Updated safety and efficacy results from a phase I/II study of the oral BRAF inhibitor dabrafenib (GSK2118436) combined with the oral MEK 1/2 inhibitor trametinib (GSK1120212) in patients with BRAFi-naive metastatic melanoma

Jeffrey S. Weber, Keith T. Flaherty, Jeffrey R. Infante, Gerald Steven Falchook, Richard Kefford, Adil Daud, Omid Hamid, Rene Gonzalez, Ragini Reiney Kudchadkar, Donald P. Lawrence, Howard A. Burris, Georgina V. Long, Alain Patrick Algazi, Karl D. Lewis, Kevin B. Kim, Igor Puzanov, Peng Sun, Shonda M. Little, Kiran Patel, Jeffrey Alan Sosman

Research output: Contribution to journalMeeting abstractpeer-review

Abstract

Background: In preclinical models, the BRAFi/MEKi combination has demonstrated enhanced activity against BRAF-mutant cancer cells compared with either drug alone, delayed emergence of BRAFi resistance, and prevented BRAFi-related proliferative skin lesions. A 3-part study investigating the dabrafenib/trametinib combination was conducted in patients (pts) with V600 BRAF mutant solid tumors. Interim data from the study were previously reported (Infante, ASCO 2011); updated safety and efficacy data are presented.

Methods: In Part 2, 125 pts with V600 BRAF mutant solid tumors enrolled, including 77 melanoma pts with no prior BRAFi, and measurable disease according to RECIST 1.1. Pts were treated on 4 escalating dose levels of dabrafenib/trametinib (mg BID/mg QD): 75/1, 150/1, 150/1.5, 150/2. Demographic and efficacy data for the 77 melanoma pts with no prior BRAFi and safety data for all 125 Part 2 pts are reported.

Results: Among 77 melanoma pts, median age was 52 years, 61% male, 57% ECOG PS of 0, 91% V600E, 65% M1c stage, 26% prior brain metastases, and 52% LDH > ULN. Confirmed ORR was 56% (95% CI: 44.1%-67.2%) with 4 CR, 39 PR, 29 SD and, 3 PD. Confirmed response rate for each dose level, respectively, was 67% (n=6), 64% (n=22), 48% (n=25), and 54% (n=24). Median PFS (months) for each dose level, respectively, was: 8.7, 8.3, 5.5; PFS is not mature for 150/2. Overall PFS was 7.4 (95% CI: 5.5-9.2). Among the 125 pts, there were 2 grade (G) 5 adverse events (AEs), pneumonia and hyponatraemia. The most common G3/4 AEs were pyrexia (n=6, 5%), fatigue (n=6, 5%) and dehydration (n=6, 5%). Skin toxicity ≥ G2 occurred in 17 (14%) pts. Cutaneous squamous cell carcinoma occurred in 3 (2%) pts and actinic keratoses in 2 (2%).

Conclusions: The combination of dabrafenib/trametinib has an acceptable safety profile, with a lower incidence of MEKi-related rash and BRAFi-induced hyperproliferative skin lesions compared with the single agents. The clinical activity of dabrafenib/trametinib observed in pts with V600 BRAF mutant metastatic melanoma is encouraging and will be investigated further in a phase III trial.
Original languageEnglish
Pages (from-to)8510-8510
Number of pages1
JournalJournal of Clinical Oncology
Volume30
Issue numberSupplement 15
Publication statusPublished - 20 May 2012
Externally publishedYes
Event48th Annual Meeting of the American-Society-of-Clinical-Oncology (ASCO) - Chicago, United States
Duration: 1 Jun 20126 Jun 2012

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