58P Cost-effectiveness analysis of trastuzumab emtansine versus trastuzumab for Chinese patients with residual invasive HER2-positive early breast cancer

Abstract

Patients with residual invasive HER2-positive early breast cancer after completion of neoadjuvant therapy have a high risk of recurrence or death despite of receiving standard treatment of Trastuzumab. Trastuzumab emtansine (T-DM1), which act as a breakthrough therapy, has been proved to reduce 50% incidence of recurrence or death compared with Trastuzumab alone. This study was aimed to estimate cost-effectiveness of T-DM1 vs. trastuzumab as the adjuvant treatment in China. 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. 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. T-DM1 provided 1.49 more QALYs with additional costs than trastuzumab. From healthcare system perspective, the ICER was CNY 112,004/QALY. Further 39% lower indirect costs in T-DM1 group resulting an ICER of CNY 98,757/QALY from the society perspective. Both ICERs were between 1∼2 times GDP per capita, far below the local threshold of 3 times GDP per capita in 2019 (CNY 212,676). 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 44% lower than that in trastuzumab group. Probabilistic sensitivity analysis showed that T-DM1 was more cost-effective in more than 95% simulations at local threshold regardless of the perspective. Compared to trastuzumab, T-DM1 is more cost-effective as the adjuvant treatment for patients with residual invasive HER2-positive early breast cancer in China.