Homology Medicines Announces Presentation of Data Supporting Clinical Programs in MPS II and PKU, including Nonclinical and Patient-Focused Research, at American Society of Human Genetics Meeting

- Oral Presentation on In Vivo Gene Therapy Product Candidate and Data on Gene Editing Candidate Paved Way for Initiation of JuMPStart and pheEDIT Trials -  

BEDFORD, Mass., October 20, 2021 – Homology Medicines, Inc. (Nasdaq: FIXX), a genetic medicines company, announced today presentations of nonclinical data and patient and caregiver feedback that support the Company’s clinical programs for mucopolysaccharidosis type II (MPS II), or Hunter syndrome, and phenylketonuria (PKU). During the American Society of Human Genetics (ASHG) 2021 Virtual Meeting, an oral presentation included data from Homology’s IND-enabling studies with HMI-203, a one-time, in vivo investigational gene therapy in development for the treatment of MPS II in the recently initiated Phase 1 juMPStart clinical trial. Patient and caregiver feedback on unmet medical needs in MPS II that informed trial design were also presented. Additionally, Homology shared results from a nonclinical study that demonstrated the precision of its nuclease-free, homologous recombination-based, in vivo gene editing candidate for PKU as the Company starts its first gene editing trial.

“Our presentations at ASHG show the holistic approach we have taken to prepare for our Hunter syndrome gene therapy and PKU gene editing trials, demonstrating our commitment to thoroughly evaluating the product candidates and the needs of the patient community ahead of clinical studies,” stated Albert Seymour, Ph.D., Chief Scientific Officer of Homology Medicines. “Armed with patient and caregiver feedback on the unmet medical needs that persist, we recently initiated our juMPStart trial to evaluate a single-dose of HMI-203 in adults with Hunter syndrome. Additionally, integration assays from our in vivo PKU gene editing program demonstrated no evidence of off-target integration in human hepatocytes in a xenograft murine model and support our Phase 1 trial.”

In the oral presentation titled, “Long-Term Systemic Expression and Cross-Correction Ability of HMI-203: Investigational Gene Therapy Candidate for Mucopolysaccharidosis Type II or Hunter Syndrome,” data showed that a single I.V. dose of HMI-203 in the MPS II murine model resulted in the following, through 52 weeks (end of study): 

  • Systemic expression of vector genomes, transcripts and functional I2S enzyme;
  • Secretion of active I2S into circulation demonstrating cross-correction;
  • Systemic reduction of disease-relevant biomarkers, including positive and significant correlation between cerebral glycosaminoglycan heparin sulfate (GAG-HS) and LAMP1 levels as well as cerebrospinal fluid (CSF) and cerebral GAG-HS levels; and
  • Prevention of progression of craniofacial and hindlimb deformities. 

Also related to HMI-203, “Patient-Focused Drug Development for a Single Intravenous Dose of HMI-203 Gene Therapy in Adult Mucopolysaccharidosis (MPS) II, or Hunter Syndrome, Patients” included qualitative data on unmet medical needs from enzyme replacement therapy (ERT)-treated adult MPS II patients and/or their caregivers. They reported: 

  • Weekly ERT infusions, surgeries and supportive therapies inadequately address range of motion and mobility, pain, and hearing loss;
  • Burdens associated with ERT and other therapies, including frequency and duration of treatment, and painful and extended recoveries; 
  • High degree of anxiety regarding prognosis, longevity, need for more invasive surgeries, and financial challenges; and
  • Expectations for a potential one-time gene therapy include ability to maintain current quality of life with ERT independence. 

To support HMI-103, its gene editing candidate for PKU, Homology also presented, “Genome-Wide Integration Assay For rAAV Mediated Homologous Recombination (HR) in Human Hepatocytes Demonstrated Precision of In Vivo Gene Editing Approach.” Using quantitative molecular methods, including long-read sequencing, in a murine liver model populated with human hepatocytes, a single I.V. dose of HMI-103 demonstrated on-target integration into the desired locus and no evidence of integration into any other genomic location.

For more information, please visit www.homologymedicines.com/publications.

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 lead clinical program, HMI-102, is an investigational gene therapy for adults with phenylketonuria (PKU) and additional programs focus on lysosomal storage disorders including Hunter syndrome, paroxysmal nocturnal hemoglobinuria (PNH) and other diseases. Homology’s proprietary platform is designed to utilize its family of 15 human hematopoietic stem cell-derived adeno-associated virus vectors (AAVHSCs) to precisely and efficiently deliver genetic medicines in vivo through a gene therapy or nuclease-free gene editing modality, as well as to deliver one-time gene therapy to produce antibodies throughout the body through the GTx-mAb 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, internal manufacturing capabilities 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. 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 beliefs regarding our manufacturing capabilities; our position as a leader in the development of genetic medicines; and our participation in upcoming presentations and conferences. 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 impact of the COVID-19 pandemic on our business and operations, including our preclinical studies and clinical trials, and on general economic conditions; 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 capabilities of our manufacturing facility; 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; 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 and significant costs as a result of operating as a public company. These and other important factors discussed under the caption “Risk Factors” in our Quarterly Report on Form 10-Q for the quarter ended June 30, 2021 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.

Company Contacts
Theresa McNeely
Chief Communications Officer
and Patient Advocate

Media Contact:
Cara Mayfield
Vice President, Patient Advocacy
and Corporate Communications