scholarly journals Progression Of Large Lymphoma Is Significantly Impeded With a Combination Of Gemcitabine Chemotherapy and Dendritic Cells Intra-Tumor Vaccination

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 5155-5155
Author(s):  
Xue-Jun Zhu ◽  
Zhong-Fa Yang ◽  
Li-Xin Wang ◽  
Alan G. Rosmarin
Keyword(s):  
Dendritic Cells ◽  
Tumor Cells ◽  
Conflicts Of Interest ◽  
B Cell Lymphoma ◽  
Chemotherapeutic Agents ◽  
Efficient Treatment ◽  
Tumor Vaccination ◽  
Tumor Bearing ◽  
Large Size

Abstract Relapsed, refractory Hodgkin’s or non-Hodgkin’s lymphoma remains to be a challenge and lacks efficient treatment. A small number of tumor cells that escape from treatment become resistant or unresponsive to chemotherapeutic agents. These cells grow rapidly and soon regenerate into large tumors. Immune vaccination with dendritic cells (DCs) efficiently inhibits growth of small size tumor only. The progression of tumors induces accumulation of Gr-1+CD11b+ myeloid derived suppressor cells (MDSCs) in the lymphatic organs and vicinity of tumor cells. MDSCs enable tumor cells to escape from host or exogenous immune cells mediated surveillance and attack. Gemcitabine is the chemotherapeutic agent used for lymphoma treatment. Gemcitabine has been reported to selectively eliminate MDSCs in tumor bearing animals. Thus, gemcitabine not only eliminates the majority of tumor to leave fewer resistant cells, it also reduces MDSCs to improve the immune environment favorable for the subsequent tumor vaccination. In this presentation, we used A20 cells to establish a large size, murine B-cell lymphoma model. We confirmed the accumulation of MDSCs in the spleen of lymphoma-bearing mice. Gemcitabine induced increased apoptosis in isolated, cultured MDSCs. In vivo injection of gemcitabine eliminated the majority of MDSCs in the spleen of lymphoma-bearing mice. Gemcitabine treatment combined with intratumoral injection of DCs markedly reduced the size of tumor, and significantly improved the survival of the lymphoma-bearing mice. We demonstrated that intra-large-size-lymphoma injection with inactivated DCs in combination with gemcitabine chemotherapy enhanced the therapeutic efficacy of either DC-based vaccination or chemotherapeutic reagent alone. Together with other studies, our report supports the hypothesis that gemcitabine-mediated reduction in MDSCs significantly reduces the immune suppression in tumor-bearing animal environment. This study established novel experimental foundation for the combination of immune-chemotherapy to treat relapsed or refractory lymphoma in large size with enhanced efficacy. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Development of Humanized Diffuse Large B-Cell Lymphoma Mouse Models

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 4501-4501
Author(s):  
Syed Mehdi ◽  
Ying-Zhi Xu ◽  
Leonard Shultz ◽  
Samantha L. Kendrick ◽  
Donghoon Yoon
Keyword(s):  
Transgenic Mice ◽  
Tumor Cells ◽  
Median Survival ◽  
Conflicts Of Interest ◽  
Xenograft Model ◽  
B Cell Lymphoma ◽  
Patient Specific ◽  
Significant Difference ◽  
Organ Specific

