A phase II study of vinorelbine and estramustine in patients with hormone-resistant prostate cancer

This phase II study was designed to evaluate the efficacy of vinorelbine in combination with estramustine in patients with chemotherapy-naïve hormone-refractory prostate cancer.

Patients received vinorelbine (i.v. 25 mg/m2) on days 1 and 8 every 3 weeks and estramustine (oral, 600 mg/m2) daily. Eligible patients were required to have progressive metastatic disease following the first hormonal manipulation.

Of the 51 patients enrolled (median age = 69 years), 84% presented bone involvement and 75% had at least two organs involved at the time of study entry and 47 were evaluable for treatment efficacy. Prostate specific antigen (PSA) response (> or =50% decrease) which was the primary efficacy criterion was reported in 21 patients (41.2%) in the intent-to-treat (ITT) population and in 20 patients (48.8%) in the per protocol (PP) population. Of the 7 patients with measurable disease, 2 achieved partial response. Median progression-free survival and overall survival were 4.7 months (range: 1.9-8.6) and 14.3 months (range: 4.2-21.2), respectively. Grade 3-4 neutropenia was reported in 6.1% of patients and in 1% of cycles. The incidence of complicated neutropenia (febrile neutropenia reported in 1 patient and septic shock with severe neutropenia reported in 2 patients) was 5.8%. The most frequent grade 3-4 non-haematological events (% of patients > or =5%) included anorexia (10%), thrombosis/embolism (8%), vomiting and hypotension (6% each). There were 3 toxic deaths (5.9 %) resulting from pulmonary embolism, angina pectoris, and septic shock. The impact of combined chemotherapy on the quality-of-life (QL) of the patients was assessed between baseline and the first evaluation scheduled at 6 weeks indicated a marked reduction in pain while the rest of the symptoms remained stable. Overall, health status improved slightly over the treatment period.

This study confirmed that the combination of vinorelbine and estramustine is an active regimen in patients with hormone-resistant prostate cancer who had not been treated previously with chemotherapy. Main toxicities included complicated neutropenia even though the incidence of severe neutropenia was low. We observed a higher incidence of toxic deaths which could have been related to the regimen of estramustine used in the study.