Abstract B035: Enhancing antitumoral activity of cell-based immunotherapies by modulating the JAK-STAT axis
Authors: Perez-Quintero Luis Alberto , Pike Kelly Anne , Claudia Penafuerte , Tremblay Michel 
Published: February 2019

Mounting a T helper 1 (Th1) type of response is required for the successful priming of antigen specific CD8 T-cells which ultimately lead to effective antitumoral responses. Several cellular components of the immune system participate of the Th1 decision-making process. They include innate cells sensing the transformed cells, mainly dendritic cells (DCs), and the further involvement of antigen specific CD4 T-cells promoting direct activation of CD8 T-cells through cross-presentation (1). The correct stimulation of DCs by type I interferons and molecular pattern sensors as STING is required to drive their differentiation to conventional DC 1 (cDC1) which through the secretion of large amounts of IL-12 and the expression of CD40 skew the CD4 T-cells differentiation to Th1 (2). However, this system is sensitive to modifications of the tumor cytokine microenvironmen,t leading to failure. Adoptive cell transfer (ACT) cancer immunotherapies are promising treatments for advanced malignancies. These therapies attempt to supply key cellular actors missing and induce proper antitumoral immunity. They include mainly the in vitro modification of autologous cells, from DCs loaded with tumor antigens to the expression of chimeric antigen receptor (CAR) on T and NK cells. Constant development of these technologies has given successful results as clinical trials have already showed up to 90 % of complete remission in relapsed/refractory B cell acute lymphoid leukemia (B-ALL) (3), treatment now approved for commercial use. However, there is still lack of consistency in the responses obtained from different individuals and in different trials. Previously our laboratory has already shown that modulation of the JAK-STAT inhibitory protein tyrosine phosphatases (PTPs), PTPN1 and PTP-N2, enhance proinflammatory type I interferon signalling while decreases the effects of immunosuppressive cytokines acting through STAT3 signaling (4, 5). Specifically, we have demonstrated that partial inhibition of these phosphatases in immune cells enhances the secretion of IL-12p70 by DCs[6] and increases the cytotoxic activity of antigen specific CD8 T-cells [Pérez-Quintero LA, Tremblay ML, unpublished results]. Moreover, the partial inhibition of these phosphatases in CD8 T-cells enhance the acquisition of a central memory (Tcm) phenotype, which has been found to be associated with better remission in CAR-T-cells therapies. Nevertheless, alternative methods to enrich this phenotype, as cytokine cocktails, have proven expensive and ineffective. Having this in mind, we propose here the use of small-molecule inhibitors specific for PTPN1 and PTPN2 as a simple and cost-effective method to enhance antitumoral responses. By treating ex vivo the cellular products in animal models for DCs and CD8 ACT therapies we show, as a proof of concept, a marked improvement on the reduction of tumor burden and remission, with the late goal of translating these findings into a clinical setup. References: 1. Gajewski TF, Schreiber H, Fu YX. Innate and adaptive immune cells in the tumor microenvironment. Nature Immunology 2013;14:1014. 2. Theisen D,Murphy K. The role of cDC1s in vivo: CD8 T-cell priming through cross-presentation [version 1]. 2017;6. 3. Oluwole OO,Davila ML. At The Bedside: Clinical review of chimeric antigen receptor (CAR) T-cell therapy for B cell malignancies. Journal of Leukocyte Biology 2016. 4. Pike KA, et al. Protein tyrosine phosphatase 1B is a regulator of the interleukin-10–induced transcriptional program in macrophages. Science Signaling 2014;7(324): ra43-ra43. 5. Pike KA, et al. TC-PTP regulates the IL-7 transcriptional response during murine early T-cell development. Scientific Reports 2017;7(1):13275. 6. Penafuerte C, et al. Downregulation of PTP1B and TC-PTP phosphatases potentiate dendritic cell-based immunotherapy through IL-12/IFNγ signaling. OncoImmunology 2017;6(6):e1321185.

Citation Format: Luis Alberto Perez-Quintero, Kelly Anne Pike, Penafuerte Claudia, Michel Tremblay. Enhancing antitumoral activity of cell-based immunotherapies by modulating the JAK-STAT axis [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr B035.