Abstract Introduction DLBCL is a commonly diagnosed, aggressive non-Hodgkin's lymphoma with ~40% of patients experiencing refractory or relapsed disease. Development of alternative therapies that target molecular features defining these unresponsive tumors is an active area of research to significantly advance the field and improve these patient's clinical management. However, few DLBCL animal models exist to test the efficacy of newly developed treatments, and are restricted to transgenic or xenograft mice that often fail to recapitulate the heterogeneous sub-classifications of this complex disease. While transgenic mice allow for spontaneous tumor formation, these models rely on inducing expression of specific oncogenes that drive a select group of DLBCL. The xenograft model offers several advantages, such as reproducing late-stage disease and shortening the model development time, but consist of implanting the tumor cells in a localized region or subcutaneously into immune-deficient mice. Despite some benefits of the transplant approach, these models are limited by their engraftment reproducibility and interactions with host micro-environments. Here, we explored the utility of humanizing Nod-Scid-IL2Rg null (NSG) mouse strains with factors associated with enhancing myeloid and lymphoma cell growth to establish a pipeline for rapid, reliable generation of in vivo DLBCL models. Methods We transduced the well-established human DLBCL cells, U2932, with the luciferase (Luc)-EGFP gene. The Luc-expressing (U2932-Luc) tumor cells were sorted for GFP positivity (GFP +) and expanded. The U2932-Luc cells (1 x 10 6/100µl PBS) were injected IV via tail vein into 8~12-week-old mice of various humanized NSG strains (representing equal numbers of each sex). NSG mice were humanized by transgenic expression of human cytokines (either human IL6 alone or IL6 plus SCF, GM-CSF, and IL-3) with the CMV promoter. Each experiment included of U2932-Luc cell transplanted group and control groups. We assessed U2932-Luc cell engraftment and growth by weekly in vivo imaging (IVIS 200 Imager, Perkin Elmer). To evaluate the organ specific engraftment/progression, we confirmed engraftment by bioluminescence imaging at the 2 nd week, then euthanized one mouse per week. At 15 minutes before euthansia, luciferin was injected via intraperitoneal injection. Following euthanasia, the organs were excised and underwent ex vivo IVIS imaging. The spleen, lungs, and liver were then fixed with 10% formalin and embedded in paraffin. Sections were stained with hematoxylin and eosin, and an anti-CD20 antibody to evaluate the tumor morphology using a Zeiss AXIO Imager M2 microscope (Zeiss, Nashville, TN). All other mice were monitored for survival and the median survival between the IL6 and IL6/SGM3 mice were compared using the Log-rank test. Results Similar to previously reported DLBCL humanized strain (MISTRG) (Hashwah, 2019), we used the IL6/SGM3 expressing strain. However, our studies also included the IL6 only humanized strain. We found that both the IL6 and IL6/SGM3 strains were highly permissive to DLBCL growth. The IL-6 strain exhibited a heightened growth of U2932 cells relative to the IL-6/SGM3 mice. As shown in Figure 1, the IL6 mice survived longer than IL6/SGM3 mice. Significant difference between the median survival of IL6 and IL6/SGM3 mice i.e. 48 days vs 42 days was observed (p < 0.0482). The organ specific evaluation demonstrated that U2932-Luc cells were initially engrafted and grew in the lung, liver, and spleen. Subsequently, U2932 cells were found in the skeleton, ovary, and brain. Of note, we detected significantly enlargements of the kidney, spleen, and ovary at the terminal stage. Conclusions Our humanized mouse model approach of using U2932 human DLBCL cells transduced with the Luc gene in the NSG-IL6 and NSG-IL6/SGM3 mice reproduced the clinical features of an aggressive DLBCL that paralleled the original patient. This model will provide a new tool to enable expansion of patient samples while overcoming the current limitations of DLBCL xenografts and transgenic mice. The ability to maintain growth of patient-derived samples within clinically relevant locations has great potential to more accurately test patient-specific, personalized treatment strategies. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

scholarly journals Dendritic cells loaded with apoptotic antibody-coated tumor cells provide protective immunity against B-cell lymphoma in vivo

Blood ◽  
2008 ◽  
Vol 111 (3) ◽  
pp. 1504-1511 ◽  
Author(s):  
Suzanne N. Franki ◽  
Kristopher K. Steward ◽  
David J. Betting ◽  
Kamran Kafi ◽  
Reiko E. Yamada ◽  
...  
Keyword(s):  
T Cells ◽  
Dendritic Cells ◽  
Tumor Cell ◽  
Tumor Cells ◽  
Tumor Antigens ◽  
B Cell Lymphoma ◽  
Lymphoma Cells ◽  
Term Survival ◽  
Dc Vaccine

