Clinical and cost impact of cabazitaxel versus lutetium-177 vipivotide tetraxetan (Lu-PSMA) for patients with metastatic castration-resistant prostate cancer (mCRPC).

41 Background: The TheraP trial compared cabazitaxel to Lu-PSMA in patients with mCRPC who previously received docetaxel. In TheraP, Lu-PSMA achieved greater PSA responses than cabazitaxel (66% vs 37%; p=0.0016), while OS was similar (HR 0.97, p=0.99; difference –0.5 months [m], p=0.77). Rates of grade 3-4 adverse events (AE) were also similar. We aimed to quantify the direct cost differences and assess the clinical outcomes associated with the use of cabazitaxel compared to Lu-PSMA in this population. Methods: An Excel-based model was developed to assess clinical and economic outcomes at 6, 12, 18, and 24m in a U.S. patient population from the U.S. Medicare payer perspective. Efficacy and safety were informed by the TheraP study, supplemented by literature when data were lacking, and confirmed by a genitourinary oncologist (PB). Drug costs were based on Medicare ASP (or RedBook). Costs of grade 3-4 AE were estimated by weighted inpatient and outpatient management costs. Outcomes included direct costs related to PSMA testing, drug acquisition and administration, supportive care, AE, and end-of-life care. Clinical outcomes included the number of patients in OS, PFS, PSA-PFS, and rPFS. The cost impact was modeled for a cohort of 100 mCRPC patients receiving cabazitaxel or Lu-PSMA. A base case time horizon of 18m was chosen to correspond with available clinical trial follow-up data, provide a balanced assessment of costs and outcomes, and align with a prior published model in third-line mCRPC. Costs were reported in 2025 US dollars. Results: At 18m, total costs for a 100-patient cohort were $9.97M with cabazitaxel versus $29.37M with Lu-PSMA, equating to $19.40M in savings overall. Cabazitaxel costs were about one-third those of Lu-PSMA, driven primarily by drug acquisition ($8.53M vs $27.76M; –$19.23M). Other cost categories contributed smaller differences, ranging from savings with PSMA testing (–$0.15M) to incremental costs associated with adverse event management (+$0.07M). Clinically, at the primary analysis timepoint of 18m, cabazitaxel was modeled to yield 9 fewer deaths, though this numerical advantage favoring cabazitaxel should be interpreted cautiously, as TheraP found no OS difference and reported OS results accounting for non-proportional hazards. Lu-PSMA demonstrated greater disease control, with 8 additional patients free of progression (PFS) and PSA-PFS at 18m, consistent with TheraP findings. Cabazitaxel was associated with consistent and substantial cost savings across all timepoints. Lu-PSMA conferred greater PFS and PSA benefits, especially during the 12–18m interval. Conclusions: Cabazitaxel is estimated to reduce direct payer costs by approximately $194,000 per patient relative to Lu-PSMA, driven primarily by lower drug acquisition expenses. These savings contrast with Lu-PSMA’s improved PFS and PSA outcomes.