High expression of adhesion molecules/activation markers with little interleukin-2, interferon gamma, and tumor necrosis factor beta gene activation in fresh tumor-infiltrating lymphocytes from lung adenocarcinoma

Challenges and prospects of immunotherapy as cancer treatment

The concept of cancer immunotherapy stems from the proposed function of the immune system, called immunosurveillance, to protect against growing tumors. Due to genetic aberrations, tumor cells display an altered repertoire of MHC-associated peptides that can lead to the activation of immune cells able to eliminate the transformed cells. In some instances, under the pressure of the immune system, both the tumor and its microenvironment are shaped and immune-resistant tumor variants are selected initiating the process of cancer immunoediting. This can impair not only host-generated immunosurveillance, but also attempts to harness the immune response for therapeutic purposes, namely immunotherapy. Rather than being an exhaustive review of the different approaches of cancer immunotherapy, the focus of this review is to provide the reader with future challenges of the field by proposing 'second generation' immunotherapy approaches that take into account immunosubversive mechanisms adopted by tumor cells. After an introduction on the process of immunosurveillance and immunoescape we will analyze why current immunotherapy approaches have not fulfilled their promise and will finish by summarizing what are the challenges for future approaches.

Immune resistance orchestrated by the tumor microenvironment

It is now little disputed that most if not all cancer cells express antigens that can be recognized by specific CD8(+) T lymphocytes. However, a central question in the field of anti-tumor immunity is why such antigen-expressing tumors are not spontaneously eliminated by the immune system. While in some cases, this lack of rejection may be due to immunologic ignorance, induction of anti-tumor T-cell responses in many patients has been detected in the peripheral blood, either spontaneously or in response to vaccination, without accompanying tumor rejection. These observations argue for the importance of barriers downstream from initial T-cell priming that need to be addressed to translate immune responses into clinical tumor regression. Recent data suggest that the proper trafficking of effector T cells into the tumor microenvironment may not always occur. T cells that do effectively home to tumor metastases are often found to be dysfunctional, pointing toward immunosuppressive mechanisms in the tumor microenvironment. T-cell anergy due to insufficient B7 costimulation, extrinsic suppression by regulatory cell populations, inhibition by ligands such as programmed death ligand-1, metabolic dysregulation by enzymes such as indoleamine-2,3-dioxygenase, and the action of soluble inhibitory factors such as transforming growth factor-beta have all been clearly implicated in generating this suppressive microenvironment. Identification of these downstream processes points to new therapeutic targets that should be manipulated to facilitate the effector phase of anti-tumor immune responses in concert with vaccination or T-cell adoptive transfer.

Immune suppression in the tumor microenvironment

The identification of tumor-expressed antigens that can be recognized by specific T lymphocytes has made it possible both to study the properties of T cells participating in anti-tumor immune responses in patients and also to develop antigen-specific immunotherapies as a treatment modality. Interestingly, moves toward intervention have proceeded at a faster pace than have investigations toward understanding. In melanoma in particular, many clinical trials of active immunization have been performed, and many of these have shown increases in tumor antigen-specific T cells circulating in the blood. However, clinical responses have been infrequent, arguing that mechanisms of resistance downstream from initial T cell priming may be dominant in many cases. In fact, may patients show spontaneous generation of immune effector cells and/or antibodies, implying that the priming phase has occurred already in such individuals even without vaccination. Recent attention has turned toward mechanisms of immune evasion at the effector phase of the anti-tumor immune response, predominantly within the tumor microenvironment. Evidence is accumulating that T cell-intrinsic hyporesponsiveness or anergy, extrinsic suppression by regulatory cell populations, inhibitory ligands such as PD-L1, soluble factors such as TGF-beta, and the activity of nutrient-catabolizing enzymes such as indoleamine 2,3-dioxygenase (IDO), may contribute to immune escape in different settings. Murine preclinical models have shown that interfering with each of these processes can translate into T cell-mediated tumor control. Clinical studies to estimate the frequency of specific immune evasion mechanisms in individual patients, to correlate specific events with clinical outcome, and to develop strategies to counter resistance mechanisms should receive a high priority.