Abstract The in vitro priming of tumor-specific T cells by dendritic cells (DCs) phagocytosing killed tumor cells can be augmented in the presence of antitumor monoclonal antibody (mAb). We investigated whether DCs phagocytosing killed lymphoma cells coated with tumor-specific antibody could elicit antitumor immunity in vivo. Irradiated murine 38C13 lymphoma cells were cocultured with bone marrow–derived DCs in the presence or absence of tumor-specific mAb. Mice vaccinated with DCs cocultured with mAb-coated tumor cells were protected from tumor challenge (60% long-term survival), whereas DCs loaded with tumor cells alone were much less effective. The opsonized whole tumor cell–DC vaccine elicited significantly better tumor protection than a traditional lymphoma idiotype (Id) protein vaccine, and in combination with chemotherapy could eradicate preexisting tumor. Moreover, the DC vaccine protected animals from both wild-type and Id-negative variant tumor cells, indicating that Id is not a major target of the induced tumor immunity. Protection was critically dependent upon CD8+ T cells, with lesser contribution by CD4+ T cells. Importantly, opsonized whole tumor cell–DC vaccination did not result in tissue-specific autoimmunity. Since opsonized whole tumor cell–DC and Id vaccines appear to target distinct tumor antigens, optimal antilymphoma immunity might be achieved by combining these approaches.

scholarly journals Histone methyltransferase WHSC1 inhibits colorectal cancer cell apoptosis via targeting anti-apoptotic BCL2

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yu Wang ◽  
Liming Zhu ◽  
Mei Guo ◽  
Gang Sun ◽  
Kun Zhou ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cancer Cell ◽  
Cell Apoptosis ◽  
B Cell Lymphoma ◽  
Histone Methyltransferase ◽  
Chemotherapeutic Agents ◽  
Cancer Cell Apoptosis ◽  
Active Transcription

AbstractWHSC1 is a histone methyltransferase that facilitates histone H3 lysine 36 dimethylation (H3K36me2), which is a permissive mark associated with active transcription. In this study, we revealed how WHSC1 regulates tumorigenesis and chemosensitivity of colorectal cancer (CRC). Our data showed that WHSC1 as well as H3K36me2 were highly expressed in clinical CRC samples, and high WHSC1 expression is associated with poorer prognosis in CRC patients. WHSC1 reduction promoted colon cancer cell apoptosis both in vivo and in vitro. We found that B cell lymphoma-2 (BCL2) expression, an anti-apoptotic protein, is markedly decreased in after WHSC1 depletion. Mechanistic characterization indicated that WHSC1 directly binds to the promoter region of BCL2 gene and regulate its H3K36 dimethylation level. What’s more, our study indicated that WHSC1 depletion promotes chemosensitivity in CRC cells. Together, our results suggested that WHSC1 and H3K36me2 modification might be optimal therapeutic targets to disrupt CRC progression and WHSC1-targeted therapy might potentially overcome the resistance of chemotherapeutic agents.

scholarly journals A Potential Antitumor Effect of Dendritic Cells Fused with Cancer Stem Cells in Hepatocellular Carcinoma

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Ye-Bin Pang ◽  
Jian He ◽  
Bi-Yu Cui ◽  
Sheng Xu ◽  
Xi-Lei Li ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dendritic Cells ◽  
Stem Cell ◽  
Tumor Cells ◽  
Hepg2 Cells ◽  
Cytotoxicity Assay ◽  
Tumor Stem Cell ◽  
Fusion Cell

