Base excision repair, which is initiated by the DNA N-glycosylase proteins, is the frontline for repairing potentially mutagenic DNA base damage. Several base excision repair genes are deregulated in cancer and affect cellular outcomes to chemotherapy and carcinogenesis. Endonuclease VIII-like 3 (NEIL3) is a DNA glycosylase protein that is involved in oxidative and interstrand crosslink DNA damage repair. Our previous work has showed that NEIL3 is required to maintain replication fork integrity. It is unknown whether NEIL3 overexpression could contribute to cancer phenotypes, and its prognostic value and use as potential drug target remain unexplored. Our analysis of cancer genomics data sets reveals that NEIL3 frequently undergoes overexpression in several cancers. Furthermore, patients who exhibited NEIL3 overexpression with pancreatic adenocarcinoma, lung adenocarcinoma, lower grade glioma, kidney renal clear cell carcinoma, and kidney papillary cell carcinoma had worse overall survival. Importantly, NEIL3 overexpressed tumors accumulate mutation and chromosomal variations. Furthermore, NEIL3 overexpressed tumors exhibit simultaneous overexpression of homologous recombination genes (BRCA1/2) and mismatch repair genes ( MSH2/MSH6). However, NEIL3 overexpression is negatively correlated with tumor overexpressing nucleotide excision repair genes ( XPA, XPC, ERCC1/ 2). Our results suggest that NEIL3 might be a potential prognosis marker for high-risk patients, and/or an attractive therapeutic target for selected cancers.

Sindbis virus (SINV) infection of neurons in the brain and spinal cord in mice provides a model system for investigating recovery from encephalomyelitis and antibody-mediated clearance of virus from the central nervous system (CNS). To determine the roles of IgM and IgG in recovery, we compared the responses of immunoglobulin-deficient activation-induced adenosine deaminase-deficient (AID), secretory IgM-deficient (sIgM), and AID sIgM double-knockout (DKO) mice with those of wild-type (WT) C57BL/6 mice for disease, clearance of infectious virus and viral RNA from brain and spinal cord, antibody responses, and B cell infiltration into the CNS. Because AID is essential for immunoglobulin class switch recombination and somatic hypermutation, AID mice produce only germ line IgM, while sIgM mice secrete IgG but no IgM and DKO mice produce no secreted immunoglobulin. After intracerebral infection with the TE strain of SINV, most mice recovered. Development of neurologic disease occurred slightly later in sIgM mice, but disease severity, weight loss, and survival were similar between the groups. AID mice produced high levels of SINV-specific IgM, while sIgM mice produced no IgM and high levels of IgG2a compared to WT mice. All mice cleared infectious virus from the spinal cord, but DKO mice failed to clear infectious virus from brain and had higher levels of viral RNA in the CNS late after infection. The numbers of infected cells and the amount of cell death in brain were comparable. We conclude that antibody is required and that either germ line IgM or IgG is sufficient for clearance of virus from the CNS. Mosquito-borne alphaviruses that infect neurons can cause fatal encephalomyelitis. Recovery requires a mechanism for the immune system to clear virus from infected neurons without harming the infected cells. Antiviral antibody has previously been shown to be a noncytolytic means for alphavirus clearance. Antibody-secreting cells enter the nervous system after infection and produce antiviral IgM before IgG. Clinical studies of human viral encephalomyelitis suggest that prompt production of IgM is associated with recovery, but it was not known whether IgM is effective for clearance. Our studies used mice deficient in production of IgM, IgG, or both to characterize the antibody necessary for alphavirus clearance. All mice developed similar signs of neurologic disease and recovered from infection. Antibody was necessary for virus clearance from the brain, and either early germ line IgM or IgG was sufficient. These studies support the clinical observation that prompt production of antiviral antibody is a determinant of outcome.

Immune checkpoint therapy (ICT) is a front-line treatment for lung cancer; however, low mutational burden and ‘non-T cell inflamed’ signatures predict poor responses to ICT in ~50% of patients. Adoptive cellular therapy (ACT) with T cells engineered to express T cell receptors (TCRs) specific for tumor-associated antigens (TAAs; native proteins that are overexpressed by cancers) is an approach that circumvents the need for endogenous T cell responses. TCR-ACT has been effective against hematologic cancers, but ACT against solid tumors is still in the early stages of exploration. A deeper understanding of the complex interaction between therapeutic T cells and the tumor microenvironment (TME) will be important for identifying successful strategies to enhance function and mitigate toxicity. Genetically engineered mouse models (GEMMs) achieve in situ tumor development alongside competent immune systems, recapitulating the native TME over the full spectrum of disease progression in a preclinical setting. Targeting TAAs naturally overexpressed by GEMM tumors, and expressed at native levels in healthy adult tissues, allows for study of the factors dictating the efficacy and toxicity of TCR-ACT in experimentally tractable systems. GEMM lung tumors driven by oncogenic Kras and deletion of the tumor suppressor p53 (KP) harbor few mutations, are poorly infiltrated by T cells, and are refractory to ICT, modeling treatment-recalcitrant patient disease. Using CD8+ T cells transduced with a TCR against the mesothelin (msln) protein, a TAA commonly overexpressed across many cancer types, including lung cancers, we showed that TAA-specific T cells recognize KP lung cancer cells and efficiently home to tumors. However, therapeutic T cells rapidly lose function in the lung TME compared to those recovered from the spleen, or from KP pancreatic tumors, which bear similar driver mutations and also overexpress the msln TAA. Repetitive TCR-ACT can extend survival of animals with lung tumors, dependent on treatment timing, but animals eventually succumb to disease. These results show promise for TCR-ACT against lung cancer but highlight the presence of tissue-specific obstacles that must be overcome to enhance efficacy. For example, TAA-specific T cells accumulate less efficiently in KP tumors engineered to express strong model T cell antigens, indicating acquired immune suppressive TME phenotypes. Preliminary studies indicate that engineered therapeutic CD8+ T cells modified to express costimulatory immunomodulatory fusion proteins (IFPs) or accompanied by engineered TAA-specific CD4+ helper T cells exhibit increased function in lung tumors, indicating that increased costimulation signaling or T cell help might partially overcome T cell suppression in the lung TME. As we continue to leverage these models to advance our understanding of tissue-specific effects on therapeutic outcomes, these findings offer inroads to uncovering more effective therapies, with the ultimate goal of benefitting cancer patients. Citation Format: Leah M. Schmidt, Oanh Tran, Shannon Oda, Quintin Inman, Sasha Tan, Cody Jenkins, Philip Greenberg. Effects of the lung tumor microenvironment on T cell therapy [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2020 Oct 19-20. Philadelphia (PA): AACR; Cancer Immunol Res 2021;9(2 Suppl):Abstract nr PO079.