M. E. Christine Lutsiak

Bio: M. E. Christine Lutsiak is an academic researcher from National Institutes of Health. The author has contributed to research in topics: CD8 & Immune system. The author has an hindex of 8, co-authored 8 publications receiving 1066 citations.

Fc-mOX40L fusion protein produces complete remission and enhanced survival in 2 murine tumor models.

Abstract: OX40L is a member of the tumor necrosis factor superfamily that provides a costimulatory signal to CD4+ and CD8+ T cells while inhibiting the effects of suppressive CD4+CD25+ regulatory T cells. Because of this dual activity, OX40L may provide significant antitumor immunity in tumor-bearing mice. To

Construction and preclinical characterization of Fc-mGITRL for the immunotherapy of cancer.

Abstract: Purpose: To provide proper costimulation required for effective cancer T-cell immunity, Fc-GITRL fusion proteins were generated for use in immunotherapy protocols. Experimental Design: Soluble fusion proteins consisting of the Fc fragment of immunoglobulin and the murine glucocorticoid-induced tumor necrosis factor–related receptor ligand (mGITRL) connected with different linkers were genetically engineered and tested for their potency in two BALB/c solid tumor models. Results: In vivo , construct #178-14 (−5aa, −linker) showed the best activity (>90% tumor reduction) at doses ranging from 5 to 25 μg and was found to be intact by gel electrophoresis. Similar doses used with construct #175-2 (-linker) produced good but not as high tumor regression. Construct #5-1 (+linker), which was found to be relatively unstable by SDS gel electrophoresis, produced 3 months compared with controls that died by day 40. T-cell depletion studies showed that CD8 + T cells play a major role in Fc-mGITRL immunotherapy, and tumors removed from Fc-mGITRL– and DTA-1–treated mice showed a significant influx of granzyme B + lymphocytes compared with controls. Finally, T regulatory (Treg) cell assays showed that, unlike other Fc fusion proteins, all three Fc-mGITRL constructs profoundly suppressed Treg activity. Conclusions: These studies suggest that a stable, intact Fc-mGITRL fusion protein can provide missing costimulation for the immunotherapy of solid tumors. In addition, Fc-mGITRL may alter Treg activity to enhance its effectiveness for tumor immunotherapy.

IL-2/Anti-IL-2 Antibody Complex Enhances Vaccine-Mediated Antigen-Specific CD8+ T Cell Responses and Increases the Ratio of Effector/Memory CD8+ T Cells to Regulatory T Cells

Abstract: IL-2 is well described as a cytokine with two markedly distinct functionalities: as a necessary signal during CD4(+) and CD8(+) T cell activation/expansion and as an essential cytokine for the maintenance of CD4(+)CD25(+)FoxP3(+) T cells (regulatory T (T(REG)) cells) during homeostasis. In this study we demonstrate for the first time that, compared with the use of IL-2 alone, a complex of IL-2 and anti-IL-2 Ab (IL-2 complex) enhances the effectiveness of a viral vaccine in a mouse model with known Ag specificity. IL-2 complex led to an increase in the number of Ag-specific effector/memory CD8(+) T cells, cytokine production, and CTL lysis following Ag-specific restimulation in a vaccination setting. Our results further demonstrate that this effect is temporary and declines over the course of a few days after the IL-2 complex treatment cycle. Moreover, in contrast to the use of IL-2 alone, IL-2 complex greatly increased the ratio of effector/memory CD8(+) T cells to T(REG) cells. This phenomenon can thus potentially be used in the enhancement of immune responses to vaccination.

TGF-β modulates the functionality of tumor-infiltrating CD8+ T cells through effects on TCR signaling and Spred1 expression

Abstract: This study demonstrates that CD8+ T cells in the tumor microenvironment display reduced functionality and hyporesponsiveness. TGF-β contributed markedly to the tumor-infiltrating CD8+ T cells’ (TILs) reduced functionality, which could be reversed using a small molecule TGF-β inhibitor. Upon T-cell receptor (TCR) activation, the activation of ITK and ERK kinases were reduced in CD8+ TILs, as compared to splenic CD8+ T cells: TGF-β inhibitor could reverse this phenomenon. This study demonstrates for the first time the association of the Spred-1 gene, an inhibitor of the Ras/MAPK pathway, with CD8+ TILs and TGF-β activity. Spred-1 was upregulated in CD8+ TILs and TGF-β enhanced the expression of Spred-1 in effector/memory CD8+ T cells and not in rested/memory CD8+ T cells. Based on these findings, this study supports the hypothesis that TGF-β mediates an inhibitory mechanism on CD8+ TILs involving TCR-signaling blockade and the upregulation of Spred-1, thus implicating Spred-1 as a potential new target for future anti-tumor immune studies.