Identifying and overcoming immune resistance mechanisms in the melanoma tumor microenvironment

The continually growing list of defined tumor antigens is broadening the potential applicability of tumor antigen-targeted cancer therapies. Although cancer vaccines and adoptive T-cell transfer have been shown to increase the frequency of circulating tumor antigen-specific T cells, these approaches cause clinical responses in a few patients. In melanoma, approximately one third of metastatic lesions contain activated T cells, including those specific for tumor antigens, arguing that the priming phase has occurred already in such individuals even without vaccination. These observations indicate that tumor resistance to immune destruction may dominate in many instances, arguing for a thorough analysis of the melanoma tumor microenvironment in individual patients. Recent work has suggested that T-cell anergy, the influence of CD4+ CD25+ regulatory T cells, the expression of inhibitory ligands, such as PD-L1, and the activity of nutrient-catabolizing enzymes, such as indoleamine 2,3-dioxygenase, may be involved. Preclinical murine models have shown that interfering with each of these processes can translate into T-cell-mediated tumor control. Importantly, each of these targets is amenable to clinical manipulation. Clinical translation of these approaches to counter negative regulation of antitumor immunity should receive high priority.

Current concepts of tumor-infiltrating lymphocytes in human malignancies

Tumor-infiltrating lymphocytes (TILs) develop as manifestations of the recognition and defense against malignant cells by the host immune system. TILs were literally defined as "tumor-infiltrating lymphocytes", which a posteriori locate within the tumor tissues. Although such cells can be found, they fail to control the growth of tumor. Many have proposed diverse mechanisms for dysfunction of TILs with regard to the roles of immunosurveillance against cancer. However, only a few cancer types, e.g. melanoma, have seen the benefits brought by activating these cells for immunotherapy. Functional defects of TILs have been linked to abnormalities of signaling molecules; however, there is conflicting data. The death of TILs was attributed to expression of cancer-derived FasL, PD-1 and RCAS1, and cancer-induced activation-induced cell death (AICD). Confirmed by studies using TILs and animal models, the compromise of tumor-specific immune responses was thought to result from not only mechanisms of clonal anergy but also exhaustion and/or deletion. Furthermore, functional cytotoxic CD8(+) TILs might be rendered incompetent by cancer-induced up-regulation of inhibitory NK receptors or proximal signaling abnormalities. Additionally, immune privilege was partly attributed to recruitment of regulatory T cells to the tumor sites. The failure of IL-2 signaling, which stands at the center of T cell functionalities, had been linked to the enzymatic activity of cancer-derived matrix metalloproteinases (MMPs). Finally, the exploitation of IDO expression, an important enzyme in pregnancy-related immunosuppression, by cancer cells might play a role in tumor immunity. The disparity of cancer types, origin, developmental stages and individual genetic backgrounds likely account for differences, or even contradictions, which might be the reason why immunotherapy works only on a few cancer types. Delineating the mechanisms behind functional defects of TILs can help not only boost chances of the development of a successful cure but understand the not fully identified roles played by immune system in the face of malignancies.

Glucose availability regulates IFN-gamma production and p70S6 kinase activation in CD8+ effector T cells

Differentiation of CD8+ T cells from the naive to the effector state is accompanied by changes in basal gene expression profiles that parallel the acquisition of effector functions. Among these are metabolism genes, and we now show that 2C TCR transgenic effector CD8+ T cells express higher levels of glycolytic enzymes and display greater glucose uptake, a higher glycolytic rate, and increased lactate production compared with naive cells. To determine whether glucose was required for effector T cell functions, we regulated glucose availability in vitro. Glucose deprivation strongly inhibited IFN-gamma gene expression, whereas IL-2 production was little affected. Inhibition correlated with diminished phosphorylation of p70S6 kinase and eIF4E binding protein 1 and a requirement for de novo protein synthesis, whereas other signaling pathways known to regulate IFN-gamma expression were unaffected. Together, our data reveal that optimal induction of IFN-gamma transcription is a glucose-dependent process, indicate that there are undefined factors that influence IFN-gamma expression, and have implications for regulation of the effector phase of CD8+ T cell responses in tissue microenvironments.

