What is the best second line treatment for a HER2+ metastatic breast cancer treated with frontline paclitaxel and anti-HER2 therapy?

I would use T-DM1 (ado trastuzumab emtansine) in this situation as a second line therapy. T-DM1 has a very favorable side effect profile. Pertuzumab added a survival benefit when combined docetaxel and trastuzumab (median of 15.7 months) though this was a first-line treatment (Swain et al. NEJM 2015...

In the 1st line space, the current standard is taxane with trastuzumab + pertuzumab. Second line, due to the results of DB-03, showing improvement of PFS from 7.2 with T-DM1 to 29.0 months with T-DXd, trastuzumab deruxtecan really became the standard treatment in the 2nd line setting. At ASCO 2024, ...