HCC stem cells were reported as posttreatment residual tumor cells that play a pivotal role in tumor relapse. Fusing dendritic cells (DCs) with tumor cells represents an ideal approach to effectively activate the antitumor immunity in vivo. DC/HCC stem cell vaccine provides a potential strategy to generate polyclonal immune response to multiple tumor stem cell antigens including those yet to be unidentified. To assess the potential capacity of DC/HCC stem cell vaccines against HCC, CD90+HepG2 cells were sorted from the HCC cell line HepG2. DC and CD90+HepG2 and DC and HepG2 fused cells were induced by polyethylene glycol (PEG). The influence of fusion cells on proliferation and immunological function transformation of lymphocytes was assessed by FCM and ELISA assay, respectively. The cytotoxicity assay of specific fusion cell-induced CTLs against HepG2 was conducted by CytoTox 96 Non-Radioactive Cytotoxicity Assay kit in vitro. At last, the prevention of HCC formation in vivo was described in a mouse model. The results of FCM analysis showed that the proportion of CD90+HepG2 cells in the spheral CD90+HepG2 enriched by suspension sphere culture was ranging from 98.7% to 99.5%, and 57.1% CD90+HepG2/DC fused cells were successfully constructed. The fusion cells expressed a higher level of costimulatory molecules CD80, CD83, CD86, and MHC-I and MHC-II molecules HLA-ABC and HLA-DR than did immature DCs (P<0.05). And the functional analysis of fusion cell-induced CTLs also illustrated that CD90+HepG2/DC fusion cells showed a greater capacity to activate proliferation of lymphocytes in vitro (P<0.05). The CD90+HepG2/DC-activated CTLs had a specific killing ability against CD90+HepG2 cells in vivo. These results suggested that CD90+HepG2/DC fusion cells could efficiently stimulate T lymphocytes to generate specific CTLs targeting CD90+HepG2 cells. It might be a promising strategy of immunotherapy for HCC.

scholarly journals Maximal killing of lymphoma cells by DNA damage–inducing therapy requires not only the p53 targets Puma and Noxa, but also Bim

Blood ◽  
2010 ◽  
Vol 116 (24) ◽  
pp. 5256-5267 ◽  
Author(s):  
Lina Happo ◽  
Mark S. Cragg ◽  
Belinda Phipson ◽  
Jon M. Haga ◽  
Elisa S. Jansen ◽  
...  
Keyword(s):  
Dna Damage ◽  
Drug Resistance ◽  
Target Genes ◽  
B Cell Lymphoma ◽  
Chemotherapeutic Agents ◽  
Lymphoid Cells ◽  
Lymphoma Cells ◽  
P53 Target Genes

Abstract DNA-damaging chemotherapy is the backbone of cancer treatment, although it is not clear how such treatments kill tumor cells. In nontransformed lymphoid cells, the combined loss of 2 proapoptotic p53 target genes, Puma and Noxa, induces as much resistance to DNA damage as loss of p53 itself. In Eμ-Myc lymphomas, however, lack of both Puma and Noxa resulted in no greater drug resistance than lack of Puma alone. A third B-cell lymphoma-2 homology domain (BH)3-only gene, Bim, although not a direct p53 target, was up-regulated in Eμ-Myc lymphomas incurring DNA damage, and knockdown of Bim levels markedly increased the drug resistance of Eμ-Myc/Puma−/−Noxa−/− lymphomas both in vitro and in vivo. Remarkably, c-MYC–driven lymphoma cell lines from Noxa−/−Puma−/−Bim−/− mice were as resistant as those lacking p53. Thus, the combinatorial action of Puma, Noxa, and Bim is critical for optimal apoptotic responses of lymphoma cells to 2 commonly used DNA-damaging chemotherapeutic agents, identifying Bim as an additional biomarker for treatment outcome in the clinic.

scholarly journals Dominant role of CD47–thrombospondin-1 interactions in myeloma-induced fusion of human dendritic cells: implications for bone disease

Blood ◽  
2009 ◽  
Vol 114 (16) ◽  
pp. 3413-3421 ◽  
Author(s):  
Anjli Kukreja ◽  
Soroosh Radfar ◽  
Ben-Hua Sun ◽  
Karl Insogna ◽  
Madhav V. Dhodapkar
Keyword(s):  
Dendritic Cells ◽  
Tumor Cells ◽  
Cell Fusion ◽  
Bone Disease ◽  
Dominant Role ◽  
Osteoclast Formation ◽  
Cell Contact ◽  
Thrombospondin 1 ◽  
Human Dendritic Cells

