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A - Viral Vector Development -> AAV Vectors – Preclinical and Proof-of-Concept In vivo Studies (excluding Non-Human Primates)

60: AAV Immuno-Gene Therapy Delivers Vectorized Cytokines to Effectively Treat High-Grade Gliomas

Type: Oral Abstract Session

Presentation Details
Session Title: AAV Vectors - Preclinical and Proof-of-Concept In Vivo Studies I
Location: Room 408 AB
Start Time: 5/17/2023 15:45
End Time: 5/17/2023 16:00

High grade gliomas (HGG) are highly refractory to treatment. Innate interferons (IFN) are pleiotropic immunomodulatory cytokines central to the body’s basal cancer immunosurveillance and many therapy-induced immunogenic anti-tumor responses. IFNs drive many anti-tumor functions including being anti-angiogenic, increasing tumor MHC-I expression, stimulating apoptosis, enabling DCs to mature and cross prime T cells against tumor antigens, and increasing the proliferation of activated macrophages and NK cells. Delivering gene therapies to the brain with AAV has proven to be safe and effective. However, common delivery routes (intrathecal, intracerebroventricular and intracisternal) are broadly dispersive and non-targeted. Direct intratumoral delivery limits off-target transduction and reduces neurotoxicity risks. Brain cancer patients often undergo surgical resection or biopsy, providing an opportunity to concomitantly infuse AAV directly using Convection-Enhanced Delivery (CED). This precise and highly targeted method allows for significantly reduced vector doses and improved safety. Here we evaluated safety and efficacy of an immuno-gene therapy utilizing AAV9 vectors to express engineered immunomodulatory payloads (IFNɑ1, IFNβ, IFNƔ, and combinations thereof). We first assessed tumorigenesis and intrinsic therapeutic responses to our suite of vectorized IFNs in primary human HGG organoids. PBS, DMSO and AAV-GFP had no effect on tumor or healthy cerebral cells in the organoids, and HGG tumor cells grew uncontrolled. Temozolomide chemotherapy (the current standard of care) significantly decimated healthy cerebral cells and only slightly delayed HGG tumor growth. In contrast, our AAV immuno-gene therapies with 12 different engineered cytokine payloads, rapidly and selectively reduced tumor size. We next tested our payloads in vivo in 3 orthotopic HGG mouse models delivered intratumorally via CED. Our AAVs effectively blocked tumor growth, resulting in tumor regression and significantly prolonged survival in human GBM6 xenografts (P<0.02-0.001 and 31-60% complete responses (CR)), mouse GL261 allografts (P<0.0009), and human patient-derived xenografts (P<0.04; 30% CR); (n = 450). Evaluation of tumor-bearing mouse brains demonstrated marked tumor changes following treatment. Within 48hrs following treatment, local intratumoral expression of our engineered IFNs led to widespread tumor cell apoptosis, activated microglia, and reactive astrogliosis. Remarkably, by day 7, there was reproducible tumor eradication, no evidence of residual proliferating cells, no engineered cytokine payload expression, and only residual reactive astrogliosis and microglial responses. This was seen at both the protein level by immunohistochemistry, and at the transcript level by RNAscope. To further probe transcriptomic responses, we performed single cell sequencing on syngeneic mouse brain tumors following treatment and demonstrated that tumor cells specifically exhibited a significant upregulation of genes linked to IFN responses (Ifit1, Ifit2, Ifitm3), as well as other immune response genes (Isg15, Bst2, Trim30a) and were specific to IFN payload expression, not AAV. These transformative results introduce universal AAV immuno-gene therapies as a promising new drug class that we’re advancing to the clinic to treat solid tumors.

Nathalie Clement1, Sarah Morris1, Akela Kuwahara1, Emily Casey1, Kyounghee Seo2, Raquel Santos2, Miko Fogarty2, Syuan-Ming Guo3, Shalin Mehta3, Yael Rossenberg-Hasson4, Jennifer Clarke5, Aaron Diaz5, Joanna Phillips6, Tomoko Ozawa2, David Raleigh7, Nicole K. Paulk1,8

1Siren Biotechnology, San Francisco, CA,2Neurological Surgery, UCSF, San Francisco, CA,3CZ Biohub, San Francisco, CA,4Institute for Immunity, Transplantation & Infection, Stanford, Stanford, CA,5Clinical Neurology, UCSF, San Francisco, CA,6Pathology, UCSF, San Francisco, CA,7Radiation Oncology, UCSF, San Francisco, CA,8Neurologic Oncology, UCSF, San Francisco, CA
  N.K. Paulk: 1; Commercial Interest i.e. Company X; Siren Biotechnology. 1; What was received? i.e. Honorarium; Salary, Ownership interest, Intellectual property rights. 1; For what role? i.e. Speaker; Employment.

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