The effect of change in PSA velocity on overall survival (OS) in men with biochemically recurrent prostate cancer (BRPC) treated with nonhormonal agents: Combined analysis of four phase 2 trials.

Abstract

121 Background: A number of phase 2 trials in men with BRPC have assessed the impact of non-hormonal agents on PSA kinetics. We have previously demonstrated that changes in PSA kinetics are correlated with metastasis-free survival; however, it is unknown whether these changes may also correlate with overall survival (OS). Methods: We performed a combined retrospective analysis of 146 men with BRPC treated on phase 2 trials using one of four investigational drugs: lenalidomide (n=60), marimastat (n=39), ATN-224 (n=22), and imatinib (n=25). We examined factors influencing OS, including within-subject changes in PSA kinetics (PSA slope, PSA doubling time, and PSA velocity) before and 6 months after treatment initiation. Results: After a median follow up of 77 months, 47 men had died. In univariate Cox regression analysis, four factors were associated with OS: prior androgen deprivation therapy (ADT), prior local radiotherapy, baseline PSA velocity, and change in PSA velocity after therapy. In a landmark multivariable model, stratified by study, which also controlled for age and Gleason score (<7 vs ≥7): prior radiotherapy, baseline PSA velocity, and increase in PSA velocity remained independent predictors of OS (Table). Median OS for men with an increase in PSA velocity on treatment was 9.1 years vs 12.3 years for men with a decrease in PSA velocity (HR 1.95; 95%CI 1.07–3.57; P=0.03). Conclusions: This hypothesis-generating study suggests that within-subject changes in PSA velocity after initiation of non-hormonal therapy may correlate with OS in men with BRPC. If validated in prospective trials using OS as the primary endpoint, change in PSA velocity may represent a reasonable intermediate endpoint for screening new agents in these patients. [Table: see text]