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This figure shows the proliferation and phneotype of tumor lines in response to NECA.

Supplementary Figure 2

This supplementary Figure shows the phenotype and function of CD8+ T cells and tumor cells following A2A blockade single agent therapy.

This supplementray Figure shows the expression of IFNy and Granzyme B on tumor-infiltrating lymphocytes 7 days post anti-PD-1/ anti-PD-1/A2A blockade.

This Supplementary Figure shows the expression of CD73 and adenosine receptors by tumor lines.

This document contains the Figure Legends for the Supplementary data Figures.

This Supplememntary Figure shows the effect of combined PD-1 and A2A blockade on in vitro effector functions of OT-I cells.

This supplementary Figure shows the expression of A2A and IFNy on tumor infiltrating lymphocytes following PD-1 blockade.

This supplementary figure shows the phenotype of tumor-infiltrating lymphocytes following PD-1 or PD-1/A2A blockade.

Immunotherapy is widely accepted as a powerful new treatment modality for the treatment of cancer. The most successful form of immunotherapy to date has been the blockade of the immune checkpoints PD-1 and CTLA-4. Combining inhibitors of both PD-1 and CTLA-4 increases the proportion of patients who respond to immunotherapy. However, most patients still do not respond to checkpoint inhibitors, and prognostic biomarkers are currently lacking. Therefore, a better understanding of the mechanism by which these checkpoint inhibitors enhance antitumor immune responses is required to more accurately predict which patients are likely to respond and further enhance this treatment modality. Our current study of two mouse tumor models revealed that CD4+Foxp3− cells activated by dual PD-1/CTLA-4 blockade modulated the myeloid compartment, including activation of conventional CD103+ dendritic cells (DC) and expansion of a myeloid subset that produces TNFα and iNOS (TIP-DCs). CD4+Foxp3− T cell–mediated activation of CD103+ DCs resulted in enhanced IL12 production by these cells and IL12 enhanced the therapeutic effect of dual PD-1/CTLA-4 blockade. Given the importance of these myeloid subsets in the antitumor immune response, our data point to a previously underappreciated role of CD4+Foxp3− cells in modulating this arm of the antitumor immune response. Cancer Immunol Res; 6(9); 1069–81. ©2018 AACR.

Immunotherapy is rapidly emerging as a cancer treatment with high potential. Recent clinical trials with anti-CTLA-4 and anti–PD-1/PD-L1 antibodies (mAbs) suggest that targeting multiple immunosuppressive pathways may significantly improve patient survival. The generation of adenosine by CD73 also suppresses antitumor immune responses through the activation of A2A receptors on T cells and natural killer (NK) cells. We sought to determine whether blockade of A2A receptors could enhance the efficacy of anti–PD-1 mAb. The expression of CD73 by tumor cells limited the efficacy of anti–PD-1 mAb in two tumor models, and this was alleviated with concomitant treatment with an A2A adenosine receptor antagonist. The blockade of PD-1 enhanced A2A receptor expression on tumor-infiltrating CD8+ T cells, making them more susceptible to A2A-mediated suppression. Thus, dual blockade of PD-1 and A2A significantly enhanced the expression of IFNγ and Granzyme B by tumor-infiltrating CD8+ T cells and, accordingly, increased growth inhibition of CD73+ tumors and survival of mice. The results of our study indicate that CD73 expression may constitute a potential biomarker for the efficacy of anti–PD-1 mAb in patients with cancer and that the efficacy of anti–PD-1 mAb can be significantly enhanced by A2A antagonists. We have therefore revealed a potentially novel biomarker for the efficacy of anti–PD-1 that warrants further investigation in patients. Because our studies used SYN-115, a drug that has already undergone phase IIb testing in Parkinson disease, our findings have immediate translational relevance for patients with cancer. Cancer Immunol Res; 3(5); 506–17. ©2015 AACR.

This supplementary figure shows the expression of PD-1 on tumor infiltrating immune subsets.