Abstract Lytic bone disease in myeloma is characterized by an increase in multinucleate osteoclasts in close proximity to tumor cells. However, the nature of osteoclast precursors and the mechanisms underlying multinuclearity are less understood. Here we show that culture of myeloma cell lines as well as primary myeloma cells with human dendritic cells (DCs) but not monocytes or macrophages leads to spontaneous cell-cell fusion, which then leads to the facile formation of multinucleate bone-resorbing giant cells. Osteoclastogenesis is cell contact dependent, leading to up-regulation of thrombospondin-1 (TSP-1) in DCs. Disruption of CD47–TSP-1 interaction by TSP-1–blocking antibodies or down-regulation of CD47 on tumor cells by RNA interference abrogates tumor-induced osteoclast formation. Blockade of CD47–TSP-1 interactions also inhibits receptor activator for nuclear factor κB ligand- and macrophage colony-stimulating factor–induced formation of osteoclasts from human monocytes. Further, TSP-1 blockade attenuates hypercalcemia induced by parathyroid hormone in vivo. These data point to a role for CD47–TSP-1 interactions in regulating cell-fusion events involved in human osteoclast formation. They also suggest that DCs, known to be enriched in myeloma tumors, may be direct precursors for tumor-associated osteoclasts. Disruption of CD47–TSP-1 interactions or preventing the recruitment of DCs to tumors may provide novel approaches to therapy of myeloma bone disease and osteoporosis.

CDDO and CDDO-Im Reduce Tumor Burden in a Transgenic Mouse Model of CLL.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3477-3477
Author(s):  
Juan M. Zapata ◽  
Christina L. Kress ◽  
Marina Konopleva ◽  
Maryla Krajewska ◽  
Mark Hyer ◽  
...  
Keyword(s):  
B Cells ◽  
Transgenic Mice ◽  
B Cell ◽  
B Cell Lymphoma ◽  
Chemotherapeutic Agents ◽  
Tumor Burden ◽  
Leukemic Cells ◽  
Medium Size ◽  
Control Group

Abstract Transgenic mice over-expressing in B lymphocytes both Bcl-2 and a TRAF2 mutant lacking the N-terminal RING and zinc finger domains (TRAF2DN), which mimics TRAF1, develop small B cell lymphoma and leukemia that have remarkably similar characteristics to human chronic lymphocytic leukemia (CLL). TRAF2DN/Bcl-2 mice develop over time leukemia, severe splenomegaly, and lymphadenopathy, which are associated with monoclonal and oligoclonal B cell neoplasms. The lifespan of TRAF2DN/Bcl-2 mice is markedly reduced compared to Bcl-2 and TRAF2DN single transgenics or wild-type littermates. The expanded B cell population in the blood of leukemic TRAF2DN/Bcl-2 double transgenic mice is primarily comprised of small-medium size, non-cycling B220M/IgMH/IgDL/CD21L/CD23−/CD11b+/CD5+ cells that were Bcl-6 negative, consistent with a B-1 phenotype, closely resembling their human CLL counterparts. Indeed, these B cells showed comparable proliferation rates to normal B-cells, but exhibited markedly increased survival and were resistant to apoptosis induced by chemotherapeutic agents and glucocorticoids. We studied the effects of synthetic triterpenoid 2-Cyano-3,12-Dioxooleana-1,9-Dien-28-Oic Acid (CDDO) and its imidazolide derivative (CDDO-Im) on cultured B-cells from the TRAF2DN/Bcl-2 transgenic mice. Both CDDO and CDDO-Im efficiently induced apoptosis of these cells in vitro, although CDDO-Im was approximately 10-times more potent than CDDO (LD50: 0.35μM CDDO-Im vs 3.8 μM CDDO). To study the effect of CDDO and CDDO-Im in vivo, groups of TRAF2DN/Bcl-2 mice that had developed leukemia were injected i.v. with liposomes alone or liposomes containing either CDDO or CDDO-Im, at a dose of 20 mg/kg/day. Each mouse received a total of nine injections administered over a period of 22 days. The concentration of B cells in the blood of these mice was monitored daily after each injection, using a mini-FACS (Guava Technologies, Inc.). CDDO-treated mice showed a steady reduction in the number of leukemic cells in blood during the treatment and this tendency was maintained 10 days after the last treatment. In contrast, CDDO-Im treated mice showed a striking increase in the concentration of B cells in blood (B220+ events) immediately after the first inoculation. One mouse of this group died after the first injection, and 2 more mice died after 5 injections. Only 2 mice treated with CDDO-Im survived the full treatment, showing a striking reduction of leukemic cells in blood by the end of the treatment. Administration of empty liposomes had no inhibitory effect on the leukemia, and mice in this control group had massive splenomegaly (1431±323 mg; n=3) and severe disseminated lymphadenopathy. In contrast, CDDO-treated mice had less severe splenomegaly (938±234; n=4) but still had severe lymphadenopathy. CDDO-Im treated mice showed a dramatic reduction in the spleen size that was evident also in those mice that died after 5 injections (474±185 mg; n=4) and had no signs of lymphadenopathy. Although preliminary, these results indicate that in vivo administration of CDDO and CDDO-Im reduced the tumor burden in a transgenic model of CLL, and illustrate the potential of triterpenoids as single agents for the treatment of CLL.

