C-Peptide and BMi predict anti-hyperglycemic treatment lines in breast cancer patients treated with Alpelisib.

Purpose: Alpelisib is a PI3K (Phosphoinositide 3-kinases) inhibitor used for breast cancer which develops hyperglycemia based on its action on glucose metabolism regulation. This study aims to identify potential risk factors predicting hyperglycemia development and the need for multiple treatments for hyperglycemia in patients receiving Alpelisib.

Methods: Fourteen women diagnosed with metastatic hormone receptor-positive breast cancer carrying PI3K mutations who initiated treatment with Alpelisib were monitored through consultations in the Oncology and Endocrinology departments. Non-parametric ROC curves were generated to assess the need for three or more antidiabetic medications to achieve glycemic control.

Results: The study population had a median age of 64 years (range:48-69) with a median body mass index (BMI) of 26.6 kg/m² (range: 22.9-29.4). Overweight was observed in 35.7% of the participants and obesity in 21.4%. Fifty percent of the participants had prediabetes, and 85.7% developed hyperglycemia requiring pharmacological treatment, although none of them needed to discontinue treatment for this reason. Baseline C-peptide levels and BMI were associated with the number of antidiabetic drugs used (Spearman's Rho 0.553, p = 0.040; Spearman's Rho 0.581, p = 0.030, respectively). ROC curve analysis showed and area under the curve (AUC) of 0.819 for the variable risk profile (defined as baseline C-peptide >10.5 ng/ml and BMI > 27 kg/m²), whereas AUC values were 0.556 and 0.514 for HbA1c and baseline glucose, respectively, (p = 0.012).

Conclusion: A joint follow-up by an Oncology department and a Diabetes Unit can prevent treatment discontinuation in patients under Alpelisib therapy. Baseline BMI and plasma C-peptide levels can predict an increased need for anti-hyperglycemic treatment.