A phase I and randomized phase II study of cabozantinib plus docetaxel and prednisone (C+DP) versus docetaxel and prednisone (DP) alone in metastatic castrate-resistant prostate cancer (mCRPC).

173Background: A phase I study of Cabozantinib (C) in combination with docetaxel (D) and prednisone (P) in patients (pts) with mCRPC determined that 40 mg daily was the maximum tolerated dose of C in combination with D and P (C+DP). We report a pooled analysis of the phase I and randomized phase II study comparing C+DP to DP alone. Methods: Eligible pts had mCRPC without prior chemotherapy in the castrate setting. All pts received a fixed dose of D (75 mg/m2IV day one of each 21 day cycle) and P (5 mg PO twice daily), and in the C+DP group, C at three escalating dose levels: 20 mg, 40 mg, or 60 mg in the phase I cohort (all PO daily) and 40 mg daily in the phase II cohort. Results: A total of 32 pts received C+DP (19 pts in phase I and 13 pts in the phase II cohort). 12 pts received DP alone. Baseline characteristics for C+DP vs DP included median age 69 (45 – 84) vs 69 (50-83) and median PSA 74.8 ng/ml (0.01-4093.7) vs 309.5 ng/ml (94.6 – 2649) respectively. Clinical trial information: NCT01683994. 18/32...