Sequential mitoxantrone/prednisone followed by docetaxel/estramustine in patients with hormone refractory metastatic prostate cancer: results of a phase II study

Background: Mitoxantrone/prednisone ameliorates symptoms in hormone refractory prostate cancer (HRPC) but has no effect on survival. Docetaxel (Taxotere)/estramustine improves response but with significant toxicity. We reasoned that a sequential administration of the two regimens could be a viable alternative for delivering full doses of chemotherapy, avoiding overlapping toxicity and preserving dose intensity. Patients and methods: Thirty HRPC patients were treated with mitoxantrone 10 mg/m(2), day 1, every 3 weeks, plus prednisone 5 mg twice daily, for three cycles, followed by estramustine phosphate, 280 mg three times daily, days I to 5, plus docetaxel 75 mg/m(2), day 2, every 3 weeks for a maximum of 10 cycles. Results: All patients were assessable for response and toxicity. After mitoxantrone/prednisone treatment, the prostate-specific antigen (PSA) response rate was 23%, which increased to 63% after completion of sequential mitoxantrone/prednisone and docetaxel/estramustine treatment (12 partial and 7 complete responses). With a median follow-up of 18 months, median survival for all patients was 18 months, and median progression-free survival was 10 months. The mitoxantrone/prednisone regimen was well tolerated, and the only grade 3-4 toxicity was grade 3 neutropenia in four (13%) patients. Twenty-nine patients received a total of 173 cycles of docetaxel/estramustine (median, 6 cycles/patient). Six (20%) patients had grade 3-4 neutropenia and two (6%) patients had febrile neutropenia episodes. The most frequent non-hematological toxic effects were asthenia, nausea and vomiting, edemas and onycholysis. Two (6%) patients had deep venous thrombosis. Conclusions: Mitoxantrone/prednisone followed by docetaxel/estramustine is a well-tolerated and active regimen in HRPC. Sequential therapy is feasible and can be used to integrate novel, more active regimens.