Cost effectiveness of eight first-line regimens in metastatic hormone-sensitive prostate cancer (mHSPC) including niraparib + abiraterone acetate/prednisone.

47 Background: An increase in radiographic progression-free survival (PFS) was observed in the AMPLITUDE trial combining androgen deprivation therapy (ADT) with niraparib + abiraterone acetate/prednisone (NAAP) for HRR-deficient metastatic hormone-sensitive prostate cancer (mHSPC) patients (pts). We conducted a cost-effectiveness analysis from a U. S. public-payer perspective comparing NAAP with seven established first-line options for mHSPC of ADT alone and added to ADT; docetaxel (DA) ; abiraterone (AAP) ; apalutamide (AAT) ; enzalutamide (ET) ; darolutamide + docetaxel (DAD) ; enzalutamide + docetaxel (EAD). Methods: A partitioned-survival model with monthly cycles over a lifetime horizon (progression-free, post-progression, death) incorporated overall survival (OS) and PFS data derived from survival curves. Drug acquisition costs were from 2025 Federal Supply Schedule (FSS). Administration, subsequent-therapy, and adverse event costs and utilities were obtained from published literature. Costs and outcomes were discounted at 3% annually. Incremental cost-effectiveness ratio (ICER) was estimated at a willingness-to-pay (WTP) threshold of 150, 000-200, 000/QALY. Deterministic and probabilistic sensitivity analyses assessed parameter uncertainty. Results: Across eight treatment strategies (N= 9, 027 pts) lifetime costs ranged from 41K (ADT) to 730K (DAD) and Quality of Life Years (QALYs) from 3. 25 to 4. 29. ET, EAD, AAT, DAD, and NAAP regimens were more costly and less effective than alternatives. Among non-dominated options, DA had an ICER of 35, 505/QALY vs ADT, and AAP yielded 189, 589/QALY. Although DAD achieved the highest lifetime QALYs (4. 29), its incremental cost was large (ICER 1. 43M/QALY). Conclusions: From a U. S. public-payer perspective, ADT remains the least costly option, but DA is consistently cost-effective, and AAP may be considered cost-effective at higher WTP thresholds. The addition of NAAP offered incremental benefit for patients with HRR-positive mHSPC; however, the ICER using niraparib’s current FSS pricing, derived from the mCRPC setting may limit its overall cost-effectiveness. These findings describe relative economic profiles rather than direct head-to-head comparisons. Cost-effectiveness results (in 2025 US dollars). Regimen Cost () Effectiveness (QALYs) ICER (US/QALY) ADT 41, 287 3. 25 DA+ADT 60, 334 3. 79 35, 505 AAP+ADT 67, 585 3. 83 189, 589 NAAP+ADT 116, 712 3. 45 Dominated 1 AAT+ADT 361, 699 2. 43 Dominated 1 ET+ADT 491, 283 3. 99 Dominated 2 EAD+ADT 562, 151 4. 16 Dominated 2 DAD+ADT 729, 270 4. 29 1, 432, 592 1 More costly and less effective than another treatment strategy (ie, absolute dominance). 2 More costly and less effective than a linear combination of other treatment strategies (ie, extended dominance).