Talazoparib plus enzalutamide improved overall survival (OS) in the biomarker-unselected TALAPRO-2 population, but OS benefit was not statistically significant in the homologous recombination repair (HRR) non-deficient or unknown subgroup, whereas radiographic progression-free survival (rPFS) was prolonged. We explored time-dependent patterns in estimated treatment effects in this subgroup.
Approximate individual-level data for 636 patients were reconstructed from published Kaplan-Meier curves; original trial-level patient data were unavailable. The proportional hazards assumption was assessed using Schoenfeld residuals and log-log plots. Interval-specific hazard ratios (HRs) were estimated using piecewise Cox models. A treatment-by-log(time + 1) interaction was evaluated formally. Sensitivity analyses included alternative interval schemes, landmark analyses, restricted mean survival time (RMST), and descriptive application of the same piecewise framework to the HRR-deficient subgroup.
The proportional hazards assumption was not rejected for OS (p = 0.63) or rPFS (p = 0.37). For OS, the 36-48-month interval showed a nominally lower hazard with talazoparib (HR 0.59; 95% confidence interval [CI] 0.36-0.97; nominal p = 0.039). For rPFS, the lowest HR occurred at 0-6 months (HR 0.56; 95% CI 0.37-0.86; p = 0.008). Treatment-by-log(time + 1) interactions were not statistically significant for OS (p = 0.44) or rPFS (p = 0.12).
This reconstructed-data post hoc analysis suggested exploratory time-dependent patterns in effect estimates without formal evidence of a time-varying treatment effect. Findings are descriptive, hypothesis-generating, and should not be extrapolated to molecularly confirmed HRR-proficient disease.
ClinicalTrials.gov: NCT03395197.
International journal of urology : official journal of the Japanese Urological Association. 2026 Jul [Epub]
Shugo Yajima, Soichiro Yoshida, Wei Chen, Hiroshi Fukushima, Hajime Tanaka, Hiroyuki Sato, Akihiro Hirakawa, Hitoshi Masuda, Yasuhisa Fujii
Department of Urology, National Cancer Center Hospital East, Chiba, Japan., Department of Urology, Institute of Science Tokyo, Tokyo, Japan., Department of Clinical Biostatistics, Graduate School of Medical and Dental Sciences, Institute of Science Tokyo, Tokyo, Japan.