– Proof of Concept Data for New GTx-mAb Platform to Be Featured at ASGCT Along With Presentations From Multiple Programs –

BEDFORD, MA, USA I April 28, 2021 I Homology Medicines, Inc. (Nasdaq: FIXX), a clinical-stage genetic medicines company, announced today a new approach to its AAVHSC platform that delivers one-time gene therapy to produce antibodies throughout the body. Preclinical data that demonstrated proof of principle for this GTx-mAb platform is the subject of an upcoming presentation, alongside other digital and oral presentations from the Company’s in vivo gene therapy and gene editing programs, that will be featured at the virtual American Society of Gene & Cell Therapy (ASGCT) 24th Annual Meeting May 11 – 13, 2021.

“We are excited to unveil our GTx-mAb platform and preclinical data targeting complement protein 5 with a one-time treatment,” stated Arthur Tzianabos, Ph.D., President and Chief Executive Officer of Homology Medicines. “These data demonstrated that our AAVHSCs delivered vectors at a high efficiency to the liver and secrete antibodies throughout the body, which resulted in sustained expression levels consistent with C5 antibody therapeutics in a humanized murine model. Importantly, this proof of concept for our approach unlocks the potential for a one-time treatment that leverages the liver to produce fully functional antibodies and the expansion of our pipeline to address diseases with larger patient populations.”

Albert Seymour, Ph.D., Chief Scientific Officer, added, “We also look forward to sharing new data across our genetic medicines pipeline programs, including PKU and Hunter syndrome, which support our plans to advance these two programs into the clinic this year. These data further demonstrated that our AAVHSCs efficiently transduced the liver and reached relevant tissues, including crossing the blood-brain and peripheral-nerve barriers with a single I.V. administration. Additionally, we plan to highlight advancements from our capsid characterizations and our internal GMP manufacturing process and platform, including an oral presentation showing the impact of novel formulations on capsid stability.”

Homology management plans to host a conference call and webcast on May 13, 2021, at 8:15 a.m. ET to discuss the new GTx-mAb platform and ASGCT data highlighting the Company’s human hematopoietic stem cell-derived adeno-associated virus vector (AAVHSC) platform and pipeline.

Homology’s digital and oral presentations include:

In Vivo AAVHSC Platform
Transducing the Liver as an Antibody Factory Using AAVHSCs
Tuesday, May 11; 8:00 – 10:00 a.m.
Abstract #: 336

Functional Characterization of AAVHSCs Compared to AAV Serotypes: Activation of Cellular Pathways In Vitro and In Vivo Transduction Properties
Tuesday, May 11; 8:00 – 10:00 a.m.
Abstract #: 304

Wildtype AAV2 Rep Protein Produces Higher Titer AAVHSC Vectors with Improved Packaging Profiles Compared to Clade F Associated Chimeric Rep
Tuesday, May 11; 8:00 – 10:00 a.m.
Abstract #: 804

In Vivo, Nuclease-Free Gene Editing for PKU
Investigational Genetic Medicine Approaches for Phenylketonuria (PKU)
Tuesday, May 11; 8:00 – 10:00 a.m.
Abstract #: 405

In Vivo Gene Therapy for Hunter Syndrome
Long-Term Expression of HMI-203: Investigational Gene Therapy Candidate for Mucopolysaccharidosis Type II (MPS II), or Hunter Syndrome
Tuesday, May 11; 8:00 – 10:00 a.m.
Abstract #: 507

Scalable Manufacturing – Oral Presentation
Next Generation AAV Drug Products: Enhanced Stability & Clinical Ease for High Titer Preparations
Tuesday, May 11; 6:45 – 7:00 p.m.
Abstract #: 27

In Vivo Gene Therapy for MLD – Oral Presentation
Gene Therapy Candidate for Metachromatic Leukodystrophy (MLD): Summary of Preclinical In Vivo Data Following an Intravenous Delivery of HMI-202
Thursday, May 13; 5:30 – 5:45 p.m.
Abstract #: 159

The abstracts are available on the ASGCT 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 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. The Company’s intellectual property covers its family 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 www.homologymedicines.com.

SOURCE: Homology Medicines