FDA Approval Summary: Alpelisib for PIK3CA-related Overgrowth Spectrum (PROS).

On April 5, 2022, FDA granted accelerated approval to alpelisib for the treatment of adult and pediatric patients two years of age and older with severe manifestations of PIK3CA-related overgrowth spectrum (PROS) who require systemic therapy. Efficacy was evaluated using real-world data (RWD) from EPIK-P1 (NCT04285723), a single-arm clinical study in patients two years of age and older with severe or life-threatening PROS who received alpelisib as part of an expanded access program (EAP) for compassionate use. The primary endpoint was confirmed radiological response rate at Week 24 as determined by blinded independent central review (BICR), using volumetric-based criteria given the atypical growth pattern and irregular shape of PROS lesions. Radiological response was defined as a ≥20% reduction from baseline in the sum of measurable target lesion volume in up to three lesions. Of the 37 patients in the efficacy population, 27% (95% CI: 14, 44) had a radiological response at Week 24. Duration of response (DOR) was an additional efficacy outcome measure, and among responders, 60% had a response lasting ≥12 months. Further, supportive clinical documentation suggested early signals of clinical benefit (i.e., improvement in PROS-related signs and symptoms). The most common (≥10%) adverse reactions were diarrhea, stomatitis and hyperglycemia.