Clinical Response to PI3K-α Inhibition in a Cohort of Children and Adults With PIK3CA-Related Overgrowth Spectrum Disorders.

Objective:The goal of this report is to describe, through a series of 5 cases, the clinical response and safety of alpelisib (BYL719) use in children and adults with PIK3CA-related overgrowth spectrum (PROS) disorders at our center. Methods:We reviewed clinical records of 5 patients from October 2019 through September 2021 followed by the pediatric hematology and multidisciplinary vascular anomalies teams at the Monroe Carell Jr. Children's Hospital at Vanderbilt (MCJCHV). All patients carried a clinical or genetic diagnosis of PROS and were treated with alpelisib provided by a Novartis managed access program. Results:We highlight improvement in reported symptoms, objective overgrowth measurements, and quality of life to varying degrees in all patients. We note dose-dependent hyperglycemia and gastrointestinal side effects in 2 of the 5 patients. No patients experienced any serious side effects. Conclusion:This case series reports on the real-world use of PI3K-α inhibition in the management of PROS. Ongoing clinical trials will provide efficacy and safety data as these drugs become more widely used in patients with vascular anomalies and syndromes secondary to somatic PIK3CA mutations.