FIXX Homology Medicines Inc

Homology Medicines, Inc. (Nasdaq: FIXX), a genetic medicines company, announced today the first presentation of results from IND-enabling studies with HMI-104, the anti-C5 GTx-mAb development candidate for paroxysmal nocturnal hemoglobinuria (PNH). These data demonstrated that a one-time administration of HMI-104 resulted in sustained expression of functional C5 monoclonal antibody (C5mAb) levels in multiple preclinical models. Homology will also present for the first time non-clinical data that show the potential for AAVHSC re-dosing across different clades of viruses. These presentations, alongside additional data supporting the Company’s gene editing and gene therapy programs, will be featured at the American Society of Gene & Cell Therapy (ASGCT) 26th Annual Meeting from May 16-20, 2023.

“These new data to be presented during ASGCT with our GTx-mAb development candidate, HMI-104, support its development as a one-time treatment for the rare, acquired disorder PNH, with potential for the platform to address other complement-mediated disorders,” said Albert Seymour, Ph.D., President and Chief Executive Officer of Homology Medicines. “We also look forward to unveiling data that demonstrate the ability to re-dose AAVHSCs across different virus clades, which is of particular importance as the field continues to focus on AAV re-dosing strategies. Additional presentations will highlight work across our AAVHSC platform, including methods to further characterize genomic targets with the highest likelihood of homologous recombination-based gene editing, as we work toward our goal of delivering best-in-class gene editing therapies.”Homology’s ASGCT 2023 presentations will include:

HMI-104: GTx-mAb Development Candidate for PNHPreclinical Studies with HMI-104, an AAVHSC Vectorized C5 Monoclonal Antibody, for the Treatment of PNH

• Wednesday, May 17 at 12:00 p.m. PT
• Abstract # 386

AAVHSC PlatformOcular Biodistribution of AAVHSCs Across Species and Routes of Administration

• Wednesday, May 17 at 12:00 p.m. PT
• Abstract # 376

Immunosuppression Regimen Used in Ongoing Clinical Trials for PKU and MPS IITargeted Approach to Immunosuppression with AAV Gene Therapy: Nonclinical Support of Clinical Approaches

• Thursday, May 18 at 12:00 p.m. PT
• Abstract # 989

HMI-204: Gene Therapy Candidate for MLDGene Therapy Candidate for Metachromatic Leukodystrophy (MLD): Optimization of HMI-202 Leading to HMI-204 Nomination

• Friday, May 19 at 12:00 p.m. PT
• Abstract # 1312

AAVHSC Re-DosingRe-Dosing of Liver-Targeted AAV within and Across Clades in Mice: Effects of Neutralizing Antibodies and Vector-Specific Factors

• Friday, May 19 at 12:00 p.m. PT
• Abstract # 1355

AAVHSC-Mediated, Homologous Recombination-Based Gene EditingMethod for Identification and Characterization of Sites of Homology Directed Strand Cross-Over Using rAAV Integration Vectors

• Friday, May 19 at 12:00 p.m. PT
• Abstract # 1497

The abstracts are available on the ASGCT website and on 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. 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, including HMI 104 for the treatment of PNH and other diseases; 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; our position as a leader in the development of genetic medicines and our participation in upcoming presentations and conferences. 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 and general economic conditions on our business and operations, including our preclinical studies and clinical trials; 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