Stromal Cross-Presentation and Host Interferon-γ Signaling and Are Required for Elimination of Antigen-Loss Variants of High-Grade B Cell Lymphomas: Implications for Adoptive T Cell Therapy

Abstract Abstract 3927 The incidence of high-grade B cell lymphomas has been increasing over the last decades in western countries for unclear reasons. Relapse after conventional chemotherapy especially in high-grade B cell lymphomas remains a very difficult clinical issue. Contrary to CML and AML, the benefit of allogeneic SCT for treatment of high-grade lymphomas is not well established. Several studies suggested a potential graft versus lymphoma (GvL) effect for acute lymphoblastic leukemia (ALL) and several types of non-Hodgkin lymphomas. To study mechanisms involved in T cell-mediated rejection of B cell lymphomas, we have developed a murine lymphoma model in which three antigens, human c-MYC protein, chicken ovalbumin (OVA) and GFP, serve as foreign antigens for rejection. Lymphomas expressing all three antigens were rejected in 60 to 70% of animals after transfer into wild type mice, whereas lymphomas expressing only human c-MYC protein were not rejected. Outgrowing OVA-expressing lymphomas were infiltrated by T cells, showed MHC class I and II upregulation and loss of antigen expression, indicating immune escape. In contrast to wild type recipients of OVA-expressing lymphomas, 80 to 100% of recipient STAT1-, IFN-γ-, or IFN-γ receptor-deficient mice died due to lymphoma growth. Remarkably, lymphomas arising in IFN-γ- and IFN-γ-receptor-deficient mice also invariably showed lost antigen expression. Thus, poor overall survival of IFN-γ- and IFN-γ-receptor-deficient recipient mice is not due to a lack of antigen-specific T cell killing but due to inefficient eradication of antigen-negative variants of the lymphoma. In order to address the role of the stroma in eradication of lymphoma cells we made use of B6bm1 animals that do not present the immunodominant OVA derived peptide SIINFEKL in the context of MHC class I. Since the wildtype MHC represents an allo-antigen in B6bm1 mice, B6bm1 and B6 wildtype control recipients were T-cell depleted by 30H12 anti CD90.2 antibody prior to transfer of lymphoma cells. Anti OVA immunity was restored by adoptive transfer of 1 Mio. primed CD90.1+ OT-I-T-cells one day after lymphoma transfer. T-cell depletion was continued for 28 days biweekly. Lymphoma growth was faster in bm1 recipients and disease free survival significantly reduced (A). In addition, T-cell expansion was significantly reduced (B) in bm1 recipients as analyzed by pentamer staining of OT-I-T-cells in peripheral blood (day 21 0.84%±0.2 vs. 3.53%±0.2 of lymphocytes, p=0.001) indicating an important role of stromal crosspresentation for the rejection of lymphoma cells. Our data show that mechanisms established for solid tumors hold true also for hematologic neoplasias such as B cell lymphomas. Antigen-dependent eradication of tumor antigen-loss variants makes antigen-specific T cell therapy particularly attractive as a novel therapeutic treatment option. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Pembrolizumab for B-cell lymphomas relapsing after or refractory to CD19-directed CAR T-cell therapy

Blood ◽

10.1182/blood.2021012634 ◽

2021 ◽

Author(s):

Elise A Chong ◽

Cécile Alanio ◽

Jakub Svoboda ◽

Sunita D Nasta ◽

Daniel J Landsburg ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Therapy ◽

B Cell ◽

B Cell Lymphomas ◽

T Cell Therapy ◽

Cell Exhaustion ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T

CD19-directed chimeric antigen receptor-modified T cells (CAR T cells) achieve durable remissions in about 30-40% of relapsed/refractory large B-cell lymphomas. T cell exhaustion and/or an immunosuppressive tumor-microenvironment may contribute to CAR T-cell failure. Pembrolizumab, an anti-PD1 immune checkpoint inhibitor, may reverse T-cell exhaustion following CAR T-cell therapy. We treated 12 patients with B-cell lymphomas who were either refractory to (N=9) or relapsed after (N=3) CD19-directed CAR T cell (4-1BB-costimulated) therapy with pembrolizumab 200mg IV every 3 weeks. Median time from CAR T-cell infusion to first pembrolizumab dose was 3.3 months (range: 0.4-42.8 months). Pembrolizumab was well-tolerated and the only ≥ grade 3 adverse events related to pembrolizumab were neutropenia (N=3; 25%). Best overall response rate after pembrolizumab was 3/12 (25%) [1 complete response; 2 partial responses]. One (8%) patient had stable disease, thus, 4/12 (33%) patients had clinical benefit. After pembrolizumab, 4 patients with clinical benefit had increase in percentage of CAR T cells by mass cytometry (CyTOF); 3 of 4 of these patients also had increases in CAR19 transgene levels by qPCR. Deep immune profiling using mass cytometry revealed increased CAR T cell activation and proliferation and less T-cell exhaustion in clinical responders. Together, PD1 blockade with pembrolizumab after CD19-directed CAR T-cell therapy appears safe and may achieve clinical responses in some patients with B-cell lymphomas refractory to or relapsed after CAR T-cell therapy.

