scholarly journals NKG2D-CAR-transduced natural killer cells efficiently target multiple myeloma

2021 ◽  
Vol 11 (8) ◽  
Author(s):  
Alejandra Leivas ◽  
Antonio Valeri ◽  
Laura Córdoba ◽  
Almudena García-Ortiz ◽  
Alejandra Ortiz ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Therapy ◽  
Nk Cells ◽  
Nk Cell ◽  
In Vitro Cytotoxicity ◽  
T Cell Therapy ◽  
Car T Cell Therapy ◽  
Wide Range

AbstractCAR-T-cell therapy against MM currently shows promising results, but usually with serious toxicities. CAR-NK cells may exert less toxicity when redirected against resistant myeloma cells. CARs can be designed through the use of receptors, such as NKG2D, which recognizes a wide range of ligands to provide broad target specificity. Here, we test this approach by analyzing the antitumor activity of activated and expanded NK cells (NKAE) and CD45RA− T cells from MM patients that were engineered to express an NKG2D-based CAR. NKAE cells were cultured with irradiated Clone9.mbIL21 cells. Then, cells were transduced with an NKG2D-4-1BB-CD3z-CAR. CAR-NKAE cells exhibited no evidence of genetic abnormalities. Although memory T cells were more stably transduced, CAR-NKAE cells exhibited greater in vitro cytotoxicity against MM cells, while showing minimal activity against healthy cells. In vivo, CAR-NKAE cells mediated highly efficient abrogation of MM growth, and 25% of the treated mice remained disease free. Overall, these results demonstrate that it is feasible to modify autologous NKAE cells from MM patients to safely express a NKG2D-CAR. Additionally, autologous CAR-NKAE cells display enhanced antimyeloma activity demonstrating that they could be an effective strategy against MM supporting the development of NKG2D-CAR-NK-cell therapy for MM.

scholarly journals 124 Functionalizing CAR T cells for selective proliferation and dual-targeting using the meditope technology

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A133-A133
Author(s):  
Cheng-Fu Kuo ◽  
Yi-Chiu Kuo ◽  
Miso Park ◽  
Zhen Tong ◽  
Brenda Aguilar ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

BackgroundMeditope is a small cyclic peptide that was identified to bind to cetuximab within the Fab region. The meditope binding site can be grafted onto any Fab framework, creating a platform to uniquely and specifically target monoclonal antibodies. Here we demonstrate that the meditope binding site can be grafted onto chimeric antigen receptors (CARs) and utilized to regulate and extend CAR T cell function. We demonstrate that the platform can be used to overcome key barriers to CAR T cell therapy, including T cell exhaustion and antigen escape.MethodsMeditope-enabled CARs (meCARs) were generated by amino acid substitutions to create binding sites for meditope peptide (meP) within the Fab tumor targeting domain of the CAR. meCAR expression was validated by anti-Fc FITC or meP-Alexa 647 probes. In vitro and in vivo assays were performed and compared to standard scFv CAR T cells. For meCAR T cell proliferation and dual-targeting assays, the meditope peptide (meP) was conjugated to recombinant human IL15 fused to the CD215 sushi domain (meP-IL15:sushi) and anti-CD20 monoclonal antibody rituximab (meP-rituximab).ResultsWe generated meCAR T cells targeting HER2, CD19 and HER1/3 and demonstrate the selective specific binding of the meditope peptide along with potent meCAR T cell effector function. We next demonstrated the utility of a meP-IL15:sushi for enhancing meCAR T cell proliferation in vitro and in vivo. Proliferation and persistence of meCAR T cells was dose dependent, establishing the ability to regulate CAR T cell expansion using the meditope platform. We also demonstrate the ability to redirect meCAR T cells tumor killing using meP-antibody adaptors. As proof-of-concept, meHER2-CAR T cells were redirected to target CD20+ Raji tumors, establishing the potential of the meditope platform to alter the CAR specificity and overcome tumor heterogeneity.ConclusionsOur studies show the utility of the meCAR platform for overcoming key challenges for CAR T cell therapy by specifically regulating CAR T cell functionality. Specifically, the meP-IL15:sushi enhanced meCAR T cell persistence and proliferation following adoptive transfer in vivo and protects against T cell exhaustion. Further, meP-ritiuximab can redirect meCAR T cells to target CD20-tumors, showing the versatility of this platform to address the tumor antigen escape variants. Future studies are focused on conferring additional ‘add-on’ functionalities to meCAR T cells to potentiate the therapeutic effectiveness of CAR T cell therapy.

