Docetaxel rechallenge in patients with metastatic castration-resistant prostate cancer

OBJECTIVE: To evaluate the benefit of docetaxel rechallenge in patients with metastatic castration-resistant prostate cancer (mCRPC) relapsing after an initial good response to first-line doxetaxel. PATIENTS AND METHODS: We retrospectively reviewed the records of consecutive mCRPC patients with a good response to first-line docetaxel (serum prostate specific antigen (PSA) decrease ≥50%; no clinical/radiological progression). We analyzed the impact of management at relapse (docetaxel rechallenge or non-taxane-based therapy) on PSA response, symptomatic response (performance status/pain/analgesic consumption), and overall survival (OS). We used multivariate stepwise logistic regression to analyze potential predictors of a favourable outcome. RESULTS: We identified 270 good responders to first-line docetaxel. Median progression-free interval (PFI) was 6 months from the last docetaxel dose. At relapse, 223 patients were rechallenged with docetaxel (82.5%) and 47 received non-taxane-based therapy. There was no significant difference in median OS (18.2 [95%CI, 16.1-22.0] and 16.8 [95%CI 13.4-21.5] months, respectively, p=0.35). However, a good PSA response and symptom relief/stable disease were more frequent on docetaxel rechallenge (40.4% vs 10.6%, p 6 months and added estramustine predicted a good PSA response and symptomatic response on docetaxel rechallenge but only a PFI >6 months predicted longer OS. Haemoglobin ( 6 months but did not prolong survival. Potential benefits should be weighed against the risk of cumulative toxicity.