A real-world observational study characterizing patients (pts) with metastatic castration-sensitive prostate cancer (mCSPC) treated with or without androgen receptor pathway inhibitors (ARPIs).

Abstract

59 Background: mCSPC treatment is rapidly evolving with androgen deprivation therapy (ADT) plus ARPIs viewed as the standard of care for most pts. Data are needed to understand the real-world characteristics and treatment patterns of mCSPC (PC) pts in this dynamic field. This study aimed to define clinical features of mCSPC pts, estimate the proportion of pts receiving ARPIs, and evaluate clinical and demographic features associated with ARPI use. Methods: This retrospective cohort study used data from electronic health records and administrative databases in the province of Alberta, Canada. All newly diagnosed metastatic PC pts between 2017-2020 were identified. Pts were considered to have mCSPC if they initiated ADT within 30 days prior to, or at any time after diagnosis. ARPI exposure was defined as receiving ARPI within 180 days of initiating ADT. ARPI-naïve pts may have received ADT alone or other non-ARPI therapy (i.e., docetaxel) within 180 days of initiating ADT. Multivariable logistic regression was used to evaluate pt characteristics related to the receipt of ARPI. Overall survival (OS) was defined as the date of diagnosis to death from any cause or last known contact. Results: Of the 976 mCSPC pts identified, 33.5% received an ARPI. In ARPI exposed pts, the median time from ADT to ARPI start was 7.9 weeks and median time on ARPI was 13.1 months (mos). In multivariable analyses, ARPI use was associated with younger pt age, more recent diagnosis, fewer comorbidities, a higher metastatic burden, treatment centre, referral to a medical oncologist, and prior local therapy (all p<0.05). The median time to next therapy was 24.6 mos (95%CI=19.5-33.0) vs. 18.5 mos (95%CI+16.9-21.1), and median OS was 38.5 mos (95%CI=32.8-NA) vs. 34.2 mos (95%CI=33.3-38.8) for APRI exposed vs. ARPI-naive pts, respectively (p=0.03). Conclusions: This study identified factors associated with ARPI use in mCSPC, potentially allowing targeted efforts to improve ARPI uptake for pts in whom use is low. These findings are important as they reflect outcomes seen in real world pts.