Roche and Exelixis head to the FDA with their melanoma combo

Partners Roche ($RHHBY) and Exelixis ($EXEL) are making their case to regulators with a melanoma-treating combination therapy, filing an FDA application for the fast-tracked treatment as they await European clearance.

The two are seeking approval for a combination of the Exelixis-discovered cobimetinib and Roche's on-the-market Zelboraf, a cocktail that targets melanoma patients with the V600 mutation in their BRAF genes. Roche's Genentech unit licensed cobimetinib back in 2006, and, if the combo wins approval, Exelixis is entitled to a 50% share of U.S. sales plus royalties on global revenue.

The FDA has granted cobimetinib its fast-track designation, promising to shorten its review time from 10 to 6 months if and when it accepts the application. Roche said it submitted the drug to the European Medicines Agency in September.

In a Phase III study disclosed over the summer, the combination helped subjects live significantly longer without tumor growth than those treated with Zelboraf alone, hitting its primary goal of progression-free survival (PFS). Patients treated with the combination charted a median PFS of 9.9 months compared to 6.2 months on Zelboraf, the companies said.

Cobimetinib's ongoing success is something of a cold comfort for Exelixis, whose long-term fate is more closely tied to the wholly owned cabozantinib. That drug, a tyrosine kinase inhibitor, failed to beat the immunosuppressant prednisone in a Phase III trial in prostate cancer earlier this year, results that sent the biotech's shares plummeting. Exelixis promptly moved to cut about 70% of its workforce, paring down its operation while holding out hope for two ongoing studies testing cabozantinib's effect on kidney and liver cancers.

The latest on cobimetinib had little effect on Exelixis' share price, which is down more than 80% since January.

Exelixis came up with cobimetinib and advanced it to the IND stage before signing on with Genentech, reaping $40 million up front. The drug works by shutting down the kinase MEK, a pathway that regulates growth factor receptors and plays a hand in helping tumors proliferate.

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