PSA response to cabazitaxel is associated with improved progression-free survival in metastatic castration-resistant prostate cancer: the non-interventional QoLiTime study.

PURPOSE: To evaluate the association between prostate-specific antigen (PSA) response and progression-free and overall survival in men with metastatic castration-resistant prostate cancer (mCRPC) treated with cabazitaxel.

METHODS: Men with mCRPC receiving cabazitaxel (25 mg/m2 , every 3 weeks) plus oral prednis(ol)one (10 mg/day) were enrolled in the non-interventional, prospective QoLiTime study. Main outcome measures were progression-free survival and overall survival, in all patients and in those who showed a ≥ 50 or a ≥ 30% decrease in PSA relative to baseline after four cycles of cabazitaxel, as well as quality-of-life parameters.

RESULTS: Of the 527 men (median age 72 years), 266 received ≥ 4 cycles of cabazitaxel and had PSA response data. After four cycles, 34.6% of men achieved a PSA decrease ≥ 50% and 49.6% a decrease ≥ 30%. Median progression-free survival was 7.7 (95% CI 6.2, 9.5) months, and overall survival was 19.5 (95% CI 16.0, 30.9) months, corresponding to 1-year event rates of 39.4 and 78.8%, respectively. Median progression-free survival was longer in PSA responders versus non-responders (15.7 vs 5.5 months at 50% cut-off; 15.7 vs 5.3 months for 30% cut-off; both P < 0.0001). Overall survival (50% cut-off) was 23.3 months in responders and 16.0 months in non-responders (P = 0.068); corresponding data at the 30% cut-off are 21.7 and 16.0 months (P = 0.057). Overall, 55.4% of men experienced ≥ 1 adverse event, 59.6% of whom had a serious adverse event.

CONCLUSION: PSA response after four cycles of cabazitaxel is associated with improved progression-free survival in men with mCRPC treated with cabazitaxel plus prednis(ol)one.