scholarly journals RTID-07. HUMAN PLACENTAL HEMATOPOIETIC STEM CELL DERIVED NATURAL KILLER CELLS (CYNK-001) FOR TREATMENT OF RECURRENT GLIOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii194-ii195
Author(s):  
Nazanin Majd ◽  
Maha Rizk ◽  
Solveig Ericson ◽  
Kris Grzegorzewski ◽  
Sharmila Koppisetti ◽  
...  
Keyword(s):  
Cell Therapy ◽  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
In Vitro Cytotoxicity ◽  
Orthotopic Mouse Model ◽  
Hematopoietic Stem ◽  
Dismal Prognosis

Abstract Glioblastoma (GBM) is the most aggressive primary brain tumor with dismal prognosis. Recent advances of immunotherapy in cancer have sparked interest in the use of cell therapy for treatment of GBM. Active transfer of Natural Killer (NK) cells is of particular interest in GBM because NK cells are capable of exerting anti-tumor cytotoxicity without the need for antigen presentation and sensitization, processes that are impaired in GBM. CYNK-001 is an allogeneic, off-the-shelf product enriched for CD56+/CD3- NK cells expanded from placental CD34+ cells manufactured by Celularity. Here, we demonstrate in vitro cytotoxicity of CYNK-001 against several GBM lines and its in vivo anti-tumor activity in a U87MG orthotopic mouse model via intracranial administration resulting in 94.5% maximum reduction in tumor volume. We have developed a phase I window-of-opportunity trial of CYNK-001 in recurrent GBM via intravenous (IV) and intratumoral (IT) routes. In the IV cohort, subjects receive cyclophosphamide for lymphodepletion followed by 3-doses of IV CYNK-001 weekly. In the IT cohort, subjects undergo placement of an IT catheter with an ommaya reservoir followed by 3-doses of IT CYNK-001 weekly. Patients are monitored for 28-days after last infusion for toxicity. Once maximum safe dose (MSD) is determined, patients undergo IV or IT treatments at MSD followed by surgical resection and the tumor tissue will be analyzed for NK cell engraftment and persistence. We will utilize a 3 + 3 dose de-escalation design (maximum n=36). Primary endpoint is safety and feasibility. Secondary endpoints are overall response rate, duration of response, time to progression, progression free survival and overall survival. Main eligibility criteria include age ≥18, KPS ≥60, GBM at first or second relapse with a measurable lesion on ≤2mg dexamethasone. This is the first clinical trial to investigate CYNK-001 in GBM and will lay the foundation for future NK cell therapy in solid tumors.

scholarly journals Sulforaphane enhances the antitumor response of chimeric antigen receptor T cells by regulating PD-1/PD-L1 pathway

BMC Medicine ◽  
2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Chunyi Shen ◽  
Zhen Zhang ◽  
Yonggui Tian ◽  
Feng Li ◽  
Lingxiao Zhou ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Death ◽  
Programmed Cell Death ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell Therapy ◽  
Car T

Abstract Background Chimeric antigen receptor T (CAR-T) cell therapy has limited effects in the treatment of solid tumors. Sulforaphane (SFN) is known to play an important role in inhibiting tumor growth, but its effect on CAR-T cells remains unclear. The goal of the current study was to determine whether combined CAR-T cells and SFN could provide antitumor efficacy against solid tumors. Methods The effect of combined SFN and CAR-T cells was determined in vitro using a co-culture system and in vivo using a xenograft mouse model. We further validated the effects of combination therapy in patients with cancer. Results In vitro, the combination of SFN and CAR-T cells resulted in enhanced cytotoxicity and increased lysis of tumor cells. We found that SFN suppressed programmed cell death 1 (PD-1) expression in CAR-T cells and potentiated antitumor functions in vitro and in vivo. As a ligand of PD-1, programmed cell death ligand 1 (PD-L1) expression was also decreased in tumor cells after SFN treatment. In addition, β-TrCP was increased by SFN, resulting in higher activation of ubiquitination-mediated proteolysis of PD-L1, which induced PD-L1 degradation. The combination of SFN and CAR-T cell therapy acted synergistically to promote better immune responses in vivo compared with monotherapy. In clinical treatments, PD-1 expression was lower, and proinflammatory cytokine levels were higher in patients with various cancers who received CAR-T cells and took SFN orally than that in the control group. Conclusion SFN improves the cytotoxicity of CAR-T cells by modulating the PD-1/PD-L1 pathway, which may provide a promising strategy for the combination of SFN with CAR-T cells for cancer immunotherapy.