Human CD4+ T cells present within the microenvironment of human lung tumors are mobilized by the local and sustained release of IL-12 to kill tumors in situ by indirect effects of IFN-gamma

By implanting nondisrupted pieces of human lung tumor biopsy tissues into SCID mice, it has been possible to establish viable grafts of the tumor, as well as the tumor-associated microenvironment, including inflammatory cells, fibroblasts, tumor vasculature, and the extracellular matrix. Using this xenograft model, we have evaluated and characterized the effects of a local and sustained release of human rIL-12 (rhIL-12) from biodegradable microspheres. In response to rhIL-12, the human CD45+ inflammatory cells present within the xenograft mediate the suppression or the complete arrest of tumor growth in SCID mice. Analysis of the cellular events reveals that human CD4+ and CD8+ T cells are induced by rhIL-12 to produce and secrete IFN-gamma. Serum levels of human IFN-gamma in mice bearing rhIL-12-treated tumor xenografts correlate directly with the degree of tumor suppression, while neutralizing Abs to human IFN-gamma abrogate the IL-12-mediated tumor suppression. Gene expression profiling of tumors responding to intratumoral rhIL-12 demonstrates an up-regulation of IFN-gamma and IFN-gamma-dependent genes not observed in control-treated tumors. Genes encoding a number of proinflammatory cytokines, chemokines (and their receptors), adhesion molecules, activation markers, and the inducible NO synthase are up-regulated following the introduction of rhIL-12, while genes associated with tumor growth, angiogenesis, and metastasis are decreased in expression. NO contributes to the tumor killing because an inhibitor of inducible NO synthase prevents IL-12-induced tumor suppression. Cell depletion studies reveal that the IL-12-induced tumor suppression, IFN-gamma production, and the associated changes in gene expression are all dependent upon CD4+ T cells.

Tumor infiltrating lymphocytes and macrophages have a potential dual role in lung cancer by supporting both host-defense and tumor progression

A prerequisite to the developement of an efficient cell and/or gene therapy for lung cancer is a precise characterization of the inflammatory cell populations spontaneously present in the tumor stroma associated with this cancer. This study was designed to define the cytotoxic potential and the relationship with stroma development of tumor infiltrating lymphocytes (TIL) and tumor associated macrophages (TAM). Tumor samples from 48 patients undergoing surgery for non-small cell lung cancer (NSCLC) were analyzed, by immunohistochemistry and in situ hybridization, with a panel of antibodies and probes specific for cell proteins linked to cytotoxicity, cytokines, and growth factors, and the replication status of TIL and TAM was evaluated by in vivo 5-bromodeoxyuridine incorporation. It was shown that, in NSCLC: (1) tumor stroma inflammatory cells are mainly TIL (approximately 2/3) (among them, 80 % are T-cells) and TAM (approximately 1/3), with almost no natural killer (NK) cells, and a few dentritic cells; (2) TAM and TIL are poorly replicating, but mainly recruited to the tumor stroma; (3) more than half TAM show an antibody-dependent cytotoxic potential, and one third of T-cells are TIA-1 positive CD8 activated cytotoxic lymphocytes; (4) cancer cells from only a few tumor express HLA class I and II antigens; (5) TAM production of cytotoxic cytokines [interleukin-1alpha (IL-1alpha), IL-1beta, IL-6, tumor necrosis factor-alpha (TNF-alpha)] and of transforming growth factor-beta1 (TGF-beta1) is low, in contrast to their strong release of platelet-derived growth factor (PDGF). We concluded that, in NSCLC, TIL cytotoxicity is likely to be low because of a poor class I MHC expression by tumor cells, and TAM low production of cytotoxic cytokines is a major limit to their possible cytotoxic activity. In contrast, TAM may favor tumor progression by contributing to tumor stroma formation and angiogenesis through their release of PDGF, in conjunction with TGF-beta1 production by tumor cells.

