Bayesian Indirect Comparison and Cost-Effectiveness of Sacituzumab Govitecan Versus Sacituzumab Tirumotecan in Metastatic Triple-Negative Breast Cancer.

OBJECTIVES

Sacituzumab govitecan (SG) and sacituzumab tirumotecan (sac-TMT) are 2 approved antibody-drug conjugates for metastatic triple-negative breast cancer but lack direct comparison. Given their similar indications and high costs, an indirect cost-effectiveness analysis is essential to inform pricing and reimbursement decisions from the perspective of the Chinese healthcare system.

METHODS

A partitioned survival model using Bayesian network meta-analysis and flexible parametric modeling estimated long-term survival, quality-adjusted life-years (QALYs), and costs. Participants were derived from the ASCENT and OptiTROP-Breast01 randomized controlled trials. Key outcomes included time-varying hazard ratio, life-years, costs, incremental cost-effectiveness ratio (ICER), incremental net health benefit, and incremental net monetary benefit. Multiple sensitivity and scenario analyses tested model robustness.

RESULTS

In the base-case analysis, SG yielded 0.095 additional QALYs compared with sac-TMT at an incremental cost of $68 266, resulting in an ICER of $719 726 per QALY and an incremental net monetary benefit of -$64 400. Sensitivity analyses identified SG price and model time horizon as key drivers of ICER. In all plausible scenarios, SG remained not cost-effective versus sac-TMT. Probabilistic results showed a 0% probability of cost-effectiveness at a willingness-to-pay threshold of $40 763 per QALY. Scenario analysis confirmed the robustness of findings across assumptions on time horizon, utility, wastage, and discounting.

CONCLUSIONS

SG showed slightly greater health gains but much higher costs than sac-TMT, leading to poor cost-effectiveness at current prices. Given the high substitutability between antibody-drug conjugates in metastatic triple-negative breast cancer, indirect comparisons with economic modeling can help guide payer decisions and pricing negotiations when head-to-head data are lacking.