Observations with alpelisib in older patients (≥ 65 year of age) with breast cancer in a non-clinical trial setting

Purpose: Alpelisib is newly-available breast cancer agent that targets PIK3 mutations and confers a somewhat unusual adverse event profile. This study focused on older patients (≥ 65 years of age) treated outside a clinical trial to gain further experience on how these under-studied patients do with this new agent. Methods: This descriptive, multi-site study relied on medical record review. Results: Fifty-one older breast cancer patients were started on alpelisib between May 2019 and September 2020. The median age and number of comorbidities at alpelisib initiation was 71 years and 4, respectively. Thirty-five patients had stopped alpelisib (median time on drug 2.6 months (range: < 1, 9.5 months)) for the following reasons: alpelisib adverse events (n = 15), cancer progression (n = 13), and other/unknown (n = 7). Alpelisib adverse events included hyperglycemia (n = 37), diarrhea (n = 23), rash (n = 19), fatigue (n = 12), and mouth sores (n = 7); (numbers in parentheses indicate the number of patients with at least one such event). Five patients were hospitalized for hyperglycemia. At the time of report, 14 patients were deceased, and median survival had not been reached. Conclusion: Older patients might derive further benefit from alpelisib if the adverse event profile of this agent, particularly the hyperglycemia, were able to be better managed.