Co-administration of AAV Vectors with SVP-Rapamycin Enables Vector Re-administration in Pre-clinical Gene Therapy Study Published in Nature Communications by Généthon and Selecta Biosciences

Généthon, a non-profit R&D organization founded by the AFM-Téléthon, and Selecta Biosciences, Inc. (Nasdaq:SELB), a clinical-stage biopharmaceutical company, today announced that Nature Communications has published their jointly authored paper entitled “Antigen-selective modulation of AAV immunogenicity with tolerogenic rapamycin nanoparticles enables successful vector re-administration”.

EVRY, France and WATERTOWN, Mass., OCTOBER 5, 2018 — Généthon, a non-profit R&D organization founded by the AFM-Téléthon, and Selecta Biosciences, Inc. (Nasdaq:SELB), a clinical-stage biopharmaceutical company, today announced that Nature Communications has published their jointly authored paper entitled “Antigen-selective modulation of AAV immunogenicity with tolerogenic rapamycin nanoparticles enables successful vector re-administration”.

The pre-clinical study led by Genethon demonstrated that co-administration of synthetic vaccine particles encapsulating rapamycin (“SVP-R”) with adeno-associated virus (“AAV”) gene therapy vectors induced safe and effective mitigation of immune responses against the capsid in an antigen-selective manner. This resulted in safe and efficient vector re-administration in both small and large animal models of hepatic gene transfer.
Immunogenicity of AAV viral vectors has been a major roadblock to vector re-administration which may be required to ensure the durability of gene therapy, particularly for systemic and pediatric applications. For many inherited metabolic and degenerative diseases, early morbidity and mortality requires treatment early in life prior to the onset of irreversible tissue damage. However, expression of the therapeutic transgene is expected to wane over time as pediatric patients grow. Maintaining the ability to re-administer viral vectors such as AAV may therefore be essential to achieve sustained therapeutic efficacy over time.

“Despite exciting therapeutic results achieved to date with AAV-mediated gene therapy, development of antibodies against the vector, hampering efficient re-administration, represents potential obstacles for long-term efficacy of the treatments.” said Frédéric Revah, Ph.D., CEO of Généthon. “Safe and effective strategies that reduce AAV vector immunogenicity and allow for stable transgene expression and re-dosing are urgently needed to allow continued advancement of the field. Co-administration of AAV vectors and SVP-R represents a potentially powerful strategy to address this long-standing challenge by modulating vector immunogenicity and enabling vector re-administration in mice and non-human primates, as was shown in the published study.”

“The potential to re-administer AAV for retreatment and sustained therapeutic efficacy over time is especially important in pediatric patients,” said Werner Cautreels, Ph.D., CEO of Selecta Biosciences. “In addition, the ability to re-dose may increase the proportion of patients able to achieve therapeutic levels of the transgene expression, while avoiding potential toxicities associated with large vector doses. This approach may create new opportunities for AAV vector-mediated gene transfer for diseases requiring systemic transduction or treatment in childhood.”

About Selecta Biosciences, Inc.
Selecta Biosciences, Inc. is a clinical-stage biopharmaceutical company that is focused on unlocking the full potential of biologic therapies by mitigating unwanted immune responses. Selecta plans to combine its tolerogenic Synthetic Vaccine Particles (SVP™) to a range of biologics for rare and serious diseases that require new treatment options. The company’s current proprietary pipeline includes SVP-enabled enzyme, oncology and gene therapies. SEL-212, the company’s lead candidate in Phase 2, is being developed to treat severe gout patients and resolve their debilitating symptoms, including flares and gouty arthritis. A Phase 1 trial is ongoing for a combination therapy consisting of SVP-Rapamycin and LMB-100 (Selecta’s SEL-403 product candidate) for the treatment of patients with malignant pleural or peritoneal mesothelioma. Selecta’s proprietary gene therapy product candidates are being developed for rare inborn errors of metabolism and have the potential to enable repeat administration. The use of SVP also holds potential in the development of vaccines and treatments for allergies and autoimmune diseases. Selecta is based in Watertown, Massachusetts. For more information, please visit http://selectabio.com and follow @SelectaBio on Twitter.