Download Full-text

Trispecific CD19-CD20-CD22–targeting duoCAR-T cells eliminate antigen-heterogeneous B cell tumors in preclinical models

Science Translational Medicine ◽

10.1126/scitranslmed.abc6401 ◽

2021 ◽

Vol 13 (586) ◽

pp. eabc6401

Author(s):

Dina Schneider ◽

Ying Xiong ◽

Darong Wu ◽

Peirong Hu ◽

Leah Alabanza ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cell ◽

Intracellular Signaling ◽

B Cell Lymphoma ◽

Target Antigen ◽

Down Regulation ◽

T Cell Therapy ◽

Number Of Patients ◽

Antigen Loss

A substantial number of patients with leukemia and lymphoma treated with anti-CD19 or anti-CD22 monoCAR-T cell therapy relapse because of antigen loss or down-regulation. We hypothesized that B cell tumor antigen escape may be overcome by a chimeric antigen receptor (CAR) design that simultaneously targets three B cell leukemia antigens. We engineered trispecific duoCAR-T cells with lentiviral vectors encoding two CAR open reading frames that target CD19, CD20, and CD22. The duoCARs were composed of a CAR with a tandem CD19- and CD20-targeting binder, linked by the P2A self-cleaving peptide to a second CAR targeting CD22. Multiple combinations of intracellular T cell signaling motifs were evaluated. The most potent duoCAR architectures included those with ICOS, OX40, or CD27 signaling domains rather than those from CD28 or 4-1BB. We identified four optimal binder and signaling combinations that potently rejected xenografted leukemia and lymphoma tumors in vivo. Moreover, in mice bearing a mixture of B cell lymphoma lines composed of parental triple-positive cells, CD19-negative, CD20-negative, and CD22-negative variants, only the trispecific duoCAR-T cells rapidly and efficiently rejected the tumors. Each of the monoCAR-T cells failed to prevent tumor progression. Analysis of intracellular signaling profiles demonstrates that the distinct signaling of the intracellular domains used may contribute to these differential effects. Multispecific duoCAR-T cells are a promising strategy to prevent antigen loss–mediated relapse or the down-regulation of target antigen in patients with B cell malignancies.

Download Full-text

A Phase I Study of CD19-Targeted 19(T2)28z1xx CAR T Cells in Adult Patients with Relapsed or Refractory B-Cell Malignancies

Blood ◽

10.1182/blood-2020-143088 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 43-44

Author(s):

