Beam Therapeutics Inc. (NASDAQ:BEAM), a biotechnology company developing precision genetic medicines through base editing, today announced that the United States (U.S.) Food and Drug Administration (FDA) has cleared the investigational new drug (IND) application for BEAM-304 for the treatment of phenylketonuria (PKU). PKU is a rare, inherited metabolic disorder that results in toxic accumulation of phenylalanine (Phe), leading to serious neurologic and neurocognitive impairments and requires strict, lifelong dietary management. Beam is advancing BEAM-304 using an innovative development approach in which multiple mutation-specific base editors are developed efficiently within a single clinical program using in vivo delivery, in accordance with the FDA's recent efforts to accelerate development of genome editing therapies.1

"PKU affects approximately 20,000 people in the U.S., with significant unmet need for therapies that address the underlying cause of disease," said Giuseppe Ciaramella, Ph.D., president of Beam. "FDA clearance of our IND for BEAM-304 supports our novel approach of developing multiple mutation-specific base editors through a single clinical platform program, leveraging emerging FDA guidance intended to accelerate development of base editing therapeutics. We look forward to initiating our Phase 1/2 trial, intending to establish clinical proof of concept for base editing in PKU."

"Many PKU-causing mutations are single-base changes, making the disease particularly well suited for correction through base editing," said Gopi Shanker, Ph.D., chief scientific officer of Beam. "By leveraging the same underlying base editing technology, LNP delivery system, and manufacturing approach across multiple mutation-specific editors, we believe we can establish a scalable development pathway that expands access to potentially transformative therapies for people living with PKU and may serve as a model for addressing other genetically diverse liver diseases in the future."

BEAM-304 leverages Beam's proprietary and clinically validated base editing technology and lipid nanoparticle (LNP) delivery capabilities to directly and durably correct mutations in the phenylalanine hydroxylase (PAH) gene that cause PKU. By correcting mutations in the PAH gene, BEAM-304 aims to restore PAH enzyme activity in order to reduce toxic Phe to the recommended guideline levels (≤ 360 µmol/L) while enabling diet normalization and freedom from medical food.

Preclinical data demonstrate that BEAM-304 normalized plasma Phe levels in PKU mouse models at clinically relevant doses with robust on-target editing in the liver. Updated preclinical data for BEAM-304 will be presented at the Federation of American Societies for Experimental Biology (FASEB) Genome Engineering: Research and Applications Conference, taking place July 6-9, 2026, in Porto, Portugal.

The planned Phase 1/2 trial will initially evaluate safety, tolerability, reduction of blood Phe levels and diet liberalization in PKU patients with the R408W mutation, followed by a base editor designed to address a second mutation, with the goal of establishing clinical proof of concept for base editing in PKU.