Phase 3, Double-Blind, Placebo-Controlled Study of Vemurafenib Versus Vemurafenib + Cobimetinib in Previously Untreated Brafv600 Mutation–Positive Patients with Unresectable Locally Advanced or Metastatic Melanoma (Nct01689519)

Abstract

was 68% in the combination and 45% in the control arm (P<0.0001), including complete response in 10% in the combination and 4% of patients in the control group. Subgroup analyses of PFS based on key demographic and tumor characteristics were consistent with PFS in the intent-to-treat population, including those with normal or elevated baseline lactate dehydrogenase (LDH). PFS assessed by independent review was comparable with investigator-assessed PFS. Interim overall survival (OS) data showed an HR of 0.65 (95% CI, 0.42-1.00) but did not cross the prespecified stopping boundary. Compared with vemurafenib alone, the combination was associated with a higher incidence of grade 3 or 4 adverse events (65% vs 59%), with no difference in the rate of adverse events leading to study drug discontinuation (13% vs 12%). Most grade ≥3 events occurred in the first 28 days and resolved quickly. Known MEK inhibitor–related toxicities such as diarrhea, serous retinopathy, elevated creatine phosphokinase, and increased liver transaminase levels were more commonly observed with the combination. The majority was grade 1 or 2, occurred between 1 and 4 months in the treatment course, and resolved quickly. The occurrence of secondary cutaneous neoplasms decreased with the combination (4% vs 18%). Photosensitivity was more common in patients treated with the combination (all grades 32% vs 18%).