Intraepithelial CD8+ tumor-infiltrating lymphocytes and a high CD8+/regulatory T cell ratio are associated with favorable prognosis in ovarian cancer

Abstract: In a recent report, [Zhang et al. (2003) N. Engl. J. Med. 348, 203–213], the presence of CD3+ tumor-infiltrating lymphocytes (TILs) was found to correlate with improved survival in epithelial ovarian cancer. We performed immunohistochemical analysis for TILs and cancer testis antigens in 117 cases of epithelial ovarian cancer. The interrelationship between subpopulations of TILs and expression of cancer testis antigens was investigated, as well as between TILs and overall survival. The median follow-up of the patients was 31 months. Patients with higher frequencies of intraepithelial CD8+ T cells demonstrated improved survival compared with patients with lower frequencies [median = 55 versus 26 months; hazard ratio = 0.33; confidence interval (C.I.) = 0.18–0.60; P = 0.0003]. No association was found for CD3+ TILs or other subtypes of intraepithelial or stromal TILs. However, the subgroups with high versus low intraepithelial CD8+/CD4+ TIL ratios had median survival of 74 and 25 months, respectively (hazard ratio = 0.30; C.I. = 0.16–0.55; P = 0.0001). These results indicate that CD4+ TILs influence the beneficial effects of CD8+ TIL. This unfavorable effect of CD4+ T cells on prognosis was found to be due to CD25+forkhead box P3 (FOXP3)+ regulatory T cells (Treg; suppressor T cells), as indicated by survival of patients with high versus low CD8+/Treg ratios (median = 58 versus 23 months; hazard ratio = 0.31; C.I. = 0.17–0.58; P = 0.0002). The favorable prognostic effect of intraepithelial CD8+ TILs did not correlate with concurrent expression of NY-ESO-1 or MAGE antigens. We conclude that intraepithelial CD8+ TILs and a high CD8+/Treg ratio are associated with favorable prognosis in epithelial ovarian cancer.

Regulatory T cells, tumour immunity and immunotherapy

Abstract: Tumours express a range of antigens, including self-antigens. Regulatory T cells are crucial for maintaining T-cell tolerance to self-antigens. Regulatory T cells are thought to dampen T-cell immunity to tumour-associated antigens and to be the main obstacle tempering successful immunotherapy and active vaccination. In this Review, I consider the nature and characteristics of regulatory T cells in the tumour microenvironment and their potential multiple suppressive mechanisms. Strategies for therapeutic targeting of regulatory T cells and the effect of regulatory T cells on current immunotherapeutic and vaccine regimens are discussed.

Immunological aspects of cancer chemotherapy.

Abstract: Accumulating evidence indicates that the innate and adaptive immune systems make a crucial contribution to the antitumour effects of conventional chemotherapy-based and radiotherapy-based cancer treatments. Moreover, the molecular and cellular bases of the immunogenicity of cell death that is induced by cytotoxic agents are being progressively unravelled, challenging the guidelines that currently govern the development of anticancer drugs. Here, we review the immunological aspects of conventional cancer treatments and propose that future successes in the fight against cancer will rely on the development and clinical application of combined chemo- and immunotherapies.

Metronomic cyclophosphamide regimen selectively depletes CD4+CD25+ regulatory T cells and restores T and NK effector functions in end stage cancer patients

Abstract: CD4+CD25+ regulatory T cells are involved in the prevention of autoimmune diseases and in tumor-induced tolerance. We previously demonstrated in tumor-bearing rodents that one injection of cyclophosphamide could significantly decrease both numbers and suppressive functions of regulatory T cells, facilitating vaccine-induced tumor rejection. In humans, iterative low dosing of cyclophosphamide, referred to as "metronomic" therapy, has recently been used in patients with advanced chemotherapy resistant cancers with the aim of reducing tumor angiogenesis. Here we show that oral administration of metronomic cyclophosphamide in advanced cancer patients induces a profound and selective reduction of circulating regulatory T cells, associated with a suppression of their inhibitory functions on conventional T cells and NK cells leading to a restoration of peripheral T cell proliferation and innate killing activities. Therefore, metronomic regimen of cyclophosphamide does not only affect tumor angiogenesis but also strongly curtails immunosuppressive regulatory T cells, favoring a better control of tumor progression. Altogether these data support cyclophosphamide regimen as a valuable treatment for reducing tumor-induced immune tolerance before setting to work anticancer immunotherapy.

Increased circulating myeloid-derived suppressor cells correlate with clinical cancer stage, metastatic tumor burden, and doxorubicin–cyclophosphamide chemotherapy

Abstract: Abnormal accumulation of myeloid-derived suppressor cells (MDSC) is an important mechanism of tumor immune evasion Cyclophosphamide (CTX) has also been shown in non-tumor bearing animals to cause transient surges in MDSC Knowledge of MDSC is primarily based on preclinical work, and to date only few published studies have involved cancer patients The goal of this study was to test the hypothesis that circulating MDSC levels correlate with clinical cancer stage, CTX-based chemotherapy, and metastatic tumor burden Whole blood was collected from 106 newly diagnosed solid tumor patients (stages I–IV) Percentages of circulating MDSC (Lin−/Lo, HLA DR−, CD33+CD11b+) were determined prior to initiation of systemic therapy In 17 early stage breast cancer patients receiving doxorubicin–cyclophosphamide chemotherapy every 14 days (ddAC) blood was collected on day 1 of each cycle Circulating MDSC were significantly increased in cancer patients of all stages relative to healthy volunteers A significant correlation between circulating MDSC and clinical cancer stage was also observed Moreover, among stage IV patients, those with extensive metastatic tumor burden had the highest percent and absolute number of MDSC Significant increases in circulating MDSC were observed with ddAC when compared with pretreatment levels Circulating MDSC levels correlate with clinical cancer stage, ddAC, and metastatic tumor burden This information must be incorporated into the design of future trials exploring immune-based therapeutic strategies Pharmacologic modulation of MDSC should also be tested in future clinical trials