carcinoma cell lines and xenografts inhibits proliferation and decreases downstream phosphorylation. Our objectives were to analyze safety and efficacy of the selective BRAF inhibitor dabrafenib in patients with metastatic BRAF-mutant thyroid carcinoma. We present the subset of patients with BRAF-mutant thyroid carcinoma enrolled in a larger phase 1 study, the main results of which are reported elsewhere. Fourteen patients with BRAF(V600E)-mutant thyroid carcinoma were enrolled, of whom 13 (93%) had received prior radioactive iodine. The median duration on treatment was 8.4 months, and seven (50%) patients received treatment for ≥10 months. The most common treatment-related adverse events were skin papillomas (n=8, 57%), hyperkeratosis (n=5, 36%), and alopecia (n=4, 29%), all of which were grade 1. Treatment-related adverse events grade ≥3 included grade 4 elevated lipase and grade 3 elevated amylase, fatigue, febrile neutropenia, and cutaneous squamous cell carcinoma (n=1 for each). Four (29%) partial responses were observed, and nine (64%) patients achieved at least 10% decrease. Only one responder progressed while on the study drug after a response duration of 9.3 months. The other three responders had not progressed, with response duration of 4.6+, 10.4+, and 21.4+ months. With seven (50%) patients showing no progression at the time of study completion, the median progression-free survival was 11.3 months. Dabrafenib was well tolerated and resulted in durable responses in BRAF-mutant differentiated thyroid carcinoma patients.

Advances in targeted therapy for melanoma: a focus on MEK inhibition

Increased knowledge of the role that dysregulated MAPK signaling plays in melanoma has opened the door for novel therapeutic strategies, among them MEK-targeted approaches. With the recent approval of the selective MEK inhibitor trametinib, both as a single agent and in combination with dabrafenib for patients with BRAF-mutant metastatic melanoma, MEK-based therapy now has a place as a standard of care option for the treatment of this disease. Early data suggest a benefit of MEK inhibition in other melanoma subtypes as well, including NRAS-mutant and uveal melanoma. This review summarizes the clinical development and the currently available data regarding the role of MEK inhibitor therapy in the treatment of advanced melanoma.

Dabrafenib for the treatment of BRAF V600-positive melanoma: a safety evaluation

Introduction: V-raf murine sarcoma viral oncogene homolog B1 (BRAF) inhibitors are emerging as the standard of care for treating advanced melanomas harboring the BRAF V600 oncogenic mutation. Dabrafenib is the second approved selective BRAF inhibitor (after vemurafenib) for the treatment of unresectable or metastatic BRAF V600-positive melanoma.Areas covered: This review covers the current data on the efficacy and safety of the selective BRAF inhibitor dabrafenib in patients with metastatic BRAF V600 positive melanoma. The pharmacological, safety and efficacy data are discussed from Phase I, II, and III studies of dabrafenib monotherapy as well as in combination with the MEK inhibitor trametinib.Expert opinion: Dabrafenib has demonstrated comparable efficacy to vemurafenib in BRAF V600E mutant melanoma patients. Dabrafenib is well tolerated in patients with metastatic melanoma, including patients with brain metastases. Nevertheless side effects are common, but usually manageable. In the Phase III study testing dabrafenib, 53% of patients reported grade 2 or higher adverse events (AEs). Toxicities were similar to those seen in the early-phase trials, with the most common being cutaneous manifestations (hyperkeratosis, papillomas, palmar-plantar erythrodysesthesia), pyrexia, fatigue, headache, and arthralgia. Combining a BRAF inhibitor with a MEK inhibitor, which may block paradoxical MAPK activation in BRAF wild type (skin) cells, may lower the incidence of squamoproliferative eruptions.