Jae H. Park ◽

Isabelle Riviere ◽

Devanjan S. Sikder ◽

Vladimir P. Bermudez ◽

Brigitte Senechal ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cell ◽

Dose Escalation ◽

Research Funding ◽

High Grade ◽

T Cell Therapy ◽

Car T Cells ◽

Car T Cell ◽

Car T

Background: Autologous CAR T cell therapy targeting the B-cell specific surface antigen CD19 has demonstrated favorable clinical responses in relapsed or refractory (R/B) B-cell lymphomas (BCL). However, despite 40-60% initial complete response (CR) rates, only a subset of patients experience durable remissions, and there is a need to further improve the efficacy of CAR therapies by preventing relapse and attaining a deeper CR. We hypothesized that the redundancy of CD28 and CD3V signaling in a CAR design incorporating all 3 CD3Vimmunoreceptor tyrosine-based activation motifs (ITAMs) might foster counterproductive T cell differentiation and exhaustion, and therefore created a new CD19 CAR construct with calibrated CAR activation potential by mutating 2 of the 3 ITAMs, termed 1XX. In systemic ALL mouse models, 19-28z1XX CAR induced effective tumor eradication at low CAR T cell doses with improved survival compared to conventional 19-28z CAR. Further preclinical studies demonstrated that the enhanced therapeutic benefit resulted from the reduced strength of activation mediated by the 19-28z1XX CAR, achieving a favorable balance of effector and memory functions, thereby enhancing persistence of functional CAR T cells and promoting effective elimination of CD19+ leukemia at lower T cell doses than needed with 19-28z CAR T cells (Feucht J et al. Nat Med 2019). To further improve the persistence of functional CAR T cells, we screened different humanized CD19-directed scFv in the context of a 19-28z1XX CAR design and proved high specificity and functionality of 19-28z1XX CARs containing a novel humanized scFv T2 - termed 19(T2)28z1XX. Study Design and Methods: This study is a single center Phase I clinical trial of 19(T2)28z1XX in patients with R/R B-cell malignancies at Memorial Sloan Kettering Cancer Center (NCT04464200). Key disease eligibility criteria include R/R diffuse large B cell lymphoma (DLBCL), high grade BCL, primary mediastinal BCL, indolent BCL and chronic lymphocytic leukemia (CLL). Patients with prior CD19 CAR therapies are eligible as long as expression of CD19 is confirmed. Key exclusion criteria include ongoing immunosuppression such as systemic GvHD therapy and active CNS disease. The study uses a 3+3 dose-escalation design to identify the maximum tolerated dose for BCL. There are 5 planned flat-dose levels. Patients will receive conditioning chemotherapy consisting of 3 days of fludarabine and cyclophosphamide followed by a single infusion of 19(T2)28z1XX CAR T cells. In the dose-escalation phase, patients with DLBCL, high grade BCL, and primary mediastinal BCL are eligible to participate. Once the recommended phase 2 dose (RP2D) is determined, the study will open to dose expansion phase with two cohorts. Cohort 1 includes DLBCL, high grade BCL and primary mediastinal BCL (i.e. same eligibility criteria as the dose-escalation phase). Cohort 2 will include patients with indolent BCL, CLL, and Richter's transformation. The dose-expansion part of the trial is designed to further characterize the safety, efficacy, and pharmacokinetics of 19(T2)28z1XX CAR in multiple indications. The primary objective of the trial is to evaluate safety and tolerability and determine the recommended Phase 2 dose of 19(T2)28z1XX. Key secondary objectives include evaluation of 19(T2)28z1XX's efficacy and cellular kinetics. Exploratory objectives include assessment of B cell aplasia, and analysis of serum cytokines. The trial has begun enrollment in August 2020. The investigators are hopeful this study will lead to development of improved CD19 CAR T cell therapy with enhanced efficacy and favorable toxicity profiles with lower infused T cell dose. Disclosures Park: AstraZeneca: Consultancy; Servier: Consultancy, Research Funding; Autolus: Consultancy, Research Funding; Amgen: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Novartis: Consultancy; Minverva: Consultancy; Artiva: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics: Research Funding; Kite: Consultancy, Research Funding; Incyte: Consultancy, Research Funding; Genentech/Roche: Research Funding; Juno Therapeutics: Research Funding; GSK: Consultancy; Intellia: Consultancy; Allogene: Consultancy. Riviere:Fate Therapeutics Inc.: Consultancy, Other: Ownership interest , Research Funding; FloDesign Sonics: Consultancy, Other: Ownership interest; Juno Therapeutics: Other: Ownership interest, Research Funding; Takeda: Research Funding; Atara: Research Funding. Palomba:Genentech: Research Funding; Juno Therapeutics, a Bristol-Meyers Squibb Company: Honoraria, Research Funding; Regeneron: Research Funding; Novartis: Honoraria; Merck: Honoraria; Celgene: Honoraria; Pharmacyclics: Honoraria. Brentjens:BMS: Research Funding; Gracell Therapeutics: Consultancy; Juno Therapeutics (a Bristol Myers Squibb company): Patents & Royalties. Sadelain:Atara: Patents & Royalties, Research Funding; Fate Therapeutics: Patents & Royalties, Research Funding; Minerva: Other: Biotechnologies , Patents & Royalties; Mnemo: Patents & Royalties; Takeda: Patents & Royalties, Research Funding. OffLabel Disclosure: Cyclophosphamide and fludarabine will be used as conditioning therapy prior to 19(T2)28z1XX CAR T cell administration.

Download Full-text

Tumor Specific T Cells Modified to Secrete IL-12 Eradicate Systemic Tumors in the Absence of Prior Toxic Chemotherapy Conditioning Regimens

Blood ◽

10.1182/blood.v118.21.3120.3120 ◽

2011 ◽

Vol 118 (21) ◽

pp. 3120-3120

Author(s):

Hollie J. Pegram ◽

James Lee ◽

Erik Hayman ◽

Gavin H Imperato ◽

Thomas J. Tedder ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cell ◽

Conflicts Of Interest ◽

Cell Activity ◽

Adoptive T Cell Therapy ◽

T Cell Therapy ◽

Tumor Bearing ◽

Conditioning Regimens ◽

Ifn Γ

Abstract Abstract 3120 T cells may be genetically modified to target tumor-associated antigens through the retroviral transduction of genes encoding chimeric antigen receptors (CARs). We have previously generated a series of CARs specific to the CD19 antigen expressed on most B cell tumors. In xenotransplant models of disease we have shown that human T cells expressing CD19 targeted CARs successfully eradicate established B cell tumors in immune compromised SCID-Beige mice. To further our understanding of the in vivo biology of CAR modified T cells, we generated a more clinically relevant syngeneic, immune competent tumor model utilizing CD19 knock out (mCD19−/−) human CD19 knock in (hCD19+/−) C57BL6 transgenic mice (C57BL6(mCD19−/− hCD19+/−)) bearing systemic syngeneic EL4(hCD19+) thymoma tumors. Treatment of tumor bearing mice with syngeneic T cells modified to express the CD19 targeted 19m ζ CAR alone failed to either eradicate tumor or induce predicted B cell aplasias. However, prior lymphodepletion with cyclophosphamide followed by infusion of 19m ζ+ T cells successfully eradicated tumor in 83% of treated mice and induced long term B cell aplasias. Translation of this therapy to the clinic has also revealed that optimal responses require pre-conditioning regimens. Given the toxicity of pre-conditioning treatments, these therapies are largely restricted to younger, healthier patients able to tolerate such intensive regimens. To further understand the mechanisms of action of improved therapy following prior cyclophosphamide therapy, we demonstrated markedly enhanced serum levels of the IL-12 and IFN γ cytokines as well as a marked reduction of endogenous CD4+ regulatory T cells. We postulated that IL-12, which induces IFN γ secretion, may in part explain the enhanced anti-tumor efficacy following prior lymphodepletion, and may potentially obviate the need for toxic conditioning pre-treatments. To address this hypothesis, we modified CAR+ T cells to constitutively secrete IL-12. Subsequent adoptive therapy of EL4(hCD19+) tumor bearing C57BL6(mCD19−/− hCD19+/−) mice with hCD19 targeted IL-12 secreting T cells successfully eradicated disease in 75% of treated mice and induced predicted B cell aplasias in the absence of prior lymphodepletion. Significantly, we found that this enhanced hCD19 targeted T cell activity required the infusion of both CD4+ and CD8+ gene modified T cells, and was further dependent upon autocrine IL-12 stimulation of the modified tumor targeted T cells as well as modified T cell IFN γ secretion and stimulation. To our knowledge, this is the first time adoptive T cell transfer has been demonstrated to successfully eradicate tumor in the absence of prior conditioning regimens. Therefore, these data support the rapid translation of this adoptive T cell therapy to the clinic, as it may enhance the anti-tumor efficacy of this therapy and further expand the patient population eligible for adoptive T cells therapy. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