T-cell subtypes in bronchoalveolar lavage fluid and in peripheral blood from patients with primary lung cancer

The changes in local immunology play an important role in lung cancer development. We used bronchoalveolar lavage fluid (BALF) and peripheral blood (PB) for the analysis of cell profiles in patients with primary lung cancer. Twenty-one patients with confirmed primary lung cancer and 13 healthy volunteers were investigated. All persons were smokers. The analysis of T-cell subsets was performed with a flow cytometry method and with the following antibodies: anti CD3, CD4, CD8, CD16, CD25, CD45, CD56, and HLA-DR. We found differences in the proportion of lymphocytes between BALF and PB, and a higher proportion of T cells and a lower proportion of B and natural-killer (NK) cells in BALF. There was a significant difference in the proportion of T-cytotoxic/suppressor lymphocytes, which was elevated in the BALF of patients and decreased in patients' PB. The T-helper:T-cytotoxic/suppressor (Th:Tc/s) ratio was significantly lower in the BALF of patients. These changes were visible in patients with a small cell type. The percentage of T cells with the alpha chain of receptor to IL-2 (IL -R) was lower in the BALF of patients than in the control group. Our observations reflect local changes in lung environment in patients affected with lung cancer.

Prognostic value of CD4+ lymphocytes in pleural cavity of patients with non-small cell lung cancer

BACKGROUND

For patients with non-small cell lung cancer the TNM staging system and other conventional prognostic factors fail to predict accurately the outcome of treatment and survival. This study attempts to determine the prognostic value for survival of the proportions of CD4+ lymphocytes in the pleural cavity (PLY) of patients with resectable non-small cell lung cancer.

METHODS

Lymphocytes in the pleural cavity separated from 51 patients with non-small cell lung cancer were examined by flow cytometry to measure the proportions of CD4+ PLY. Univariate and multivariate analyses were performed to assess the association between the proportion of CD4+ PLY and survival.

RESULTS

The 5 year survival rate of patients with percentage CD4+ PLY of ⩽30% was 84% whereas that of patients with %CD4+ PLY >30% was 26.9%. The difference in survival between the %CD4+ PLY ⩽30% and %CD4+ PLY >30% groups was significant (p<0.0001). The %CD4+ PLY in those who survived for 5 years was significantly lower than that in the patients who died within 5 years (p<0.0001). The difference in survival between patients with stage IA and IB lung cancer with %CD4+ PLY ⩽30% and those with %CD4+ PLY >30% was also significant (p =0.015). Multivariate analysis showed that the proportion of CD4+ PLY (hazard ratio=6.9, 95% CI 0.045 to 0.47) and nodal status (hazard ratio=22.7, 95% CI 0.006 to 1.806) are significant and independent prognostic factors for the survival of patients with lung cancer.

CONCLUSIONS

The proportion of CD4+ PLY may help to select patients who are likely to have a poorer prognosis after surgery and therefore may be suitable for consideration of adjuvant treatments. These results need confirmation in a larger prospective study.

Prognostic value of CD4+ lymphocytes in pleural cavity of patients with non-small cell lung cancer

BACKGROUND

For patients with non-small cell lung cancer the TNM staging system and other conventional prognostic factors fail to predict accurately the outcome of treatment and survival. This study attempts to determine the prognostic value for survival of the proportions of CD4+ lymphocytes in the pleural cavity (PLY) of patients with resectable non-small cell lung cancer.

METHODS

Lymphocytes in the pleural cavity separated from 51 patients with non-small cell lung cancer were examined by flow cytometry to measure the proportions of CD4+ PLY. Univariate and multivariate analyses were performed to assess the association between the proportion of CD4+ PLY and survival.

RESULTS

The 5 year survival rate of patients with percentage CD4+ PLY of < or = 30% was 84% whereas that of patients with %CD4+ PLY > 30% was 26.9%. The difference in survival between the %CD4+ PLY < or = 30% and %CD4+ PLY > 30% groups was significant (p < 0.0001). The %CD4+ PLY in those who survived for 5 years was significantly lower than that in the patients who died within 5 years (p < 0.0001). The difference in survival between patients with stage IA and IB lung cancer with %CD4+ PLY < or = 30% and those with %CD4+ PLY > 30% was also significant (p = 0.015). Multivariate analysis showed that the proportion of CD4+ PLY (hazard ratio = 6.9, 95% CI 0.045 to 0.47) and nodal status (hazard ratio = 22.7, 95% CI 0.006 to 1.806) are significant and independent prognostic factors for the survival of patients with lung cancer.

