Preliminary study of the specific endothelin a receptor antagonist zibotentan in combination with docetaxel in patients with metastatic castration-resistant prostate cancer.
de Bono, JS
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Background This two-part study assessed the safety and tolerability of combined treatment with zibotentan (ZD4054), a specific endothelin A receptor antagonist, plus docetaxel in patients with metastatic castration-resistant prostate cancer.Methods Part A was an open-label, dose-finding phase to determine the safety and toxicity profile of zibotentan in combination with docetaxel. Patients received once-daily oral zibotentan 10 mg (initial cohort) or 15 mg in combination with docetaxel 75 mg/m(2) (administered on day 1 of each 21-day cycle) for up to 10 cycles. Part B was a double-blind phase which evaluated the safety and preliminary activity of zibotentan plus docetaxel. Patients were randomized 2:1 to receive zibotentan (at the highest tolerated dose identified in part A) plus docetaxel or placebo plus docetaxel.Results Six patients were enrolled in part A (n = 3, zibotentan 10 mg; n = 3, zibotentan 15 mg). No dose-limiting toxicity was observed, thus zibotentan 15 mg in combination with docetaxel was evaluated in part B (n = 20, zibotentan plus docetaxel; n = 11, placebo plus docetaxel). CTCAE grade ≥3, most commonly neutropenia or leucopenia, were reported in 10 (50%) and nine (82%) patients in the zibotentan and placebo groups, respectively. One (17%) patient receiving placebo achieved complete response, two (22%) patients receiving zibotentan achieved partial response and stable disease occurred in six (67%) and three (50%) patients receiving zibotentan and placebo, respectively.Conclusions The tolerability of zibotentan plus docetaxel was consistent with the known profiles of each drug. Sufficient preliminary activity was seen with this combination to merit continued development.
Drug Therapy, Combination
Dose-Response Relationship, Drug
Aged, 80 and over
Endothelin A Receptor Antagonists
Prostate Cancer Targeted Therapy Group
License start date
The Prostate, 2011, 71 (12), pp. 1264 - 1275