Homology Medicines, which specializes in gene therapies for rare diseases and is developing two potential such therapies — HMI-102 and HMI-103 — for people with phenylketonuria (PKU), has received a $60 million equity investment from Pfizer.
Homology stated in a press release that it intends to use proceeds from this common stock purchase to support ongoing and planned PKU clinical trials, as well as programs for other diseases of the central nervous system.
PKU is caused by mutations in the PAH gene. These mutations lead to insufficient activity of the phenylalanine hydroxylase (PAH) enzyme, causing the amino acid phenylalanine, one of the building blocks of proteins, to build to toxic levels.
Both HMI-102 and HMI-103 work through the same general concept: the therapies are designed to deliver a non-mutated version of the PAH gene to a patient’s liver cells, allowing the body to produce functional PAH enzyme. HMI-102 is being developed for adults with PKU, whereas HMI-103 is for pediatric patients.
Both HMI-102 and HMI-103 have shown promise in animal models of PKU. HMI-102 has been granted orphan drug and fast track designations by the U.S. Food and Drug Administration, and orphan drug status by the European Medicines Agency.
HMI-102 is currently being investigated in the pheNIX Phase 1/2 clinical trial (NCT03952156). Homology, which is sponsoring the trial, recently reported positive results from the initial dose-escalation part. Based on those results, the trial is advancing into its randomized, expansion part, which will continue to investigate two selected doses of the therapy.
The trial is currently enrolling adults (ages 18-55) with PKU at sites across the U.S.; more information is available here.
“With the positive clinical data from the dose-escalation phase of our pheNIX Phase 1/2 trial for adults with phenylketonuria (PKU) and our plans to move to the expansion phase of the trial … we believe Pfizer’s investment in Homology is a testament to their enthusiasm for our PKU gene therapy and gene editing programs to treat people living with this disease,” said Arthur Tzianabos, PhD, Homology’s president and CEO.
As part of the Pfizer Breakthrough Growth Initiative, the company purchased 5 million shares of Homology’s common stock at $12 per share.
“Pfizer Rare Disease has a 30-year heritage of developing treatment options for patients with some of the greatest unmet needs, including in the area of rare metabolic disorders,” said Seng Cheng, PhD, senior vice president and chief scientific officer of Pfizer’s Rare Disease Research Unit.
In connection with the investment, Cheng will join Homology’s scientific advisory board to participate in matters related to the development of HMI-102 and HMI-103.
“We believe gene therapy could help provide a potentially transformational therapeutic option for patients living with PKU,” Cheng said.
Homology also granted Pfizer a right of first refusal on future transactions involving its PKU programs, meaning it will have the right to enter into such transactions before others can.