Jinsheng Weng

TCL1: a shared tumor-associated antigen for immunotherapy against B-cell lymphomas

Immunotherapy with therapeutic idiotype vaccines offers promise for treatment of B-cell malignancies. However, identification of novel immunogenic lymphoma-associated antigens that are universally expressed is necessary to overcome the barriers of patient-specific idiotype vaccines. Here, we determined whether T-cell leukemia/lymphoma 1 (TCL1) oncoprotein encoded by the TCL1 gene could be a target for immunotherapy of B-cell malignancies. We show that TCL1 mRNA and protein are selectively expressed in normal B cells but markedly hyperexpressed in multiple human B-cell lymphomas, including follicular lymphoma, chronic lymphocytic leukemia, mantle cell lymphoma, diffuse large B-cell lymphoma, and splenic marginal zone B-cell lymphoma. We demonstrated that TCL1-specific CD8(+) T cells can be generated from HLA-A*0201 (HLA-A2)(+) normal donors and identified TCL1(71-78) (LLPIMWQL) as the minimal epitope recognized by these T cells. More importantly, TCL1(71-78) peptide-specific T cells were present in the peripheral blood and tumor-infiltrating lymphocytes of lymphoma patients, could be expanded in vitro, and lysed autologous tumor cells but not normal B cells in an HLA-A2-restricted manner. Our results suggest that TCL1 is naturally processed and presented on the surface of lymphoma cells for recognition by cytotoxic T cells and can serve as a novel target for development of immunotherapeutic strategies against common B-cell lymphomas.

Identification of human idiotype-specific T cells in lymphoma and myeloma.

Idiotype protein, among the first identified tumor-specific antigens, has been found to stimulate both humoral and cellular responses in lymphoma and myeloma patients. With the increasing use of B cell depletion treatments such as rituximab in clinic, the cellular response mediated by idiotype-specific T cells has become increasingly important as an adjunct therapy for lymphoma and myeloma. Here, we review the idiotype protein as a tumor antigen and the characteristics of the T cell response elicited idiotype vaccination. We also analyze the T cell epitopes that have been identified in idiotype protein and introduce our new findings of additional T cell epitopes derived from the Ig light chain. Finally, we propose new directions in the generation of idiotype-specific T cells for tumor therapy.

Identification of Prostate-Specific G-Protein Coupled Receptor as a Tumor Antigen Recognized by CD8+ T Cells for Cancer Immunotherapy

Background Prostate cancer is the most common cancer among elderly men in the US, and immunotherapy has been shown to be a promising strategy to treat patients with metastatic castration-resistant prostate cancer. Efforts to identify novel prostate specific tumor antigens will facilitate the development of effective cancer vaccines against prostate cancer. Prostate-specific G-protein coupled receptor (PSGR) is a novel antigen that has been shown to be specifically over-expressed in human prostate cancer tissues. In this study, we describe the identification of PSGR-derived peptide epitopes recognized by CD8+ T cells in an HLA-A2 dependent manner. Methodology/Principal Findings Twenty-one PSGR-derived peptides were predicted by an immuno-informatics approach based on the HLA-A2 binding motif. These peptides were examined for their ability to induce peptide-specific T cell responses in peripheral blood mononuclear cells (PBMCs) obtained from either HLA-A2+ healthy donors or HLA-A2+ prostate cancer patients. The recognition of HLA-A2 positive and PSGR expressing LNCaP cells was also tested. Among the 21 PSGR-derived peptides, three peptides, PSGR3, PSGR4 and PSGR14 frequently induced peptide-specific T cell responses in PBMCs from both healthy donors and prostate cancer patients. Importantly, these peptide-specific T cells recognized and killed LNCaP prostate cancer cells in an HLA class I-restricted manner. Conclusions/Significance We have identified three novel HLA-A2-restricted PSGR-derived peptides recognized by CD8+ T cells, which, in turn, recognize HLA-A2+ and PSGR+ tumor cells. The PSGR-derived peptides identified may be used as diagnostic markers as well as immune targets for development of anticancer vaccines.

IL-15 enhances the antitumor effect of human antigen-specific CD8+ T cells by cellular senescence delay

ABSTRACT Optimal expansion protocols for adoptive human T-cell therapy often include interleukin (IL)-15; however, the mechanism by which IL-15 improves the in vivo antitumor effect of T cells remains to be elucidated. Using human T cells generated from HLA-A2+ donors against novel T-cell epitopes derived from the human U266 myeloma cell line Ig light chain V-region (idiotype) as a model, we found that T cells cultured with IL-15 provided superior resistance to tumor growth in vivo, compared with IL-2, after adoptive transfer into immunodeficient hosts. This effect of IL-15 was associated with delayed/reversed senescence in tumor antigen-specific memory CD8+ T cells mediated through downregulation of P21WAF1, P16INK4a, and P53 expression. Compared to IL-2, IL-15 stimulation dramatically activated JAK3-STAT5 signaling and inhibited the expression of DNA damage genes. Thus, our study elucidates a new mechanism for IL-15 in the regulation of STAT signaling pathways and CD8+ T-cell senescence.

