RF07 | PSUN359 Alpelisib-induced Diabetic Ketoacidosis

BACKGROUND: Alpelisib is an oral α-specific phosphatidylinositol 3-kinase (PI3K) inhibitor use in combination with fulvestrant to treat postmenopausal women with HR+/HER2−, PIK3CA-mutated, advanced or metastatic breast cancer that has acquired resistance to endocrine-based therapy. (1)Alpelisib interferes with the PI3K/Akt signalling pathway resulting in impaired peripheral glucose uptake, increased liver glycogenolysis, loss of beta-cell mass and insulin secretion dysfunction(2). Hyperglycemia is a frequent adverse effect of alpelisib but diabetic ketoacidosis (DKA) is considered a rare occurrence. We describe a patient without a previous history of diabetes who developed DKA after 2 months on alpelisib.Clinical caseA 81 year-old woman with metastatic ER+ PR – Her2 - breast cancer, presented with a 1 week history of nausea, vomiting, and polyuria. Her hemoglobin A(1)C was 5.5% on two separate occasions last year. She had started alpelisib at 300 mg/day 7 weeks prior to presentation. She presented with a blood glucose (BG) of 659 mg/dL, anion gap of 21, serum bicarbonate 17 mmol/L, beta-hydroxybutyrate 3.82 mmol/L (normal < 0.27 mmol/L), serum osmolarity 319 mOsm/kg, serum creatinine 2.83 mg/dL (baseline 1.38 mg/dL), C-peptide 4.3 ng/mL (normal 1.1–4.4 ng/mL), negative GAD-65 antibodies and Islet Antigen 2 antibodies, septic workup were non-revealing, leading to the diagnosis of alpelisib-associated DKA. Alpelisib was held, and she was treated with intravenous insulin and hydration. DKA resolved in 12 hours, however, she had persistent hyperglycemia. She was started with insulin regimen of 0.2 units/kg and discharged with Humalog 75/25 5 units twice daily. CONCLUSION: Patients with no pre-existing history of diabetes mellitus can also be at risk for DKA which may develop within weeks to months of initiation of alpelisib. Risk factors for development of DKA are yet to be identified, but would be useful to help tailor frequency of BG monitoring. This warrants further research. The hyperglycemic effects of alpelisib appear to be reversible upon drug discontinuation, however when DKA is the presenting syndrome, insulin therapy is indicated. REFERENCE: André F, Ciruelos E, Rubovszky G, Campone M, Loibl S, Rugo HS, Iwata H, Conte P, Mayer IA, Kaufman B, Yamashita T, Lu YS, Inoue K, Takahashi M, Pápai Z, Longin AS, Mills D, Wilke C, Hirawat S, Juric D; SOLAR-1 Study Group. Alpelisib for PIK3CA-Mutated, Hormone Receptor-Positive Advanced Breast Cancer. N Engl J Med. 2019 May 16;380(20): 1929-1940. doi: 10.1056/NEJMoa1813904. PMID: 31091374. Nguyen P, Musa A, Samantray J. Alpelisib-Induced Diabetic Ketoacidosis. Cureus. 2021 May 1;13(5): e14796. doi: 10.7759/cureus.14796. PMID: 34084688; PMCID: PMC8166359. Presentation: Saturday, June 11, 2022 1:36 p.m. - 1:41 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.