Actr Platform As an Adaptable, Universal T Cell Therapy That Can Target Multiple Tumor Antigens to Overcome Antigen Escape

Blood ◽

10.1182/blood.v128.22.3362.3362 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3362-3362

Author(s):

Greg Motz ◽

Eugene Choi ◽

Tooba Cheema ◽

Taylor Friedman ◽

Taylor Hickman ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Therapy ◽

B Cell ◽

Tumor Targeting ◽

Tumor Antigens ◽

T Cell Therapy ◽

Multiple Tumor ◽

Car T ◽

Antigen Loss

Abstract Adoptive T-cell therapy with single-chain variable fragment (scFv)-derived chimeric antigen receptors (CARs) has transformed cancer therapy. Nevertheless, treatment failure can occur and is often associated with loss of the targeted antigen-an outcome affecting nearly 65% of patients that have failed CD19-targeted CAR T cell therapy (1). Targeting more than one tumor antigen expressed on the surface of tumor cells to mitigate antigen loss is a strategy that has been tested preclinically with CAR-T therapy. This approach is challenging due to the complexities of validating numerous CAR constructs or generating functional CARs which contain several tandem scFvs. The Antibody-Coupled T-cell Receptor (ACTR) platform is a universal, engineered T-cell therapy technology developed to mediate anti-tumor activity in combination with tumor-targeting antibodies. The ACTR construct, derived from human CD16 and coupled to T-cell signaling domains, is designed to engage the Fc domain of therapeutic antibodies, resulting in a novel platform for T-cell targeted cancer therapy. In contrast to CAR T-cell constructs that are restricted to a single antigen, the ACTR platform is highly adaptable, which can be targeted against a diverse set of tumor antigens-thus circumventing the need to generate and characterize multiple CAR-T therapeutics. We first determined whether ACTR expressing T cells could be combined with a diverse array of tumor-targeting antibodies directed against B cell malignancies. Using cell lines derived from B cell lymphomas or multiple myeloma, we found that ACTR-expressing T cells could be activated with antibodies against multiple B-cell targets including CD19, CD20, CD22, CD38, and CS1. One approach to address CD19 antigen loss in patients relapsing following CD19 CAR-T therapy is to treat with a CD22 CAR-T therapy (2). Given that ACTR can be paired with single antibodies as described above, a flexible sequential administration of targeted antibodies could be utilized. However, we also sought to determine whether combinations of antibodies against CD19 and CD22, when used concurrently, could improve ACTR-activity. We found that dual antigen targeting with anti-CD19 and anti-CD22 antibodies could enhance both ACTR-mediated cytotoxicity and cytokine production in an antibody dose-dependent manner. Taken together, our results provide preclinical evidence for ACTR as a universal, chimeric receptor that could engage multiple tumor antigens with potential to improve patient outcomes by eliminating antigen negative relapse. References 1. Grupp SA, et al. 681 Durable Remissions in Children with Relapsed/Refractory ALL Treated with T Cells Engineered with a CD19-Targeted Chimeric Antigen Receptor (CTL019). ASH. Dec 2015 2. Xinqiao Hospital of Chongqin. Anti-CD22 CAR-T Therapy for CD19-refractory or Resistant Lymphoma Patients.https://www.clinicaltrials.gov/ct2/show/NCT02721407 Disclosures Motz: Unum Therapeutics: Employment. Choi:Unum Therapeutics: Employment. Cheema:Unum Therapeutics: Employment. Friedman:Unum Therapeutics: Employment. Hickman:Unum Therapeutics: Employment. Nelson:Unum Therapeutics: Employment. Shin:Unum Therapeutics: Employment. Boomer:Unum Therapeutics: Employment. Hemphill:Unum Therapeutics: Employment. McGinness:Unum Therapeutics: Employment. Huet:Unum Therapeutics: Employment. Ettenberg:Unum Therapeutics: Employment.

