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Since their initial description by Elie Metchnikoff, phagocytes have sparked interest in a variety of biologic disciplines. These important cells perform central functions in tissue repair and immune activation as well as tolerance. Myeloid cells can be immunoinhibitory, particularly in the tumor microenvironment, where their presence is generally associated with poor patient prognosis. These cells are highly adaptable and plastic, and can be modulated to perform desired functions such as antitumor activity, if key programming molecules can be identified. Human clear cell renal cell carcinoma (ccRCC) is considered immunogenic; yet checkpoint blockades that target T cell dysfunction have shown limited clinical efficacy, suggesting additional layers of immunoinhibition. We previously described "enriched-in-renal cell carcinoma" (erc) DCs that were often found in tight contact with dysfunctional T cells. Using transcriptional profiling and flow cytometry, we describe here that ercDCs represent a mosaic cell type within the macrophage continuum co-expressing M1 and M2 markers. The polarization state reflects tissue-specific signals that are characteristic of RCC and renal tissue homeostasis. ErcDCs are tissue-resident with increasing prevalence related to tumor grade. Accordingly, a high ercDC score predicted poor patient survival. Within the profile, therapeutic targets (VSIG4, NRP1, GPNMB) were identified with promise to improve immunotherapy.

Background: Programmed death ligand (PD-L1)-based immune checkpoint blockade therapy for metastatic renal cell carcinoma (RCC) achieves significant response rates in a subgroup of patients. The relevance of PD-L1 gene regulation for disease outcome is not clear., Objective: To evaluate PD-L1 expression and its dependence on interferon-γ (IFN-γ) in RCC cell lines and tissues in relation to disease outcome., Methods and Patients: Regulation of PD-L1-mRNA and PD-L1 protein was studied in cell lines from clear cell RCC (ccRCC) and papillary RCC (pRCC) by quantitative RT-PCR and Western-blot analysis. PD-L1-mRNA correlation and gene-set enrichment analysis (GSEA) of the IFN-γ pathway were conducted with RNA-Seq from ccRCC, pRCC, and skin cutaneous melanoma (SKCM) tissue. In addition, patient overall survival (OS) and disease-free survival (DFS) (cBioPortal for Cancer Genomics) were considered., Results: In ccRCC-like cell lines, PD-L1 was induced by canonical IFN-γ signaling, whereas in a pRCC-like cell line, PD-L1 was refractory towards IFN-γ signaling. In ccRCC and SKCM tissues, GSEA revealed significant IFN-γ pathway activation in tissue samples with high PD-L1-mRNA levels. This was not observed in pRCC tissue. ccRCC and SKMC patients with low PD-L1-mRNA levels had significantly shorter OS and DFS than those with high PD-L1-mRNA levels. In pRCC patients, no significant difference in OS and DFS with regard to PD-L1-mRNA tissue levels was obvious., Conclusions: The findings suggest that ccRCC and pRCC differ with respect to PD-L1 regulation by IFN-γ-signaling. High PD-L1-mRNA levels in tumor tissues with a positive IFN-γ signature favorably affect OS and DFS.

The relevance of NK cells in tumor control is well established in mouse models and human hematologic malignancies; however, their contribution to the control of human solid tumors remains disputed due to problems with in situ detection and reports of functional inactivity in the tumor milieu. In this study, we established a reliable in situ detection method for NK cells. Moreover, we performed analysis to elucidate mechanisms that impair NK-cell function in the tumor milieu and thereby identify therapeutic targets that allow recovery of NK-cell functionality. It was observed that NK cells from clear cell renal cell carcinoma (ccRCC), compared to NK cells from nontumor kidney and peripheral blood lymphocytes (PBLs), displayed conjoint phenotypic alterations and dysfunction induced by the tumor milieu, which were associated mechanistically with high levels of signaling attenuator diacylglycerol kinase (DGK)-α and blunted mitogen-activated protein kinase pathway activation (ERK1/2, Jun kinase). Reinstating NK-cell functionality was possible by DGK inhibition or brief IL-2 culture, interventions that de-repressed the ERK pathway. The extent of alteration and magnitude of recovery could be linked to NK-cell frequency within ccRCC-infiltrating lymphocytes, possibly explaining the observed survival benefit of patients with NK(high) tumors. In conclusion, DGK-mediated dampening of the ERK pathway ensuing in NK-cell dysfunction was identified as an important escape mechanism in ccRCC. DGK and the ERK pathway thus emerge as promising therapeutic targets to restore suppressed NK-cell activity for the improvement of antitumor immunity., (© 2014 UICC.)

