Degui Geng

Redirecting Gene-Modified T Cells toward Various Cancer Types Using Tagged Antibodies

Purpose: To develop an adaptable gene-based vector that will confer immune cell specificity to various cancer types. Experimental Design: Human and mouse T cells were genetically engineered to express a chimeric antigen receptor (CAR) that binds a fluorescein isothiocyanate (FITC) molecule, termed anti-FITC CAR T cells. Various antibodies (Ab) currently in clinical use including cetuximab (Ctx), trastuzumab (Her2), and rituximab (Rtx) were conjugated with FITC and tested for their ability to bind tumor cells, activate T cells, and induce antitumor effects in vitro and in vivo. Results: Anti-FITC CAR T cells recognize various cancer types when bound with FITC-labeled Abs resulting in efficient target lysis, T-cell proliferation, and cytokine/chemokine production. The treatment of immunocompromised mice with human anti-FITC CAR T cells plus FITC-labeled cetuximab (FITC-Ctx) delayed the growth of colon cancer but unexpectedly led to the outgrowth of EGF receptor (EGFR)-negative tumor cells. On the other hand, in a human pancreatic cancer cell line with uniform EGFR expression, anti-FITC CAR T cells plus FITC-Ctx eradicated preestablished late-stage tumors. In immunocompetent mice, anti-FITC CAR T cells exhibited potent antitumor activity against syngeneic mouse breast cancer expressing Her2 and B-cell lymphoma expressing CD20 by combining with FITC-Her2 and FITC-Rtx, respectively. In addition, the activity of anti-FITC CAR T cells could be attenuated by subsequent injections of nonspecific FITC-IgG. Conclusion: These studies highlight an applicability of anti-tag CAR technology to treat patients with different types of cancers and a possibility to regulate CAR T-cell functions with competing FITC molecules. Clin Cancer Res; 18(23); 6436–45. ©2012 AACR.

Engagement of Toll-like receptor-2 on cytotoxic T-lymphocytes occurs in vivo and augments antitumor activity.

Toll‐like receptors (TLRs) are among the fundamental molecules that alert the immune system to the presence of an infection by recognizing pathogen‐associated molecules. Much of our understanding regarding TLR function stems from the study of innate immune cells. Recent studies by several groups, including ours, have shown that TLRs can function as costimulatory receptors for antigen‐specific T cells, resulting in enhanced T‐cell survival and increased expression of effector molecules. We report that the ligation of the TLR1/2 heterodimer on OT‐1 cytotoxic T‐lymphocytes (CTL) but not TLR2–/–OT‐1 T cells increased cytolytic activity in vitro and in vivo. On the basis of these data, we tested the hypothesis that TLR1/2 stimulation on CTLs would enhance antitumor activity in a therapeutic model of B16‐Ova melanoma. Adoptive OT‐1 T‐cell transfer into wild‐type and MyD88–/– mice, followed by injection with TLR1/2 ligand, resulted in a synergistic antitumor effect, which correlated with the induction of CD8 T cells specific to various tumor antigens. In contrast, mice receiving TLR2–/–OT‐1 T cells and TLR1/2 ligand showed minimal therapeutic efficacy. These findings emphasize the physiological significance of TLR2 engagement on CTLs and could make possible new approaches for the development of effective immunotherapies by manipulating TLR signaling within CTLs.—Asprodites, N., Zheng, L., Geng, D., Velasco‐Gonzalez, C., Sanchez‐ Perez, L., Davila, E. Engagement of Toll‐like receptor‐2 on cytotoxic T‐lymphocytes occurs in vivo and augments antitumor activity. FASEB J. 22, 3628–3637 (2008)

Dichotomous regulation of GVHD through bidirectional functions of the BTLA-HVEM pathway.

B and T lymphocyte attenuator (BTLA) is a co-inhibitory receptor that interacts with herpesvirus entry mediator (HVEM), and this interaction regulates pathogenesis in various immunologic diseases. In graft-versus-host disease (GVHD), BTLA unexpectedly mediates positive effects on donor T-cell survival, whereas immunologic mechanisms of this function have yet to be explored. In this study, we elucidated a role of BTLA in GVHD by applying the newly established agonistic anti-BTLA monoclonal antibody that stimulates BTLA signal without antagonizing BTLA-HVEM interaction. Our results revealed that provision of BTLA signal inhibited donor antihost T-cell responses and ameliorated GVHD with a successful engraftment of donor hematopoietic cells. These effects were dependent on BTLA signal into donor T cells but neither donor non-T cells nor recipient cells. On the other hand, expression of BTLA mutant lacking an intracellular signaling domain restored impaired survival of BTLA-deficient T cells, suggesting that BTLA also serves as a ligand that delivers HVEM prosurvival signal in donor T cells. Collectively, current study elucidated dichotomous functions of BTLA in GVHD to serve as a costimulatory ligand of HVEM and to transmit inhibitory signal as a receptor.

