In this study, we investigated whether CD4+CD25high regulatory T cells (Treg) are increased in the tumor tissue and peripheral blood of early-stage prostate cancer patients undergoing prostatectomy. We show that the prevalence of CD4+CD25high T cells inside the prostate was significantly higher in the tumor compared with benign tissue from the same prostate. Furthermore, the frequency of CD4+CD25high T cells in peripheral blood was significantly higher in prostate cancer patients compared with normal donors. A proportion of the CD4+CD25high T cells was also shown to be glucocorticoid-induced TNF receptor, ICOS, and FOXP3 positive. Moreover, CD4+CD25+ T cells from blood and supernatants from cultured prostate tumor tissue samples exhibited immunosuppressive function in vitro. Furthermore, supernatants from cultured prostate tissue samples and prostate cancer ascites fluid induced migration of CD4+CD25+ T cells and were shown to contain the regulatory T cell chemokine CCL22 by ELISA. Our findings indicate that Tregs are an important cellular component of early-stage prostate tumors, and thus new therapeutic strategies aimed at inhibition or depletion of Tregs may improve prostate cancer immunotherapy.

It is now widely accepted that the detection of minimal residual disease (MRD) has prognostic value in acute leukemia. However clinical MRD studies need standardized techniques. Therefore, several European laboratories have aligned their goals and performed comparative studies to achieve optimization and standardization of MRD techniques. This was achieved via the BIOMED-1 Concerted Action "Investigation of minimal residual disease in acute leukemia: International standardization and clinical evaluation." This report describes the development of PCR primers and protocols for the detection of MRD in acute lymphoblastic leukemia (ALL) using clone-specific junctional regions of immunoglobulin and T cell receptor gene rearrangements and TAL1 deletions as PCR targets. A total of 54 primers was developed (1) to amplify rearrangements of the TCRD, TCRG, and IGK (Kde) genes as well as TAL1 deletions; (2) to sequence the junctional regions and breakpoint fusion regions; and (3) to perform MRD detection in bone marrow or peripheral blood samples during follow-up of ALL patients. Protocols were established to identify PCR targets at diagnosis by performing 25 PCR reactions per patient using appropriate positive and negative controls. Standardized protocols were developed for MRD monitoring via single amplification of the PCR target followed by dot blot hybridization with the corresponding patient-specific junctional region probe. In addition, alternative approaches were designed for cases where the target sensitivity of at least 10 −4 was not obtained. The standardization described here of MRD-PCR techniques is essential for the process of translating MRD research into clinical practice.

Dysfunctional T cells present in malignant lesions are characterized by a sustained and highly diverse expression of inhibitory receptors, also referred to as immune checkpoints. Yet, their relative functional significance in different cancer types remains incompletely understood. In this study, we provide a comprehensive characterization of the diversity and expression patterns of inhibitory receptors on tumor-infiltrating T cells from patients with non-small cell lung cancer. In spite of the large heterogeneity observed in the amount of PD-1, Tim-3, CTLA-4, LAG-3, and BTLA expressed on intratumoral CD8 þ T cells from 32 patients, a clear correlation was established between increased expression of these inhibitory coreceptors and progression of the disease. Notably, the latter was accompanied by a progressively impaired capacity of T cells to respond to polyclonal activation. Coexpression of several inhibitory receptors was gradually acquired, with early PD-1 and late LAG-3/BTLA expression. PD-1 blockade was able to restore Tcell function only in a subset of patients. A high percentage of PD-1 hi T cells was correlated with poor restoration of T-cell function upon PD-1 blockade. Of note, PD-1 hi expression marked a particularly dysfunctional T-cell subset characterized by coexpression of multiple inhibitory receptors and thus may assist in identifying patients likely to respond to inhibitory receptorspecific antibodies. Overall, these data may provide a framework for future personalized T-cell-based therapies aiming at restoration of tumor-infiltrating lymphocyte effector functions.

The p53 tumor suppressor protein inhibits the formation of tumors through induction of cell cycle arrest and/or apoptosis. In the present study we demonstrated that p53 is also a powerful inhibitor of human telomerase reverse transcriptase (hTERT), a key component for telomerase. Activation of either exogenous temperature-sensitive (ts) p53 in BL41 Burkitt lymphoma cells or endogenous wild type (wt) p53 at a physiological level in MCF-7 breast carcinoma cells triggered a rapid downregulation of hTERT mRNA expression, independently of the induction of the p53 target gene p21. Co-transfection of an hTERT promoter construct with wt p53 but not mutant p53 in HeLa cells inhibited the hTERT promoter activity. Furthermore, the activation of the hTERT promoter in Drosophila Schneider SL2 cells was completely dependent on the ectopic expression of Sp1 and was abrogated by wt p53. Finally, wt p53 inhibited Sp1 binding to the hTERT proximal promoter by forming a p53-Sp1 complex. Since activation of telomerase, widely observed in human tumor cell lines and primary tumors, is a critical step in tumorigenesis, wt p53-triggered inhibition of hTERT/telomerase expression may re¯ect yet another mechanism of p53-mediated tumor suppression. Our ®ndings provide new insights into both the biological function of p53 and the regulation of hTERT/telomerase expression. Oncogene (2000) 19, 5123 ± 5133.