Supplementary Figure 1 - PDF file 73K, Tumor cells express high levels of PD-L1

Supplementary Figure 2 - PDF file 20K, Expression of PD-1 is upregulated on CAR T cells following antigen stimulation with e0771-Her2+ tumor cells

upplementary Figure 3 - PDF file 17K, Gr1+ cells express PD-1 and PD-L1

Purpose: To determine the antitumor efficacy and toxicity of a novel combination approach involving adoptive T-cell immunotherapy using chimeric antigen receptor (CAR) T cells with an immunomodulatory reagent for blocking immunosuppression.Experimental Design: We examined whether administration of a PD-1 blocking antibody could increase the therapeutic activity of CAR T cells against two different Her-2+ tumors. The use of a self-antigen mouse model enabled investigation into the efficacy, mechanism, and toxicity of this combination approach.Results: In this study, we first showed a significant increase in the level of PD-1 expressed on transduced anti-Her-2 CD8+ T cells following antigen-specific stimulation with PD-L1+ tumor cells and that markers of activation and proliferation were increased in anti-Her-2 T cells in the presence of anti-PD-1 antibody. In adoptive transfer studies in Her-2 transgenic recipient mice, we showed a significant improvement in growth inhibition of two different Her-2+ tumors treated with anti-Her-2 T cells in combination with anti-PD-1 antibody. The therapeutic effects observed correlated with increased function of anti-Her-2 T cells following PD-1 blockade. Strikingly, a significant decrease in the percentage of Gr1+ CD11b+ myeloid-derived suppressor cells (MDSC) was observed in the tumor microenvironment of mice treated with the combination therapy. Importantly, increased antitumor effects were not associated with any autoimmune pathology in normal tissue expressing Her-2 antigen.Conclusion: This study shows that specifically blocking PD-1 immunosuppression can potently enhance CAR T-cell therapy that has significant implications for potentially improving therapeutic outcomes of this approach in patients with cancer. Clin Cancer Res; 19(20); 5636–46. ©2013 AACR.

Supplementary Figure Legends - PDF file 66K, Supplementary Figure legends

Supplementary Figure S1. Expression of activation and memory markers on transduced mouse T cells. Supplementary Figure S2. CAR T cell cytotoxic responses are not modulated by anti-4-1BB mAb therapy. Supplementary Figure S3. Her2 expression level on the mouse breast cancer cell line e0771-Her2 is comparable to the Her2-overexpressing human breast cancer cell line SKBR3. Supplementary Figure S4. Tumor weight is significantly reduced following CAR T cell and alpha-4-1BB therapy. Supplementary Figure S5. Anti-4-1BB therapy does not modulate the frequency of transferred or endogenous CD8+ tumor-infiltrating T cells. Supplementary Figure S6. Anti-4-1BB therapy modulates the frequency of mature dendritic cells in tumors and draining lymph nodes. Supplementary Figure S7. Anti-4-1BB does not modulate the frequency of MDSCs and DCs in RAG -/- mice. Supplementary Figure S8. Anti-4-1BB therapy drives maturation of NK cells.

Adoptive immunotherapy utilizing chimeric antigen receptor (CAR) T cells has demonstrated high success rates in hematologic cancers, but results against solid malignancies have been limited to date, due in part to the immunosuppressive tumor microenvironment. Activation of the 4-1BB (CD137) pathway using an agonistic α-4-1BB antibody is known to provide strong costimulatory signals for augmenting and diversifying T-cell responses. We therefore hypothesized that a combination of α-4-1BB and CAR T-cell therapy would result in improved antitumor responses. Using a human-Her2 self-antigen mouse model, we report here that α-4-1BB significantly enhanced CAR T-cell efficacy directed against the Her2 antigen in two different established solid tumor settings. Treatment also increased the expression of IFNγ and the proliferation marker Ki67 in tumor-infiltrating CAR T cells when combined with α-4-1BB. Strikingly, α-4-1BB significantly reduced host immunosuppressive cells at the tumor site, including regulatory T cells and myeloid-derived suppressor cells, correlating with an increased therapeutic response. We conclude that α-4-1BB has a multifunctional role for enhancing CAR T-cell responses and that this combination therapy has high translational potential, given current phase I/II clinical trials with α-4-1BB against various types of cancer. Cancer Res; 77(6); 1296–309. ©2017 AACR.

