Docetaxel is the standard of care for patients with metastatic, castrate-resistant prostate cancer (CRPC). Gemcitabine is a nucleoside analogue with broad antitumor activity. In a phase 2 study of combined docetaxel and gemcitabine, the authors assessed its safety and activity in patients with chemotherapy-naive, metastatic CRPC.
Eligible patients had untreated, metastatic CRPC with radiologic and/or biochemical evidence of progression after antiandrogen withdrawal with castrate testosterone levels, an Eastern Cooperative Oncology performance status (ECOG PS) of 0 to 2, and adequate organ function; no previous chemotherapy was permitted. Patients received gemcitabine (800 mg/m²) Days 1 and 8 and docetaxel (75 mg/m²) on Day 8 every 21 days for a maximum of 6 cycles. Response was evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) for measurable disease. A prostate-specific antigen (PSA) response was defined as a decline ≥ 50% in baseline PSA level.
Thirty-five patients with chemotherapy-naive, metastatic CRPC were enrolled. The median age was 67 years, and 60% of patients had an ECOG PS of 0. PSA responses were observed in 49% of patients. Among the patients who had measurable disease (n = 25), 3 patients (12%) had a confirmed, RECIST-defined partial response (PR); 4 patients (16%) had an unconfirmed PR; and 15 patients (60%) achieved stable disease. The most common adverse events included grade 1 and 2 fatigue (69%), alopecia (80%), and nausea/vomiting (54%). No treatment-related deaths were noted, but an unusually high incidence of grade 3 and 4 neutropenia was observed.
The efficacy of combined gemcitabine and docetaxel in metastatic CRPC was similar to that observed with single-agent docetaxel. In contrast to single-agent docetaxel, the combination was moderately toxic and had an impact primarily on bone marrow reserve.