BEAM-301

October 13, 2026: Beam Therapeutics (NASDAQ: BEAM) reported initial Phase 1/2 data for BEAM-301, an in vivo base-editing therapy targeting the R83C mutation in glycogen storage disease type Ia (GSDIa), and said the data will be presented at ESGCT on October 28, 2026.

As of the June 26, 2026 cutoff, six patients had received a single IV infusion (three at 20 mg, three at 40 mg; one 40 mg patient not yet evaluable for efficacy). The company said BEAM-301 showed an acceptable safety profile consistent with LNP-based therapies: all patients had at least one related TEAE; five serious AEs resolved within 2-10 days, including three Grade 3 infusion-related reactions; no dose-limiting toxicities, treatment discontinuations, or deaths were reported. Transaminase elevations were transient and mostly Grade 1.

Efficacy signals were dose dependent. Median time to fasting hypoglycemia increased from 2.9 to 4.3 hours by Day 36 in the 20 mg cohort; both evaluable 40 mg patients reached the protocol-defined maximum controlled fasting duration of at least 15 hours, described as consistent with restored endogenous glucose production. Prescribed daily starch intake fell 74%, 71%, and 11% at Days 128, 227, and 387 in the 20 mg cohort, and 71% and 92% at Days 50 and 93 in the 40 mg cohort. Updated data are planned at the ESGCT poster session.