Cabozantinib Fails to Meet Primary End-Point in mCRPC

Failure of the drug in the phase 3 COMET-2 study was anticipated following the reported failure of the earlier COMET-1 trial.

Exelixis announced Monday that treatment with cabozantinib failed to alleviate bone pain compared to a steroid control in men with advanced, metastatic prostate cancer. A negative outcome from the so-called COMET-2 prostate cancer study of cabozantinib was widely expected given the previously announced failure of the COMET-1 study in September. Still, Exelixis shares fell another 10% to $1.49--an all-time low--on heightened concerns that ongoing cabozantinib studies in kidney and liver cancer may also prove disappointing.

A few years ago, there was much optimism for cabozantinib based on phase II data showing the drug cleared bone lesions and reduced pain in advanced prostate cancer patients. Cancer that metastasizes, or spreads, to bones is a serious complication leading to fractures, increased pain and eventual death. While many cancer drugs can shrink or eliminate tumors in soft tissue, few if any had ever demonstrated an ability to clear up bone metastases.

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