The onset of cancer progression is largely mediated by a dysfunctional adaptive immune system which fails to actively eradicate tumor cells. Adding to the demand for viable long-term curative options for advanced or metastatic cancers, immunotherapeutic strategies have been developed with the intent of efficiently restoring antitumor immunity. An approach to achieve the latter consists in the generation and expansion of tumor-specific T-cells for adoptive infusion in cancer patients, in a process defined as adoptive T-cell therapy (ACT). Clinical application of ACT has provided effective and durable antitumor responses in some advanced or metastatic cancers, however employment of toxic pre- and postconditioning in ACT treatment regimens does not render this therapeutic modality accessible to all cancer patients. The applicability of ACT is further narrowed considering that its efficacy is tightly linked to a niche of tumor types which feature high immunogenicity and low immunosuppressive capabilities. Given the safety and immunological effects of oncolytic adenovirus therapy, we hypothesized that oncolytic adenoviruses coding for tumor necrosis factor alpha (TNFα) and interleukin-2 (IL-2) (Ad5/3-E2F-D24-TNFα-IRES-IL2) could supply, additional proinflammatory stimulus for improved safety and, efficacy of ACT in immunosuppressive tumors. For in vivo validation of this concept, Syrian hamsters were used, considering that human adenovirus replication is possible, human TNFα and IL-2 are bioactive and, tumor-infiltrating lymphocyte (TIL) therapy can be performed. Studies in mice with cytokine-coding replication-incompetent adenoviruses allowed, detailed immunological characterization after virus therapy and the use of T-cell receptor (TCR)-engineered ACT. Ex vivo studies in ovarian cancer clinical samples allowed the study of Ad5/3-E2F-D24-hTNFα-IRES-hIL2 in an immunosuppressive microenvironment in the context of TIL therapy. Local therapy with Ad5/3-E2F-D24-hTNFα-IRES-hIL2 induced systemic virus spread, increased TIL trafficking and NK cells and, decreased M2 macrophages in local and distant tumors. Cytokine-coding adenovirus treatment negatively impacted tumor growth with the increased expression levels of chemokines and other immunologically important genes. Replacement of a lymphodepleting regimen with TNFα and IL-2 coding adenoviruses allowed comparable antitumor efficacy and survival of animals receiving ACT. Adenovirus therapy and lymphodepleting preconditioning promoted similar CD8+ T cell infiltration and dendritic cell maturation profiles, but with the adenovirus promoting higher proinflammatory status. The use of IL-2-coding adenovirus therapy instead of high-dose IL-2 postconditioning allowed the best tumor growth control in animals receiving ACT. Such results, were accompanied by the intratumoral accumulation of CD8+ T-cells, M1-like macrophages and decreased levels Tregs, a phenomenon not seen in control groups or animals receiving high-dose IL-2 postconditioning. Importantly, the confinement of adenovirus-derived cytokine production to the tumor site enables negligible systemic toxicity as opposed to the toxicity caused in vital organs and blood from animals receiving pre and post-conditioning regimens. Furthermore, Ad5/3-E2F-D24-hTNFα-IRES-hIL2 therapy caused significant changes in the immunosuppressive ovarian tumor microenvironment, including CD8+ and CD4+ activation and increased shedding of IL-2, TNFα, IFN-γ and CXCL10. Such favorable effects reflected on the increased IFN-γ tumor-reactivity of autologous TILs transferred into virus-infected ex vivo tumor cultures, a phenomenon not associated with PD-L1 expression. In conclusion, TNFα and IL-2 coding oncolytic adenoviruses appear to be a potent immunotherapeutic which can amplify the local and systemic effects of ACT in immunosuppressive tumors while lowering the toxicity of ACT.
|Place of Publication||Helsinki|
|Publication status||Published - 2020|
|MoE publication type||G5 Doctoral dissertation (article)|
Bibliographical noteM1 - 115 s. + liitteet
Fields of Science
- 3122 Cancers
- 3111 Biomedicine