The interval from the last cycle of docetaxel-based chemotherapy to progression is associated with the efficacy of subsequent docetaxel in patients with prostate cancer

There is currently no standard treatment after first-line docetaxel-based chemotherapy for patients with castration-refractory prostate cancer (CRPC). Some patients are likely to discontinue first-line docetaxel-based chemotherapy because of either completed treatment or the occurrence of manageable side-effects. The aim of this study was to determine whether a rechallenge with docetaxel might be appropriate in patients with CRPC previously treated with docetaxel. Between December 2004 and July 2009, 39 patients diagnosed with metastatic cancer prostate at the Institut Gustave Roussy were administered subsequent docetaxel after front-line docetaxel-based chemotherapy. The medical records of these patients were extracted from the database. The PSA response rate (PSA decline ≥30% and ≥50%), progression-free survival (PFS) and overall survival (OS) of patients receiving docetaxel as a subsequent line of therapy were evaluated using consensus criteria. The effect of pre-treatment variables on efficacy was studied. A PSA decline ≥30% and ≥50% was observed in 64% and 38% of patients, respectively, median PFS was 4.3 months [confidence interval (CI) 95%: 3.6-4.9] and median OS was 15.8 months (CI 95%: 11.7-20.3) in 39 patients who received subsequent docetaxel. The interval between the last cycle of first-line docetaxel and progression [median: 3.0 months; range: 1-30 months] was associated with PFS: median PFS was 3.4 months (CI 95%: 2.6-4.1) and 6.3 months (CI 95%: 3.0-5.6), respectively, in patients with an interval <3.0 months and an interval ≥3.0 months, (p = 0.04). Tolerance of re-treatment with docetaxel was acceptable with no toxicity-related death. Re-treatment with subsequent docetaxel in patients with CRPC pretreated with first-line docetaxel is safe and demonstrates some activity. The interval from the last cycle of first-line docetaxel-based chemotherapy to progression is associated with the efficacy of subsequent docetaxel.