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Oncolytic virotherapy using vaccinia virus (Vv) has shown some encouraging antitumor responses in mouse models and patients, but the breadth of efficacy in clinical trials has been somewhat limited. Given that antitumor effects have correlated with increased host immune responses, we hypothesized that improved therapeutic outcomes may be achieved by using oncolytic virus (OV) in combination with a potent immune agonist reagent. In this study, we carried out a preclinical evaluation of a genetically engineered strain of oncolytic vaccinia virus (Vvdd) for its capacity to induce antitumor responses when combined with an agonist antibody (Ab) specific for the costimulatory molecule 4-1BB (CD137). In immune-competent syngeneic mouse models of cancer, this combination therapy significantly reduced the growth of established subcutaneous tumors relative to either treatment alone. Importantly, the development of pulmonary metastatic lesions was also reduced. Tumor growth inhibition was associated with increased numbers of CD11b+ and CD11c+ myeloid cells in the tumor draining lymph nodes, greater infiltration of CD8+ effector T and natural killer (NK) cells, and a more sustained presence of neutrophils at the tumor site. Depletion of T or NK cells or neutrophils reduced efficacy, confirming their contribution to an effective therapeutic response. We further extended this conclusion through results from IFNγ-deficient mice. In summary, our findings offered a proof-of-concept for a combinatorial approach to enhance the antitumor efficacy of an OV, suggesting a strategy to improve their use as an immunotherapeutic treatment for cancer. Cancer Res; 72(7); 1651–60. ©2012 AACR.

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Immunotherapy is widely accepted as a powerful new treatment modality for the treatment of cancer. The most successful form of immunotherapy to date has been the blockade of the immune checkpoints PD-1 and CTLA-4. Combining inhibitors of both PD-1 and CTLA-4 increases the proportion of patients who respond to immunotherapy. However, most patients still do not respond to checkpoint inhibitors, and prognostic biomarkers are currently lacking. Therefore, a better understanding of the mechanism by which these checkpoint inhibitors enhance antitumor immune responses is required to more accurately predict which patients are likely to respond and further enhance this treatment modality. Our current study of two mouse tumor models revealed that CD4+Foxp3− cells activated by dual PD-1/CTLA-4 blockade modulated the myeloid compartment, including activation of conventional CD103+ dendritic cells (DC) and expansion of a myeloid subset that produces TNFα and iNOS (TIP-DCs). CD4+Foxp3− T cell–mediated activation of CD103+ DCs resulted in enhanced IL12 production by these cells and IL12 enhanced the therapeutic effect of dual PD-1/CTLA-4 blockade. Given the importance of these myeloid subsets in the antitumor immune response, our data point to a previously underappreciated role of CD4+Foxp3− cells in modulating this arm of the antitumor immune response. Cancer Immunol Res; 6(9); 1069–81. ©2018 AACR.

Adoptive immunotherapy utilizing chimeric antigen receptor (CAR) T cells has demonstrated high success rates in hematologic cancers, but results against solid malignancies have been limited to date, due in part to the immunosuppressive tumor microenvironment. Activation of the 4-1BB (CD137) pathway using an agonistic α-4-1BB antibody is known to provide strong costimulatory signals for augmenting and diversifying T-cell responses. We therefore hypothesized that a combination of α-4-1BB and CAR T-cell therapy would result in improved antitumor responses. Using a human-Her2 self-antigen mouse model, we report here that α-4-1BB significantly enhanced CAR T-cell efficacy directed against the Her2 antigen in two different established solid tumor settings. Treatment also increased the expression of IFNγ and the proliferation marker Ki67 in tumor-infiltrating CAR T cells when combined with α-4-1BB. Strikingly, α-4-1BB significantly reduced host immunosuppressive cells at the tumor site, including regulatory T cells and myeloid-derived suppressor cells, correlating with an increased therapeutic response. We conclude that α-4-1BB has a multifunctional role for enhancing CAR T-cell responses and that this combination therapy has high translational potential, given current phase I/II clinical trials with α-4-1BB against various types of cancer. Cancer Res; 77(6); 1296–309. ©2017 AACR.

