Data from study DESTINY-04 have established T-DXd as the standard second-line treatment for HER2-Low breast tumors. In that study, about 90% of the population had estrogen-positive receptor (ER+) tumors, under-representing negative ER population. The investigators propose to assess T-DXd efficacy in HER2-Low/ER ≤10% patients in Brazilian population by means of a RWE analysis. Endpoints will be assessment of time to the next treatment, objective response rate, and real-world progression-free survival and real-world overall survival.