Download Full-text

Antitumor efficacy of BAFF-R targeting CAR T cells manufactured under clinic-ready conditions

Cancer Immunology Immunotherapy ◽

10.1007/s00262-020-02614-8 ◽

2020 ◽

Vol 69 (10) ◽

pp. 2139-2145

Author(s):

Zhenyuan Dong ◽

Wesley A. Cheng ◽

D. Lynne Smith ◽

Brian Huang ◽

Tiantian Zhang ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Therapy ◽

B Cell ◽

T Cell Therapy ◽

Car T Cells ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T ◽

Antigen Loss

Abstract B-cell malignancies can potentially be cured by CD19 chimeric antigen receptor (CAR) T-cell therapy. Although clinical response rates can be up to 93% in acute lymphoblastic leukemia, treatment-related antigen loss and lack of therapeutic persistence contribute to disease relapse. These shortcomings of current CAR T-cell therapy indicate the need for biologically relevant target selection and for improving the efficacy and persistence of the CAR T cells, which we have addressed by developing a novel B-cell activating factor receptor (BAFF-R) CAR T-cell therapy with improved therapeutic persistence. BAFF-R is a B-cell survival receptor and highly expressed in B-cell malignancies. We developed a prototype CAR T cell that efficiently and specifically eliminated BAFF-R expressing human B-cell tumors in several xenogeneic mouse models, including models of CD19 antigen loss. We proceeded with translational development and validation of BAFF-R CAR T cells produced under current good manufacturing practices (cGMP). cGMP-grade BAFF-R CAR T cells underwent in vitro and in vivo validation in established models to confirm that the potency and efficacy of our original research modeling was replicated. Food and Drug Administration required release testing was performed to ensure our BAFF-R CAR T cells meet specifications for new drug products. Completing and exceeding these requirements, the data fully support the initiation of a first-in-human Phase 1 trial for BAFF-R-positive relapsed/refractory (r/r) B-ALL.

Download Full-text

Novel BAFF-R CAR T-Cell Therapy for CD19 Antigen-Loss Relapsed B Cell Tumors

Blood ◽

10.1182/blood-2018-99-117513 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 1411-1411

Author(s):

Hong Qin ◽

Zhenyuan Dong ◽

Xiuli Wang ◽

Wesley Cheng ◽

Diane Lynne Smith ◽

...

Keyword(s):

T Cells ◽

Targeted Therapy ◽

T Cell ◽

B Cell ◽

T Cell Therapy ◽

Car T Cells ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T ◽

Antigen Loss

Abstract Background: Chimeric antigen receptor (CAR) T cells against CD19 have shown great potential in treatment of B cell malignancies. However, tumor relapse from antigen loss can limit efficacy. B-cell activating factor-receptor (BAFF-R), a tumor necrosis factor receptor superfamily protein (TNFRSF13C), is another potential B-cell specific target of B cell malignancies. BAFF-R is an especially interesting alternative to CD19 as BAFF-R signaling is a driver of B-cell survival, which may limit the capacity of clonal B-cell tumors to escape therapy by down-regulation of antigen expression. However, while the BAFF/BAFF-R axis has been successfully targeted for autoimmune diseases, the promise for cancer therapy has not yet been fulfilled. Methods and Results: A humanized, single-chain variable fragment (scFv) derivative of an anti-human BAFF-R antibody (Qin et al. Clin Can Res 2018;24:1114-1123) was engineered onto a second generation CAR construct containing 4-1BB costimulatory and CD3ζ intracellular signaling domains. BAFF-R-CAR T cells demonstrated cytotoxicity against human lymphoma and acute lymphocytic leukemia (ALL) lines. Adoptively transferred BAFF-R-CAR T cells eradicated 10-day pre-established tumor xenografts after a single treatment and were superior to CD19-CAR T cells (not shown) and retained efficacy against xenografts deficient in CD19 expression, including one primary patient-derived xenograft (PDX). Specifically, we modeled disease relapse due to the loss of CD19 by generating CRISPR CD19 gene knock-out of the ALL (Nalm-6) cell line and a gRNA-silenced CD19 gene knock-down of an ALL PDX. We confirmed the absence of CD19 and presence BAFF-R expression, which was unaffected, on the resulting cell lines by surface staining (Fig. 1A). Using transduced CD8 TN cells, we found that CD19-CAR T cells demonstrated cytotoxicity only against wild-type tumor cells, while BAFF-R-CAR T cells maintained significant cytotoxicity against both wild-type and CD19-negative tumors in vitro (Fig. 1B). The therapeutic efficacy of BAFF-R-CAR T cells was tested against human ALL Nalm-6-CD19 deficient xenografts established in NSG mice following IV tumor challenge on day 0 with luciferase-expressing cells. A single dose of 2.5 x 106 CD4 TN + 106 CD8 TN BAFF-R- or CD19-CAR T cells/mouse infused IV on day 11 post tumor implantation completely eliminated established Nalm-6-CD19KO ALL tumors and conferred long-term survival. In contrast, treatment with PBS or identical mixtures of CD19-CAR T cells or non-transduced T cells from the same donor were associated with progressive tumor growth and 100% mortality by Day 60 (Fig. 1C). Finally, four relapsed, antigen loss primary ALLs obtained after CD19-directed therapy retained BAFF-R expression and activated BAFF-R-, but not CD19-CAR T cells. Specifically, cell surface staining demonstrated CD19 and BAFF-R expression in tumors obtained prior to CD19-targeted therapy. However, post-treatment samples exhibited clear down-regulation of CD19, while retaining positive BAFF-R expression (Fig. 1D, results from a single representative patient shown). The ability of the primary tumor samples to activate either CD19- or BAFF-R-CAR T cells was determined by expression of the degranulation marker CD107a on the CAR T cells. Cryopreserved ALL samples were co-cultured with BAFF-R or CD19 CAR-T cells derived from the same healthy donor in the presence of anti-CD107a antibody for 6 h. Non-transduced T cells (non-CAR) from the same donor were used as a negative control. Activation of CD19-CAR T cells by all four CD19-negative post-blinatumomab therapy tumors was significantly reduced, compared with BAFF-R-CAR T cells and with corresponding available CD19-positive pre-therapy tumors, while BAFF-R-CAR T cells were equally activated by pre- and post-CD19-targeted therapy tumors (Fig.1E-F). We observed similar trends for both CD19- and BAFF-R-CAR T cell activation by pre- and post-CD19-targeted therapy tumors, as measured by specific intracellular CAR T-cell TNF-α and IFN-γ production (not shown). Conclusion: Taken together, our data suggest that BAFF-R is amenable to CAR T-cell therapy and that targeting it may add to existing alternative strategies to overcome relapse from CD19 antigen loss, such as CD22 CAR T cells. Future strategies combining dual targeting of CD19 and BAFF-R may also be effective. Disclosures Wang: Mustang Therapeutics: Other: Licensing Agreement, Patents & Royalties, Research Funding. Forman:Mustang Therapeutics: Other: Licensing Agreement, Patents & Royalties, Research Funding.

