Abstract
The efficacy of T cell-activating therapies against glioma is limited by an immunosuppressive tumor microenvironment and tumor-induced T cell sequestration. We investigated whether peripherally infused non-antigen specific autologous lymphocytes (ALT) could accumulate in intracranial tumors. We observed that non-specific autologous CD8+ ALT cells can indeed accumulate in this context, despite endogenous T cell sequestration in bone marrow. Rates of intratumoral accumulation were significantly increased when expanding lymphocytes with IL-7 compared to IL-2. Pre-treatment with IL-7 ALT also enhanced the efficacy of multiple tumor-specific and non-tumor-specific T cell-dependent immunotherapies against orthotopic murine and human xenograft gliomas. Mechanistically, we detected increased VLA-4 on mouse and human CD8+ T cells following IL-7 expansion, with increased transcription of genes associated with migratory integrin expression (CD9). We also observed that IL-7 increases S1PR1 transcription in human CD8+ T cells, which we have shown to be protective against tumor-induced T cell sequestration. These observations demonstrate that expansion with IL-7 enhances the capacity of ALT to accumulate within intracranial tumors, and that pre-treatment with IL-7 ALT can boost the efficacy of subsequent T cell-activating therapies against glioma. Our findings will inform the development of future clinical trials where ALT pre-treatment can be combined with T cell-activating therapies.
Competing Interest Statement
1. KS reports grants paid to his institution and research contracts from Adaptin Bio, which has licensed intellectual property from Duke related to the use of Brain Bi-specific T cell Engagers (BRiTE) and combination autologous lymphocyte therapy. 2. KMH reports no relevant disclosures. 3. SLC reports grants paid to her institution from Immorna Therapeutics, Immvira Therapeutics. 4. PN reports no relevant disclosures. 5. YZ reports no relevant disclosures. 6. EMM reports no relevant disclosures. 7. COR reports no relevant disclosures. 8. EEB reports no relevant disclosures. 9. BP reports no relevant disclosures. 10. SW reports no relevant disclosures. 11. PKN reports no relevant disclosures. 12. GEA reports no relevant disclosures. 13. BS reports no relevant disclosures. 14. KA reports no relevant disclosures. 15. JHS reports an equity interest in Istari Oncology, which has licensed intellectual property from Duke related to the use of poliovirus and D2C7 in the treatment of glioblastoma. JHS is an inventor on patents related to BRiTE, PEP-CMV DC vaccine with tetanus, as well as poliovirus vaccine and D2C7 in the treatment of glioblastoma. 16. MK reports grants paid to his institution, or contracts from BMS, AbbVie, BioNTech, CNS Pharmaceuticals, Daiichi Sankyo Inc., Immorna Therapeutics, Immvira Therapeutics, JAX lab for genomic research, and Personalis Inc. MK also received consulting fees from AnHeart Therapeutics, George Clinical, Manarini Stemline, and Servier and is on a data safety monitoring board for BPG Bio. 17. PEF reports funding from a Cancer Research Institute (CRI) Arash Ferdowsi Lloyd J.Old STAR Award.
Footnotes
This revised manuscript contains several new experiments, including toxicity studies of combination ALT/mAb therapy, assessment of endothelial/pericyte VCAM-1 levels, functional assays comparing IL-7-ALT and IL-2-ALT and bulkRNA sequencing of CD8+ T cells expanded from glioblastoma donors. Important new findings we highlight are that combination therapy does not appear to induce systemic toxicity or result in deranged liver function, though minor histological changes are seen. IL-7 expanded CD8+ cells appear to demonstrate similar functionality to IL-2 expanded CD8+ cells in vitro, while possessing enhanced expression of the migratory integrin VLA-4. We also observe that endothelial/pericyte levels of VCAM-1 increase in the presence of glioma, a finding which has not been seen in another intracranial models of malignancy. Finally, we mechanistically determine that IL-7 upregulates multiple genes involved in enhanced migratory integrin expression, as well as S1PR1, which we have previously identified as protective against glioma-induced sequestration. These findings will help to inform cellular manufacturing processes, guiding future approaches to select for highly infiltrative (VLA-4Hi) CD8+ populations that are resistant to sequestration and can thus accumulate in intracranial tumors.
