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Homology Medicines Presents Preclinical Data from PKU Gene Therapy Program Demonstrating Restored Metabolic Pathway and Increased Neurotransmitter Production

- Company Announced IND Clearance Today for Phase 1/2 Clinical Trial -

BEDFORD, Mass., April 4, 2019 – Homology Medicines, Inc. (Nasdaq: FIXX), a genetic medicines company, announced today preclinical data demonstrating that HMI-102, its gene therapy candidate for the treatment of phenylketonuria (PKU), restored the normal phenylalanine metabolic pathway as evidenced by measurements of key biomarkers in the disease model. The presentation at the ACMG Annual Clinical Genetics Meeting demonstrated long-term durability of the one-time administration of HMI-102 in reducing serum phenylalanine (Phe) and increasing tyrosine levels, due to an increase in phenylalanine hydroxylase (PAH) enzyme activity. HMI-102 also demonstrated reduction in brain Phe and the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA), as well as a positive impact on melanin production.

“As we prepare to start our Phase 1/2 clinical trial with HMI-102 for adults with PKU, we are pleased to share further evidence that our one-time gene therapy candidate has restored the normal biochemical pathway that is lost in PKU,” stated Albert Seymour, Ph.D., Chief Scientific Officer of Homology Medicines. “We believe the data support the potential for HMI-102 to address the underlying genetic cause of PKU, and we look forward to advancing this product candidate forward and reporting initial clinical data this year.”

As previously reported today, the U.S. Food and Drug Administration (FDA) provided clearance for Homology to begin its Phase 1/2 clinical trial with HMI-102. Homology’s presentation received a Top Rating from the ACMG.

For more information about the presentation, visit Homology’s website at

About Phenylketonuria (PKU)
PKU is a rare, inherited inborn error of metabolism caused by a mutation in the PAH gene. The current standard of care is a highly restrictive diet, but it is not always effective, and there are currently no treatments available that address the genetic defect in PKU. If left untreated, PKU can result in progressive and severe neurological impairment. PKU affects approximately 15,000 people in the U.S., and an estimated 300 newborns are diagnosed each year.

About Homology Medicines, Inc.
Homology Medicines, Inc. is a genetic medicines company dedicated to transforming the lives of patients suffering from rare genetic diseases with significant unmet medical needs by curing the underlying cause of the disease. Homology’s proprietary platform is designed to utilize its human hematopoietic stem cell-derived adeno-associated virus vectors (AAVHSCs) to precisely and efficiently deliver genetic medicines in vivo either through a gene therapy or nuclease-free gene editing modality across a broad range of genetic disorders. Homology has a management team with a successful track record of discovering, developing and commercializing therapeutics with a particular focus on rare diseases, and intellectual property covering its suite of 15 AAVHSCs. Homology believes that its compelling preclinical data, scientific expertise, product development strategy, manufacturing capabilities and intellectual property position it as a leader in the development of genetic medicines. For more information, please visit

Forward-Looking Statements
This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including statements regarding the potential for HMI-102 to address the underlying genetic cause of PKU; our expectations surrounding initiation and timing of clinical trials for our PKU gene therapy program; advancing our novel gene therapy and gene editing technology platform and pipeline; our beliefs regarding our supply and manufacturing capabilities; our goal of improving the lives of patients with rare genetic diseases; the anticipated timing of the release of clinical data for the Phase 1/2 clinical trial; beliefs about preclinical data; and our position as a leader in the development of genetic medicines. These statements are neither promises nor guarantees, but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements, including, but not limited to, the following: the fact that we have and expect to continue to incur significant losses; our need for additional funding, which may not be available; failure to identify additional product candidates and develop marketable products; the early stage of our development efforts; our failure or the failure of our collaborators to successfully develop and commercialize drug candidates; potential unforeseen events during clinical trials could cause delays or other adverse consequences; risks relating to the capabilities and potential expansion of our manufacturing facility; risks relating to the regulatory approval process; our product candidates may cause serious adverse side effects; inability to maintain our collaborations, or the failure of these collaborations; our reliance on third parties; the inability to obtain orphan drug exclusivity; failure to obtain U.S. or international marketing approval; ongoing regulatory obligations; effects of significant competition; unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives; product liability lawsuits; failure to attract, retain and motivate qualified personnel; the possibility of system failures or security breaches; risks relating to intellectual property; the price of our common stock may be volatile; significant costs as a result of operating as a public company; and any securities class action litigation. These and other important factors discussed under the caption “Risk Factors” in our Annual Report on Form 10-K for the year ended December 31, 2018 and our other filings with the SEC could cause actual results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking statements represent management’s estimates as of the date of this press release. While we may elect to update such forward-looking statements at some point in the future, we disclaim any obligation to do so, even if subsequent events cause our views to change.

Investor Contact:
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SVP, Corporate Communications and Patient Advocacy

Media Contact:
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Senior Director, Patient Advocacy and Corporate Communications