Post-progression survival of patients with metastatic hormone-sensitive prostate cancer (mHSPC) who received darolutamide or placebo: Post hoc analysis of ARASENS.

5083 Background: Darolutamide (DARO) is a structurally distinct and highly potent androgen receptor pathway inhibitor (ARPI). In ARASENS (NCT02799602), the addition of DARO to androgen-deprivation therapy (ADT) and docetaxel (DOC) significantly reduced the risk of death by 32.5% in patients (pts) with mHSPC, despite most placebo (PBO) pts (75.6%) receiving subsequent therapy. DARO also delayed time to progression to metastatic castration-resistant prostate cancer (mCRPC; median, not reached vs 19.1 months for PBO), resulting in a longer time in mHSPC, which is associated with improved quality of life vs mCRPC. We report post-progression subsequent anticancer therapies and related survival from ARASENS. Methods: Pts with mHSPC were randomized 1:1 to DARO 600 mg twice daily or PBO in addition to ADT + DOC. After treatment discontinuation, pts entered active and long-term survival follow-up periods during which assessments included subsequent therapies and survival outcomes. Post-progression survival was defined as time from first subsequent therapy to death using Kaplan-Meier estimates. Results: Of 1305 treated pts (DARO n=651; PBO n=654), 315 receiving DARO and 495 receiving PBO entered follow-up. Of these, 57% (n=179) and 76% (n=374), respectively, received subsequent therapy; abiraterone and enzalutamide were the most frequent first subsequent therapy (Table). In the DARO arm, 90% of first subsequent therapies were ARPI or chemotherapy. Minimal difference was observed in post-progression survival between subsequent therapies, suggesting subsequent therapy with another ARPI does not provide further survival benefit vs non-ARPI options (mainly chemotherapy). In contrast, in the PBO arm where the majority (78%) received first subsequent therapy with an ARPI, a survival benefit was observed vs non-ARPI subsequent therapies (median, 23.0 vs 13.5 months). Conclusions: DARO+ADT+DOC increased overall survival vs PBO+ADT+DOC and also delayed time to progression to mCRPC. DARO pts had similar survival with all post-progression therapies. Pts receiving PBO+ADT+DOC quickly progressed to mCRPC and treatment with an ARPI in ARPI-naïve pts improved survival. Clinical trial information: NCT02799602 . Table: see text