What would you choose as second-line therapy in patients with ER/PR-positive, HER2-negative metastatic breast cancer progressing on first-line CDK 4/6 inhibitor/AI combination?

While we don't have direct comparative data, my own preference is fulvestrant both because in treatment-naive patients it appears better than NSAI (20% improvement in PFS in FALCON), and because the toxicity profile favors fulvestrant over everolimus/exemestane.

Combination fulvestrant/everolimus is feasible in second line-see link. The dose we used was loading dose, so conceivably high dose fulvestrant is more effective. The problem with everolimus is of course toxicity, which can be problematic, and we don't know the benefit after AI/CDK4/6 combo, only af...

Currently, there is no data upon which to base endocrine therapy decisions after disease progression on a CDK4/6 inhibitor. I would consider either fulvestrant or a combination with everolimus (Exemestane or fulvestrant) and base the decision on factors such as desire for an all oral regimen, AE pro...