CD8(+) tumor-infiltrating T cells (CD8-TILs) are found in many types of tumors including human renal cell carcinoma. However, tumor rejection rarely occurs, suggesting limited functional activity in the tumor microenvironment. In this study, we document that CD8-TILs are unresponsive to CD3 stimulation, showing neither lytic activity, nor lytic granule exocytosis, nor IFN-γ production. Mechanistically, no deficits in TCR proximal signaling molecules (lymphocyte-specific protein tyrosine kinase, phospholipase Cγ) were identified. In contrast, distal TCR signaling was suppressed, as T cells of TILs showed strongly reduced steady-state phosphorylation of the MAPK ERK and were unable to increase phosphorylation of ERK and JNK as well as AKT and AKT client proteins (IκB, GSK3) after stimulation. These deficits were tumor-specific as they were not observed in CD8(+) T cells infiltrating non-tumor kidney areas (CD8(+) non-tumor kidney-infiltrating lymphocytes; CD8-NILs). Diacylglycerol kinase-α (DGK-α) was more highly expressed in CD8-TILs compared with that in CD8-NILs, and its inhibition improved ERK phosphorylation and lytic granule exocytosis. Cultivation of TILs in low-dose IL-2 reduced DGK-α protein levels, increased steady-state phosphorylation of ERK, improved stimulation-induced phosphorylation of ERK and AKT, and allowed more CD8-TILs to degranulate and to produce IFN-γ. Additionally, the protein level of the AKT client molecule p27kip, an inhibitory cell cycle protein, was reduced, whereas cyclin E, which promotes G1-S phase transition, was increased. These results indicate that the tumor-inflicted deficits of TILs are reversible. DGK-α inhibition and provision of IL-2 signals could be strategies to recruit the natural CD8(+) T cells to the anti-tumor response and may help prevent inactivation of adoptively transferred T cells thereby improving therapeutic efficacy.

Clear cell renal cell carcinoma (ccRCC) is an aggressive and difficult to manage cancer. Immunotherapy has the potential to induce long-lasting regression in a small group of patients. However, severe side effects limit broad application which highlights the need for a marker to distinguish responder from nonresponder. TNMG staging, referring to tumor size, lymph node involvement, presence of metastasis, and grade of tumor differentiation, represents an important prognostic system but is not useful for predicting responders to immunotherapy. NK cells are potent antitumor effector cells, and a role as prognostic marker in some solid tumors has been suggested. As NK cells are responsive to various immune modifiers, they may be important mediators of patient response to immunotherapies, in particular those including IL-2. We report that the NK cell percentage within RCC-infiltrating lymphocytes, as determined by flow cytometry, allows ccRCC subgrouping in NK(high)/NK(low) tissues independent of TNMG classification. Quantitative reverse transcriptase polymerase chain reaction using whole-tissue RNA identified four markers (NKp46, perforin, CX(3)CL1, and CX(3)CR1) whose transcript levels reproduced the NK(high)/NK(low) tissue distinction identified by flow cytometry with high selectivity and specificity. Combined in a multiplex profile and analyzed using neural network, the accuracy of predicting the NK(high)/NK(low) groups was 87.8%, surpassing that of each single marker. The tissue transcript signature, based on a robust high-throughput methodology, is easily amenable to archive material and clinical translation. This now allows the analysis of large patient cohorts to substantiate a role of NK cells in cancer progression or response to immunotherapy.

Tissue dendritic cells (DCs) may influence the progression of renal cell carcinoma (RCC) by regulating the functional capacity of antitumor effector cells. DCs and their interaction with T cells were analyzed in human RCC and control kidney tissues. The frequency of CD209(+) DCs in RCCs was found to be associated with an unfavorable T(H)1 cell balance in the tissue and advanced tumor stages. The CD209(+) DCs in RCC were unusual because most of them co-expressed macrophage markers (CD14, CD163). The phenotype of these enriched-in-renal-carcinoma DCs (ercDCs) could be reiterated in vitro by carcinoma-secreted factors (CXCL8/IL-8, IL-6, and vascular endothelial growth factor). ErcDCs resembled conventional DCs in costimulatory molecule expression and antigen cross-presentation. They did not suppress cognate cytotoxic T-lymphocyte function and did not cause CD3ζ down-regulation, FOXP3 induction, or T-cell apoptosis in situ or in vitro; thus, they are different from classic myeloid-derived suppressor cells. ErcDCs secreted high levels of metalloproteinase 9 and used T-cell crosstalk to increase tumor-promoting tumor necrosis factor α and reduce chemokines relevant for T(H)1-polarized lymphocyte recruitment. This modulation of the tumor environment exerted by ercDCs suggests an immunologic mechanism by which tumor control can fail without involving cytotoxic T-lymphocyte inhibition. Pharmacologic targeting of the deviated DC differentiation could improve the efficacy of immunotherapy against RCC., (Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Purpose: Adoptive therapy with genetically engineered T cells carrying redirected antigen specificity is a new option for the treatment of cancer. This approach is not yet available for metastatic renal cell carcinoma (RCC), due to the scarcity of therapeutically useful reagents. We analyzed tumor-infiltrating lymphocytes (TIL) from RCC to identify T-cell specificities with shared tumor-specific recognition to develop T-cell receptor (TCR)-engineered T lymphocytes for adoptive therapy of RCC., Experimental Design: We established a T-cell clone from TIL that recognized a human leukocyte antigen (HLA)-A2-restricted tumor antigen. The TCR alpha- and beta-chain genes were isolated, modified by codon optimization and murinization, and retrovirally transduced into peripheral blood lymphocytes (PBL). A TCR-expressing indicator line (B3Z-TCR53) was established to screen for antigen prevalence in RCC, other malignancies, and normal cell counterparts., Results: TCR53-engineered PBL recapitulated the specificity of the TIL and showed tumor-specific HLA-A2-restricted effector activities (IFN-gamma, tumor necrosis factor-alpha, interleukin-2, macrophage inflammatory protein-1beta, cytotoxicity). PBL-TCR53 of healthy donors and RCC patients exhibited similar transduction efficiency, expansion, and polyfunctional profile. Using B3Z-TCR53 cells, 130 tumor and normal cells were screened and shared TCR53 peptide: MHC expression was found in >60% of RCC and 25% of tumor lines of other histology, whereas normal tissue cells were not recognized., Conclusions: To date, TCR53 is the only TCR with shared HLA-A2-restricted recognition of RCC. It fulfills the criteria for utilization in TCR gene therapy and advances T cell-based immunotherapy to patients with RCC and other malignancies expressing the TCR ligand.

