• Gerald S Falchook, Karl D Lewis, Jeffrey R Infante, Michael S Gordon, Nicholas J Vogelzang, Douglas J DeMarini, Peng Sun, Christopher Moy, Stephen A Szabo, Lori T Roadcap, Vijay G R Peddareddigari, Peter F Lebowitz, Ngocdiep T Le, Howard A Burris, Wells A Messersmith, Peter J O'Dwyer, Kevin B Kim, Keith Flaherty, Johanna C Bendell, Rene Gonzalez, Razelle Kurzrock, and Leslie A Fecher.
• Department of Investigational Cancer Therapeutics, Division of Cancer Medicine, University of Texas MD Anderson Cancer Center, Houston, TX, USA. gfalchoo@mdanderson.org
• Lancet Oncol. 2012 Aug 1; 13 (8): 782789782-9.

BackgroundMEK is a member of the MAPK signalling cascade that is commonly activated in melanoma. Direct inhibition of MEK blocks cell proliferation and induces apoptosis. We aimed to analyse safety, efficacy, and genotyping data for the oral, small-molecule MEK inhibitor trametinib in patients with melanoma.MethodsWe undertook a multicentre, phase 1 three-part study (dose escalation, cohort expansion, and pharmacodynamic assessment). The main results of this study are reported elsewhere; here we present data relating to patients with melanoma. We obtained tumour samples to assess BRAF mutational status, and available tissues underwent exploratory genotyping analysis. Disease response was measured by Response Evaluation Criteria in Solid Tumors, and adverse events were defined by common toxicity criteria. This study is registered with ClinicalTrials.gov, number NCT00687622.Findings97 patients with melanoma were enrolled, including 81 with cutaneous or unknown primary melanoma (36 BRAF mutant, 39 BRAF wild-type, six BRAF status unknown), and 16 with uveal melanoma. The most common treatment-related adverse events were rash or dermatitis acneiform (n=80; 82%) and diarrhoea (44; 45%), most of which were grade 2 or lower. No cutaneous squamous-cell carcinomas were recorded. Of 36 patients with BRAF mutations, 30 had not received a BRAF inhibitor before; two complete responses (both confirmed) and ten partial responses (eight confirmed) were noted in this subgroup (confirmed response rate, 33%). Median progression-free survival of this subgroup was 5·7 months (95% CI 4·0-7·4). Of the six patients who had received previous BRAF inhibition, one unconfirmed partial response was recorded. Of 39 patients with BRAF wild-type melanoma, four partial responses were confirmed (confirmed response rate, 10%).InterpretationOur data show substantial clinical activity of trametinib in melanoma and suggest that MEK is a valid therapeutic target. Differences in response rates according to mutations indicate the importance of mutational analyses in the future.FundingGlaxoSmithKline.Copyright © 2012 Elsevier Ltd. All rights reserved.

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