Nivolumab 1 mg/kg plus ipilimumab 3 mg/kg (NIVO1+IPI3) is approved for first-line treatment of patients with advanced melanoma in several countries.,We conducted a phase IIIb/IV study (CheckMate 511) to determine if nivolumab 3 mg/kg plus ipilimumab 1 mg/kg (NIVO3+IPI1) improves the safety profile of the combination.,Patients (N = 360) age 18 years or older with previously untreated, unresectable stage III or IV melanoma were randomly assigned 1:1 to NIVO3+IPI1 or NIVO1+IPI3 once every 3 weeks for four doses.,After 6 weeks, all patients received NIVO 480 mg once every 4 weeks until disease progression or unacceptable toxicity.,The primary end point was a comparison of the incidence of treatment-related grade 3 to 5 adverse events (AEs) between groups.,Secondary end points included descriptive analyses of objective response rate, progression-free survival, and overall survival.,The study was not designed to formally demonstrate noninferiority of NIVO3+IPI1 to NIVO1+IPI3 for efficacy end points.,At a minimum follow-up of 12 months, incidence of treatment-related grade 3 to 5 AEs was 34% with NIVO3+IPI1 versus 48% with NIVO1+IPI3 (P = .006).,In descriptive analyses, objective response rate was 45.6% in the NIVO3+IPI1 group and 50.6% in the NIVO1+IPI3 group, with complete responses in 15.0% and 13.5% of patients, respectively.,Median progression-free survival was 9.9 months in the NIVO3+IPI1 group and 8.9 months in the NIVO1+IPI3 group.,Median overall survival was not reached in either group.,The CheckMate 511 study met its primary end point, demonstrating a significantly lower incidence of treatment-related grade 3-5 AEs with NIVO3+IPI1 versus NIVO1+IPI3.,Descriptive analyses showed that there were no meaningful differences between the groups for any efficacy end point, although longer follow up may help to better characterize efficacy outcomes.
B-RAF is the most frequently mutated protein kinase in human cancers.1 The finding that oncogenic mutations in BRAF are common in melanoma2 followed by the demonstration that these tumors are dependent on the RAF/MEK/ERK pathway3 offered hope that inhibition of B-RAF kinase activity could benefit melanoma patients.,Herein, we describe the structure-guided discovery of PLX4032 (RG7204), a potent inhibitor of oncogenic B-RAF kinase activity.,Preclinical experiments demonstrated that PLX4032 selectively blocked the RAF/MEK/ERK pathway in BRAF mutant cells and caused regression of BRAF mutant xenografts.4 Toxicology studies confirmed a wide safety margin consistent with the high degree of selectivity, enabling Phase 1 clinical trials using a crystalline formulation of PLX4032.5 In a subset of melanoma patients, pathway inhibition was monitored in paired biopsy specimens collected before treatment initiation and following two weeks of treatment.,This analysis revealed substantial inhibition of ERK phosphorylation, yet clinical evaluation did not show tumor regressions.,At higher drug exposures afforded by a new amorphous drug formulation,4,5 greater than 80% inhibition of ERK phosphorylation in the tumors of patients correlated with clinical response.,Indeed, the Phase 1 clinical data revealed a remarkably high 81% response rate in metastatic melanoma patients treated at an oral dose of 960 mg twice daily.5 These data demonstrate that BRAF-mutant melanomas are highly dependent on B-RAF kinase activity.