The clear evidence that tumor-infiltrating lymphocytes with anti-tumor activity exist in situ raises the question why renal cell carcinomas (RCCs) progress in vivo. A complex array of factors and pathways has been identified that impinges on innate and adaptive effector cells thereby inhibiting their activity against RCCs. The current picture of suppressive mechanisms that contribute to the failure of the immune system to control RCCs is reviewed here. Understanding these complex host-tumor interactions has broad implications for successful application of cytokine therapy and other forms of immunotherapy for RCC.

Purpose: Renal cell carcinoma harbors high numbers of infiltrating lymphocytes with apparent limited efficacy in tumor control. This study focused on the natural killer (NK) cells infiltrating renal cell carcinoma., Experimental Design: Tumor-infiltrating lymphocytes (TIL) were isolated from renal cell carcinoma and analyzed for NK cell frequency and phenotype (n = 34). NK cells were enriched and tested for effector function., Results: Two renal cell carcinoma subtypes were identified, one containing high (>20% of the lymphocyte population, n = 14), the other low (<20%, n = 20), NK cell numbers. NK cells of both groups were noncytolytic ex vivo but differed in CD16 and cytotoxic effector molecule expression as well as in their capacity to acquire cytotoxic activity: The majority of NK cells from tumors with high NK cell content (high NK-TIL) were CD16(bright), whereas few CD16bright NK cells were found in tumors with low NK cell frequencies (low NK-TIL). The CD16 dichotomy correlated with different capacities to develop cytotoxicity after short-term activation with interleukin-2 ex vivo: Low NK-TIL remained noncytolytic against K562 and unresponsive to signals via the activating receptor NKp46 despite expression of receptor and adaptor molecules. In contrast, high NK-TIL acquired cytotoxic function. As described for peripheral CD16bright NK cells, NK cells from high-NK tumors showed high per cell expression of granzyme A, granzyme B, and perforin. NK cells from low NK-TIL resembled CD16(neg/dim) peripheral NK cells with few cytotoxin+ cells and lower expression of perforin., Conclusion: The extent of NK cell infiltration and the expression of markers (CD16 and cytotoxins) predict the functional capacity of NK cells infiltrating renal cell carcinoma and can be used to characterize subgroups of renal cell carcinoma.

Initial vaccine developments for renal cell carcinoma (RCC) have concentrated on cell-based approaches in which tumor cells themselves provide mixtures of unknown tumor-associated antigens as immunizing agents. Antigens derived from autologous tumors can direct responses to molecular composites characteristic of individual tumors, whereas antigens derived from allogeneic tumor cells must be commonly shared by RCC. Three types of cell-based vaccine for RCC have been investigated: isolated tumor cell suspensions, gene modified tumor cells and dendritic cells (DCs) expressing RCC-associated antigens. Approaches using genetic modification of autologous RCC have included ex vivo modification of tumor cells or modification of tumors in vivo. We have used gene-modification of allogeneic tumor cell lines to create generic RCC vaccines. More recently, emphasis has shifted to the use of DCs as cell-based vaccines for RCC. DCs have moved to a position of central interest because of their excellent stimulatory capacity, combined with their ability to process and present antigens to both naive CD4 and CD8 cells. The long impasse in identifying molecular targets for specific immunotherapy of RCC is now rapidly being overcome through the use of tools and information emerging from human genome research. Identification of candidate molecules expressed by RCC using cDNA arrays, combined with protein arrays and identification of peptides presented by MHC molecules, allow specific vaccines to be tailored to the antigenic profile of individual tumors, providing the basis for development of patient-specific vaccines.

