Abstract 4064: Targeting the anti-tumor function of B cells in non-small cell lung cancer patient tumors
Authors: Tullia Carmela Bruno, Brandon L. Moore, Daniel J. Munson, Peggy Ebner, Jeffrey Kern, Jill E. Slansky
Journal: Cancer Research (2015)

Abstract Despite improvements in surgical techniques and combined chemotherapies, the 5-year survival rate for all stages of non-small cell lung cancer (NSCLC) is only 18%. Understanding the function of tumor infiltrating lymphocytes (TILs) in NSCLC patient tumors will contribute to the development of rationally designed treatments and improved statistics. B cells in tumors (TIL-Bs) are detected in NSCLC and their frequency correlates with improved survival, however, they are understudied in human tumors. We hypothesize that TIL-Bs help generate potent, long-term immune responses against cancer. We used un-manipulated, primary human B cells from fresh tumor, tumor-adjacent, and normal (cancer-free) lung tissue. We performed a comprehensive flow cytometric analysis of all TILs in NSCLC: CD4 and CD8 TILs, T regulatory cells, TIL-Bs, NK and NKT cells. We further examined the phenotype of TIL-Bs by analyzing markers of lymphocyte activation (anti-tumor; CD69, CD86, HLA-DR, CD27) and exhaustion (pro-tumor; CD95, CD21, PD-1, PD-L1). We developed an in vitro antigen presentation assay that analyzed if TIL-Bs present tumor-specific antigens to CD4 TILs to help stimulate an anti-tumor response in NSCLC patient tumors. The total number of B cells at the site of the tumor versus the tumor-adjacent tissue was increased compared to other immune subsets. In analyzing the markers of activation and exhaustion, we observed a spectrum of activation of TIL-Bs. Further, we observed that TIL-Bs present autologous tumor antigens to CD4 TILs in a subset of NSCLC patients. These data suggest that some patients have functional TIL-Bs and some patients have nonfunctional TIL-Bs. XAGE-1b is an immunogenic, lung cancer-specific antigen that generates CD4 and CD8 T cell responses in lung cancer patients. It was overexpressed in the tumor cells of our NSCLC patients, and we demonstrated that some TIL-Bs could present recombinant XAGE-1b antigen to CD4 TILs. The TIL-Bs that could not present tumor-specific antigens had higher expression of B cell exhaustion markers on the cell surface. Further, because PD-1 expression is increased on CD4 TILs in our NSCLC patients, we are combining blockade of the immune inhibitory PD-1:PD-L1 pathway in our antigen presentation assays. In conclusion, the anti-tumor function of TIL-Bs can be stimulated in some NSCLC patients, and TIL-Bs that cannot be stimulated have increased immune exhaustion. Ultimately, results from this study will advance the understanding of the anti-tumor function of TIL-Bs in solid tumors and will help develop a model of B cell exhaustion in human cancer. It will also help predict which TIL-B functions to target in future TIL-B-specific immunotherapies or in combination with current successful immunotherapies for NSCLC patients like blockade of the immune inhibitory PD-1:PD-L1 pathway. Citation Format: Tullia Carmela Bruno, Brandon L. Moore, Daniel J. Munson, Peggy Ebner, Jeffrey Kern, Jill E. Slansky. Targeting the anti-tumor function of B cells in non-small cell lung cancer patient tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4064. doi:10.1158/1538-7445.AM2015-4064