OBJECTIVES: In a pre-specified cohort of patients with mCRPC with homologous recombination repair mutations (HRRm), TALAPRO-2, an international phase 3 trial (NCT03395197) comparing first-line (1L) treatment with talazoparib + enzalutamide (n=200) vs placebo + enzalutamide (n=199), produced a statistically significant improvement in the primary endpoint of radiographic progression free survival (rPFS) by blinded independent committee review (HR=0.45; 95% CI 0.33-0.61; P<0.0001). EQ-5D-5L was administered during the trial (baseline, every 4 weeks until week 53 or rPFS, every 8 weeks after week 53 until rPFS when no such progression had been documented or every 12 weeks after progression until end of study). Published health state utility values (HSUVs) are not available for this population. The aim of this research was to estimate pre-progression HSUVs suitable for use in cost-effectiveness analyses in 1L HRRm mCRPC.

METHODS: Data from the HRRm cohort from TALAPRO-2 were analyzed. Pre-progression HSUVs were estimated regardless of and by treatment arm using multivariate linear mixed effects regression analysis adjusted for covariates. Analyses employed value sets for US and UK.

RESULTS: For US, mean (95% CI) pre-progression HSUV regardless of treatment arm was 0.835 (0.822-0.848). US treatment-specific pre-progression HSUVs for talazoparib + enzalutamide and placebo + enzalutamide were 0.846 (0.828-0.863) and 0.824 (0.805-0.842), respectively (difference not statistically significant, P=0.092). Consistent results were found for UK (overall 0.815 (0.803-0.827); by treatment arm 0.825 (0.809-0.842) vs 0.803 (0.786-0.821); P=0.070) for talazoparib + enzalutamide vs. placebo + enzalutamide, respectively.

CONCLUSIONS: This analysis generated pre-progression HSUVs suitable for use in cost-effectiveness analyses in 1L HRRm mCRPC. HSUVs were numerically greater for talazoparib + enzalutamide.