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Genentech launches PhIII for melanoma combo with GSK in hot pursuit

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Melanoma under a microscope--Image courtesy of NIH

Genentech has joined a race to prove that two kinds of targeted cancer drugs are better than one of them. It's jumped into a late-stage trial of a two-drug combo therapy against deadly skin cancer amid growing competition for such treatments in the pharma industry.

The trial comes after GlaxoSmithKline's ($GSK) rival dual therapy began Phase III development on the heels of promising results in an earlier-stage study.

This week Genentech, the U.S. biotech unit of drug giant Roche ($RHHBY), made known that the first patient was dosed in a pivotal study of the experimental MEK inhibitor GDC-0973 from its partners Exelixis ($EXEL) and its marketed skin-cancer drug Zelboraf in certain melanoma patients, Exelixis said in an SEC filing.

The study aims to compare Zelboraf, a BRAF inhibitor that was FDA-approved in 2011, as a standalone treatment with treatment on both Zelboraf and GDC-0973 in previously untreated patients with malignant melanomas that express the BRAF V600 mutation. According to the FDA, BRAF protein mutations crop up in about half of all advanced cases of melanoma. And the protein is a key target for treatment.

London-based GSK has shown that adding a MEK blocker to the mix could improve treatment for melanoma patients. The drug giant has in its crosshairs Zelboraf, which Genentech developed in collaboration with Daiichi Sankyo's Plexxikon, and GSK aims to show in a late-stage study whether its experimental MEK inhibitor trametinib and BRAF blocker dabrafenib can trump treatment on Zelboraf alone.

Glaxo aims to get approvals for trametinib and dabrafenib as single agents against melanoma this year. Experts have already begun to warm up to data that support the MEK-BRAF cocktail as a way to keep melanomas at bay longer than BRAF alone, researcher Decision Resources said in September.

Exelixis, which has co-developed GDC-0978 with Genentech since late-2006, has a chance to capitalize on the focus its big partner has given its anti-MEK candidate. It's got the next 12 months to decide whether to take its option to co-promote the drug in the U.S.

- here's the SEC filing
- see the news from the San Francisco Business Times

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