A Pilot Study of Monitoring Insulin Levels and Treating Hyperinsulinemia and Hyperglycemia With Pioglitazone in Patients Treated With Alpelisib for Metastatic Breast Cancer.

The goal of this study is to test whether monitoring insulin levels and using pioglitazone to treat hyperglycemia and hyperinsulinemia in patients treated with Alpelisib for metastatic breast cancer is feasible and safe, and to assess the rates of glycemic control, dose reductions and treatment discontinuation and the progression free survival of patients treated with this regimen.

Inclusion Criteria:Patients with ER positive HER2 negative metastatic breast cancer, harboring an activating PIK3CA mutation, scheduled to start treatment with Alpelisib and fulvestrant.Ages 18 - 85ECOG performance status 0, 1 or 2Ability to understand and willingness to sign a written informed consent.Exclusion Criteria:Impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of AlpelisibUncontrolled diabetes mellitus, defined as HbA1c above 8%Diabetes mellitus controlled by insulinUncontrolled intercurrent illness including, but not limited to: active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with study requirementsPregnancyKnown allergy to pioglitazone