Genetically-informed Therapy for ER+ Breast Cancer Post-CDK4/6 Inhibitor

Fulvestrant will be administered intramuscularly into the buttocks in combination with one of the other interventions as outlined above.

Neratinib will be administered orally in tablet form once daily with food in combination with fulvestrant administration as outlined above.

Alpelisib will be administered orally in tablet form once daily with food in combination with fulvestrant administration as outlined above.

Everolimus will be administered orally in tablet form once daily in combination with fulvestrant administration as outlined above.

Abemaciclib will be administered orally in tablet form twice daily in combination with fulvestrant administration as outlined above.