Abtl0812, A Phase 2 Clinical Stage Pro-Autophagy Anticancer Drug Exhibits Immunomodulatory Effects That Modify Tumor Microenvironment In Pancreatic Cancer Models.

Abstract ABTL0812 induces cytotoxic autophagy in cancer cells through the combination of ER stress induction and Akt/mTOR blockade. ABTL0812 induces ER stress mediated activation of JNK-Jun pathway and inhibition of the STAT3-IL10 axis in cancer and immune cells in vitro and induces ER stress markers TRIB3 and CHOP in white blood cells of patients with no toxic effects and showing clinical efficacy in Phase 2 trial in combination with chemotherapy vs chemotherapy alone (historical data). In primary and immortalized monocytes-derived macrophages in vitro, ABTL0812 promoted M1 phenotypes potentiating IL-1β and TNFα expression and suppressed M2 phenotypes by decreasing IL-10 expression, as detected by RT-qPCR. Additionally, ABTL0812 inhibited the release of immunosuppressive chemokines (CXCL5, CCL5, CCL8) detected by protein array. In human primary T cells cultured in vitro, ABTL0812 decreased PD1 surface expression in non-activated and activated CD4 and CD8 cells detected by flow cytometry. In pancreatic cancer cells in vitro, ABTL0812 inhibited the release of immunosuppressive chemokines (CCL5, CXCL6, CXCL16), as detected by a protein array. ABTL0812 induced Immunogenic Cell Death (ICD) as indicated by a dose-dependent increase of ICD markers: extracellular Hmgb1 and ATP, surface calreticulin, and caspases 3 and 8 activation, as detected by ELISA, luciferase assay, flow cytometry and fluorescence based substrate assays, respectively. Cultured media from ABTL0812 treated pancreatic cancer cells transferred to differentiated macrophages potentiated the activation of immortalized THP1 macrophages (increased metabolic activity) and promoted M1 polarization potentiating IL-1β and TNFα expression measured by RT-qPCR. In a syngeneic murine model using MT5 murine pancreatic cancer cells (K-Ras and p53 mutated), ABTL0812 showed significant tumor volume reduction compared to vehicle treatment, and similar efficacy to anti-PD1 treatment. Flow cytometry analysis of tumors revealed that ABTL0812 increased intratumor myeloid and Natural Killer T-cells more efficiently than anti-PD1. Importantly, ABTL0812 also increased T helpers Th1/Th2 ratio in spleen. ABTL0812 shows immunomodulatory effects in vitro and in vivo in pancreatic cancer models through the inhibition of the secretion of immunosuppressive chemokines and the induction of ICD in cancer cells, while potentiates M1 phenotypes in macrophages and inhibits PD1 expression in T cells, ultimately promoting increased myeloid and NK cells within tumors and increased Th1/Th2 ratio. Overall, these multiple actions could potentially help to transform “cold” non-immunogenic tumors into “hot” immunogenic tumors and contribute to elicit anticancer immunosurveillance. These novel findings support further investigation of ABTL0812 in combination with immunotherapy to treat cancer Citation Format: Guillermo Yoldi, Pau Munoz-Guardiola, Elisabet Megias, Hector Perez-Montoyo, Marc Yeste-Velasco, Jose Alfon, Carles Domenech, Jose Miguel Lizcano. ABTL0812, a Phase 2 clinical stage pro-autophagy anticancer drug exhibits immunomodulatory effects that modify tumor microenvironment in pancreatic cancer models [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 1805.