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Homology Medicines Announces Peer-Reviewed Publication Indicating Low Prevalence of Pre-existing Neutralizing Antibodies to its Human-Derived AAVHSC Vectors

- Study Suggests Broad Application of Homology’s Novel AAVHSCs for Gene Therapy and Gene Editing-Based Treatments -

BEDFORD, Mass., March 1, 2018 – Homology Medicines, Inc., a genetic medicines company, announced today that the peer-reviewed journal Human Gene Therapy Clinical Development published a study suggesting that there is low prevalence of pre-existing neutralizing antibodies (Nabs) in humans to Homology’s proprietary adeno-associated virus vectors isolated from human hematopoietic stem cells (AAVHSCs). This initial study indicates that approximately 80 percent of the human population is negative for pre-existing Nabs and may be suitable for treatment with AAVHSC-based therapeutics.

“We believe this publication is supportive of the therapeutic potential of our proprietary AAVHSC platform among a broad human population, supporting our technology’s use in gene therapy as well as in nuclease-free homologous recombination-based gene editing,” said Albert Seymour, Ph.D., Chief Scientific Officer of Homology Medicines. “It is important to characterize the levels of pre-existing neutralizing antibodies to viral vectors used for gene delivery, which could limit their effectiveness, and we are pleased that this study suggests a low prevalence of Nabs to our AAVHSC vectors.”

In this study, the seroprevalence of pre-existing Nabs to Homology’s Clade F vectors, AAVHSC15 and AAVHSC17, were compared to that of Clade F AAV9. Nab levels were measured in 100 unique human sera of different races and gender, and no statistically significant differences in prevalence of Nabs to the Clade F AAVs were detected, with the majority of positive sera observed at low titer. The publication titled, “Low Seroprevalence of Neutralizing Antibodies Targeting Two Clade F AAV in Humans,” is available on Homology’s website at

Homology’s AAVHSC15 and AAVHSC17 vectors are part of a suite of 15 novel, naturally occurring AAVs that belong to Clade F, which Homology believes are uniquely capable of both in vivo gene transfer and gene editing. In preclinical studies, AAVHSCs have demonstrated significant broad biodistribution to key tissues with a single intravenous injection. When used for gene editing, these vectors are designed to harness the body’s natural DNA repair mechanism to replace entire diseased genes, correct individual mutations or knock out diseased genes with high efficiencies and precision, and without cutting DNA with a nuclease.

About Homology Medicines, Inc.
Homology Medicines is a genetic medicines company focused on translating proprietary gene editing and gene therapy technologies into novel treatments for patients with rare diseases. The combination of a new multidimensional gene correction platform and a management team that has successfully developed and commercialized therapies for the treatment of rare diseases positions the Company to potentially move beyond the current limitations of gene therapy and gene editing approaches to improve patient care. Homology Medicines has built foundational intellectual property on gene editing and gene therapy using vectors derived from naturally occurring human adeno-associated viruses (AAVs). The Company’s technology is designed to be precise, on-target and highly efficient for in vivo editing of genetic mutations. The team and technology create a significant opportunity for Homology to advance a diverse pipeline of new medicines that address and potentially cure the underlying cause of genetic diseases.

Theresa McNeely
SVP, Corporate Communications & Patient Advocacy

Cara Mayfield Director
Corporate Communications
781-301-7277, ext. 141