CONCLUSIONS

The proportion of CD4+ PLY may help to select patients who are likely to have a poorer prognosis after surgery and therefore may be suitable for consideration of adjuvant treatments. These results need confirmation in a larger prospective study.

Lung carcinoma: analysis of T helper type 1 and 2 cells and T cytotoxic type 1 and 2 cells by intracellular cytokine detection with flow cytometry

BACKGROUND

T helper type 1 cells (Th1), Th2, T cytotoxic type 1 cells (Tc1), and Tc2 play important immunoregulatory roles. Some recent studies have demonstrated that an elevated level of type 2 cytokines, such as interleukin-10, contributes to the ability of cancer cells to escape immunosurveillance. However, the impacts of Th1, Th2, Tc1, and Tc2 on tumor immunity are unclear.

METHODS

The authors evaluated the ratio of Th1 to Th2 and that of Tc1 to Tc2 among peripheral blood lymphocytes (PBL), regional lymph node lymphocytes (RLNL), and tumor-infiltrating lymphocytes (TIL) in 46 nonsmall cell lung carcinoma patients who had just undergone surgery; the evaluation involved detecting the intracellular interferon-gamma and interleukin-4 production with 3-color flow cytometry. They also evaluated the same ratios in the peripheral blood lymphocytes of 29 lung carcinoma patients with or without recurrence after surgery, and in the peripheral blood of normal volunteers.

RESULTS

The Th1-to-Th2 and Tc1-to-Tc2 ratios were significantly elevated in the tumor tissues. These ratios in the TIL were significantly elevated in the groups of patients with squamous cell carcinoma and a history of smoking. The Th1-to-Th2 and Tc1-to-Tc2 ratios were significantly depressed in the PBL of the patients with tumor recurrences.

CONCLUSIONS

A favorable Th1- and Tc1-dominant pathway is induced in the tumor tissues of operable patients, but their pathway can be expected to shift from Th1 or Tc1 to Th2 or Tc2 with the progression of cancer.

Phenotypic analysis of lymphocytes and monocytes/macrophages in peripheral blood and bronchoalveolar lavage fluid from patients with pulmonary sarcoidosis

BACKGROUND

The granulomatous inflammation in sarcoidosis is driven by the interplay between T cells and macrophages. To gain a better understanding of this process the expression by these cells of cell surface activation markers, co-stimulatory molecules, and adhesion molecules was analysed.

METHODS

CD4+ and CD8+ T lymphocytes from peripheral blood (PBL) or bronchoalveolar lavage (BAL) fluid, as well as paired peripheral blood monocytes and alveolar macrophages from 27 patients with sarcoidosis were analysed by flow cytometry.

RESULTS

CD26, CD54, CD69, CD95, and gp240 were all overexpressed in T cells from BAL fluid compared with those from PBL in both the CD4+ and CD8+ subsets, while CD57 was overexpressed only in BAL CD4+ cells. In contrast, CD28 tended to be underexpressed in the BAL T cells. Monocyte/macrophage markers included CD11a, CD11b, CD11c, CD14, CD16, CD54, CD71, CD80 and CD86 and HLA class II. CD11a expression in alveolar macrophages (and peripheral blood monocytes) was increased in patients with active disease and correlated positively with the percentage of BAL lymphocytes. Expression of CD80 in macrophages correlated with the BAL CD4/CD8 ratio.

CONCLUSIONS

Our data indicate substantial activation of both CD4+ and CD8+ lung T cells in sarcoidosis. There were also increased numbers of BAL lymphocytes whose phenotypic characteristics have earlier been associated with clonally expanded, replicatively senescent cells of the Th1 type.