scholarly journals PTK7-Targeting CAR T-Cells for the Treatment of Lung Cancer and Other Malignancies

2021 ◽  
Vol 12 ◽  
Author(s):  
Yamin Jie ◽  
Guijun Liu ◽  
Lina Feng ◽  
Ying Li ◽  
Mingyan E ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Lung Cancers ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

In spite of impressive success in treating hematologic malignancies, adoptive therapy with chimeric antigen receptor modified T cells (CAR T) has not yet been effective in solid tumors, where identification of suitable tumor-specific antigens remains a major obstacle for CAR T-cell therapy due to the “on target off tumor” toxicity. Protein tyrosine kinase 7 (PTK7) is a member of the Wnt-related pseudokinases and identified as a highly expressed antigen enriched in cancer stem cells (CSCs) from multiple solid tumors, including but not limited to triple-negative breast cancer, non-small-cell lung cancer, and ovarian cancer, suggesting it may serve as a promising tumor-specific target for CAR T-cell therapy. In this study, we constructed three different PTK7-specific CAR (PTK7-CAR1/2/3), each comprising a humanized PTK7-specific single-chain variable fragment (scFv), hinge and transmembrane (TM) regions of the human CD8α molecule, 4-1BB intracellular co-stimulatory domain (BB-ICD), and CD3ζ intracellular domain (CD3ζ-ICD) sequence, and then prepared the CAR T cells by lentivirus-mediated transduction of human activated T cells accordingly, and we sequentially evaluated their antigen-specific recognition and killing activity in vitro and in vivo. T cells transduced with all three PTK7-CAR candidates exhibited antigen-specific cytokine production and potent cytotoxicity against naturally expressing PTK7-positive tumor cells of multiple cancer types without mediating cytotoxicity of a panel of normal primary human cells; meanwhile, in vitro recursive cytotoxicity assays demonstrated that only PTK7-CAR2 modified T cells retained effective through multiple rounds of tumor challenge. Using in vivo xenograft models of lung cancers with different expression levels of PTK7, systemic delivery of PTK7-CAR2 modified T cells significantly prevented tumor growth and prolonged overall survival of mice. Altogether, our results support PTK7 as a therapeutic target suitable for CAR T-cell therapy that could be applied for lung cancers and many other solid cancers with PTK7 overexpression.

PTK7-Targeting CAR T-cells for the Treatment of Lung Cancer and other Malignancies

2020 ◽  
Author(s):  
Yamin Jie ◽  
Guijun Liu ◽  
Lina Feng ◽  
Ying Li ◽  
Mingyan E ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Lung Cancers ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

Abstract Background: In spite of impressive success in treating hematologic malignancies, adoptive therapy with chimeric antigen receptor modified T cells (CAR T) has not yet been effective in solid tumors, where identification of suitable tumor-specific antigens remains a major obstacle for CAR T-cell therapy due to the “on target off tumor” toxicity. Protein tyrosine kinase 7 (PTK7) is a member of the Wnt-related pseudokinases and identified as a highly expressed antigen enriched in cancer stem cells (CSCs) from multiple solid tumors, including but not limited to triple-negative breast cancer, non-small cell lung cancer, and ovarian cancer, suggesting it may serve as a promising tumor-specific target for CAR T-cell therapy. Methods: In this study, we constructed 3 different PTK7-specific CAR (PTK7-CAR1/2/3) each comprising a humanized PTK7-specific single chain variable fragment (scFv), hinge and transmembrane (TM) regions of the human CD8α molecule, 4-1BB intracellular co-stimulatory domain (BB-ICD), and CD3ζ intracellular domain (CD3ζ-ICD) sequence, and then prepared the CAR T cells by lentivirus mediated transduction of human activated T cells accordingly, and sequentially evaluated their antigen-specific recognition and killing activity in vitro and in vivo.Results: T cells transduced with all 3 PTK7-CAR candidates exhibited antigen-specific cytokine production and potent cytotoxicity against naturally expressing PTK7-positive tumor cells of multiple cancer types without mediating cytotoxicity of a panel of normal primary human cells; meanwhile, in vitro recursive cytotoxicity assays demonstrated that only PTK7-CAR2 modified T cells retained effective through multiple rounds of tumor challenge. Using in vivo xenograft models of lung cancers with different expression level of PTK7, systemic delivery of PTK7-CAR2 modified T cells significantly prevented tumor growth and prolonged overall survival of mice. Conclusion: Altogether, our results support PTK7 as a therapeutic target suitable for CAR T-cell therapy that could be applied for lung cancers and many other solid cancers with PTK7 overexpression.