Amplifying TLR-MyD88 Signals within Tumor-Specific T Cells Enhances Antitumor Activity to Suboptimal Levels of Weakly Immunogenic Tumor Antigens

The efficacy of T cell-based immunotherapy to treat cancer patients remains a challenge partly because of the weak activity toward subdominant tumor antigens (TAg) and to tumors expressing suboptimal TAg levels. Recent reports indicate that Toll-like receptor (TLR) stimulation on T cells can lower the activation threshold. In this study, we examined the antitumor activity and survival of TLR2-MyD88-stimulated CD8 T cells derived from melanoma patients and T-cell receptor transgenic pmel mice. TLR2-stimulated pmel CD8 T cells, but not TLR2(-/-)pmel or MyD88(-/-)pmel T cells, responded to significantly lower TAg levels and resulted in increased production of effector molecules and cytotoxicity. Wild-type or MyD88(-/-) mice treated with TLR2 ligand and pmel T cells, but not TLR2(-/-)pmel or MyD88(-/-)pmel T cells, showed tumor regression of an established melanoma tumor. Overexpressing TLR2 in TAg-specific T cells eradicated tumors; four times fewer cells were needed to generate antitumor responses. The enhanced antitumor activity of TLR2-MyD88-stimulated T cells was associated with increased effector function but perhaps more importantly with improved survival of T cells. Activating TLR-MyD88 signals in patient-derived T cells also reduced the activation threshold to several weakly immunogenic TAgs, resulting in increased cytokine production, expansion, and cytotoxicity. These data highlight a previously unappreciated role for activating TLR-MyD88 signals in tumor-reactive T lymphocytes.

TLR5 ligand-secreting T cells reshape the tumor microenvironment and enhance antitumor activity

The tumor microenvironment counters antitumor T-cell responses, in part, by blunting their activation and infiltration. Ligands that engage Toll-like receptors (TLR) on T cells and antigen-presenting cells can act as potent immune adjuvants. In this study, we show how tumor-reactive T cells engineered to secrete bacterial flagellin, a TLR5 ligand (TLR5L), can engender a costimulatory signal that augments antitumor activity. Human T cells engineered to express TLR5L along with DMF5, a T-cell receptor that recognizes the melanoma antigen MART-127-35 (DMF5(TLR5L) T cells), displayed increased proliferation, cytokine production, and cytolytic activity against melanoma cells. In a xenogenetic model, adoptive transfer of DMF5(TLR5L) T cells reduced tumor growth kinetics and prolonged mouse survival. In a syngeneic model, similarly engineered melanoma-reactive T cells (pmel(TLR5L)) displayed a relative increase in antitumor activity against established tumors, compared with unmodified T cells. In this model, we documented increased T-cell infiltration associated with increased levels of CCR1 and CXCR3 levels on T cells, a reduction in PD-1(+)Lag3(+) T cells and CD11(+)Gr1(+) myeloid-derived suppressor cells, and changes in the chemokine/cytokine profile of tumors. Our findings show how T cell-mediated delivery of a TLR agonist to the tumor site can contribute to antitumor efficacy, in the context of adoptive T-cell immunotherapy.

Abstract B31: IRAK-4 signaling in melanoma contributes to reduced expression of inflammatory factors in vitro while contributing to tumor growth in vivo

An underlying and universal hindrance to T-cell-based cancer therapies is the development of immunosuppressive mechanisms that in large part originate from the persistent expression of inflammatory factors. Understanding the fundamental mechanisms that regulate chronic inflammation and targeting of this pathway(s) is critical for developing effective strategies to restore anti-tumor T-cell activity. We recently reported that the IL-1 receptor associated kinase-4 (IRAK-4) is over-expressed and activated in most melanoma cases. IRAK-4 is a central kinase in the inflammatory process that regulates the expression of various inflammatory and immunosuppressive molecules. Inhibiting IRAK-4 activity in melanoma drastically reduced the expression of various inflammatory factors in vitro. Furthermore, IRAK-4 signaling in melanoma contributed to tumor growth in vivo and was associated with an increased frequency of phenotypically exhausted (PD1+Lag3+) tumor infiltrating T-cells, myeloid derived suppressor cells, and a trend toward higher numbers of CD4+ T regs. Ongoing studies are focused on testing the hypothesis that targeting IRAK-4 signaling in tumor cells will alter the expression of inflammatory factors in the tumor environment which will reduce immunosuppression and sensitize melanoma to T-cell-mediated killing. Citation Format: Jackline Joy Martin Lasola, Degui Geng, Rojesh Shrestha, Eduardo Davila. IRAK-4 signaling in melanoma contributes to reduced expression of inflammatory factors in vitro while contributing to tumor growth in vivo. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2016 Oct 20-23; Boston, MA. Philadelphia (PA): AACR; Cancer Immunol Res 2017;5(3 Suppl):Abstract nr B31.