OBJECTIVES: Cancer is the leading cause of death in China with breast cancer being the most common cancer among Chinese women. Trastuzumab is indicated for the treatment of adult patients with HER2 positive metastatic breast cancer (MBC) as a monotherapy for the treatment patients who have received at least two chemotherapy regimens for their metastatic disease. The aim of the study was to evaluate the economic impact of switching to a trastuzumab biosimilar product in patients with MBC from a Chinese payer perspective.

METHODS: A one-year budget impact model was created in Microsoft Excel to estimate the number of patients covered by the Shanghai Municipal Health and Family Planning Commission with MBC. Incident and prevalent populations were eligible to receive the biosimilar, with a 50% uptake among incident patients and 25% uptake among prevalent patients. MBC incidence and prevalence rates, and population and treatment characteristics were obtained from available literature. The analysis only included drug costs as the same efficacy and safety was assumed for trastuzumab and the biosimilar. Trastuzumab cost was based on reported price of the Chinese pharmaceutical market; a 20% discount was assumed with the biosimilar. Patients were assumed to be on treatment without breaks in the base-case scenario.

RESULTS: Among the 36,123 patients estimated to be on treatment for MBC, 10,286 were predicted to receive the biosimilar, resulting in a cost reduction of ¥6,243,779,967 (5.7%). When additional patients who had stopped and restarted treatment with the biosimilar were also accounted for, similar savings were estimated.

CONCLUSIONS: Because of China’s large population, even a small percentage of biosimilar introduction could result in substantial savings. These findings should be evaluated in light of actual treatment and prescribing patterns.