OBJECTIVES : To evaluate the cost-effectiveness of adding Neratinib to endocrine therapy for the extended adjuvant treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive, hormone receptor (HR)-positive early-stage breast cancer (eBC) from the Chinese healthcare system perspective.

METHODS : A Markov model was constructed to simulate the lifetime outcomes and costs for eBC patients. Five model health states were defined, including disease free, local recurrence, remission, distant recurrence, and death. The model cycle was one-month. The state transition probabilities were calculated from the ExteNET clinical trial and literature. The main benefit from the extended adjuvant treatment was indicated by the decreased probability of local recurrence and distant recurrence for the post-surgery eBC patients. Health state resources use and costs were estimated from a survey of clinical experts in five hospitals in China. Health states utilities were estimated from the ExteNET clinical trial and published literature. Incremental cost-effectiveness ratio (ICER) was calculated for quality-adjusted life-years(QALYs) gained. Deterministic and probabilistic sensitivity analyses were conducted.

RESULTS : Neratinib plus endocrine therapy experienced 14.23 QALYs with the average total health care costs of ¥272,629, resulting in an ICER of ¥102,574 per QALY gained compared with endocrine therapy alone (QALYs: 13.44, average health care costs: ¥191,598). The ICER was lower than the generally accepted Chinese cost-effectiveness threshold of ¥217,341 per QALY gained (3 times per-capita GDP, 2020 China). The relative dose intensity of Neratinib was the most sensitive parameter and Neratinib had 88.1% probability of being cost-effective at the current threshold.

CONCLUSIONS : As the extended adjuvant treatment for patients with HER2+, HR+ eBC, Neratinib plus endocrine therapy is likely to be more cost-effective than endocrine therapy in China.