A phase I/II trial of BKM120 combined with vemurafenib (PLX4032) in BRAF^V600E/k mutant advanced melanoma.

Abstract

TPS8602 Background: Vemurafenib induces transient objective responses in half of BRAFV600E mutant melanoma patients and a median PFS of 5.3 months (NEJM. 2011;364:2507-2516). BRAF mutations are not sufficient to cause melanoma, but the combination of BRAFV600E mutation and PTEN loss is sufficient to recapitulate the malignant melanoma phenotype in vivo (Nat. Genet. 2009;41:544-552). PTEN loss and PI3K activation are common in BRAF mutant metastatic melanoma, and PI3K activation has been implicated as a cause acquired resistance to BRAF inhibitors (Cancer Cell. 2010;18:683-695). This phase I/II study is the first trial to test the safety and efficacy of combining a potent BRAF inhibitor, vemurafenib, with a potent PI3K inhibitor, BKM120, in patients with metastatic BRAF mutant melanoma. Methods: Design: Phase I patients receive a single dose of oral BKM120 (d -7) then vemurafenib twice daily with BKM120 daily (starting on c1d1). PK analysis is performed for BKM120 alone and for both drugs in combination. Doses of both drugs will be escalated in 3+3 scheme. Phase II patients receive continuous dosing of vemurafenib twice daily and BKM120 daily. Serial biopsies for PD and mRNA expression analyses are required for patients with visible or palpable tumors. Reimaging will be performed every 8 weeks.Eligibility: This study is enrolling BRAFV600E/K mutant metastatic melanoma patients with no prior exposure to BRAF inhibitors or PI3K inhibitors, ECOG PS ≥ 2 and adequate organ function. Endpoints: The primary endpoint for phase 1 is the recommended phase 2 dose of the combination. The primary endpoint for phase II is the 6 month PFS rate. Secondary endpoints include median PFS and OS. Baseline PTEN expression and changes is pS6 protein levels will be examined as predictors of efficacy, and changes in gene expression profiles will be assessed. Summary: This is the first trial examining the safety and efficacy of combined BRAF/PI3K inhibition in BRAF mutant melanoma patients.