International audience; While adoptive immunotherapy using chimeric antigen receptor (CAR)-modified T cells can induce remission of some tumors, the role of other CAR-modified leukocytes is not well characterized. In this study, we characterize the function of leukocytes including natural killer (NK) cells, macrophages and CAR T cells from transgenic mice expressing a CAR under the control of the pan-hematopoietic promoter, vav, and determine the ability of these mice to respond to ERB expressing tumors. We demonstrate the anti-tumor functions of leukocytes, including antigen specific cytotoxicity and cytokine secretion. The adoptive transfer of CAR T cells provided a greater survival advantage in the E0771ERB tumor model than their wildtype (WT) counterparts. In addition, CAR NK cells and CAR T cells also mediated increased survival in the RMAERB tumor model. When challenged with Her2 expressing tumors, F38 mice were shown to mount an effective immune response, resulting in tumor rejection and long-term survival. This was shown to be predominantly dependent on both CD8(+) T cells and NK cells. However, macrophages and CD4(+) T cells were also shown to contribute to this response. Overall, this study highlights the use of the vav-CAR mouse model as a unique tool to determine the anti-tumor function of various immune subsets, either alone or when acting alongside CAR T cells in adoptive immunotherapy.

Immunotherapy is widely accepted as a powerful new treatment modality for the treatment of cancer. The most successful form of immunotherapy to date has been the blockade of the immune checkpoints PD-1 and CTLA-4. Combining inhibitors of both PD-1 and CTLA-4 increases the proportion of patients who respond to immunotherapy. However, most patients still do not respond to checkpoint inhibitors, and prognostic biomarkers are currently lacking. Therefore, a better understanding of the mechanism by which these checkpoint inhibitors enhance antitumor immune responses is required to more accurately predict which patients are likely to respond and further enhance this treatment modality. Our current study of two mouse tumor models revealed that CD4

Immunotherapy is rapidly emerging as a cancer treatment with high potential. Recent clinical trials with anti-CTLA-4 and anti–PD-1/PD-L1 antibodies (mAbs) suggest that targeting multiple immunosuppressive pathways may significantly improve patient survival. The generation of adenosine by CD73 also suppresses antitumor immune responses through the activation of A2A receptors on T cells and natural killer (NK) cells. We sought to determine whether blockade of A2A receptors could enhance the efficacy of anti–PD-1 mAb. The expression of CD73 by tumor cells limited the efficacy of anti–PD-1 mAb in two tumor models, and this was alleviated with concomitant treatment with an A2A adenosine receptor antagonist. The blockade of PD-1 enhanced A2A receptor expression on tumor-infiltrating CD8+ T cells, making them more susceptible to A2A-mediated suppression. Thus, dual blockade of PD-1 and A2A significantly enhanced the expression of IFNγ and Granzyme B by tumor-infiltrating CD8+ T cells and, accordingly, increased growth inhibition of CD73+ tumors and survival of mice. The results of our study indicate that CD73 expression may constitute a potential biomarker for the efficacy of anti–PD-1 mAb in patients with cancer and that the efficacy of anti–PD-1 mAb can be significantly enhanced by A2A antagonists. We have therefore revealed a potentially novel biomarker for the efficacy of anti–PD-1 that warrants further investigation in patients. Because our studies used SYN-115, a drug that has already undergone phase IIb testing in Parkinson disease, our findings have immediate translational relevance for patients with cancer. Cancer Immunol Res; 3(5); 506–17. ©2015 AACR.

