Homology Medicines Announces Peer-Reviewed Publication of Five-Year Retrospective Study Conducted in Collaboration with Two PKU Key Opinion Leaders Demonstrating Substantially Elevated Phe Levels in Adults with Classical PKU on Standard of Care

These Data Highlight Unmet Medical Need for Therapies to Control Phe Concentrations by Targeting the Underlying Cause of PKU

BEDFORD, Mass., Dec. 16, 2019 (GLOBE NEWSWIRE) -- Homology Medicines, Inc. (Nasdaq: FIXX), a genetic medicines company, announced today a peer-reviewed publication of findings from a five-year retrospective chart review that demonstrated phenylalanine (Phe) concentrations remain elevated in adult patients with classical phenylketonuria (PKU) even when closely monitored and on the standard of care highly restricted protein diet. Elevated Phe can cause neurocognitive deficits and, as diet alone is often insufficient for achieving target Phe levels, these data support the need for new therapies to control Phe levels in patients with PKU.

The publication describes a retrospective review of electronic health records of patients 10-40 years old with hyperphenylalaninemia (HPA), or mild, moderate or classical PKU, to capture historical data associated with managing PKU under the standard of care for the study’s time period of November 2012 through November 2017, characterize a representative population, and understand the unmet medical need.

“This retrospective analysis emphasizes the importance of developing new treatment options, including genetic medicines that aim to control Phe levels by addressing the genetic cause of PKU, obviating the need for a highly restrictive, difficult-to-maintain and often ineffective diet in the most common form of the disease, classical PKU,” said Albert Seymour, Ph.D., Chief Scientific Officer of Homology Medicines. “This work, conducted in collaboration with our academic partners, informed the design of our pheNIX gene therapy trial, from which we plan to share initial data this month.”

The data were collected and analyzed at two specialized clinics — Boston Children’s Hospital in Boston, Massachusetts and the UPMC Children’s Hospital of Pittsburgh in Pittsburgh, Pennsylvania — in collaboration with Homology. The data were consistent between the two centers.

Additional key observations in the publication include:

• Of the 152 patients in the study, 65.8% had classical PKU, which is the most common and most severe form of the disease.
• Although over 95% of patients were prescribed a Phe-restricted diet, blood Phe concentrations in the classical PKU patients remained substantially elevated above 360 µmol/L, a level considered well-controlled based on current U.S. treatment guidelines, particularly in patients with classical PKU.
• As Phe threshold was lowered (Phe less than 600, 360, 120 or 30 µmol/L), the number of patients with consecutive lab values below the threshold decreased, suggesting many patients’ Phe levels were inadequately controlled.
• 62.5% of patients were reported as having a history of at least one neuropsychiatric comorbidity, and adults were more likely than adolescents (69.5% vs. 54.3%).

The publication, “5-Year Retrospective Analysis of Patients with Phenylketonuria (PKU) and Hyperphenylalaninemia Treated at Two Specialized Clinics,” was peer-reviewed and published in the journal Molecular Genetics & Metabolism. For more information, please visit www.homologymedicines.com/publications.