A single-centre experience of patients with metastatic melanoma enrolled in a dabrafenib named patient programme

We studied the efficacy, tolerability and clinical courses of dabrafenib in patients with metastatic melanoma who were ineligible for enrolment into a clinical trial. Between July 2011 and May 2013, patients with unresectable stage III or stage IV, V600-mutated metastatic melanoma who were not eligible for inclusion into clinical trials were offered treatment with dabrafenib through a named patient programme. Routine efficacy and toxicity data were collected throughout treatment and studied retrospectively. The endpoints were progression-free survival (PFS), overall survival and best overall response. Thirty-one patients commenced dabrafenib therapy including six individuals who had progressed on a prior BRAF-inhibitor treatment. The majority of patients had cerebral metastases (n=17) and/or a poor performance status [Eastern Cooperative Oncology Group (ECOG)≥2, n=11]. Median overall survival was 5.6 months (range 0.1-22 months). Median PFS was 3.3 months (range 0.1-21) and was similar despite performance status. One patient had a complete response and eight showed partial responses to treatment. Patients with cerebral metastases (n=17) had a median PFS of 4.6 months. Five patients (16%) had dose-limiting toxicities. Despite several poor prognostic features, dabrafenib is a safe and effective treatment in the community setting, with occasional impressive outcomes.

Effects of particle size, food, and capsule shell composition on the oral bioavailability of dabrafenib, a BRAF inhibitor, in patients with BRAF mutation-positive tumors

Dabrafenib is a small-molecule inhibitor of BRAF kinase activity that is currently being developed for the treatment of BRAF V600 mutation-positive melanoma. This clinical, open-label, two-cohort (n = 14 per cohort), randomized study was designed to evaluate the effect of drug substance particle size, and food on the plasma pharmacokinetics of a single oral dose of dabrafenib in patients with BRAF V600 mutation-positive solid tumors. In addition, an exploratory cross-cohort comparison of the relative bioavailability of single-dose dabrafenib administered in gelatin and hydroxypropyl methylcellulose (HPMC) capsules was performed. Higher bioavailability was noted with nonmicronized drug substance (larger particle size), under fasting conditions, and with HPMC capsules. Initial dissolution results at pH 1.2 showed higher dissolution of gelatin relative to HPMC capsules inconsistent with clinical data. Subsequent in vitro dissolution studies were conducted in fasted-state simulated gastric fluid over a 24-h period and showed that HPMC capsules reached a higher percentage of dabrafenib dissolved than gelatin capsules. The presence of HPMC is believed to inhibit precipitation of dabrafenib as the freebase, thereby maintaining a supersaturated solution over an extended period of time. Dabrafenib has been administered in pivotal clinical studies on an empty stomach using micronized drug substance in HPMC capsules. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:3100–3109, 2013

Concomitant Oral and Intravenous Pharmacokinetics of Dabrafenib, a BRAF Inhibitor, in Patients with BRAF V600 Mutation‐Positive Solid Tumors

Dabrafenib is an orally bioavailable, potent, and selective inhibitor of human wild-type BRAF and CRAF kinases as well as mutant forms of BRAF kinase. The aim of this phase 1, single-center, open-label study in four patients with BRAF mutation-positive solid tumors was to determine the absolute bioavailability of a 150 mg oral dose of dabrafenib. A microtracer study approach, in which a 50 µg radiolabeled intravenous (IV) microdose of dabrafenib was given concomitantly with a 150 mg oral dose, was used to simultaneously recover IV and oral pharmacokinetic parameters. The least squares mean (90% CI) absolute bioavailability of dabrafenib (HPMC capsules) was 94.5% (81.3%, 109.7%). Median T(max) after oral administration was 2.0 hours and the geometric mean terminal half-life was 4.8 hours. The geometric mean clearance and volume of distribution after IV administration were 12.0 L/h and 45.5 L, respectively. Human clearance and volume of distribution at steady state were in agreement with predictions made using allometric scaling of pharmacokinetic parameters from four preclinical species. In conclusion, dabrafenib absolute bioavailability was high, whereas first-pass metabolism was low. Furthermore, the microtracer approach provided an innovative and efficient method for assessing the absolute bioavailability of dabrafenib in patients with advanced cancer.