Chimeric antigen receptors (CARs) have been used extensively in adoptive immunotherapy to modify T lym- phocytes (CTLs), conferring the effector abilities of these cells towards a tumor-associated antigen (TAA). However, the ability of a CAR to redirect the effector function in a range of immune cells has not been well characterized, mainly due to the limitations in current genetic modification techniques. To overcome these limitations, we used the rapid technique of electroporation to transiently modify a macrophage, CD4 + T and CD8 + T cell line to express a CAR. This CAR consisted of an anti-ErbB2 extracellular single chain variable fragment region linked to the intracellular signaling domain compris- ing CD28-CD3ζ. The ability of three different promoters (CMV, Vav and LTR) to drive CAR expression was compared within each of the cell lines. CAR expression was highest under the CMV promoter in all cell lines, with expression rang- ing from 20-80%. We subsequently performed functional analysis of these CMV-CAR expressing cells, and observed an- tigen-specific release of IFN-γ from the CD8 + and CD4 + T cell lines. In addition, antigen-specific release of both IL-2 and IL-17 was also detected from the CD4 + T cell line, EL4. Overall this investigation demonstrated the feasibility of elec- troporation to compare promoter activity, induce rapid expression and subsequent function of a CAR in a number of he- matopoietic cell lines.

CD73 inhibits antitumor immunity through the activation of adenosine receptors expressed on multiple immune subsets. CD73 also enhances tumor metastasis, although the nature of the immune subsets and adenosine receptor subtypes involved in this process are largely unknown. In this study, we revealed that A 2A /A 2B receptor antagonists were effective in reducing the metastasis of tumors expressing CD73 endogenously (4T1.2 breast tumors) and when CD73 was ectopically expressed (B16F10 melanoma). A 2A −/− mice were strongly protected against tumor metastasis, indicating that host A 2A receptors enhanced tumor metastasis. A 2A blockade enhanced natural killer (NK) cell maturation and cytotoxic function in vitro, reduced metastasis in a perforin-dependent manner, and enhanced NK cell expression of granzyme B in vivo, strongly suggesting that the antimetastatic effect of A 2A blockade was due to enhanced NK cell function. Interestingly, A 2B blockade had no effect on NK cell cytotoxicity, indicating that an NK cell-independent mechanism also contributed to the increased metastasis of CD73 + tumors. Our results thus revealed that CD73 promotes tumor metastasis through multiple mechanisms, including suppression of NK cell function. Furthermore, our data strongly suggest that A 2A or A 2B antagonists may be useful for the treatment of metastatic disease. Overall, our study has potential therapeutic implications given that A 2A /A 2B receptor antagonists have already entered clinical trials in other therapeutic settings.

Chimeric antigen receptor (CAR) T cells have been highly successful in treating hematological malignancies, including acute and chronic lymphoblastic leukemia. However, treatment of solid tumors using CAR T cells has been largely unsuccessful to date, partly because of tumor-induced immunosuppressive mechanisms, including adenosine production. Previous studies have shown that adenosine generated by tumor cells potently inhibits endogenous antitumor T cell responses through activation of adenosine 2A receptors (A2ARs). Herein, we have observed that CAR activation resulted in increased A2AR expression and suppression of both murine and human CAR T cells. This was reversible using either A2AR antagonists or genetic targeting of A2AR using shRNA. In 2 syngeneic HER2+ self-antigen tumor models, we found that either genetic or pharmacological targeting of the A2AR profoundly increased CAR T cell efficacy, particularly when combined with PD-1 blockade. Mechanistically, this was associated with increased cytokine production of CD8+ CAR T cells and increased activation of both CD8+ and CD4+ CAR T cells. Given the known clinical relevance of the CD73/adenosine pathway in several solid tumor types, and the initiation of phase I trials for A2AR antagonists in oncology, this approach has high translational potential to enhance CAR T cell efficacy in several cancer types.

Adaptive immunity, involving distinctive antibody- and cell-mediated responses to specific antigens based on "memory" of previous exposure, is a hallmark of higher vertebrates. It has been argued that adaptive immunity arose rapidly, as articulated in the "big bang theory" surrounding its origins, which stresses the importance of coincident whole-genome duplications. Through a close examination of the key molecules and molecular processes underpinning adaptive immunity, this review suggests a less-extreme model, in which adaptive immunity emerged as part of longer evolutionary journey. Clearly, whole-genome duplications provided additional raw genetic materials that were vital to the emergence of adaptive immunity, but a variety of other genetic events were also required to generate some of the key molecules, whereas others were preexisting and simply co-opted into adaptive immunity.

