Beam Therapeutics launched BEAM‑304, a liver‑targeted base‑editing program designed to correct pathogenic PAH mutations that cause phenylketonuria (PKU), and secured a $500 million strategic financing agreement with Sixth Street to support its broader pipeline. Beam plans to file an IND in 2026 and pursue a Phase I/II trial targeting the R408W mutation first. The program leverages Beam’s validated base‑editing platform and LNP delivery to pursue potentially one‑time genomic corrections across multiple mutation‑specific editors within a single program. Preclinical mouse data reportedly showed normalization of plasma phenylalanine at clinically relevant doses with on‑target liver editing. For the gene‑editing field, BEAM‑304 represents another example of companies modularizing multiple mutation‑specific editors under one clinical umbrella, highlighting the operational and regulatory challenges of scaling base‑editing to address genetically heterogeneous rare diseases.