Open-Label Umbrella Study To Evaluate Safety And Efficacy Of Elacestrant In Various Combination In Participants With Metastatic Breast Cancer

This is a multicenter, Phase 1b/2 trial. The Phase 1b aims at selecting the RP2D dose, defined as a dose that is associated with less than 33% of participants experiencing a dose-limiting toxicity (DLT) of elacestrant when administered in combination with alpelisib, everolimus, palbociclib, ribociclib, and capivasertib that is, ≤1 participant experiencing a DLT out of 6 DLT-evaluable participants. For each combination, this phase will have approximately 3 cohorts of up to 6 DLT-evaluable participants each. The total number of DLT-evaluable participants in all the combinations will be up to 125.

The Phase 2 part of the trial will evaluate the efficacy and safety of the various combinations.

The treatment arms will be:

* Arm A: 50 participants: elacestrant with alpelisib; * Arm B: 50 participants: elacestrant with everolimus; * Arm C: 60 participants (30 participants in each combination): elacestrant with either abemaciclib or ribociclib; * Arm D: 90 participants (30 participants in each combination): elacestrant with either palbociclib, abemaciclib, or ribociclib; * Arm E: 60 participants: elacestrant with capivasertib

Phase 1b will have a total of 125 participants, while Phase 2 will have 310 participants for all treatment arm combinations.