Targeting Bcl-2 Family Proteins in Adult T-Cell Leukemia/Lymphoma: In Vitro and In Vivo Effects of a Novel Bcl-2 Family Inhibitor ABT-737.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1685-1685
Author(s):  
Kenji Ishitsuka ◽  
Chie Ishikawa ◽  
Fusanori Yotsumoto ◽  
Hiroo Katsuya ◽  
Naoko Kunami ◽  
...  
Keyword(s):  
Patient Outcome ◽  
T Cell ◽  
Conflicts Of Interest ◽  
Interleukin 2 ◽  
Chemotherapeutic Agents ◽  
Improve Patient Outcome ◽  
Type I ◽  
Induced Apoptosis ◽  
Improve Patient

Abstract Abstract 1685 Poster Board I-711 Adult T-cell lymphoma/leukemia (ATLL) is a T-cell malignancy caused by human T-lymphotrophic virus type I (HTLV-I), and its therapeutic outcome is still remains very poor. Therefore, novel therapeutic strategies are needed to improve patient outcome. In this study, we elucidated the therapeutic potential to target anti-apoptotic Bcl-2 family proteins for the treatment of ATLL by using ABT-737 (Abbott Laboratories, Abbott Park, IL, USA), a small molecule inhibitor of Bcl-2, Bcl-XL and Bcl-w. We first validated the rationale of this study by assessing the expression of Bcl-2 family proteins among 25 lymph-node specimens derived from ATLL patients by using immunohistochemistory. Both or either of Bcl-2 and Bcl-XL proteins was highly expressed in 80% of specimens. We next examined the cytotoxicity of ABT-737 against ATLL cell lines. ABT-737 significantly inhibited growth of MT-1, MT-2 and HuT 102 cells with a concentration of 50 percent inhibition (IC50) at 72 h of 2.4, 0.23 and 0.008μM, respectively. We then elucidated the mechanism of growth inhibition induced by ABT-737 using MT-1 and MT-2 cells. ABT-737 induced apoptosis in MT-1, MT-2 cells with cleavage of caspase 9, 3 and PARP. ABT-737 also induced apoptosis in fresh tumor cells derived from patients with ATLL. We next elucidated the potential of ABT-737 to enhance the cytotoxicity induced by conventional chemotherapeutic agents. The interaction between them was evaluated using the Chou-Talalay method by determining the combination index. ABT-737 synergistically enhanced the cytotoxicity and apoptosis induced by either of doxorubicin, vincristine or etoposide, which is a current key drug to treat ATLL. Most importantly, ABT-737 significantly inhibited tumor growth of in vivo ATLL model using SCID mice inoculated by HuT 102 cells subcutaneously. The mean tumor volume, weight and serum level of soluble interleukin-2 receptor á of ABT-737 (100mg/kg/day)-treated mice were significantly lower than those of vehicle-treated mice after treatment for 21 days. Moreover, massive induction of apoptosis in tumors treated by ABT-737 was observed by immunofluorescent TUNEL assay. These results suggest that ABT-737 used either alone or in combination with conventional cytotoxic drugs, represents a promising novel targeted approach to overcome drug resistance and improve patient outcome in ATLL. Disclosures No relevant conflicts of interest to declare.

