OBJECTIVES: To estimate cost-effectiveness of trastuzumab emtansine (T-DM1) vs. pertuzumab with trastuzumab (PH) as the adjuvant treatment for Chinese patients with residual invasive HER2-positive early breast cancer.

METHODS: A validated 6-state Markov model with monthly cycle was constructed to estimate the lifetime incremental cost-effectiveness ratio (ICER). Main clinical input was the time spent in invasive disease-free survival state, estimated by parametric extrapolations to survival data observed in the clinical trial Katherine and APHINITY, which was compared indirectly using Bucher method. Utilities were calculated from EQ-5D of patients in Katherine and the published literatures. The costs obtained both from real world data and local published resources including drugs, administration, adverse events management, follow-up and therapeutic costs. Furthermore, indirect costs were included when analyzed from the society perspective. Costs and outcomes were both discounted at 5%. Sensitivity analysis were conducted to verify the robustness of the results.

RESULTS: T-DM1 provided 0.88 more QALYs with additional costs than PH. From healthcare system perspective, the ICER was CNY 151,177/QALY. Further 28% lower indirect costs in T-DM1 group resulting an ICER of CNY 137,404/QALY from the society perspective. Both ICERs were below the local threshold of 3 times GDP per capita in 2020 (CNY 216,000) and between 1~2 times GDP per capita when from the society perspective. Acquisition cost of T-DM1 is partially offset by the prevention of disease recurrences over the time. Cost for managing recurrences in T-DM1 group was 27% lower than that in PH group. Probabilistic sensitivity analysis showed that T-DM1 was more cost-effective in 100% simulations at local threshold regardless of the perspective.

CONCLUSIONS: Compared to pertuzumab with trastuzumab, T-DM1 is more cost-effective as the adjuvant treatment for patients with residual invasive HER2-positive early breast cancer in China.