Updated analysis of the phase III, double-blind, randomized, multinational study of radium-223 chloride in castration-resistant prostate cancer (CRPC) patients with bone metastases (ALSYMPCA) (original) (raw)

LBA4512 Background: Radium-223 chloride (Ra-223), a targeted alpha-emitter, targets bone metastases (mets) with high-energy alpha-particles of short range (<100 µm). ALSYMPCA, a phase III double-blind, randomized, multinational study, compared Ra-223 plus best standard of care (BSC) vs placebo plus BSC in CRPC patients (pts) with bone mets. In a planned interim analysis (n = 809), based on 314 events, Ra-223 significantly improved overall survival (OS) vs placebo (median 14.0 mo vs 11.2 mo, respectively; HR = .695; 95% CI, .552-.875; 2-sided p = .00185). Secondary endpoints were met and Ra-223 safety was favorable. An updated analysis was conducted prior to the crossover to further assess the effect of Ra-223 on the primary endpoint (OS), secondary endpoints including skeletal-related events (SREs), and safety. Eligible pts had confirmed symptomatic CRPC with ≥ 2 bone mets; no known visceral mets; and were post-docetaxel, unfit for docetaxel, or had declined docetaxel. Pts were r...