EGFR and HER2 Hyper-Activation Mediates Resistance to Endocrine Therapy and CDK4/6 Inhibitors in ER+ Breast Cancer

Cetuximab treatment overcame tumor resistance to fulvestrant and abemaciclib in FAR and EGFR-overexpressing breast cancer spheroids and xenografts. Likewise, patient-derived organoids from individuals with ER + mBC, progressing on palbociclib, exhibited up-regulation of EGFR and HER2 pathways.