A Phase Ib/III, Open-label, Randomised Study of Capivasertib Plus CDK4/6 Inhibitors and Fulvestrant Versus CDK4/6 Inhibitors and Fulvestrant in Hormone Receptor-Positive and Human Epidermal Growth Factor Receptor 2-Negative Locally Advanced, Unresectable or Metastatic Breast Cancer (CAPItello-292)

This Phase Ib/III study (CAPItello-292) aims to evaluate the efficacy, safety and the degree of added benefit of capivasertib combined with CDK4/6i and fulvestrant in participants with locally advanced (inoperable) or metastatic HR+/HER2- breast cancer. Although the dosing regimens of capivasertib + fulvestrant and of CDK4/6i + fulvestrant are established separately, the dose and schedule for the triplet combinations (capivasertib + CDK4/6i + fulvestrant) need to be confirmed. Therefore, the initial dose finding Phase Ib part of the study will determine the recommended Phase III doses (RP3D) of the triplet combinations. The Phase III part of the study will evaluate the efficacy, safety and the degree of added benefit of the triplet combinations of capivasertib and fulvestrant with investigator's choice of CDK4/6i (either palbociclib or ribociclib at safe and tolerable doses, once identified) in comparison with a control arm (fulvestrant + investigator's choice of CDK4/6i [palbociclib or ribociclib]) in a ER+ HER2- maC high risk population that did not receive prior endocrine therapy in the advanced setting.