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

Part 1 and 2: Percent change from baseline in lesion volume

Time frame: Baseline, Week 24

Part 1 and 2: Duration of response, defined as the time of first documented response to the date of first documented disease progression or death due to any cause

Time frame: Approximately every 3 months for approximately the first year, and then every 6 months during treatment

Part 1 and 2: Percentage of participants with volumetric response

Time frame: Baseline, week 12, week 24

Part 1 and 2: Plasma concentrations and PK parameters of RLY-2608

Time frame: Approximately every 2 weeks in Cycle 1, then again at Cycles 2, 4 and Cycle 7 depending on the participant's group

Part 1 and 2: PIK3CA mutational status in lesional fluid and/or tissue

Time frame: Prior to enrollment

Part 3: Percentage of participants with improvement compared to baseline based on PGI-S, PGI-C and IGIC

Time frame: Approximately once a month until end of treatment

Part 3: Change from baseline by age-appropriate PROMIS Profile

Time frame: Approximately once a month until end of treatment

Part 3: Change from baseline in EQ-5D, EQ-5D-Y, or EQ-5D-Y Proxy

Time frame: Approximately once a month until end of treatment

Part 3: Percent change from baseline in lesion volume

Time frame: Approximately every 3 months for approximately the first year, and then every 6 months during treatment