Strategy to detect pre-existing immunity to AAV gene therapy

Area of Science:

• Biotechnology
• Immunology
• Gene Therapy

Background:

• Gene therapy using adeno-associated virus (AAV) vectors is a potential treatment for severe hemophilia.
• Pre-existing immunity, specifically antibodies against AAVs, can limit the efficacy of these gene therapies.
• Understanding the prevalence and nature of AAV immunity is crucial for successful clinical application.

Purpose of the Study:

• To validate sensitive and scalable in vitro assays for detecting AAV5 total antibodies and transduction inhibition (TI).
• To investigate the prevalence of pre-existing AAV5 immunity, including non-antibody-based neutralizing factors, in healthy individuals and hemophilia A patients.
• To develop a dual-assay strategy for identifying suitable candidates for AAV5-directed gene therapy.

Main Methods:

• Validated two complementary in vitro assays to measure AAV5 total antibodies and TI.
• Assessed 100 healthy male individuals and 24 individuals with hemophilia A using the developed assays.
• Analyzed results to categorize individuals based on antibody presence and neutralizing activity.

Main Results:

• 53% of healthy individuals were negative for both AAV5 antibodies and TI.
• 18% were positive for both, 5% for antibodies only, and 24% for TI only, suggesting non-antibody neutralization.
• Similar patterns of AAV5 immunity were observed in hemophilia A patients.

Conclusions:

• A dual-assay strategy can effectively identify individuals lacking AAV5 antibodies and neutralizing factors.
• These assays provide a transferable platform for assessing global AAV5 immunity in patient populations.
• This approach can inform clinical development strategies for AAV5-based gene therapies.