Cost‐effectiveness analysis of tumor‐infiltrating lymphocytes biomarkers guiding chemotherapy de‐escalation in early triple‐negative breast cancer

Abstract Background To accelerate the clinical translation of tumor‐infiltrating lymphocytes (TILs) biomarkers for guiding chemotherapy de‐escalation in early‐stage triple‐negative breast cancer (TNBC), cost‐effectiveness evidence is essential but has not been investigated. We intend to evaluate the cost‐effectiveness of using TILs to guiding chemotherapy de‐escalation in patients with early‐stage TNBC from the perspective of the Chinese health service system. Methods The hybrid decision‐tree‐Markov model was designed to compare the cost‐effectiveness of cytotoxic chemotherapy guided by whether TILs assay was performed in 50‐year‐old female patients with early‐stage TNBC over a lifetime horizon. In Strategy (1), if TILs testing was performed, patients with TILs values exceeding 30% could be spared from chemotherapy. In Strategy (2), where no TILs testing was performed, all patients were administered chemotherapy following China's clinical practices. Based on the algorithm built by Guyot, the individual patient data were reconstructed from the published Kaplan–Meier curves, and the survival functions were calculated by parametric methods. Cost estimates were valued in Chinese yuan (as per rates in 2022). Results In 50‐year‐old female patients with early‐stage TNBC, Strategy (1), which employs TILs testing to guide cytotoxic chemotherapy yielded an additional 0.47 quality‐adjusted life years (QALYs) and saved 40,976 yuan, with an incremental cost‐effectiveness ratio (ICER) of −87,182.98 yuan per QALY gained compared with Strategy (2). This indicates that compared with Strategy (2), Strategy (1) is the dominant scheme. The results were sensitive to utility parameters, discount rates, and treatment costs after relapse. At a willingness‐to‐pay threshold of 85,700 yuan (based on GDP per capita) per QALY, the probability of TILs being cost‐effective was almost 100%. Conclusions The application of biomarkers (TILs) to guide decisions for chemotherapy de‐escalation is a cost‐effective strategy for early‐stage TNBC patients and deserves to be widely promoted in clinical practice.