A Phase 2 Study of Mutant-selective PI3Kα Inhibitor, RLY-2608, in Adults and Children With PIK3CA Related Overgrowth Spectrum and Malformations Driven by PIK3CA Mutation (The ReInspire Study)

The participant must have a clinical diagnosis of PROS or a malformation within the ISSVA classification.

One or more documented activating PIK3CA mutation(s) that are targeted by selective PI3Kα inhibitors in lesional tissue and/or cell-free DNA from the lesion or blood. Some participants may be eligible without a documented PIK3CA mutation, with the sponsor's approval, as long as no other genetic driver has been documented.

Lansky (<16 yo) or Karnofsky (≥16 yo) performance status of ≥50.

Agree to provide archived lesional fluid and/or tissue or be willing to undergo pretreatment lesional biopsy (if considered safe and medically feasible) to assess PIK3CA status.