On October 6, 2015 Exelixis, Inc. (NASDAQ:EXEL) reported positive overall survival (OS) results from coBRIM, the phase 3 pivotal trial evaluating cobimetinib, a specific MEK inhibitor discovered by Exelixis, in combination with vemurafenib in previously untreated patients with unresectable locally advanced or metastatic melanoma carrying a BRAF V600 mutation (Press release, Exelixis, OCT 6, 2015, View Source [SID:1234507644]). Schedule your 30 min Free 1stOncology Demo! Exelixis’ collaborator Genentech, a member of the Roche Group, informed the company that coBRIM met its secondary endpoint of demonstrating a statistically significant and clinically meaningful increase in overall survival for patients receiving the combination of cobimetinib and vemurafenib, as compared to vemurafenib monotherapy. Ongoing study monitoring did not identify any new safety signals. Long-term safety data are expected later this year. These data will be the subject of a presentation at an upcoming medical meeting.
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"The positive effect of the combination of cobimetinib and vemurafenib on overall survival is a major step forward for patients with advanced BRAF V600 mutation-positive melanoma in search of new treatment options," said Michael M. Morrissey, Ph.D., president and chief executive officer of Exelixis. "We continue to work with our partners at Genentech in preparation for the potential U.S. approval and launch of cobimetinib to deliver this important potential treatment option to patients, physicians and caregivers in the United States as quickly as possible."
Exelixis announced the first regulatory approval of cobimetinib in Switzerland in August 2015. U.S. and EU regulatory applications sponsored by Genentech and Roche, respectively, are currently under review. In the United States, the Prescription Drug User Fee Act action date is November 11, 2015. In the EU, Roche anticipates a regulatory decision by the end of this year following a positive opinion from the European Committee for Medicinal Products for Human Use announced in late September.
About the coBRIM Study
The coBRIM trial is an international, randomized, double-blind, placebo-controlled Phase III study evaluating the safety and efficacy of 60 mg once daily of cobimetinib in combination with 960 mg twice daily of vemurafenib, compared to 960 mg twice daily of vemurafenib 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 randomized to receive vemurafenib every day on a 28-day cycle plus either cobimetinib or placebo for days 1-21. Treatment was continued until disease progression, unacceptable toxicity or withdrawal of consent. Investigator-assessed PFS is the primary endpoint. Secondary endpoints include PFS by independent review committee, overall response rate, overall survival, duration of response and other safety, pharmacokinetic and quality of life measures.
About the Cobimetinib Development Collaboration
Exelixis discovered cobimetinib internally and advanced the compound to investigational new drug (IND) status. In late 2006, Exelixis entered into a worldwide co-development agreement with Genentech, under which Exelixis received initial upfront and milestone payments for signing the agreement and submitting the IND. Exelixis was responsible for development of cobimetinib through the end of phase 1, at which point Genentech exercised its option to further develop the compound.
If cobimetinib is approved in the United States, Exelixis is entitled to an initial equal share of U.S. profits and losses, which will decrease as sales increase, and will share in U.S. marketing and commercialization costs. In November 2013, Exelixis exercised its option to co-promote cobimetinib in the United States and, under the terms of the agreement, the company is prepared to field up to 25 percent of the U.S. sales force.
About the Combination of Cobimetinib and Vemurafenib
Cobimetinib is a selective inhibitor that blocks the activity of MEK, a protein kinase that is part of a key pathway (the RAS-RAF-MEK-ERK pathway) that promotes cell division and survival. This pathway is frequently activated in human cancers including melanoma, where mutation of one of its components (BRAF) causes abnormal activation in about 50 percent of tumors. About 50 percent of patients with BRAF mutation positive melanoma experience a tumor response when treated with a BRAF inhibitor, however development of resistance and subsequent tumor progression limits treatment benefit. Clinical and preclinical analyses indicated that reactivation of the MEK-ERK pathway may underlie development of resistance to BRAF inhibitors in many progressing tumors, and that co-treatment with a BRAF and MEK inhibitor delays the emergence of resistance in the preclinical setting, providing the rationale for testing the combination of vemurafenib and cobimetinib in clinical trials. In addition to the combination with vemurafenib in melanoma, cobimetinib is also being investigated in combination with several investigational medicines, including an immunotherapy, in several tumor types, including non-small cell lung cancer, colorectal cancer, triple-negative breast cancer and melanoma.
About Melanoma and its BRAF V600 Mutation-Positive Form
Melanoma is the less common, but more serious category of skin cancer that starts in the skin’s pigment producing cells known as melanocytes. According to the American Cancer Society, approximately five percent of skin cancer diagnoses are melanoma, but melanoma accounts for a large majority of skin cancer deaths. In recent years, there have been significant advances in treatment for metastatic melanoma and people with the disease have more options. However, it continues to be a serious health issue with a high unmet need and a steadily increasing incidence over the past 30 years. It is projected that approximately half of all melanomas, and eight percent of solid tumors, contain a mutation of the BRAF protein. BRAF is a key component of the RAS-RAF-MEK-ERK pathway involved in normal cell growth and survival. However, mutations that keep the BRAF protein in an active state may cause excessive signaling in the pathway, leading to uncontrolled cell growth and survival. The BRAF V600 mutation-positive form of melanoma is associated with high-risk characteristics of the disease, including early onset, the absence of chronic skin damage, and decreased survival.