Early data show promising results for cabozantinib, a new therapeutic agent for castration-resistant prostate cancer (CRPC), particularly against tumors that have metastasized to the bone. In a phase 2 study of men (median age 68 years) with metastatic CRPC (mCRPC) who were followed for a median of four months, 47% of the 100 evaluable patients had undergone prior treatment with docetaxel.

Seventy-eight percent had bone metastasis. Among the 65 patients evaluable by bone scan, 56 (86%) experienced complete or partial resolution of bone lesions as early as week 6 of cabozantinib treatment. In addition, 64% of the 28 men receiving narcotics for bone pain had improved pain relief, with narcotics reduced or halted in 46%. By week 12, the disease control rate was 71%.

Cabozantinib, an inhibitor of the MET and VEGF pathways, showed clinical activity regardless of prior docetaxel therapy. Maha Hussain, MD, and colleagues presented their findings at the annual meeting of the American Society of Clinical Oncology in Chicago.

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