Adoptive immunotherapy utilising chimeric antigen receptor (CAR) T cells has demonstrated high success rates in hematological cancers, with up to 90% complete remission being reported in patients with acute lymphoblastic leukemia (ALL). However, this success is not currently transferrable to solid malignancies due in part to the immunosuppressive tumor microenvironment limiting CAR T cell responses. Given that activation of the 4-1BB (CD137) pathway using an agonistic α-4-1BB antibody is known to provide strong co-stimulatory signals for augmenting and diversifying T cell responses, we hypothesized that the combination of α-4-1BB and CAR T cell therapy would result in improved anti-tumor responses. Using a human-Her2 self-antigen mouse model, we found that α-4-1BB significantly enhanced CAR T cell efficacy directed against the Her2 antigen in two different established solid tumor settings. Investigation into the mechanism revealed increased expression of IFNγ and the proliferation marker Ki67 by tumor-infiltrating CAR T cells when combined with α-4-1BB. The importance of IFNγ was demonstrated in vivo where synergistic effects of the combination therapy were abrogated when IFNγ was depleted. Strikingly, we also found that α-4-1BB significantly reduced host immunosuppressive cells at the tumor site including regulatory T cells (Tregs) and myeloid derived suppressor cells (MDSCs), correlating with an increased therapeutic response. Investigation in immunocompromised RAG -/- mice showed reduced synergistic effects following the combination therapy, suggesting some contribution by host T cells. Furthermore, we found increased frequency of endogenous T cells and dendritic cells in the tumor-draining lymph nodes, supporting potential engagement of host immune cells. We therefore conclude α-4-1BB has a multifunctional role for enhancing CAR T cell responses including engagement of endogenous immune cells, and this combination approach has high translational potential given that CAR T cell therapy has recently been FDA approved for pediatric ALL, and that α-4-1BB is currently being tested in clinical trials against various types of cancer. Citation Format: Sherly Mardiana, Liza B. John, Michael H. Kershaw, Paul A. Beavis, Phillip K. Darcy. A multifunctional role for adjuvant anti-4-1BB therapy in augmenting antitumor responses by CAR T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 1530.

Members of the Ikaros family of transcription factors are important for immune system development. Analysis of Ikaros-related genes from a range of species suggests the Ikaros family derived from a primordial gene, possibly related to the present-day protostome Hunchback genes. This duplicated before the divergence of urochordates to produce two distinct lineages: one that generated the Ikaros factor-like (IFL) 2 genes of urochordates/lower vertebrates and the Pegasus genes of higher vertebrates, and one that generated the IFL1 genes of urochordates/lower vertebrates, the IKFL1 and IKFL2 genes of agnathans and the remaining four Ikaros members of higher vertebrates. Expansion of the IFL1 lineage most likely occurred via the two intervening rounds of whole genome duplication. A proposed third whole genome duplication in teleost fish produced a further increase in complexity of the gene family with additional Pegasus and Eos members. These findings question the use of IFL sequences as evidence for the existence of adaptive immunity in early chordates and vertebrates. Instead, this study is consistent with a later emergence of adaptive immunity coincident with the appearance of the definitive lymphoid markers Ikaros, Aiolos, and Helios.

Advanced stages of cancer often involve multiple tumors in different locations in the body. These tumors are associated with a microenvironment that can influence tumor responses to immunotherapy. Whether tumors and their disparate microenvironment can interact together at distance in a multiple tumor setting, through a form of cross-talk, and affect their responses to immunotherapy has never been described. Our study investigated the cross-talk between two tumors with disparate microenvironments in a mouse model. We demonstrated that immunosuppressive visceral tumors could influence distant subcutaneous (SC) tumors to render them resistant to immunotherapy. We observed distinct modifications in the SC tumor microenvironment following cross-talk with kidney tumors that exhibit a type-2 macrophage-related immunosuppressive microenvironment. Indeed, when a concomitant kidney tumor was present in the mouse, the SC tumors were highly infiltrated with M2 macrophages and had a reduced T cell and NK cell effector immune profile. Finally, blocking the M2-associated chemokine CCL2 or depleting macrophages, significantly improved the effect of immunotherapy on growth of SC tumors in the presence of concomitant kidney tumors. This work emphasizes the potential negative influence that a tumor, with a strong immunosuppressive microenvironment, can exert on distant tumors that would normally be treatment-responsive. This report may lead to a new vision of the prioritization in the treatment of advanced metastatic cancer.

