Clinical Stage and Regulatory Timeline BMN-307 is an investigational gene transfer therapy intended to deliver its phenylalanine hydroxylase (PAH) gene to the liver tissue for the production of PAH enzyme protein. Biomarin is conducting a Phase 1/2 clinical trial (PHEARLESS) to evaluate the safety and efficacy of AAV-PAH gene therapy in subjects with PKU. On September 2020, Biomarin announced the dosing of the first patients in their clinical studies. Viral Vector and Gene Construct: AAV5.-Liver-specific promoter- PAH. The PAH gene under the liver tissue-specific promoter that drives the expression in the liver tissue. AAV5 is an adeno-associated virus that has been previously used to deliver the gene into liver tissue and successful transgene expression. Clinical Phase: Biomarin is currently conducting a Phas e 1 /2 (NCT04480567) open-label, dose-escalation study to evaluate the safety and efficacy of BMN307 in PKU subjects with PAH deficiency . The propos...