Is there a role for endocrine therapy alone in patients with metastatic HR+, HER2+ breast cancer after all HER2 directed therapies have been used?  

There is no clear evidence specifically for this question, but the extrapolation of data from trials and general experience would predict a low chance of benefit with endocrine therapy alone. Growth factor signaling, particularly driven by HER2, is associated with resistance to endocrine therapy as ...