Overall survival with darolutamide vs placebo in combination with androgen-deprivation therapy (ADT) and docetaxel: A sensitivity analysis from ARASENS accounting for subsequent therapy.

Abstract

166 Background: Darolutamide (DARO) + ADT + docetaxel (DOC) is approved for metastatic hormone-sensitive prostate cancer (mHSPC) based on the phase 3 ARASENS study (NCT02799602). To address the impact of informative intercurrent events (eg, use of subsequent therapy) in censored patients (pts), as defined by the European Medicines Agency, we performed a post hoc sensitivity analysis of OS. Methods: Pts with mHSPC were randomized 1:1 to oral DARO 600 mg twice daily or placebo (PBO) + ADT + DOC. The primary endpoint was OS using a log-rank test, with HR (95% CI) calculated by Cox model, stratified by extent of disease (EoD; nonregional lymph node vs bone ± lymph node vs visceral ± lymph node/bone metastases) and alkaline phosphatase (< vs ≥ upper limit of normal). Pts with no documented death were censored at last known alive or data cut-off date, whichever was earlier. The post hoc sensitivity analysis counted initiation of subsequent systemic antineoplastic therapy as an event in censored pts still alive at end of follow-up. In addition planned sensitivity analyses used an unstratified log-rank test/Cox model, a log-rank test/Cox model with stratification factors from electronic case report forms, and a log-rank test/Cox model with EoD stratification factors from central imaging review. Results: In the primary analysis DARO + ADT + DOC significantly improved OS ( P<0.0001; Table), despite a high percentage of pts who entered follow-up in the PBO group receiving subsequent life-prolonging systemic therapies (374/495, 76%). Time to first subsequent systemic antineoplastic therapy (a key secondary endpoint) was significantly longer with DARO + ADT + DOC vs PBO + ADT + DOC (HR 0.39, 95% CI 0.33–0.46, P<0.001). Findings from the post hoc sensitivity analysis counting initiation of subsequent systemic antineoplastic therapy as an event in censored pts (pts with events: DARO 300/651, 46.1%; PBO 476/654, 72.8%) and the planned sensitivity analyses were consistent and supported the primary OS analysis (Table). Treatment-emergent adverse events (TEAEs) were similar between groups. TEAEs led to DARO/PBO discontinuation in 13.5%/10.6% of pts. Conclusions: The results of the post hoc and planned sensitivity analyses were consistent with and supportive of the ARASENS primary OS analysis. These data reinforce DARO + ADT + DOC as an effective and well tolerated new standard of care for early treatment intensification in pts with mHSPC. Clinical trial information: NCT02799602 . [Table: see text]