scholarly journals Enhancing the Antigen-Sensitivity of the CD22 CAR through Modulation of the Affinity and Linker-Length of the Single-Chain Fragment Variable

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 41-42
Author(s):  
M. Eric Kohler ◽  
Zachary Walsh ◽  
Kole Degolier ◽  
Terry J. Fry
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

The advent of chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of relapsed/refractory acute lymphoblastic leukemia (r/r ALL). CD19 directed CAR T cells have demonstrated the ability to induce complete remissions in up to 90% of r/r ALL patients. Despite this remarkable upfront success, relapse after CAR T cell therapy remains a major obstacle to long term remissions. A major mechanism for relapse after CD19-directed CAR T cell therapy is the recurrence of antigen-negative ALL cells. In recent years, CD22 CAR T cell therapy has emerged as an effective salvage therapy for patients with CD19-negative ALL. In a phase I clinical trial, CD22 CAR T cells were able to induce remission in up to 80% of patients with CD19-negative ALL. Patients achieving remission, who did not undergo a consolidative hematopoietic stem cell transplant, were found to be at high risk of relapse due to downregulation of the CD22 antigen below the threshold required for effective CD22 CAR T cell activity. Thus, strategies to increase the antigen-sensitivity of CD22 CAR T cells have the potential to enhance the induction and duration of remission in ALL patients. As the properties of a CAR that influence sensitivity to antigen are not well defined, we began by testing the impact of increasing the affinity of the single-chain fragment variable (scFv) for the CD22 antigen. T cells from healthy donors were activated and transduced with a second-generation, 4-1BB CAR containing either the standard affinity (SA)-m971 scFv used in the prior clinical trial, or a high affinity (HA) scFv generated by affinity maturation of the m971 scFv. SA- and HA-CD22 CAR T cells were evaluated in vitro and in vivo against clones of the pre-B ALL cell line, NALM6, which express CD22 at wild type levels (CD22WT), sub-physiologic levels (CD22Lo), supra-physiologic levels (CD22Hi) or in which CD22 was deleted (CD22Neg). We found that the amount of CD22 expressed on the leukemia cells resulted in dose-dependent expression of activation markers, such as CD69 and CD25 (p<0.05) on CD22 CAR T cells. Similarly, CAR T cell functions, such as the secretion of interferon-gamma (IFNg, p<0.0001) and interleukin-2 (IL-2, p<0.0001) as well as cytotoxic degranulation (p<0.0001) were all significantly impacted by the amount of CD22 on the surface of NALM6. A similar pattern of antigenic dose-response was seen in the signaling of CAR T cells, with phosphorylation of ERK reflecting the level of CD22 antigen (p<0.001) and correlating with the increased in vivo efficacy of the CAR T cells against CD22WT NALM6, relative to CD22Lo NALM6. Increasing the affinity of the CD22 CAR did not impact the in vivo efficacy against CD22WT NALM6 at either a therapeutic or subtherapeutic dose, however, HA-CD22 CAR T cells significantly prolonged the survival of NSG mice with CD22Lo NALM6, relative to SA-CD22 CAR T cells (p<0.01). The enhanced activity of HA-CD22 CAR T cells against CD22Lo leukemia did not correlate with improved in vitro functionality, as the HA-CD22 CAR T cells surprisingly demonstrated lower IL-2 secretion (p<0.01), lower proliferation (p<0.05) and diminished in vitro lysis of CD22Lo NALM6 (p<0.05), relative to SA-CD22 CAR T cells. ERK phosphorylation, however, was significantly increased in HA-CD22 CAR T cells (p<0.01) and was the only in vitro marker which correlated with the enhanced in vivo activity seen with the affinity-matured CAR. Previous clinical experience has demonstrated the importance of using a short linker (consisting of a single G4S sequence) between the heavy and light chains of the m971 scFv, therefore we next evaluated the impact of linker length on the activity of the HA-CD22 CAR. HA-CD22 CARs were generated with either a short- or long-linker (G4S x1 vs G4S x3, respectively) and evaluated in vitro and in vivo. While the short linker improved proliferation in vitro, there was no significant impact of linker length on cytokine production or lysis of CD22Lo NALM6. In a xenograft model, HA-CD22 CAR T cells with the long-linker demonstrated slower progression of CD22Lo leukemia and significantly prolonged survival of NSG mice with CD22WT leukemia relative to HA-CD22 CAR T cells with the short-linker (p<0.01). Taken together, these studies suggest that increasing the affinity of a scFv is a promising strategy for enhancing CAR sensitivity to low levels of target antigen, with the potential to decrease post-CAR T cell relapses due to antigen downregulation. Disclosures No relevant conflicts of interest to declare.

