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Tumor-Specific Delivery of Immune Checkpoint Inhibitors by Engineered AAV Vectors
Johanna Reul1,2, Janina Frisch1, Christine E Engeland3
1Molecular Biotechnology and Gene Therapy, Paul-Ehrlich-Institut, Langen, Germany.
Abstract:
Immune checkpoint inhibitors (ICIs) can block distinct receptors on T cells or tumor cells thus preventing T cell inactivation and tumor immune escape. While the clinical response to treatment with ICIs in cancer patients is impressive, this therapy is often associated with a number of immune-related adverse events. There is therefore a need to explore innovative strategies of tumor-specific delivery of ICIs. Delivery of therapeutic proteins on a genetic level can be accomplished with viral vectors including those derived from adeno-associated virus (AAV). Here, we assessed the tumor-targeted Her2-AAV, a receptor-targeted AAV vector binding to the tumor antigen Her2/neu for cell entry, as vehicle for ICI gene delivery. Initially, we packaged the coding sequence of a scFv-Fc fusion protein directed against mouse programmed cell death protein-1 (PD-1) into Her2-AAV. Upon transduction of Her2/neu+ RENCA cells, AAV-encoded αPD-1 was readily detectable in the cell culture supernatant and revealed specific binding to its target antigen. In vivo, in BALB/c mice bearing subcutaneous RENCA-Her2/neu tumors, Her2-AAV mediated specific gene delivery into tumor tissue upon intravenous administration as verified by luciferase gene transfer and in vivo imaging thus demonstrating unimpaired tumor-targeting by Her2-AAV vectors in immunocompetent animals. When delivering the αPD-1 gene, levels of ICI were similar in tumor tissue for Her2-AAV and AAV2 but substantially reduced in liver for Her2-AAV. When combined with chemotherapy a tendency for reduced progression of tumor growth was documented for Her2-AAV treated mice. To get closer to the clinical situation, AAV constructs that deliver the complete coding sequence of the therapeutic antibody nivolumab which is directed against human PD-1 were generated next. The AAV-Nivolumab constructs were expressed and released from transduced MDA-MB-453 cells in vitro and from RENCA-Her2/neu cells upon intratumoral as well as intravenous administration in vivo. Antibody processing and expression levels were further improved through optimization of construct design. In conclusion, we provide proof-of-principle for redirecting the biodistribution of ICIs from liver and serum to tumor tissue by the use of engineered AAV vectors. This strategy can be easily combined with other types of immunotherapeutic concepts.
Insights
Engineered adeno-associated virus (AAV) vectors target immune checkpoint inhibitors (ICIs) to tumors, reducing off-target effects. This novel gene delivery strategy enhances ICI delivery specifically to tumor tissues, improving cancer immunotherapy potential.
Area of Science:
- Oncology
- Gene Therapy
- Immunotherapy
Background:
- Immune checkpoint inhibitors (ICIs) are effective cancer treatments but cause immune-related adverse events due to systemic distribution.
- Targeted delivery of ICIs is crucial to enhance efficacy and minimize side effects.
- Adeno-associated virus (AAV) vectors offer a potential platform for targeted gene delivery.
Purpose of the Study:
- To assess the efficacy of a tumor-targeted Her2-AAV vector for delivering immune checkpoint inhibitor genes.
- To evaluate the tumor-specific gene delivery and biodistribution of Her2-AAV vectors.
- To investigate the potential of Her2-AAV mediated delivery of anti-PD-1 antibodies for cancer treatment.
Main Methods:
- Engineered Her2-AAV vectors were constructed to target the Her2/neu tumor antigen.
- AAV vectors carrying genes for anti-mouse PD-1 (αPD-1) and anti-human PD-1 (nivolumab) were generated.
- In vitro and in vivo studies in mice were conducted to assess gene delivery, protein expression, and tumor targeting.
Main Results:
- Her2-AAV demonstrated specific binding to Her2/neu+ cells and efficient gene delivery to tumors in vivo.
- Her2-AAV mediated ICI delivery resulted in reduced liver accumulation compared to standard AAV2.
- AAV-Nivolumab constructs showed successful expression and release of therapeutic antibodies in vitro and in vivo.
Conclusions:
- Engineered Her2-AAV vectors can effectively redirect immune checkpoint inhibitor delivery from the liver to tumor tissue.
- This targeted gene delivery strategy holds promise for improving the safety and efficacy of cancer immunotherapy.
- The Her2-AAV platform is adaptable for delivering various therapeutic antibodies and can be combined with other treatments.