Genetic modification of primary mouse T cells with chimeric antigen receptors (CAR) has emerged as an important tool for optimizing adoptive T cell immunotherapy strategies. However, limitations in current protocols for generating highly pure and sufficient numbers of enriched effector and helper CAR(+) T cell subsets remain problematic. Here, we describe a new retroviral transduction protocol for successfully generating transduced CD8(+) and CD4(+) T lymphocytes for in vitro and in vivo characterization.

Genetic modification of primary mouse T cells with chimeric antigen receptors (CAR) has emerged as an important tool for optimizing adoptive T cell immunotherapy strategies. However, limitations in current protocols for generating highly pure and sufficient numbers of enriched effector and helper CAR(+) T cell subsets remain problematic. Here, we describe a new retroviral transduction protocol for successfully generating transduced CD8(+) and CD4(+) T lymphocytes for in vitro and in vivo characterization.

The presence of an immunosuppressive microenvironment can limit the full potential of adoptive T cell immunotherapy. However, specific blockade of the PD-1 immunosuppressive pathway can significantly enhance the function of gene-modified T cells expressing a chimeric antigen receptor (CAR) leading to enhanced tumor eradication.

The tumor microenvironment is a complex assortment of cells that includes a variety of leukocytes. The overall effect of the microenvironment is to support the growth of tumors and suppress immune responses. Immunotherapy is a highly promising form of cancer treatment, but its efficacy can be severely compromised by an immunosuppressive tumor microenvironment. Chemotherapy and radiation treatment can mediate tumor reduction through cytotoxic effects, but it is becoming increasingly clear that these forms of treatment can be used to modify the tumor microenvironment to liberate tumor antigens and decrease immunosuppression. Chemotherapy and radiotherapy can be used to modulate the tumor microenvironment to enhance immunotherapy.

Purpose: To determine the antitumor efficacy and toxicity of a novel combination approach involving adoptive T-cell immunotherapy using chimeric antigen receptor (CAR) T cells with an immunomodulatory reagent for blocking immunosuppression. Experimental Design: We examined whether administration of a PD-1 blocking antibody could increase the therapeutic activity of CAR T cells against two different Her-2+ tumors. The use of a self-antigen mouse model enabled investigation into the efficacy, mechanism, and toxicity of this combination approach. Results: In this study, we first showed a significant increase in the level of PD-1 expressed on transduced anti-Her-2 CD8+ T cells following antigen-specific stimulation with PD-L1+ tumor cells and that markers of activation and proliferation were increased in anti-Her-2 T cells in the presence of anti-PD-1 antibody. In adoptive transfer studies in Her-2 transgenic recipient mice, we showed a significant improvement in growth inhibition of two different Her-2+ tumors treated with anti-Her-2 T cells in combination with anti-PD-1 antibody. The therapeutic effects observed correlated with increased function of anti-Her-2 T cells following PD-1 blockade. Strikingly, a significant decrease in the percentage of Gr1+ CD11b+ myeloid-derived suppressor cells (MDSC) was observed in the tumor microenvironment of mice treated with the combination therapy. Importantly, increased antitumor effects were not associated with any autoimmune pathology in normal tissue expressing Her-2 antigen. Conclusion: This study shows that specifically blocking PD-1 immunosuppression can potently enhance CAR T-cell therapy that has significant implications for potentially improving therapeutic outcomes of this approach in patients with cancer. Clin Cancer Res; 19(20); 5636–46. ©2013 AACR . See related article by Morales-Kastresana, et al., [p. 5546][1] This article is featured in Highlights of This Issue, [p. 5543][2] [1]: /lookup/volpage/19/5546?iss=20 [2]: /lookup/volpage/19/5543?iss=20