scholarly journals DNAM-1 promotes activation of cytotoxic lymphocytes by nonprofessional antigen-presenting cells and tumors

2008 ◽  
Vol 205 (13) ◽  
pp. 2965-2973 ◽  
Author(s):  
Susan Gilfillan ◽  
Christopher J. Chan ◽  
Marina Cella ◽  
Nicole M. Haynes ◽  
Aaron S. Rapaport ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Adhesion Molecules ◽  
Cd8 T Cells ◽  
Nk Cell ◽  
Cd8 T Cell ◽  
Antigen Presenting

Natural killer (NK) cells and CD8 T cells require adhesion molecules for migration, activation, expansion, differentiation, and effector functions. DNAX accessory molecule 1 (DNAM-1), an adhesion molecule belonging to the immunoglobulin superfamily, promotes many of these functions in vitro. However, because NK cells and CD8 T cells express multiple adhesion molecules, it is unclear whether DNAM-1 has a unique function or is effectively redundant in vivo. To address this question, we generated mice lacking DNAM-1 and evaluated DNAM-1–deficient CD8 T cell and NK cell function in vitro and in vivo. Our results demonstrate that CD8 T cells require DNAM-1 for co-stimulation when recognizing antigen presented by nonprofessional antigen-presenting cells; in contrast, DNAM-1 is dispensable when dendritic cells present the antigen. Similarly, NK cells require DNAM-1 for the elimination of tumor cells that are comparatively resistant to NK cell–mediated cytotoxicity caused by the paucity of other NK cell–activating ligands. We conclude that DNAM-1 serves to extend the range of target cells that can activate CD8 T cell and NK cells and, hence, may be essential for immunosurveillance against tumors and/or viruses that evade recognition by other activating or accessory molecules.

scholarly journals Targeting glycosylation of PD-1 to enhance CAR-T cell cytotoxicity

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiaojuan Shi ◽  
Daiqun Zhang ◽  
Feng Li ◽  
Zhen Zhang ◽  
Shumin Wang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Inhibitory Effects ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T Cell Therapy ◽  
Car T

AbstractAsparagine-linked (N-linked) glycosylation is ubiquitous and can stabilize immune inhibitory PD-1 protein. Reducing N-linked glycosylation of PD-1 may decrease PD-1 expression and relieve its inhibitory effects on CAR-T cells. Considering that the codon of Asparagine is aac or aat, we wondered if the adenine base editor (ABE), which induces a·t to g·c conversion at specific site, could be used to reduce PD-1 suppression by changing the glycosylated residue in CAR-T cells. Our results showed ABE editing altered the coding sequence of N74 residue of PDCD1 and downregulated PD-1 expression in CAR-T cells. Further analysis showed ABE-edited CAR-T cells had enhanced cytotoxic functions in vitro and in vivo. Our study suggested that the single base editors can be used to augment CAR-T cell therapy.

scholarly journals GPRC5D is a target for the immunotherapy of multiple myeloma with rationally designed CAR T cells

2019 ◽  
Vol 11 (485) ◽  
pp. eaau7746 ◽  
Author(s):  
Eric L. Smith ◽  
Kim Harrington ◽  
Mette Staehr ◽  
Reed Masakayan ◽  
Jon Jones ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Cell Therapy ◽  
B Cell ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell Therapy ◽  
Car T

