A larger number of docetaxel cycles may improve survival among men with metastatic castration-resistant prostate cancer (mCRPC), according to a post-hoc analysis of phase III clinical trial results.
Scientists and health care professionals have not yet been able to determine the optimal total number of docetaxel cycles for patients with mCRPC. Therefore, researchers led by Ellen S de Morree’, MSc, Erasmus MC Cancer Institute (Rotterdam, the Netherlands), conducted a study to investigate whether the number of docetaxel cycles administered to patients deriving clinical benefit was an independent prognostic factor for overall survival.
Data for the study were taken from the MAINSAIL trial, which was a multinational randomized phase III trial that analyzed 1059 patients with mCRPC receiving docetaxel, prednisone, and lenalidomide (DPL), or docetaxel, prednisone, and a placebo. Patients in the trial were treated until disease progression or unacceptable toxicity based on adverse event occurrence. Since dose intensity was similar between the two treatment arms, researchers looked at how the number of docetaxel cycles patients received affected survival outcomes.
Patients in the DPL arm were administered a median of 6 cycles while those in the control group received a median of 8 cycles. Researchers conducted primary univariate and multivariate analyses for the intention-to-treat population. Additional sensitivity analyses were done, excluding patients who stopped treatment for reasons of disease progression and those who received 4 or fewer cycles of docetaxel for other reasons, minimizing the effect of confounding factors.
Overall, they found that patients who were treated with 8 or more cycles of docetaxel exhibited superior overall survival—regardless of lenalidomide treatment—than those who received less than 8 cycles. Further, a sensitivity analysis revealed that patients who received more than 10 cycles derived even greater benefit with a median overall survival of 33 months compared with 26.9 months in those treated with 8 to 10 cycles. Median overall survival was lowest among patients who were treated with 5 to 7 cycles of docetaxel (22.8 months).
Thus, researchers concluded that continuing docetaxel treatment beyond 6 cycles may improve overall survival for men with mCRPC. A prospective study, potentially in the setting of metastatic hormone-sensitive disease, may help to lend additional evidence to these initial findings.