The tumor microenvironment can promote tumor growth and reduce treatment efficacy. Tumors can occur in many sites in the body, but how surrounding normal tissues at different anatomical sites affect tumor microenvironments and their subsequent response to therapy is not known.We demonstrated that tumors from renal, colon, or prostate cell lines in orthotopic locations responded to immunotherapy consisting of three agonist antibodies, termed Tri-mAb, to a much lesser extent than the same tumor type located subcutaneously. A tissue-specific response to Tri-mAb was confirmed by ex vivo separation of subcutaneous (SC) or orthotopic tumor cells from stromal cells, followed by reinjection of tumor cells into the opposite site. Compared with SC tumors, orthotopic tumors had a microenvironment associated with a type 2 immune response, related to immunosuppression, and an involvement of alternatively activated macrophages in the kidney model. Orthotopic kidney tumors were more highly vascularized than SC tumors. Neutralizing the macrophage- and Th2-associated molecules chemokine (C-C motif) ligand 2 or interleukin-13 led to a significantly improved therapeutic effect. This study highlights the importance of the tissue of implantation in sculpting the tumor microenvironment. These are important fundamental issues in tumor biology and crucial factors to consider in the design of experimental models and treatment strategies.

Aim: The aim of the current study was to fully elucidate the functions of T cells genetically modified with an erbB2-specific chimeric antigen receptor (CAR). Material & methods: In this study, key functional parameters of CAR T cells were examined following antigen-specific stimulation of the chimeric anti-erbB2 receptor. Results: Gene-modified T cells produced the cytokines IFN-γ, IL-2, IL-4, IL-10, TNF-α and IL-17, and the chemokine RANTES upon CAR ligation. A multifunctional capacity of these CAR T cells was also demonstrated, where 13.7% of cells were found to simultaneously express IFN-γ and CD107a, indicative of cytolytic granule release. In addition, the CAR T cells were able to respond to a greater degree on the second ligation of CAR, which has not been previously shown. IFN-γ secretion levels were significantly higher on second ligation than those secreted following initial ligation. CAR-expressing T cells were also demonstrated to lyze erbB2-expressing tumor cells in the absence of activity against bystander cells not expressing the erbB2 antigen, thereby demonstrating exquisite specificity. Conclusion: This study demonstrates the specificity of CAR gene-engineered T cells and their capacity to deliver a wide range of functions against tumor cells with an enhanced response capability after initial receptor engagement.

Genetic engineering of cellular function holds much promise for the treatment of a variety of diseases including gene deficiencies and cancer. However, engineering the full complement of cellular functions can be a daunting genetic exercise since many molecular triggers need to be activated to achieve complete function. In the case of T cells, genes encoding chimeric antigen receptors (CARs) covalently linking antibodies to cytoplasmic signaling domains can trigger some, but not all, cellular functions against cancer cells. To date, relatively few CAR formats have been investigated using a candidate molecule approach, in which rationally chosen molecules were trialed one by one. Therefore, to expedite this arduous process we developed an innovative screening method to screen many thousands of CAR formats to identify genes able to enhance the anticancer ability of T cells. We used a directional in-frame library of randomly assembled signaling domains in a CAR specific for the tumor associated antigen erbB2. Several new and original CARs were identified, one of which had an enhanced ability to lyse cancer cells and inhibit tumor growth in mice. This study highlights novel technology that could be used to screen a variety of molecules for their capacity to induce diverse functions in cells.

Malignant cells are susceptible to viral infection and consequent cell death. Virus-induced cell death is endowed with features that are known to stimulate innate and adaptive immune responses. Thus danger signals emitted by cells succumbing to viral infection as well as viral nucleic acids are detected by specific receptors, and tumor cell antigens can be routed to professional antigen-presenting cells. The anticancer immune response triggered by viral infection is frequently insufficient to eradicate malignancy but may be further amplified. For this purpose, transgenes encoding cytokines as co-stimulatory molecules can be genetically engineered into viral vectors. Alternatively, or in addition, it is possible to use monoclonal antibodies that either block inhibitory receptors of immune effector cells, or act as agonists for co-stimulatory receptors. Combined strategies are based on the ignition of a local immune response at the malignant site plus systemic immune boosting. We have recently reported examples of this approach involving the Vaccinia virus or Semliki Forest virus, interleukin-12 and anti-CD137 monoclonal antibodies.