Early clinical results of chimeric antigen receptor (CAR) T cell therapy targeting B cell maturation antigen (BCMA) for multiple myeloma (MM) appear promising, but relapses associated with residual low-to-negative BCMA-expressing MM cells have been reported, necessitating identification of additional targets. The orphan G protein–coupled receptor, class C group 5 member D (GPRC5D), normally expressed only in the hair follicle, was previously identified as expressed by mRNA in marrow aspirates from patients with MM, but confirmation of protein expression remained elusive. Using quantitative immunofluorescence, we determined that GPRC5D protein is expressed on CD138+ MM cells from primary marrow samples with a distribution that was similar to, but independent of, BCMA. Panning a human B cell–derived phage display library identified seven GPRC5D-specific single-chain variable fragments (scFvs). Incorporation of these into multiple CAR formats yielded 42 different constructs, which were screened for antigen-specific and antigen-independent (tonic) signaling using a Nur77-based reporter system. Nur77 reporter screen results were confirmed in vivo using a marrow-tropic MM xenograft in mice. CAR T cells incorporating GPRC5D-targeted scFv clone 109 eradicated MM and enabled long-term survival, including in a BCMA antigen escape model. GPRC5D(109) is specific for GPRC5D and resulted in MM cell line and primary MM cytotoxicity, cytokine release, and in vivo activity comparable to anti-BCMA CAR T cells. Murine and cynomolgus cross-reactive CAR T cells did not cause alopecia or other signs of GPRC5D-mediated toxicity in these species. Thus, GPRC5D(109) CAR T cell therapy shows potential for the treatment of advanced MM irrespective of previous BCMA-targeted therapy.

Mechanisms of IL-21 Enhancement of Rituximab Efficacy in a Lymphoma Xenograft Model.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 1404-1404
Author(s):  
Steve D. Hughes ◽  
Ken Bannink ◽  
Cecile Krejsa ◽  
Mark Heipel ◽  
Becky Johnson ◽  
...  
Keyword(s):  
T Cells ◽  
Nk Cells ◽  
Nk Cell ◽  
Antibody Therapy ◽  
Xenograft Model ◽  
Tumor Model ◽  
Cell Types ◽  
Current Evidence

Abstract Interleukin 21 (IL-21) is an IL-2 family cytokine produced by activated CD4+ T cells. Potent effects of IL-21 have been observed on the growth, survival, and functional activation of T cells, B cells, and natural killer (NK) cells. A Phase I clinical trial of IL-21 in metastatic melanoma and renal cell carcinoma is currently in progress. We recently reported that IL-21 significantly enhanced rituximab mediated clearance of CD20+ lymphoma cell lines both in vitro and in vivo, and that these effects were potentially mediated through IL-21 enhancement of NK cell capacity to effect antibody dependent cellular cytotoxicity (ADCC). Specifically, NK cells treated with IL-21 showed increased cytotoxicity, granzyme B and IFNg production. Current studies aim to further evaluate the mechanisms by which IL-21 enhances ADCC. A number of observations suggest a multi-factorial basis for IL-21 synergy with rituximab. In a xenograft tumor model, SCID mice were injected IV with HS Sultan cells on day 0. Treatment with recombinant murine IL-21 (mIL-21; starting day 1) combined with rituximab (starting day 3) resulted in significantly increased survival (70% vs. 20% on day 100), compared to rituximab alone. In separate studies, the spleens of mice treated with mIL-21 showed increased numbers of activated macrophages and granulocytes. As macrophages and granulocytes can participate in ADCC, IL-21 synergy with rituximab in vivo may be partly dependent on its activation of these cell types. We have also evaluated whether direct effects of IL-21 on lymphoma cells contribute to enhancement of rituximab efficacy. The xenogeneic B lymphoma models in which IL-21 plus rituximab exhibited enhanced survival are highly aggressive and these models were not shown to respond to treatment with mIL-21 alone. In vitro studies were performed to determine if IL-21 could potentiate the growth inhibitory and pro-apoptotic effects of rituximab. In the absence of effector cells synergistic interaction was not observed. In addition, we tested the ability of IL-21 to enhance cytotoxicity when combined with antibodies targeting non-hematopoietic tumor cells (e.g. trastuzumab). Human NK cells treated with IL-21 displayed significantly increased cytotoxicity in ADCC assays using trastuzumab to target breast cancer cells expressing varying levels of HER-2 antigen. In summary, the current evidence suggests that IL-21 can enhance antibody-mediated tumor cell lysis through activation of multiple effectors of ADCC. Thus IL-21 may prove to be broadly applicable to monoclonal antibody therapy of cancer.

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