PD-L1 expression is strongly associated with TIGIT, FOXP3 and LAG3 across advanced cancers, but not OX40, TIM3 and IDO

Abstract

Background: Immune checkpoint inhibitors (ICI) induce durable tumor responses and increased overall survival (OS) of cancer patients. Patients with low PD-L1, low tumor mutational burden (TMB) or without intra-tumoral CD8þ T cells, have a poor response rate to ICIs. Pegilodecakin (AM0010) is a pegylated recombinant human interleukin-10, which overcomes tumor immune escape by stimulating the activation, survival and clonal expansion of intra-tumoral, tumor antigen specific CD8þ T cells. Pegilodecakin up-regulates IFNc in CD8þ T cells and MHC expression, which facilitates antigen presentation even in tumors with low CD8þ T cells and low TMB. Here we explore the combination of Pegilodecakin with SOC docetaxel in an ICI resistant mouse triple negative breast cancer model. Methods: 4T1 cells were established SC for two weeks prior to treatment. Pegilodecakin was administered at suboptimal doses, docetaxel was dosed at the MTD. Quantitation of T cell infiltration and tumor cell death was quantified by IHC. Intra-tumoral and sys-temic cytokine and T cell activity were evaluated. Results: Docetaxel did not induce regressions but inhibited tumor growth by 65%. Pegilodecakin alone induced tumor growth inhibition and delayed tumor regression in 75% of mice with an 80% reduction of tumor size after 4 weeks of treatment. Pegilodecakin þ docetaxel lead to a synergistic tumor control and complete responses in 75% of mice. While pegilodecakin induced T cell infiltration and tumor cell apopto-sis with 95% of the measurable tumor being reduced to scar tissue, the tumor size initially continued to increase, indicative of pseudo-progression. In contrast, Pegilodecakin / docetaxel therapy led to a complete eradication of the tumor without pseudoprogression. Conclusions: The determination of clinical efficacy of immune therapy can be difficult due to delayed immune responses and pseudoprogression related to immune effector cell infiltration. Here we show that largely necrotic tumors on pegilodecakin may have a delayed clearance despite overwhelming anti-tumor efficacy. The combination of immunotherapy with chemotherapy may facilitate clearance of the necrotic tumor mass leading to complete responses of measurable tumor burden. Legal entity responsible for the study: ARMO BioSciences. Funding: ARMO BioSciences. Disclosure: N. Ratti, N. Shifrin, S. McCauley, R. Verma, P. Van Vlasselaer, M. Oft, J. Leveque: Employee: ARMO BioSciences. 1181P Mutations in interferon gamma and antigen presentation pathways are frequent in hiper/ultra-mutated (HiMut) tumors and could be result of immune-editing processes in HiMut tumors Background: Tumors with a phenotype associated with a high mutational load such as POLE-mutated or those showing microsatellite instability (MSI) are more likely to have clinical responses to immune-checkpoints blockade therapy. Indeed, several clinical trials are currently ongoing targeting PD-1 in a variety of cancer types. However, some of these patients do not respond to immunotherapy. Recently, mutations in JAK1 and JAK2 has been reported to be responsible for this resistance. Methods: Here we explore the effect of functional mutations in genes in the interferon gamma (IFG) signaling and antigen presentation (AP) pathway in endometrial, color-ectal, and gastric POLE-mutated and MSI tumors extracted from TCGA. Results: As a result, we have found that POLE-MSI tumors accumulated more mutations in IFG and AP pathways than randomly expected. Using gene expression data, we corroborate that IFN pathway is under-expressed in IGF/AP mutant tumors. MSI IGF/ AP mutant tumors over-express T cell receptor pathway probably as a compensatory mechanism. Moreover, when cell infiltration was assessed, these tumors have a tendency to present higher levels of cytotoxic lymphocytes than non-mutated tumors. However, they showed over-expression of pathways related to anti-PD1 resistance such as epithelial to mesenchymal transition or angiogenesis. These results suggest that despite being infiltrated, IGF/AP mutant tumors are able to evade immune surveillance. Regarding survival, although overall these tumors have a very good prognosis, we observed that IGF/AP mutated endometrial tumors showed higher clinical grade than the non-mutated ones. Conclusions: Based on these results, we show that regardless of cancer type, HiMut tumors with functional mutations in IFG and AP pathways shows a more aggressive phenotype, and present activation of cellular processes that have been related to immune-resistance, probably to evade destruction by a very active T-cell stroma due to the high amount of neoantigens. This phenotype is even more evident in ultra-mutated POLE tumors. Therefore, HiMut tumors could be exploited as a surrogate to understand mechanisms of immune-resistance. Background: While anti-CTLA4 immunotherapy (IT) improves survival in metastatic melanoma patients, it manifests with severe toxicity. Recently, we identified serum antibody signatures associated with toxicity outcomes following anti-CTLA4 IT. In this study, capitalizing on our recent data showing that the expression of autoimmunity risk genes is controlled by germline genetic variation in melanoma survival, we tested whether antibody profiles linked with IT-related toxicity are impacted by underlying genetic variation. Methods: We have integrated serum data from 37 anti-CTLA4 IT-treated patients, profiled by HuProt human proteome array with germline whole-exome sequencing (WXS), comparing 28 patients with none/mild toxicity (CTCAE score 0-2) and 9 patients with severe toxicity (CTCAE score 3-5). The associations between toxicity and germline genetic variation were assessed by gene-burden analysis (SKAT). SKAT was integrated with differential proteome analysis of toxicity to identify individual proteins coded by genes and/or pathway enrichment putatively controlled by genetic variation associated with anti-CTLA4 related toxicity. Results: The proteomic analysis identified 915 proteins that were differentially expressed (p < 0.05) in non/mild versus sever toxicity outcomes in anti-CTLA4 IT. SKAT analysis of genetic variation identified 1947 significant genes (p < 0.05) associated with toxicity, of which 78 were also significant (p < 0.05) in the proteomic analysis. The functional pathway analysis of 78 proteins showed enrichment for the regulation of interferon production, and a significant enrichment was observed for molecular pathways involved in autoimmunity. Conclusions: We present a novel framework integrating germline genetic information and serum protein expression levels to identify associations with toxicity in anti-CTLA4 IT. We found enrichment for interferon production and pathways involved in autoimmunity controlled by genetic variation. The data strongly support the importance of genetic variation in immune system regulation and its effect on IT-related toxicity. The effect of genetic variants on protein expression is currently further tested in the context of toxicity response to IT treatment. Legal entity responsible for the study: Tomas Kirchoff.