In Vitro and In Vivo Effects of CT-011, a Humanized Anti–PD-1 Monoclonal Antibody, in Combination with Rituximab against Human B-Cell Lymphomas.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 724-724
Author(s):  
Fuliang Chu ◽  
Myriam Foglietta ◽  
Hong Qin ◽  
Rakesh Sharma ◽  
Qing Yi ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
T Cells ◽  
B Cell ◽  
Nk Cells ◽  
Tumor Cells ◽  
Cell Lymphoma ◽  
B Cell Lymphoma ◽  
In Vivo Effects ◽  
Human B Cell

Abstract Abstract 724 Background: Programmed death (PD)–1 is an inhibitory receptor that impairs the function of activated T-cells and natural killer (NK) cells when engaged by its ligands PD-L1 or PD-L2. We have previously demonstrated that PD-1 is markedly up-regulated in intratumoral and peripheral blood CD4+ and CD8+ T cells in patients with follicular lymphoma (FL), a finding associated with impaired T-cell function, suggesting that PD-1 blockade may improve FL immune control. CT-011, a humanized anti PD-1 monoclonal antibody, was previously studied in a phase I clinical trial in patients with advanced hematological malignancies. CT-011 was well tolerated and induced sustained elevations of CD4+ T cells in the peripheral blood. More importantly, apparent clinical benefit was observed in six patients, including one patient with FL who had large tumor masses that achieved a durable complete remission lasting >14 months. Here, we studied the in vitro and in vivo effects of CT-011 on T-cell and/or NK-cell immune responses against human B-cell lymphoma and the hypothesis that CT-011 may improve tumor control when combined with rituximab, a chimeric anti-CD20 monoclonal antibody for the treatment of human FL. Materials and Methods: To determine the effects of CT-011 on antitumor T cells, intratumoral T cells were isolated from primary FL tumor samples, and cultured with or without autologous tumor cells in the presence or absence of CT-011 or isotype control antibody (50 μg/ml each) for 5 days, and tested for proliferation by 3H thymidine incorporation assay. To determine the effects of CT-011 on NK cells, peripheral blood mononuclear cells (PBMCs) derived from normal donors or patients with FL were cultured in the presence or absence of CT-011 (50 μg/ml) with or without IL-2 for 96 hours and analyzed for expression of various activating receptors including CD16, CD32, CD64, Fas ligand, NKG2D, NKp30, NKp44, and NKp46. The in vivo effects of CT-011 were tested in two B-cell lymphoma xenograft models. Ramos and RL lymphoma tumor cells were injected subcutaneously into nude and SCID mice, respectively, and CT-011 (10 μg/mouse) was injected weekly with or without rituximab starting approximately 7–10 days after tumor inoculation. Results: We observed that CT-011 significantly increased the proliferation of intratumoral T cells in response to autologous tumor cells compared with isotype control antibody. Treatment with CT-011 enhanced the expression of Fas ligand, CD32, CD64, and NKp30 on human NK cells in the presence of IL-2 as compared with PBMCs treated with IL-2 alone or media control. In the RL lymphoma xenograft model in SCID mice, treatment with CT-011 significantly delayed tumor growth (P≤0.05) and improved survival (P≤0.01) compared with control mice injected with saline. In a Ramos lymphoma xenograft model in nude mice, treatment with CT-011 and rituximab eradicated established tumors in a significant proportion of mice (P≤0.05) and markedly improved survival compared with rituximab alone or saline. Conclusions: Taken together, these studies suggest that blockade of PD-1 with CT-011 enhances the function of anti-tumor T-cells and augments the expression of activating receptors on NK cells. Treatment with CT-011 led to improved tumor control against human B-cell lymphoma in xenograft models and the combined use of CT-011 and rituximab was more effective that rituximab alone. These results provide the rationale to test the combination of CT-011 with rituximab in patients with B-cell lymphoma, given that the combination is likely to be complementary and may even be synergistic, leading to enhanced clinical efficacy without increasing toxicity. The development of such approaches that activate both the innate (NK-cells) and adaptive (T-cells) immune systems is likely to minimize the emergence of immune escape variants and improve clinical outcome in patients with lymphoma. A clinical trial evaluating CT-011 in combination with rituximab is planned in patients with relapsed FL. Disclosures: Rodionov: Cure Tech Ltd.: Employment. Rotem-Yehudar:Cure Tech Ltd.: Employment.

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