Download Full-text

Mechanisms of Antigen Dependent and Independent Rejection of High Grade B-Cell Lymphoma in a Murine Model.

Blood ◽

10.1182/blood.v114.22.4091.4091 ◽

2009 ◽

Vol 114 (22) ◽

pp. 4091-4091

Author(s):

Armin Gerbitz ◽

Madhusudhanan Sukumar ◽

Florian Helm ◽

Andrea Wilke ◽

Thomas Kammertoens ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cell ◽

Nk Cells ◽

Mhc Class I ◽

Cell Lines ◽

Interferon Gamma ◽

Class I ◽

High Grade ◽

Lymphoma Cells

Abstract Abstract 4091 Poster Board III-1026 The rejection of Non Hodgkin Lymphomas expressing foreign, for example viral, antigens is compromised despite the presence of specific T-cells. The underlying immunosuppressive mechanisms are poorly understood. Using a transgenic mouse lymphoma model, where the proto-oncogene c-myc is driven by parts of the immunoglobulin lambda locus representing a t(8;22) translocation as found in Burkitt's lymphoma, we investigated the anti-lymphoma activity of specific T-cells. By retroviral transduction of a specific foreign antigen (chicken Ovalbumin-IRES-GFP, OVA) into cell lines from primary c-myc transgenic lymphomas we established a syngeneic model that would allow us to address the role of interferon gamma signalling in rejection of high grade lymphomas. All primary lymphoma cells displayed normal MHC class I and II levels on the surface when compared to wildtype splenic B-cells. This expression could be enhanced by treatment with interferon gamma (IFNg,100U/ml) up to 10 fold. When retrovirally OVA-transduced lymphoma cells were injected into either wildtype or GFP transgenic recipients, animals displayed a significant delay in lymphoma growth compared to non transduced or IRES-GFP transduced control cell lines. 80% of the recipient mice rejected OVA expressing lymphomas. By contrast, we observed 100% mortality when GFP expressing control lymphomas were injected in GFP transgenic recipients, which are tolerant for GFP. Developing OVA expressing lymphomas (20%) displayed a loss of GFP expression indicating a selection for antigen negative cells (p=0.001). In spleens from mice rejecting OVA-expressing lymphomas we found up to 1.8% SIINFEKL specific T-cells. To gain more mechanistic insights, we transferred OVA expressing lymphoma cells into IFNg, Stat1-/- or IFNg-/-receptor deficient recipients. Lack of STAT1-/- or IFNg-receptor on the recipient side or inability to secrete IFNg was associated with fast lymphoma progression and growth was not different when compared to non transduced, antigen negative cell lines. When IFNg-receptor or STAT1 deficient OVA expressing cell lines were transferred into wildytpe mice, rejection was not influenced. Outgrowing OVA expressing lymphomas in wildtype mice displayed a high MHC class I and II expression compared to the cell line prior to injection. MHC induction was absent in lymphomas transferred to Stat1 or IFNg deficient recipients. Depletion of NK cells by anti AsialoGM antibody in wildtype recipients resulted in a significant reduction of disease free survival (80% vs. 50%, p=0.002) and animals developed larger tumors which were eventually rejected resulting in a comparable overall survival. In peripheral blood of NK depleted mice significantly more OVA specific T-cells were detectable through pentamer staining. When lymphoma cell lines were injected into Rag1-/- mice, NK cell mediated rejection was also significantly impaired upon depletion. Our results suggest that T-cell mediated rejection of high grade B-cell lymphomas is strongly dependent on host IFNg secretion and that NK cells substantially contribute to T-cell mediated rejection. Disclosures: No relevant conflicts of interest to declare.

