Robert Dreicer, MD, MS, FACP, FASCO reviewing de Morrée ES et al. JAMA Oncol 2016 Aug 25.
In a retrospective study, treatment with eight or more cycles was associated with superior overall survival.
Docetaxel remains an important therapeutic option for patients with metastatic castration-resistant prostate cancer (mCRPC), despite the approval of many new agents. In a pivotal study that led to approval of docetaxel for mCRPC (N Engl J Med 2004; 351:1502), patients received a median of 9.5 cycles of docetaxel administered every 3 weeks. However, the optimal number of cycles remains undefined.
To determine whether the number of docetaxel cycles is an independent prognostic factor for overall survival (OS), investigators retrospectively analyzed data from the Mainsail trial (Lancet Oncol 2015; 16:417), in which 1059 patients with mCRPC were randomized to receive docetaxel plus prednisone with or without lenalidomide. This study was stopped early when the OS of patients receiving the investigational combination with lenalidomide was found to be inferior to docetaxel and prednisone plus placebo. Of note, the median number of docetaxel cycles was six in patients receiving lenalidomide and eight in patients receiving placebo. Also, patients receiving fewer than four cycles were excluded, as were those who stopped docetaxel secondary to disease progression.
Patients who received eight or more cycles of therapy had improvement in OS regardless of lenalidomide treatment. Also, patients who received more than 10 cycles had a median OS of 33.0 months compared with 26.9 months for those receiving 8 to 10 cycles and 22.8 months for those receiving 5 to 7 cycles (P<0.001).
de Morrée ES et al. Association of survival benefit with docetaxel in prostate cancer and total number of cycles administered: A post hoc analysis of the Mainsail study. JAMA Oncol 2016 Aug 25; [e-pub].