(296) Cost-effectiveness of xofigo in bone-metastatic castration-resistant prostate cancer: a markov model analysis

Background: : Metastatic castration-resistant prostate cancer (mCRPC) frequently results in bone metastases, causing substantial morbidity from skeletal-related events such as fractures and spinal cord compression. As systemic therapies lose efficacy with disease progression, bone-targeted treatments like Xofigo (radium-223 dichloride) offer a more focused approach by delivering alpha radiation to areas of increased bone turnover. Given its high cost, assessing the value of Xofigo through cost-effectiveness analysis is essential, particularly for patients with symptomatic bone metastases and no visceral disease.

Objective: : To evaluate the cost-effectiveness of Xofigo compared to the current standard of care - goserelin, denosumab, and external beam radiation therapy - in patients with bone-metastatic CRPC without visceral involvement.

Methods: : Cost-effectiveness was evaluated using a Markov model with five health states: progression-free survival without symptomatic skeletal events (PFS without SSE), progression without SSE, PFS with SSE, progression with SSE, and death. The model was implemented in R using the “heemod,” “dplyr,” and “ggplot2” packages, with a 1-month cycle length over a 24-month time horizon. Xofigo was capped at six months of use, consistent with FDA-approved dosing. The analysis was conducted from a U.S. payer perspective using quality-adjusted life years (QALYs), with willingness-to-pay (WTP) thresholds ranging from $50,000 to $150,000 per QALY. Model inputs for transitions, costs, and utilities were derived from published literature and clinical trial data.

Results: : Xofigo incurred a total cost of $234,970 and yielded 10.8 QALYs, compared to $141,722 and 9.2 QALYs with standard care. This resulted in an incremental cost of $93,247 and an incremental cost-effectiveness ratio (ICER) of $58,012 per QALY gained.

Conclusions: : Despite its higher cost, Xofigo offers meaningful clinical benefits and demonstrates a favorable cost-effectiveness profile, with an incremental gain of 1.6 QALYs - equivalent to 20 months of perfect health or approximately 35 months at a utility of 0.55. While based on modeled assumptions, these findings suggest Xofigo may represent a high-value treatment option for appropriately selected patients with bone-metastatic CRPC, depending on payer priorities and WTP thresholds.

Sponsorship:: None