Adoptive T cell therapy of renal cell carcinoma (RCC) is limited by the difficulty in generating sufficient numbers of RCC-reactive T cells in vitro. To circumvent this problem, we cloned T cell receptor (TCR) alpha and beta chains from a tumor-infiltrating lymphocyte clone specific for an RCC tumor antigen and transferred the TCR into human T cell lines and primary T lymphocytes. Efficient TCR expression in primary T lymphocytes was obtained only with a mouse myeloproliferative sarcoma virus (MPSV)-based retroviral vector, not with a Moloney murine leukemia virus (MLV)-based vector, although both viral supernatants were similar in titer, as shown by analysis of copy number integration in transduced T cells. Reverse transcription-polymerase chain reaction analysis revealed a higher amount of TCR-encoding transcripts when T cells were transduced with the MPSV vector in comparison with the MLV vector, indicating that high TCR expression levels can be achieved by appropriate cis-regulatory vector elements. The biological activity of the transferred TCR was shown by specific lysis of RCC cells ((51)Cr release assay) and by interferon gamma and tumor necrosis factor alpha release (enzyme-linked immunosorbent assay) in an antigen-specific and HLA-A*0201-restricted fashion. Comparison of the redirected T lymphocytes with the original tumor-infiltrating lymphocyte clone revealed similar killing and cytokine secretion capabilities. The functional activity of TCR-redirected T lymphocytes was stable over time. The results demonstrate that use of an optimized retroviral vector yielded a high TCR transduction efficiency and stable and high TCR expression in primary human T lymphocytes and redirected their specificity toward RCC cells.

Purpose: A renal cell carcinoma (RCC) line, RCC-26, has been identified as a suitable candidate for development of an allogeneic tumor cell vaccine based on its expression of a variety of tumor-associated antigens (TAA). To improve immunogenicity, RCC-26 cells were genetically engineered to express CD80 alone or in combination with interleukin (IL)-2 or IL-7. The effect of these modifications on proliferation, function, and survival of autologous and allogeneic tumor-specific CTLs was assessed., Experimental Design: RCC-26 sublines expressing different transgenes were tested for their capacity to reactivate cytokine secretion and cytotoxicity in autologous tumor-infiltrating lymphocytes, to improve proliferation and survival of tumor-associated T cells present in autologous peripheral blood, and to induce tumor-associated responses in naive allogeneic lymphocytes. The expression of several common TAA was quantitated in the RCC-26 sublines using reverse transcription-PCR to identify surrogate markers for immune monitoring in clinical trials., Results: Gene-modified RCC-26 cells showed enhanced immunogenicity. CD80 expression was necessary to induce RCC-associated CTL in blood of healthy allogeneic donors. It also improved proliferation of autologous effector-memory T cells. Further enhancement was achieved with IL-2 through induction of the antiapoptosis protein Bcl-x(L). The candidate vaccine lines overexpressed several common TAA that are suitable markers for immune monitoring., Conclusions: RCC-26 cells coexpressing CD80 and cytokine transgenes display improved immunogenic characteristics, supporting their use as allogeneic tumor cell vaccines for HLA-A2-matched patients with metastatic RCC.

Lymphokine activated killer (LAK) cells represent mixtures of natural killer (NK) and non-MHC-restricted CTLs that have the capacity to lyse a variety of tumor cells and MHC class I-negative target cells. Although it is clear that NK cells are negatively regulated by interactions with MHC class Ia or class Ib molecules, the regulation of LAK-derived T cells has not been clarified to date. In the studies presented here, we demonstrate that IFN-gamma treatment of tumor cells can induce their resistance to LAK-derived T cells in a manner similar to that seen for NK cells. The IFN-gamma-mediated suppression of LAK activity correlates with increased MHC class I expression by the tumor cells, and the inhibition of LAK-mediated cytotoxicity can be reversed in the presence of class I-specific antibody. Furthermore, the expression of MHC class Ia or class Ib molecules in class I-negative cell lines can reduce their susceptibility to LAK-mediated cytotoxicity. This principle of negative regulation by MHC class I molecules applies to LAK-derived T cells generated from peripheral blood lymphocytes of renal cell carcinoma patients and healthy, control donors. Although LAK-derived T cells can be inhibited in their lytic activity through interactions with MHC class Ia and class Ib molecules, they do not express the known inhibitory receptors specific for these ligands that are found on NK cells. Apparently, LAK-derived T cells are negatively regulated by as yet undefined inhibitory receptors.