Gerald Vockley, MD, PhD, Head of the Division of Medical Genetics at UPMC Children’s Hospital of Pittsburgh, discusses new data testing a probiotic to treat individuals with phenylketonuria (PKU). 

PKU is a rare genetic metabolic disorder that results in reduced activity of phenylalanine hydroxylase that leads to an accumulation of phenylalanine in the body, which can cause significant organ damage, especially in the central nervous system. If left untreated, PKU patients can develop chronic intellectual, neurodevelopmental, and psychiatric disabilities, as well as seizures and heart problems. 

SYNB1934 is engineered probiotic bacteria (E. coli Nissle) designed to allow the bacteria to convert phenylalanine into non-toxic metabolites in the intestines, and thereby allow people with PKU to eat a less restrictive diet. As Dr. Vockley explains, the data from the phase 2 study showed SYNb1934 to display clinically meaningful reductions in levels of plasma phenylalanine. A second preparation tested in the phase 2 study,  SYNB1618, was also effective but to a lesser extent. 

A Phase 3 study is expected to begin in 2023.

To learn more about PKU and other rare metabolic disorders, visit