SummaryInterleukin 10 (IL-10) is a cytokine with a variety of reported effects including inhibition of monocyte major histocompatibility complex (MHC) class II-dependent antigen presentation, type 1 helper T cell cytokine production, and inhibition of T cell proliferation. Herein we report the effect of IL-10 pretreatment on antigen presentation to tumor-and allo-specific CD8 + cytotoxic T lymphocytes (CTL). Prior incubation of human melanoma cells with recombinant IL-10 (rlL-10) for 48-72 h resulted in a dose-dependent, up to 100% inhibition, of autologous CTL-mediated, HLA-A2.1-restricted, tumor-specific lysis. Allo-specific CTL cytotoxicity against Epstein-Barr virus-transformed lymphoblastoid cell lines (LCL) was also inhibited, demonstrating a protective effect also on lymphoid calls. In contrast, IL-10 pretreatment of allogeneic LCL or K562 targets had either no effect or slightly enhanced cytotoxic activity mediated by freshly isolated or IL-2-activated natural killer cells. Flow cytometric analysis with monoclonal antibodies against HLA-A2, or nonpolymorphic determinants of MHC class I proteins, revealed a 20-50% reduction in call-surface expression, whereas intercellular adhesion molecules 1, and 2, and lymphocyte function-associated antigen 3 levels were not affected. In addition, relative to untreated target cells, IL-10 pretreated tumor ceils were unaltered in their capacity to affect CTL-mediated lysis by cold target inhibition, demonstrating that the effect of IL-10 is unrelated to the initial binding of CTL to their targets. These results are compatible with an effect of IL-10 on the MHC class I antigen presentation pathway, and suggest a novel mechanism of immune tolerance, based on escape from CTL-mediated tumor and allo-transplant rejection. I L-10 was discovered because of its ability to suppress cytokine expression by type 1 helper T cells (Thl) and NK cells (1). More recently, it has been shown to have pleitropic immunosuppressive effects. In vitro, IL-10 also blocks monocytedependent T cell proliferation (2), inhibits monocyte class II MHC expression (3), the upregulation of B7 on monocytes (4), and monocyte-associated production of nitric oxide and killing of parasites (5).IL-IO is produced by a variety of cell types, including T cells, B cells, and macrophages (6, 7). Higher levels of human IL-10 were produced by Th2 than Thl clones (8), and several human carcinoma lines, freshly isolated tumor biopsies, patient serum, and ascites fluid express or contain IL-10 (9-11). These observations suggest that the presence of IL-IO may be a common feature of several types of human tumors-a finding of potential importance regarding adverse effects on the host immune response.In view of these findings, and since there is evidence suggesting that tumors can be rejected by infiltrating CTL, we analyzed the effect that IL-10 pretreatment of tumors had on their sensitivity to MHC class I-restricted CTL. Our results show that pretreated melanoma and human B cell lines were impervious to otherwise lethal C...

Whereas the chimeric type I anti-CD20 Ab rituximab has improved outcomes for patients with B-cell malignancies significantly, many patients with non-Hodgkin lymphoma (NHL) remain incurable. Obinutuzumab (GA101) is a glycoengineered, humanized anti-CD20 type II Ab that has demonstrated superior activity against type I Abs in vitro and in preclinical studies. In the present study, we evaluated the safety, efficacy, and pharmacokinetics of GA101 in a phase 1 study of 21 patients with heavily pretreated, relapsed, or refractory CD20 ؉ indolent NHL. Patients received GA101 in a doseescalating fashion (3 per cohort, range 50/100-1200/2000 mg) for 8 ؋ 21-day cycles. The majority of adverse events (AEs) were grades 1 and 2 (114 of 132 total AEs). Seven patients reported a total of 18 grade 3 or 4 AEs. Infusion-related reactions were the most common AE, with most occurring during the first infusion and resolving with appropriate management.Three patients experienced grade 3 or 4 drug-related infusion-related reactions. The best overall response was 43%, with 5 complete responses and 4 partial responses. Data from this study suggest that GA101 was well tolerated and demonstrated encouraging activity in patients with previously treated NHL up to doses of 2000 mg. This trial is registered at www.clinicaltrials.gov as NCT00517530.

Immune system-based approaches for the treatment of malignant disease over the past decades have often focused on cytolytic effector cells such as cytotoxic T lymphocytes (CTL), and natural killer (NK) cells. It has also been demonstrated that tumor-bearing mice can be cured using a wide variety of approaches, some of which involve cytokine-mediated enhancement of CTL and NK cell activity. However, the apparent success in mice stands in contrast to the current situation in the clinic, wherein only a minority of patients have thus far benefited from CTL- or NK cell-based antitumor approaches. The underlying causes of tumor-associated immune suppression of CTL and NK cell activity are discussed, and features of interest shared with HIV infection, leprosy, and rheumatoid arthritis are also be mentioned. Remarkable and very recent observations have shed more light upon the causes of dysfunctional alterations in CTL and NK cells often associated with these diseases, that in turn have suggested new immunotherapeutic approaches for cancer and infectious disease.

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