Targeting Human B-cell Malignancies through Ig Light Chain–Specific Cytotoxic T Lymphocytes

Purpose: The variable regions of Ig (idiotype, Id) expressed by malignant B cells can be used as tumor-specific antigens that induce humoral and cellular immunity. However, epitopes derived from Id that stimulate human CD8+ T-cell immunity are incompletely characterized. Experimental Design: The clonal Ig VL of human myeloma cell line U266 and five primary B-cell tumors were sequenced, and peptides corresponding to the Ig VL region were tested for their ability to stimulate CTLs from 10 HLA-A*0201–positive normal donors. The CTLs thus generated were tested against peptide-pulsed T2 cells and autologous tumor cells. Results: Fourteen peptides derived from Ig light chain (VL) of U266 and primary B-cell tumors were used to generate 68 CTLs lines that specifically produced IFN-γ when cocultured with peptide-pulsed T2 cells. These CTLs lysed peptide-pulsed T2 cell as well as U266 or autologous tumor targets in an HLA class I–dependent manner. Sequence analysis revealed shared VL T-cell epitopes in U266 and primary B-cell tumors, not previously reported within Ig heavy chain (VH) sequences. Conclusion: This study thus identifies novel immunogenic CTLs epitopes from Id VL, suggests that they are naturally presented on the surface of B-cell malignancies, and supports their inclusion in next-generation Id vaccines. The ability to prime T cells derived from normal HLA-matched donors, rather than patients, may also have direct application to current strategies, designed to generate allogeneic tumor-specific T cells for adoptive transfer. Clin Cancer Res; 17(18); 5945–52. ©2011 AACR.

Targeting the Leukemia Antigen PR1 with Immunotherapy for the Treatment of Multiple Myeloma

Purpose: PR1 is a human leukocyte antigen (HLA)-A2 nonameric peptide derived from neutrophil elastase (NE) and proteinase 3 (P3). We have previously shown that PR1 is cross-presented by solid tumors, leukemia, and antigen-presenting cells, including B cells. We have also shown that cross-presentation of PR1 by solid tumors renders them susceptible to killing by PR1-targeting immunotherapies. As multiple myeloma is derived from B cells, we investigated whether multiple myeloma is also capable of PR1 cross-presentation and subsequently capable of being targeted by using PR1 immunotherapies. Experimental Design: We tested whether multiple myeloma is capable of cross-presenting PR1 and subsequently becomes susceptible to PR1-targeting immunotherapies, using multiple myeloma cell lines, a xenograft mouse model, and primary multiple myeloma patient samples. Results: Here we show that multiple myeloma cells lack endogenous NE and P3, are able to take up exogenous NE and P3, and cross-present PR1 on HLA-A2. Cross-presentation by multiple myeloma utilizes the conventional antigen processing machinery, including the proteasome and Golgi, and is not affected by immunomodulating drugs (IMiD). Following PR1 cross-presentation, we are able to target multiple myeloma with PR1-CTL and anti-PR1/HLA-A2 antibody both in vitro and in vivo. Conclusions: Collectively, our data demonstrate that PR1 is a novel tumor-associated antigen target in multiple myeloma and that multiple myeloma is susceptible to immunotherapies that target cross-presented antigens. Clin Cancer Res; 24(14); 3386–96. ©2018 AACR.

Abstract 3961: IL-15 improves the effect of adoptive T cell therapy through cellular senescence delay.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Adoptive T-cell therapy is one of the most effective forms of immunotherapy in the clinical setting. However, the mechanism that regulates the in vivo effect of T-cell therapy still remains unclear. Using T cells generated from normal donors against previously identified T-cell epitopes in U266 idiotype light chain model, we expanded the antigen-specific T cells with IL-2 or IL-15 cytokines, we found that antigen specific T cells expanded with IL-2 have temperate inhibitory effect in vivo, whereas IL-15-expanded antigen-specific T cells provide a much stronger in vivo effect. Approximately 30% experimental mice remained tumor free after adoptive transfer with IL-15 expanded- antigen-specific T cells. Detailed analysis revealed that IL-15-expanded T cells have down-regulated expression of cellular senescence signature genes, decreased SA-s-Gal activity, and decreased P53, P21WAF1 and P16INK4a expression. The expression level of CD27 and CD28 is significantly greater in IL-15-expanded T cells, indicating that IL-15-expanded T cells have delayed cellular senescence. This result is also confirmed by the memory CD8+ T cells purified from general normal donors. Memory CD8+ T cells cultured with IL-15 have significantly greater levels of CD27 and CD28 expression, lower SA-s-Gal activity and lower P53, P21WAF1 and P16INK4a protein level after 5 days culture in vitro. To identify the molecular mechanism of the effect of IL-15 on the cellular senescence, we cultured the memory CD8+ T cells with IL-15 in the presence of different signaling pathway inhibitors and we found that IL-15 regulated cellular senescence through JAK3-STAT3 and JAK3-STAT5 signaling pathways. DNA damage molecules ATM, MDC1, and TP53bp1 are also down-regulated by IL-15, and there are three STATs potential binding sites in the promoter of TP53bp1. Using a CHIP assay, we found that IL-15 directly regulates p-STAT3 and p-STAT5 binding to the -123 site of TP53bp1 promoter. This site is also bound by tri-methy-H3(Lys27) and P300 after IL-15 stimulation, indicating that IL-15 induces both epigenetic and transcriptional mechanism to repress TP53bp1 expression. Cellular senescence was initially reported in human fibroblast cells of irreversible growth arrest, active metabolism, and specific gene signatures, and recent studies showed that senescence can be reversed and delayed by certain treatments. Our study provides the first evidence of IL-15 in memory CD8+ T cell senescence delay, which has provided a detailed molecular mechanism. Our study provides important information for the future improvement of adoptive T cell therapy in the clinic. Citation Format: Jinsheng Weng, Sung-Doo Kim, Haiyan Li, Jin He, Jianfei Qian, Hiroki Torikai, Liang Zhang, Jing Yang, qing yi, Larry W. Kwak. IL-15 improves the effect of adoptive T cell therapy through cellular senescence delay. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3961. doi:10.1158/1538-7445.AM2013-3961