Recent developments have set the stage for immunotherapy as a supplement to conventional cancer treatment. Consequently, a significant effort is required to further improve efficacy and specificity, particularly the identification of optimal therapeutic targets for clinical testing. Cancer/testis antigens are immunogenic, highly cancer-specific, and frequently expressed in various types of cancer, which make them promising candidate targets for cancer immunotherapy, including cancer vaccination and adoptive T-cell transfer with chimeric T-cell receptors. Our current understanding of tumor immunology and immune escape suggests that targeting oncogenic antigens may be beneficial, meaning that identification of cancer/testis antigens with oncogenic properties is of high priority. Recent work from our lab and others provide evidence that many cancer/testis antigens, in fact, have oncogenic functions, including support of growth, survival and metastasis. This novel insight into the function of cancer/testis antigens has the potential to deliver more effective cancer vaccines. Moreover, immune targeting of oncogenic cancer/testis antigens in combination with conventional cytotoxic therapies or novel immunotherapies such as checkpoint blockade or adoptive transfer, represents a highly synergistic approach with the potential to improve patient survival.

Relapse to anti-HER2 monoclonal antibody (mAb) therapies, such as trastuzumab in HER2 + breast cancer (BC), is associated with residual disease progression due to resistance to therapy. Here, we identify interferon-γ inducible protein 16 (IFI16)-dependent STING signaling as a significant determinant of trastuzumab responses in HER2 + BC. We show that down-regulation of immune-regulated genes (IRG) is specifically associated with poor survival of HER2 + , but not other BC subtypes. Among IRG, IFI16 is identified as a direct target of EZH2, the underexpression of which leads to deficient STING activation and downstream CXCL10/11 expression in response to trastuzumab treatment. Dual inhibition of EZH2 and histone deacetylase (HDAC) significantly activates IFI16-dependent immune responses to trastuzumab. Notably, a combination of a novel histone methylation inhibitor with an HDAC inhibitor induces complete tumor eradication and long-term T cell memory in a HER2 + BC mouse model. Our findings demonstrate an epigenetic regulatory mechanism suppressing the expression of the IFI16-CXCL10/11 signaling pathway that provides a survival advantage to HER2 + BC to confer resistance to trastuzumab treatment.

Purpose: Immunoscore is a prognostic tool defined to quantify in situ immune cell infiltrates, which appears to be superior to the tumor-node-metastasis (TNM) classification in colorectal cancer. In non-small cell lung cancer (NSCLC), no immunoscore has been established, but in situ tumor immunology is recognized as highly important. We have previously evaluated the prognostic impact of several immunological markers in NSCLC, yielding the density of stromal CD8 þ tumor-infiltrating lymphocytes (TIL) as the most promising candidate. Hence, we validate the impact of stromal CD8 þ TIL density as an immunoscore in NSCLC.Experimental Design: The prognostic impact of stromal CD8þ TILs was evaluated in four different cohorts from Norway and Denmark consisting of 797 stage I-IIIA NSCLC patients. The Tromso cohort (n ¼ 155) was used as training set, and the results were further validated in the cohorts from Bodo (n ¼ 169), Oslo (n ¼ 295), and Denmark (n ¼ 178). Tissue microarrays and clinical routine CD8 staining were used for all cohorts.Results: Stromal CD8 þ TIL density was an independent prognostic factor in the total material (n ¼ 797) regardless of the endpoint: disease-free survival (P < 0.001), disease-specific survival (P < 0.001), or overall survival (P < 0.001). Subgroup analyses revealed significant prognostic impact of stromal CD8 þ TIL density within each pathologic stage (pStage). In multivariate analysis, stromal CD8 þ TIL density and pStage were independent prognostic variables. Conclusions: Stromal CD8 þ TIL density has independent prognostic impact in resected NSCLC, adds prognostic impact within each pStage, and is a good candidate marker for establishing a TNM-Immunoscore.