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In a 495-patient Phase 3 clinical trial, the combination of the investigational MEK inhibitor cobimetinib and Genentech's (OTCQX:RHHBY) BRAF inhibitor Zelboraf (vemurafenib) helped advanced melanoma patients live significantly longer without their disease worsening (progression-free survival or PFS) compared to Zelboraf alone.
- Cobimetinib blocks the activity of MEK, one of a series of proteins inside cells that constitute a signaling pathway the helps regulate cell division and survival. Zelboraf binds to BRAF, another protein in the pathway.
- Nothing is disclosed about the combination therapy's success in achieving its secondary endpoints of OS, objective response rate, duration of response and other safety and quality of life measures. PFS is a lower standard of efficacy than OS but drug firms greatly prefer this endpoint due to the lower cost and shorter follow-up period.
- Cobimetinib is being co-developed by Genentech and Exelixis (NASDAQ:EXEL). Shares of EXEL are up 16% premarket on light volume.