Exelixis, Inc. (NASDAQ:EXEL) today announced preliminary results from BRIM7, an ongoing Phase Ib trial conducted by Roche and Genentech, Exelixis' collaborator and a member of the Roche Group (SIX: RO, ROG; OTCQX: RHHBY), of the BRAF inhibitor (BRAFi) vemurafenib in combination with the MEK inhibitor GDC-0973 in patients with locally advanced/unresectable or metastatic melanoma carrying a BRAF V600 mutation. Rene Gonzalez, M.D., Professor of Medicine and Dermatology and Director of the Melanoma Research Clinics at the University of Colorado Denver, and an investigator on the trial, presented the data today at the European Society for Medical Oncology (ESMO) 2012 Annual Meeting (Abstract #LBA28), which is taking place in Vienna, Austria. The results of the study were also highlighted in an ESMO press briefing. Roche has disclosed that it intends to evaluate the combination of vemurafenib with GDC-0973 versus vemurafenib in a multicenter, randomized, double-blind, placebo-controlled Phase III trial in previously untreated patients with BRAF V600 mutation positive, unresectable locally advanced or metastatic melanoma. Study Design The Phase Ib dose escalation study was designed to evaluate the safety and tolerability of vemurafenib in combination with GDC-0973. The study was not designed to measure efficacy. The dose escalation stage of the trial comprised 10 dosing cohorts of 3-6 patients and evaluated three different dosing schedules for GDC-0973. Cohorts that met the protocol-specified criteria for safety were expanded to include up to 20 BRAFi-naïve and vemurafenib-progressing patients. Study Results As of July 6, 2012, 70 patients had been treated. The majority of patients (74.3%) had Stage IV, M1c melanoma at the time of enrollment, and 54.3% had disease progression following prior treatment with vemurafenib. The median number of prior treatment cycles to date was three. Six of the 10 dose escalation cohorts have met the protocol-specified criteria for safety. One dose-limiting toxicity (Grade 3 QT interval prolongation) was observed out of six patients in the dose escalation stage receiving 960 mg of vemurafenib and 60 mg of GDC-0973 on a 21/7 day schedule. Two cohorts receiving 60 mg of GDC-0973 on a 21/7 day schedule with vemurafenib at 720 mg and 960 mg were selected for expansion.