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Cancer Drug Could Be First New Melanoma Medication Approved Since 1975

Cobimetinib helped patients live 1 year without disease progression

In a report posted on the BioSpace website, an executive with Genentech has expressed the opinion that information presented at the American Society of Clinical Oncology’s annual meeting regarding cobimetinib is a promising sign that the investigational cancer drug could be the first new treatment for melanoma approved by the FDA since 1975.

Findings from the pivotal, phase III coBRIM trial are part of a push by the firm to have combination therapy with cobimetinib and vemurafenib (Zelboraf, Genentech/Daiichi Sankyo) approved by August.

Updated data from the coBRIM study showed that the combination helped people with previously untreated BRAF V600 mutation-positive advanced melanoma live a median of 1 year (12.3 months) without their disease worsening or death (progression-free survival [PFS]) compared with 7.2 months with vemurafenib alone (hazard ratio [HR], 0.58).

The updated results from coBRIM also demonstrated higher response rates with cobimetinib and vemurafenib compared with vemurafenib alone. The objective response rate (ORR) with the combination was 70% percent (16% complete response [CR] and 54% partial response [PR]) compared with an ORR of 50% (11% CR and 40% PR) in the vemurafenib monotherapy arm. With further follow-up, the CR rate increased from 10% to 16% with the combination as some patients who had a PR achieved a CR after more than 1 year of treatment.

CoBRIM was an international, randomized, double-blind, placebo-controlled study evaluating the safety and efficacy of cobimetinib 60 mg once daily in combination with vemurafenib 960 mg twice daily, compared with vemurafenib 960 mg twice daily alone. In the study, 495 patients with BRAF V600 mutation-positive unresectable locally advanced or metastatic melanoma (detected by the Cobas 4800 BRAF mutation test) and previously untreated for advanced disease were randomly assigned to receive vemurafenib every day on a 28-day cycle plus either cobimetinib or placebo on days 1 to 21. Treatment was continued until disease progression, unacceptable toxicity, or withdrawal of consent. Investigator-assessed PFS was the primary endpoint. Secondary endpoints include PFS by an independent review committee, the overall response rate, overall survival, the duration of response, and other safety, pharmacokinetic, and quality-of-life measures.

The most common adverse events (occurring in more than 20% of subjects) reported in patients treated with the cobimetinib/vemurafenib combination included diarrhea, rash, nausea, fever, sun sensitivity, liver laboratory abnormalities, elevated creatine phosphokinase levels, and vomiting. Serous retinopathy was observed more often in the combination arm (26% vs. 3%), with most of these events either grade 1 or 2, asymptomatic, and temporary in nature. Some AEs, including cutaneous squamous cell carcinomas and keratoacanthomas, were reported less often in the combination arm.

Sources: BioSpace; June 1, 2015; and Genentech; May 30, 2015.

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