AKT Inhibitor, Ipatasertib, With Endocrine and CDK 4/6 Inhibitor for Patients With Metastatic Breast Cancer (TAKTIC)

This research study is a Phase I clinical trial, which tests the safety of an investigational drug and also tries to define the appropriate dose of the investigational drug to use for further studies. "Investigational" means that the drug is being studied. The U.S. Food and Drug Administration (FDA) has not approved ipatasertib as a treatment for any disease. The FDA has approved fulvestrant, the aromatase inhibitors, and palbociclib as treatment options for this disease. This research study will evaluate the safety and tolerability of ipatasertib in combination with an aromatase inhibitor or fulvestrant with or without palbociclib. Resistance to standard of care treatment for people with your type of cancer is common. Stopping (inhibiting) an enzyme called Akt in the cancer cells may overcome resistance to the standard of care treatment. Ipatasertib is a type of inhibitor that is believed to work by inhibiting Akt. Through the different combinations of ipatasertib and the standard of care drugs, the chance of cancer cells becoming resistant to the standard of care drugs may decrease, causing the cancer cells to stop growing and spreading.