FIXX Homology Medicines Inc

Homology Medicines, Inc. (Nasdaq: FIXX), a genetic medicines company, announced two presentations during the ACMG Annual Clinical Genetics Meeting, which highlight the preclinical data that supported initiation of the Company’s Phase 1 pheEDIT gene editing trial for phenylketonuria (PKU) and the Phase 1 juMPStart gene therapy trial for Hunter syndrome (MPS II). Additionally, the presentations feature trial design, including the targeted immunosuppression regimen incorporated in both studies. The pheEDIT-focused presentation also includes preclinical potency data with HMI-103, the nuclease-free, in vivo, gene editing candidate for PKU.

“Our ongoing clinical trials are supported by robust preclinical data packages that informed the design and selected dose levels. Additionally, data on the immunosuppression regimen from non-human primates demonstrated the ability to temporarily dampen the immune response, which could potentially enhance expression following vector administration,” stated Albert Seymour, Ph.D., President and Chief Executive Officer of Homology Medicines. “Related to the pheEDIT trial for PKU, data presented at ACMG showed the murine surrogate of HMI-103 was ten times more potent at reducing blood Phe levels as compared to non-integrating gene therapy vector HMI-102, which we believe relates to its dual mechanism of action of integration and episomal expression as well as additional optimizations we made to the candidate. We remain on track to share initial pheEDIT clinical data by mid-year, and anticipate sharing initial juMPstart clinical data in the second half of 2023.”

Homology’s poster presentation details are as follows:

• Title: pheEDIT: A Phase 1, Open-Label, Dose-Escalation Safety and Efficacy Gene Editing Study Evaluating HMI-103 in Adults with Classical PKUDate and Time: Friday, March 17, 2023 at 10:30 a.m. MT

• Title: juMPStart: Phase 1, Open-Label, Dose-Escalation Safety and Efficacy Gene Therapy Study Evaluating HMI-203 in Adults with MPS IIDate and Time: Thursday, March 16, 2023 at 10:30 a.m. MT

For more information, please visit the Publications and Presentations page on Homology’s website.

About Homology Medicines, Inc.Homology Medicines, Inc. is a clinical-stage genetic medicines company dedicated to transforming the lives of patients suffering from rare diseases by addressing the underlying cause of the disease. The Company’s clinical programs include HMI-103, a gene editing candidate for phenylketonuria (PKU); HMI-203, an investigational gene therapy for Hunter syndrome; and HMI-102, an investigational gene therapy for adults with PKU. Additional programs focus on paroxysmal nocturnal hemoglobinuria (PNH), metachromatic leukodystrophy (MLD) and other diseases. Homology’s proprietary platform is designed to utilize its family of 15 human hematopoietic stem cell-derived adeno-associated virus (AAVHSCs) vectors to precisely and efficiently deliver genetic medicines in vivo through a nuclease-free gene editing modality, gene therapy, or GTx-mAb, which is designed to produce antibodies throughout the body. Homology established an AAV manufacturing and innovation business in partnership with Oxford Biomedica, which was based on Homology’s internal process development and manufacturing platform. Homology has a management team with a successful track record of discovering, developing and commercializing therapeutics with a focus on rare diseases. Homology believes its initial clinical data and compelling preclinical data, scientific and product development expertise and broad intellectual property position the Company as a leader in genetic medicines. For more information, visit www.homologymedicines.com.

Forward-Looking Statements This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. We intend such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. All statements contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements, including without limitation statements regarding: our expectations surrounding the potential, safety, efficacy, and regulatory and clinical progress of our product candidates; the potential of our gene therapy and gene editing platforms, including our GTx-mAb platform; our plans and timing for the release of additional preclinical and clinical data; our plans to progress our pipeline of genetic medicine candidates and the anticipated timing for these milestones; and our position as a leader in the development of genetic medicines. The words “believe,” “may,” “will,” “estimate,” “potential,” “continue,” “anticipate,” “intend,” “expect,” “could,” “would,” “project,” “plan,” “target,” and similar expressions are intended to identify forward-looking statements, though not all forward-looking statements use these words or expressions. 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: 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 or commercialize marketable products; the early stage of our development efforts; potential unforeseen events during clinical trials could cause delays or other adverse consequences; risks relating to the regulatory approval process; interim, topline and preliminary data may change as more patient data become available, and are subject to audit and verification procedures that could result in material changes in the final data; 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, including for the manufacture of materials for our research programs, preclinical and clinical studies; 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; securities class action litigation; the impact of the COVID-19 pandemic on our business and operations, including our preclinical studies and clinical trials, and on general economic conditions; failure to attract, retain and motivate qualified personnel; the possibility of system failures or security breaches; risks relating to intellectual property and significant costs incurred as a result of operating as a public company. 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, 2022 and our other filings with the Securities and Exchange Commission 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.

Company Contacts:Cara MayfieldVice President, Patient Advocacyand Corporate Communicationscmayfield@homologymedicines.com781-691-3510Investor Contact:Brad Smith Chief Financial and Business Officer bsmith@homologymedicines.com 781-301-7277