Bone-targeted therapy that combines strontium-89 (Sr-89) with alternating weekly chemohormonal therapy may improve clinical outcomes in patients with metastatic hormone-refractory prostate cancer. This phase II study investigated the addition of Sr-89 to an alternating weekly regimen of doxorubicin and ketoconazole with paclitaxel and estramustine in patients with progressive prostate cancer and bone involvement.
Twenty-nine patients with progressive adenocarcinoma of the prostate and osteoblastic bone metastases who failed conventional hormonal therapy were registered for the study. Of those, 27 were treated with Sr-89 on day 1 of week 1. On weeks 1, 3, and 5, patients received doxorubicin (20 mg/m2 on day 1) and oral ketoconazole (400 mg 3 times a day for 7 days). On weeks 2, 4, and 6, patients received paclitaxel (100 mg/m2) and oral estramustine (280 mg 3 times a day for 7 days). No treatment was given during weeks 7 and 8. Cycles were repeated every 8 weeks.
A ≥50% reduction in prostate-specific antigen level was maintained for at least 8 weeks in 77.7% of the patients (21 patients) at 16 weeks and in 66.6% (18 patients) at 32 weeks. The median progression-free survival was 11.27 months (range, 1.83–29.53), and the median overall survival was 22.67 months (1.83–57.73+). Two patients died during study because of disease progression. Overall, the chemotherapy combined with Sr-89 was well tolerated.
Our results demonstrate that the combination of alternating weekly chemohormonal therapies with Sr-89 demonstrates a prolonged progression-free and overall survival with acceptable toxicity. Further investigation of combination therapies with Sr-89 is warranted.