Adoptive T-cell therapy with TILs, CAR-T cells, and TCR-engineered T-cells is achieving remarkable clinical efficacy. Retroviral gene transfer of IL-12 into the T cell cultures markedly enhances efficacy but has shown unacceptable severe side effects in the clinic. To ensure transient gene transfer, tumor specific CD8 T cells were engineered by electroporation of mRNA encoding single chain IL-12 into OT1 and Pmel-1 TCR transgenic lymphocytes. Engineered T cells were injected intratumorally and achieved complete rejections not only of the injected lesion but also of distant concomitant tumors. Efficacy was further enhanced if a small dose of agonist anti-CD137 mAb was co-injected or if CD137-ligand mRNA was co-electroporated. Importantly, intratumor T-cell administration was more efficacious that the intravenous or subcutaneous routes. Therapeutic effects were dependent on IFNγ, cDC1 dendritic cells and endogenous T cells. Interestingly, treatment induced epitope spreading of the immune response to antigens not recognized by the adoptively transferred lymphocytes. Efficacy was also achieved when mouse TILs cultures were used and human TIL cultures can also be transiently IL-12 mRNA engineered. Intratumor release, transient IL-12 mRNA-engineering and repeated administration jointly constitute a safe, feasible and powerful cancer immunotherapy strategy. Note: This abstract was not presented at the meeting. Citation Format: Inaki Etxeberria, Elixabet Bolaños, Alvaro Teijeira, Arantza Azpilicueta, Jose Ignacio Quetglas, Alfonso Rodriguez Sanchez-Paulete, Itziar Otano, Uxua Mancheño, Sandra Hervas-Stubbs, Susana Inoges, Saray Garasa, Maite Alvarez, Pedro Berraondo, Ignacio Melero. Intratumor adoptive transfer of IL-12 mRNA transiently engineered anti-tumor CD8+ T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2331.

In cancer pathogenesis, soluble mediators are responsible for a type of inflammation that favors the progression of tumors. The mechanisms chiefly involve changes in the cellular composition of the tumor tissue stroma and in the functional modulation of myeloid and lymphoid leukocytes. Active immunosuppression, pro-angiogenesis, changes in leukocyte traffic, extracellular-matrix remodeling and alterations in tumor-antigen presentation are the main mechanisms linked to the inflammation that fosters tumor growth and metastasis. Soluble inflammatory mediators and their receptors are amenable to various types of inhibitors that can be combined with other immunotherapy approaches. The main pro-inflammatory targets which can be interfered with at present and which are under preclinical and clinical development are IL-1b, IL-6, the CXCR1/2 chemokine axis, TNFa, VEGF, LIF, CCL2, IL-35 and prostaglandins. In many instances, the corresponding neutralizing agents are already clinically available and can be repurposed as a result of their use in other areas of medicine such as autoimmune diseases and chronic inflammatory conditions.

CD137 (4-1BB, TNFSFR9) costimulation provides antigen-primed T cells with increased survival, proliferation and effector functions as well as metabolic advantages. These immunobiological mechanisms are being harnessed for cancer immunotherapy with agonist CD137-binding and crosslinking-inducing agents that elicit CD137 intracellular signaling. In this study, side-by-side comparisons show that provision of CD137 costimulation in-cis with regard to the TCR-CD3-ligating cells is far superior to that provided in-trans in terms of T-cell activation, proliferation, survival, cytokine secretion and mitochondrial fitness in mice and humans. Cis ligation of CD137 relative to the TCR-CD3 complex results in more intense canonical and non-canonical NF-κB signaling and provides a more robust induction of cell-cycle and DNA damage repair gene expression programs. Superiority of cis versus trans CD137-costimulation is readily observed in vivo and is relevant for understanding the immunotherapeutic effects of CAR T cells and CD137 agonistic therapies currently undergoing clinical trials, which provide costimulation either in cis or in trans. Citation Format: Itziar Otano, Arantza Azpilikueta, Javier Glez-Vaz, Peter Ellmark, Sara Fritzell, Gabriela Fernandez-Hoyos, Michelle Hase Nelson, Maite Alvarez, María del Carmen Ochoa, Elixabet Bolaños, Doina Cuculescu, Patricia Jauregui, Sandra Sanchez, Iñaki Etxeberría, María E. Rodriguez-Ruiz, Miguel F. Sanmamed, Alvaro Teijeira, Pedro Berraondo, Igancio Melero. CD137 (4-1BB) costimulation of CD8 T cells is more potent when provided in cis than in trans with respect to CD3-TCR stimulation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1691.