Impact of new systemic therapies on overall survival (OS) of patients (pts) with metastatic castration resistant prostate cancer (mCRPC) in a hospital-based registry.

Abstract

203 Background: From 2004 to 2009, mCRPC treatment options were limited to docetaxel (D), mitoxantrone, first generation anti-androgens (AA), estrogens, steroids, and ketoconazole, with only D showing OS benefit. Since 2010, five new therapies prolonged OS and were approved for mCRPC: sipuleucel-T, cabazitaxel, abiraterone acetate, enzalutamide, and radium 223. We sought to assess the aggregate impact of new therapies on OS. Methods: We used the DFCI CRIS database to identify cohorts of pts who developed mCRPC between 2004-2007 (cohort A) and 2010-2013 (cohort B). Therapies for mCRPC in each cohort were annotated. Given the median follow-up (FU) was 10.6 years (yrs) in cohort A and 4.6 yrs in cohort B, we evaluated OS, defined as time from mCRPC per PCWG3 criteria to death from all causes or last follow-up visit within 5 yrs (truncated OS). Kaplan-Meier method estimated the time to events distribution with median (95% CI). Cox proportional hazards model evaluated effects of treatment groups on disease outcomes with estimates of hazard ratio (95% CI). Results: Of the 583 pts identified, 317 (54%) were in cohort A and 266 (46%) in cohort B. Pts in cohort B had a significantly longer median OS (p<0.001), a 5-yr OS of 26% vs. 10%, and a 31% reduced risk of death compared to cohort A (HR=0.69; 95% CI, 0.57-0.83) (see Table). On multivariable analysis, adjusting for prior local Rx, ECOG PS, and the number of agents received, longer OS is confirmed associated with cohort B vs. A and also with ECOG PS status 0 vs. 1, number of agents received 5-12 vs. ≤3. Conclusions: Using the DFCI prostate cancer database, therapies approved for mCRPC since 2010 showed a modest impact on OS, with a median improvement of 6 months. There was a more substantial effect on long term survivors with 2.6 fold increase of 5-yr OS. [Table: see text]