Objective: To evaluate the activity and tolerability of weekly high-dose calcitriol and docetaxel in patients with metastatic hormone-refractory prostate cancer (HRPC) previously exposed to docetaxel, as patients who progress after docetaxel treatment might be considered for second-line chemotherapy, but with no standard salvage therapy available we hypothesised that high-dose calcitriol might restore sensitivity to chemotherapy.
Patients and methods: The study comprised 26 patients who had progressed after first-line treatment with docetaxel-based chemotherapy had failed. Treatment cycles consisted of calcitriol (32 microg orally as 0.5 microg tablets) on day 1 and docetaxel (30 mg/m(2) intravenous) on day 2, administered for six consecutive weeks followed by a 2-week rest interval for a maximum of 24 cycles.
Results: There was a response in prostate-specific antigen (PSA) level in eight patients (31%); seven (27%) had a stable PSA level for >/= 12 weeks. The median time to PSA progression was 4.2 months and the median survival was 9.3 months. The regimen was generally well tolerated; there was grade 2 hypercalcaemia, probably related to calcitriol, in one patient after six treatment cycles.
Conclusion: Weekly high-dose calcitriol and docetaxel seems to be an effective and well-tolerated treatment option for patients with metastatic HRPC previously exposed to docetaxel-based chemotherapy.