Randomized, Open-Label Phase III Trial of Docetaxel Plus High-Dose Calcitriol Versus Docetaxel Plus Prednisone for Patients With Castration-Resistant Prostate Cancer

Abstract

Purpose To compare the efficacy and safety of docetaxel plus high-dose calcitriol (DN-101) to docetaxel plus prednisone in an open-label phase III trial. Patients and Methods Nine hundred fifty-three men with metastatic castration-resistant prostate cancer (CRPC) were randomly assigned to Androgen-Independent Prostate Cancer Study of Calcitriol Enhancing Taxotere (ASCENT; 45 μg DN-101, 36 mg/m2 docetaxel, and 24 mg dexamethasone weekly for 3 of every 4 weeks) or control (5 mg prednisone twice daily with 75 mg/m2 docetaxel and 24 mg dexamethasone every 3 weeks) arms. The primary end point was overall survival (OS), assessed by the Kaplan-Meier method. Results At an interim analysis, more deaths were noted in the ASCENT arm, and the trial was halted. The median-follow-up for patients alive at last assessment was 11.7 months. Median OS was 17.8 months (95% CI, 16.0 to 19.5) in the ASCENT arm and 20.2 months (95% CI, 18.8 to 23.0) in the control arm (log-rank P = .002). Survival remained inferior after adjusting for baseline variables (hazard ratio, 1.33; P = .019). The two arms were similar in rates of total and serious adverse events. The most frequent adverse events were GI (reported in 75% of patients), and blood and lymphatic disorders (48%). Docetaxel toxicity leading to dose modification was more frequent in the ASCENT (31%) than in the control arm (15%). Conclusion ASCENT treatment was associated with shorter survival than the control. This difference might be due to either weekly docetaxel dosing, which, in a prior study, showed a trend toward inferior survival compared with an every-3-weeks regimen, or DN-101 therapy.