BACKGROUND Resistance to therapy with BRAF kinase inhibitors is associated with reactivation of the mitogen-activated protein kinase (MAPK) pathway. To address this problem, we conducted a phase 1 and 2 trial of combined treatment with dabrafenib, a selective BRAF inhibitor, and trametinib, a selective MAPK kinase (MEK) inhibitor. METHODS In this open-label study involving 247 patients with metastatic melanoma and BRAF V600 mutations, we evaluated the pharmacokinetic activity and safety of oral dabrafenib (75 or 150 mg twice daily) and trametinib (1, 1.5, or 2 mg daily) in 85 patients and then randomly assigned 162 patients to receive combination therapy with dabrafenib (150 mg) plus trametinib (1 or 2 mg) or dabrafenib monotherapy. The primary end points were the incidence of cutaneous squamous-cell carcinoma, survival free of melanoma progression, and response. Secondary end points were overall survival and pharmacokinetic activity. RESULTS Dose-limiting toxic effects were infrequently observed in patients receiving combination therapy with 150 mg of dabrafenib and 2 mg of trametinib (combination 150/2). Cutaneous squamous-cell carcinoma was seen in 7% of patients receiving combination 150/2 and in 19% receiving monotherapy (P = 0.09), whereas pyrexia was more common in the combination 150/2 group than in the monotherapy group (71% vs. 26%). Median progression-free survival in the combination 150/2 group was 9.4 months, as compared with 5.8 months in the monotherapy group (hazard ratio for progression or death, 0.39; 95% confidence interval, 0.25 to 0.62; P<0.001). The rate of complete or partial response with combination 150/2 therapy was 76%, as compared with 54% with monotherapy (P = 0.03). CONCLUSIONS Dabrafenib and trametinib were safely combined at full monotherapy doses. The rate of pyrexia was increased with combination therapy, whereas the rate of proliferative skin lesions was nonsignificantly reduced. Progression-free survival was significantly improved. (Funded by GlaxoSmithKline; ClinicalTrials.gov number, NCT01072175.)

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Background Dabrafenib (GSK2118436) is a potent ATP-competitive inhibitor of BRAF kinase and was highly selective for mutant BRAF in kinase panel screening, cell lines, and xenografts. Methods A Phase I trial of dabrafenib was conducted to evaluate safety and tolerability in patients with incurable solid tumours. Efficacy at the recommended Phase II dose (RP2D) was studied in patients with BRAF-mutant tumours, including those with non-V600E mutations, in three cohorts: (1) metastatic melanoma, (2) melanoma with untreated brain metastases, and (3) non-melanoma solid tumours. Findings 184 patients enrolled, and 150 mg twice daily was chosen as the RP2D, based on safety, pharmacokinetic, and pharmacodynamic data. At the RP2D in patients with V600 BRAF-mutant melanoma, a response rate of 69% (a confirmed response rate of 50%) was observed overall and a 78% response rate (a confirmed response rate of 56%) in V600E BRAF-mutant melanoma. In V600 BRAF-mutant melanoma, responses were durable, with 17 patients (47%) on treatment for more than 6 months and a median progression-free survival (PFS) of 5·5 months. Responses were observed in patients with non-V600E BRAF mutations, including V600K and V600G. In the RP2D expansion of melanoma with untreated brain metastases, nine of ten patients (90%) showed reduction in brain lesion size and the median PFS was 4.2 months. Among BRAF-mutant non-melanoma solid tumours, antitumour activity was observed in gastrointestinal stromal tumour, papillary thyroid, non-small cell lung, ovarian, and colorectal cancer. Interpretation Dabrafenib is a highly active inhibitor of V600-mutant BRAF with a high response rate in V600E melanoma, and is the first drug of its class to demonstrate activity in melanoma brain metastases. Funding This study was funded and sponsored by GlaxoSmithKline

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Summary Purpose The mitogen-activated extracellular signal-related kinase kinase (MEK) is a member of the RAS/RAF/MEK/ERK signalling cascade, which is commonly activated in melanoma. Direct inhibition of MEK inhibits ERK signalling. Methods We conducted a multicentre, first-in-human, three-part study (dose escalation, cohort expansion, and pharmacodynamic evaluation) to evaluate the oral small-molecule MEK inhibitor trametininb (GSK1120212) in advanced cancer. Intermittent and continuous dosing regimens were evaluated. Safety and efficacy data in patients with melanoma are presented here, with exploratory analyses of available tumour tissues performed on an Illumina genotyping platform. This completed study is registered with ClinicalTrials.gov, number NCT00687622. Findings Ninety-seven melanoma patients, including 81 with cutaneous or unknown primary melanoma (36 BRAF-mutant, 39 BRAF wild-type, six BRAF status unknown) and 16 uveal melanoma patients were enrolled. The most common treatment-related adverse events were rash/dermatitis acneiform (80 out of 97; 82%) and diarrhoea (n=44; 45%), most of which were grade 2 or lower. No cutaneous squamous cell carcinomas were observed. Among the 36 BRAF-mutant patients, 30 were BRAF-inhibitor naïve. Among these 30 patients, 2 complete responses (CRs) and 10 partial responses (PRs) were observed (unconfirmed response rate=40%) including 2 confirmed CRs and 8 confirmed PRs (confirmed response rate=33%); the median progression-free survival was 5·7 months (95% CI, 4·0–7·4). Among the 6 BRAF-mutant patients who received prior BRAF inhibitor therapy, 1 unconfirmed PR was observed. Among 39 patients with BRAF wild-type melanoma, 4 PRs (all confirmed) were observed (confirmed response rate=10%). Conclusions To our knowledge, this is the first demonstration of substantial clinical activity by a MEK inhibitor in melanoma. These data suggest that MEK is a valid therapeutic target.

Purpose We initiated a personalized medicine program in the context of early clinical trials, using targeted agents matched with tumor molecular aberrations. Herein, we report our observations. Patient and Methods Patients with advanced cancer were treated in the Clinical Center for Targeted Therapy. Molecular analysis was conducted in the MD Anderson Clinical Laboratory Improvement Amendments (CLIA) -certified laboratory. Patients whose tumors had an aberration were treated with matched targeted therapy, when available. Treatment assignment was not randomized. The clinical outcomes of patients with molecular aberrations treated with matched targeted therapy were compared with those of consecutive patients who were not treated with matched targeted therapy. Results Of 1,144 patients analyzed, 460 (40.2%) had 1 or more aberration. In patients with 1 molecular aberration, matched therapy (n = 175) compared with treatment without matching (n = 116) was associated with a higher overall response rate (27% vs. 5%; P < 0.0001), longer time-to-treatment failure (TTF; median, 5.2 vs. 2.2 months; P< 0.0001), and longer survival (median, 13.4 vs. 9.0 months; P= 0.017). Matched targeted therapy was associated with longer TTF compared with their prior systemic therapy in patients with 1 mutation (5.2 vs. 3.1 months, respectively; P < 0.0001). In multivariate analysis in patients with 1 molecular aberration, matched therapy was an independent factor predicting response (P = 0.001) and TTF (P = 0.0001). Conclusion Keeping in mind that the study was not randomized and patients had diverse tumor types and a median of 5 prior therapies, our results suggest that identifying specific molecular abnormalities and choosing therapy based on these abnormalities is relevant in phase I clinical trials.