Beam Therapeutics provides updata on BEAM-302 development progress

Positive initial safety and efficacy data from the Phase 1/2 trial of BEAM-302 were previously reported in March 2025, establishing clinical proof of concept for BEAM-302 as a potential single-course treatment for AATD through in vivo base editing correction of the causative genetic mutation. Preliminary results for nine patients from the first three single-ascending dose cohorts from Part A of the trial, designed to evaluate BEAM-302 in AATD patients with lung disease, demonstrated that treatment was well tolerated, and single doses of BEAM-302 led to increases in total and functional alpha-1 antitrypsin to therapeutic levels, as well as a significant reduction in the mutant protein, thereby addressing the underlying pathophysiology of both the liver and lung disease. To finalize dose selection and prepare BEAM-302 for registrational development, Beam has expanded dose exploration in Part A of the Phase 1/2 trial and initiated enrollment in Part B, designed to evaluate AATD patients with mild to moderate liver disease with or without lung disease. In Part A, Beam is enrolling a total of six patients each in the 60 mg and 75 mg cohorts and initiated screening for a multi-dose cohort of two 60 mg doses administered eight weeks apart. Continued dose escalation may be evaluated based on ongoing safety and efficacy findings. In Part B, patients will initially receive 30 mg of BEAM-302, followed by additional dose escalation cohorts. As of August 1, 2025, a total of 17 patients have been dosed in Part A, with follow-up ranging from three days to 14 months. All adverse events were mild to moderate, with no serious AEs and no dose-limiting toxicities reported. All liver transaminase elevations continued to be Grade 1 and resolved to normal without intervention. All infusion-related reactions were mild to moderate. Treatment with BEAM-302 continued to demonstrate restoration of AAT physiology by inducing production of corrected and functional M-AAT, reducing circulating mutant Z-AAT, and correcting the disease-causing mutation in a dose-dependent manner, as measured by the percent change in total circulating AAT from baseline. Changes in total and functional AAT levels and the ratio of circulating M-AAT to Z-AAT continued to be durable for all patients. Beam expects to finalize dose selection for registrational development based on the totality of data from the BEAM-302 trial. Clinical data from Part A and Part B are expected to be shared in early 2026, along with an updated clinical development plan for BEAM-302 in patients with AATD.