Download Full-text

CD3/Bars: A Novel Bispecific Format for the Treatment of B-Cell Lymphomas

Blood ◽

10.1182/blood.v128.22.3516.3516 ◽

2016 ◽

Vol 128 (22) ◽

pp. 3516-3516

Author(s):

Moritz Bewarder ◽

Klaus-Dieter Preuss ◽

Natalie Fadle ◽

Evi Regitz ◽

Lorenz Thurner ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cell ◽

Cell Lines ◽

Cell Receptor ◽

B Cell Receptor ◽

Lymphoma Cell ◽

Bispecific Antibodies ◽

B Cell Lymphomas ◽

Lymphoma Cells

Abstract Background Autoantigens are suspected to play an important role in the pathogenesis of different types of B cell neoplasia. Suggestive of this hypothesis is the restricted usage of a stereotyped IgHv repertoire in CLL, MCL and DLBCL. Further evidence supporting this notion is the identification of specific autoantigens as the target of the B-cell receptor from malignant lymphomas and myelomas, such as paratarg-7 as antigenic target for 15% of paraproteins of MGUS and MM patients. ARS2 was previously identified as the autoantigenic target for the B-cell receptor of approximately 25% of DLBCLs of the ABC type, here termed ARS2 reactive lymphomas. We had recently shown that the B-cell receptor antigens can be used to target B-cell lymphoma cells in vitro and in vivo in an approach designated as BARs (B-cell receptor antigens for reverse targeting), the first therapeutic strategy in oncology with absolute and exclusive specificity for the malignant clone. To test whether BARs can substitute the B-cell binding antibody (e.g. CD19) in T-cell engaging bispecific antibodies, we designed a bispecific CD3/BAR product consisting of a recombinant single chain fragment (scFv) against CD3 linked to ARS2 (CD3-ARS2). One arm of this construct should engage the T cell co-receptor CD3 of human T cells, and the other site should bind to the B cell receptor of ARS2 reactive lymphomas thus specifically redirecting and activating T cells against lymphoma cells. Material and methods VL and VH genes of the CD3 - OKT3 hybridoma and the DNA sequence of the 33 amino acids containing the B-cell receptor binding epitope of ARS2 were cloned into a pcDNA 3.1 vector by standard cloning techniques. VH and VL were linked by a glycine-serine linker, as was VL to the ARS2 epitope resulting in VH-(Gly₄Ser₁)ⁿ-VL-(Gly₄Ser₁)ⁿ-ARS2 peptide chain. The final cloning product was transfected in HEK cells for production of the bispecific construct. Binding capacity to lymphoma cell lines (OCI-Ly3, U2932, HBL-1) and PBMCs was assessed by flow cytometry. Western blot analysis was used for detection of CD3-ARS2 after incubation with the monoclonal anti-His Tag antibody. Cytotoxicity was evaluated by LDH release assay. Results The CD3 - ARS2 bispecific construct bound to CD3 on T cells and the B-cell receptor of ARS2 reactive lymphoma cells. CD3/ARS2 induced rapid cytotoxicity exclusively in ARS2 reactive lymphoma cell lines at concentrations as low as 250 ng/ml with an effector - target ratio of 10:1. Specific T-cell mediated cytotoxicity reached 40% after 4 hours. Lymphoma cell lines with BCRs of a specificity other than ARS2 were not affected. Conclusion The CD3/BAR construct is a novel therapeutic principle for the treatment of B-cell lymphomas, suggesting that BARs might also be useful as part of CAR-T cells. Compared to CD3/CD19 bispecific antibodies the CD3/BARs are exclusively cytotoxic against the malignant clone and spare normal B-cells. This should considerably reduce the acute toxicity of T-cell engaging bispecific constructs and circumvent long-term B cell depletion. Experiments comparing the cytotoxic capacity of CD3/BARs with CD3/CD19 bispecific antibodies are underway, as are analyses evaluating possible synergisms of these constructs. Disclosures No relevant conflicts of interest to declare.

