Evaluation of PSA decline patterns in the Chinese subgroup of LIBERTAS, a phase 3 study of apalutamide plus continuous versus intermittent androgen deprivation therapy in metastatic castration-sensitive prostate cancer.

154 Background: LIBERTAS is a global phase 3 study evaluating apalutamide (APA) plus intermittent versus continuous androgen deprivation therapy (ADT) in patients with metastatic castration-sensitive prostate cancer (mCSPC). The study aims to determine reduces hot flash burden compared with APA + continuous ADT and whether APA + intermittent ADT provides noninferior radiographic progression-free survival (rPFS). Initial findings demonstrated that treatment with 6 months of APA + ADT resulted in rapid and deep PSA responses in most patients with mCSPC. This abstract presents PSA response results from patients enrolled in China. Methods: Overall, eligible mCSPC participants had ≤3 months of prior ADT, ECOG PS 0–1, and confirmed metastases by conventional or next-generation imaging. All received APA 240 mg/day + ADT during the initial 6-month treatment phase. In the main phase, 22 participants from China with PSA <0.2 ng/mL were randomized 1:1 to continuous or intermittent ADT. Primary endpoints: reduction of hot flash burden, measured by severity-adjusted hot flash score, and rPFS, measured by 18-mo event-free survival rate. Results: In total, 36 participants from China were enrolled from 8 sites, with 22 randomized to the main treatment phase. Median age was 71.0 years (range: 51–79) and median baseline PSA was 64.7 ng/mL (range: 2.6–2399.0). After 3 months of treatment with apalutamide plus ADT, 100.0% of participants achieved a ≥50% PSA decline (PSA50), 94.4% achieved a ≥90% decline (PSA90), and 30.6% achieved PSA <0.2 ng/mL (PSA0.2). Among those who completed the initial 6-month treatment phase, 100% achieved PSA50, 97.2% achieved PSA90, and 61.1% achieved PSA0.2. No new safety signals were observed in the Chinese subgroup. Conclusions: Participants enrolled in the LIBERTAS study had rapid and deep PSA responses to APA plus ADT, with patients in China having a similar rapid and deep PSA decline. The LIBERTAS results confirm the efficacy of APA + ADT in Chinese patients with mCSPC and aligned with the pivotal TITAN Phase 3. The safety profile of APA remained consistent with prior experience, supporting APA’s tolerability in this population. The LIBERTAS study remains on track for results readout in 2027. We would like to acknowledge Todd Simon for his statistical support. Clinical trial information: NCT05884398 .