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ESMO 2019: Cobimetinib Plus Atezolizumab Versus Pembrolizumab in BRAF V600 Wild-Type Melanoma

The combination treatment of the MEK inhibitor cobimetinib and the anti–PL-L1 antibody atezolizumab did not demonstrate an improvement in progression-free survival when compared with pembrolizumab in patients who have BRAF V600 wild-type melanoma. The primary analysis of the IMspire170 trial, presented by Ana M. Arance, MD, PhD, of the Hospital Clinic in Barcelona, was showcased at the 2019 European Society for Medical Oncology (ESMO) Congress (Abstract LBA69).

This phase III study enrolled a total of 446 patients with previously untreated and unresectable stage III or IV BRAF V600 wild-type melanoma. Patients were randomly assigned 1:1 to receive either 60 mg of cobimetinib on days 1 through 21 plus 840 mg of atezolizumab every 2 weeks in a 28-day cycle or 200 mg of pembrolizumab every 3 weeks. Treatment was continued until there was a loss of clinical benefit, unacceptable toxicity, or consent was withdrawn.

Approximately 68% of patients included in this study had PD-L1–positive tumors, and 25% of the patients had levels of lactate dehydrogenase above the upper limit of normal. The median follow-up for all patients was 7 months.

The combination treatment of cobimetinib and atezolizumab did not significantly improve progression-free survival compared with pembrolizumab (5.5 vs. 5.7 months). The objective response rate was 26% in patients assigned to receive the combination treatment and 32% in the pembrolizumab group. Disease control rates were 46% and 44% with cobimetinib plus atezolizumab and with monotherapy, respectively. The median overall survival rates could not be reached in either arm of the study.

Grade 3 or higher adverse events occurred in 67% of patients treated with the combination therapy compared with 33% of patients treated with pembrolizumab. Adverse events led to discontinuation of treatment for 12% of patients receiving the combination therapy and 6% of patients receiving monotherapy.

Disclosure: Full disclosures of the study authors can be found at


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