Download Full-text

221 CRISPR screen identifies loss of IFNγR signaling and downstream adhesion as a resistance mechanism to CAR T-cell cytotoxicity in solid but not liquid tumors

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.221 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A234-A234

Author(s):

Rebecca Larson ◽

Michael Kann ◽

Stefanie Bailey ◽

Nicholas Haradhvala ◽

Kai Stewart ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cell ◽

Solid Tumors ◽

T Cell Therapy ◽

Car T Cells ◽

Car T Cell ◽

Car T Cell Therapy ◽

Car T

BackgroundChimeric Antigen Receptor (CAR) therapy has had a transformative impact on the treatment of hematologic malignancies1–6 but success in solid tumors remains elusive. We hypothesized solid tumors have cell-intrinsic resistance mechanisms to CAR T-cell cytotoxicity.MethodsTo systematically identify resistance pathways, we conducted a genome-wide CRISPR knockout screen in glioblastoma cells, a disease where CAR T-cells have had limited efficacy.7 8 We utilized the glioblastoma cell line U87 and targeted endogenously expressed EGFR with CAR T-cells generated from 6 normal donors for the screen. We validated findings in vitro and in vivo across a variety of human tumors and CAR T-cell antigens.ResultsLoss of genes in the interferon gamma receptor (IFNγR) signaling pathway (IFNγR1, JAK1, JAK2) rendered U87 cells resistant to CAR T-cell killing in vitro. IFNγR1 knockout tumors also showed resistance to CAR T cell treatment in vivo in a second glioblastoma line U251 in an orthotopic model. This phenomenon was irrespective of CAR target as we also observed resistance with IL13Ralpha2 CAR T-cells. In addition, resistance to CAR T-cell cytotoxicity through loss of IFNγR1 applied more broadly to solid tumors as pancreatic cell lines targeted with either Mesothelin or EGFR CAR T-cells also showed resistance. However, loss of IFNγR signaling did not impact sensitivity of liquid tumor lines (leukemia, lymphoma or multiple myeloma) to CAR T-cells in vitro or in an orthotopic model of leukemia treated with CD19 CAR. We isolated the effects of decreased cytotoxicity of IFNγR1 knockout glioblastoma tumors to be cancer-cell intrinsic because CAR T-cells had no observable differences in proliferation, activation (CD69 and LFA-1), or degranulation (CD107a) when exposed to wildtype versus knockout tumors. Using transcriptional profiling, we determined that glioblastoma cells lacking IFNγR1 had lower upregulation of cell adhesion pathways compared to wildtype glioblastoma cells after exposure to CAR T-cells. We found that loss of IFNγR1 reduced CAR T-cell binding avidity to glioblastoma.ConclusionsThe critical role of IFNγR signaling for susceptibility of solid tumors to CAR T-cells is surprising given that CAR T-cells do not require traditional antigen-presentation pathways. Instead, in glioblastoma tumors, IFNγR signaling was required for sufficient adhesion of CAR T-cells to mediate productive cytotoxicity. Our work demonstrates that liquid and solid tumors differ in their interactions with CAR T-cells and suggests that enhancing T-cell/tumor interactions may yield improved responses in solid tumors.AcknowledgementsRCL was supported by T32 GM007306, T32 AI007529, and the Richard N. Cross Fund. ML was supported by T32 2T32CA071345-21A1. SRB was supported by T32CA009216-38. NJH was supported by the Landry Cancer Biology Fellowship. JJ is supported by a NIH F31 fellowship (1F31-MH117886). GG was partially funded by the Paul C. Zamecnik Chair in Oncology at the Massachusetts General Hospital Cancer Center and NIH R01CA 252940. MVM and this work is supported by the Damon Runyon Cancer Research Foundation, Stand Up to Cancer, NIH R01CA 252940, R01CA238268, and R01CA249062.ReferencesMaude SL, et al. Tisagenlecleucel in children and young adults with B-cell lymphoblastic leukemia. N Engl J Med 2018;378:439–448.Neelapu SS, et al. Axicabtagene ciloleucel CAR T-cell therapy in refractory large B-cell lymphoma. N Engl J Med 2017;377:2531–2544.Locke FL, et al. Long-term safety and activity of axicabtagene ciloleucel in refractory large B-cell lymphoma (ZUMA-1): a single-arm, multicentre, phase 1–2 trial. The Lancet Oncology 2019;20:31–42.Schuster SJ, et al. Chimeric antigen receptor T cells in refractory B-cell lymphomas. N Engl J Med 2017;377:2545–2554.Wang M, et al. KTE-X19 CAR T-cell therapy in relapsed or refractory mantle-cell lymphoma. N Engl J Med 2020;382:1331–1342.Cohen AD, et al. B cell maturation antigen-specific CAR T cells are clinically active in multiple myeloma. J Clin Invest 2019;129:2210–2221.Bagley SJ, et al. CAR T-cell therapy for glioblastoma: recent clinical advances and future challenges. Neuro-oncology 2018;20:1429–1438.Choi BD, et al. Engineering chimeric antigen receptor T cells to treat glioblastoma. J Target Ther Cancer 2017;6:22–25.Ethics ApprovalAll human samples were obtained with informed consent and following institutional guidelines under protocols approved by the Institutional Review Boards (IRBs) at the Massachusetts General Hospital (2016P001219). Animal work was performed according to protocols approved by the Institutional Animal Care and Use Committee (IACUC) (2015N000218 and 2020N000114).

Download Full-text