RESUMO
ABSTRACT Objective Human epidermal growth factor receptor 2 (HER2) overexpression occurs in up to 30% of breast cancer cases. Ado-trastuzumab emtansine (T-DM1) is approved to treat residual HER2-positive breast cancer after neoadjuvant therapy. The aim of this study was to determine the quality-adjusted time with symptoms or toxicity and without symptoms or toxicity (Q-TWiST) of T-DM1 compared to trastuzumab for residual invasive HER2-positive breast cancer. Methods The authors developed an analytical model extracting individual patient data and estimated invasive disease-free survival and overall survival over a 30-year time horizon. Only direct costs from adjuvant treatment were considered as well as relapse treatment from Brazilian and American payer perspectives. Heart events were considered for utility and cost analysis. Results The 30-year projection utilizing the Weibull method estimated a mean invasive disease-free survival of 16.4 years for T-DM1 and 10.4 for Trastuzumab, in addition to a mean overall survival of 18.1 and 15.4 years, respectively. We determined a Q-TWiST gain of 3,812 years for the T-DM1 arm when compared to trastuzumab and an Incremental cost-effectiveness ratio per Q-TWiST of US$ 11,467.65 in the United States and US$ 3,332.73 in Brazil. Conclusion Ado-trastuzumab emtansine is cost-effective from both Brazilian and American perspectives.