Alpelisib-Induced Diabetic Ketoacidosis

We present the third case of alpelisib-induced diabetic ketoacidosis. Alpelisib is an antineoplastic agent that inhibits phosphatidylinositol 3-kinase (PI3K), which plays a key role in multiple biological processes such as cell differentiation, proliferation, and survival. Thereby, the inhibition of this pathway should cause antitumor activity. Alpelisib was recently approved by the Food and Drug Administration (FDA) for use in PIK3CA-mutated breast cancer. This mutation is a common indicator of poor prognosis and is also the most commonly mutated gene in hormone receptor (HR)-positive and human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer. During its trial, ketoacidosis was reported in only 0.7% of patients, with the more common side effects (>20%) being diarrhea (58%), rash (52%), nausea (45%), fatigue (42%), decreased appetite (36%), stomatitis (30%), vomiting (27%), weight loss (27%), and alopecia (20%). As breast cancer is the second most common cancer in women and approximately 40% of HR+/HER2- advanced breast cancer patients have a PIK3CA mutation, alpelisib will be prescribed more by oncologists and, therefore, appropriate screening with fasting plasma glucose, hemoglobin A1c (HbA1C), and monitoring during drug administration is of utmost importance.