Leukemic Cell Expressed CTLA-4 Suppresses T Cells Via Down-Modulation of CD80 By Trans-Endocytosis

Abstract The function of CTLA-4 on non-T cells is largely ignored and currently ill defined despite rapidly growing interest in targeting this immune checkpoint protein in several cancers. While anti-CTLA-4 therapy is proposed to work through inhibition of the immunosuppressive effect of CTLA-4 on T cells, multiple examples of non-T cell expressed CTLA-4 have been reported. These cells include tumor cells of hematological and non-hematological origin and normal B cells. In this study, we have defined a novel immune suppressive role for non-T cell, tumor expressed CTLA-4 in Chronic Lymphocytic Leukemia (CLL). We have detected by microarray that CTLA-4 is in the top 5 most differentially expressed genes between pooled samples of healthy donor normal B cells (N=6) and pooled CLL leukemic B cells (N=5). Upregulation of CTLA-4 by CLL B cells compared to normal B cells was validated by RT-qPCR and flow cytometry. CTLA-4 was predominantly intracellular (42/46 CTLA-4+) and not on the cell surface (2/48 CTLA-4+) in primary CLL samples. B cell activating factors (CD40L, PMA/Ionomycin, LPS, IL4, LPS+IL4, CD40L+IL4, CpG, and anti-IgM) could not induce surface expression of CTLA-4; however, co-culture with anti-CD3/anti-CD28 or ConA activated T cells (autologous or allogeneic) resulted in detectable CTLA-4 on the cell surface of leukemic B cells. This induction did not occur with resting T cells. This finding suggests a role for CTLA-4+ tumor cells in sites of T cell activation, such as the lymph node, a site of leukemic cell proliferation in CLL. To mechanistically study leukemic B cell expressed CTLA-4, we generated CLL-derived Mec1 and OSU-CLL that inducibly express CTLA-4 upon doxycycline (dox) treatment. Mec1 and OSU-CLL cells highly express the ligands for CTLA-4, CD80 and CD86. Dox-induction of CTLA-4 resulted in decreased expression of Mec1 and OSU-CLL expressed CD80, a critical T cell co-stimulatory protein (N=3). Blockade of CTLA-4 using the anti-CTLA-4 therapeutic antibody, Ipilimumab, could restore CD80 on Mec1 and OSU-CLL cells (N=3). Because T cell-expressed CTLA-4 has been previously shown by others to down-modulate CD80 via trans-endocytosis, we co-cultured CTLA-4+ Mec1 and CTLA-4+ primary CLL cells with stably transfected CD80-GFP or CD86-GFP Hek293 cell lines to assess uptake of CD80/CD86 into CTLA-4 expressing tumor cells as the mechanism of CD80 down-modulation. Transfer of CD80-GFP and CD86-GFP was detected by flow cytometry in primary CLL cells and the Mec1 cell line, consistent with the ability of T cell expressed CTLA-4 to trans-endocytose CD80 and CD86. Furthermore, uptake of CD80-GFP or CD86-GFP by primary tumor cells was CTLA-4 dependent, demonstrated by inhibition of GFP uptake in the presence of Ipilimumab. Following determination of decreased CD80, we found that co-culture of primary T cells with Mec1 CTLA-4+ cells resulted in decreased IL2 production measured by Cytokine Bead Array. The loss of IL2 signified decreased co-stimulation as a result of tumor expressed CTLA-4. Studies are ongoing regarding dependence on CD80 or CD86. A minor subset of T cells, Tregs, are known to exert profound immunosuppressive effects through their expression of CTLA-4. Due to our results, tumor expressed CTLA-4 has an overlapping function with Treg CTLA-4, and it is imperative that we define the immunosuppressive effects as, in patients, the leukemic cells may comprise a much larger proportion of white blood cells than T cells. Efforts are now underway to address the effect of tumor expressed CTLA-4 in suppressing anti-tumor immunity in vivo utilizing a novel mouse model. Suppression of T cells by tumor expressed CTLA-4 is a novel finding that is broadly applicable to fields within and outside of cancer research as the pathway and mechanism described here are potentially applicable to CTLA-4 in diverse disease contexts and to the general biology of CTLA-4. [Funding: This work was supported by P01 CA95426. PD received the Pelotonia Graduate Fellowship. Any opinions, findings, and conclusions expressed in this material are those of the author(s) and do not necessarily reflect those of the Pelotonia Fellowship Program] Disclosures Jones: AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics, LLC, an AbbVie Company: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Development of Novel Second Generation DC/Tumor Fusion Vaccine in Lymphoma

Blood ◽

10.1182/blood-2019-124768 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 392-392 ◽

Cited By ~ 1

Author(s):

Shira Orr ◽

Marzia Capelletti ◽

Haider Ghiasuddin ◽

Dina Stroopinsky ◽

Jessica Liegel ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Tumor Cells ◽

Research Funding ◽

Second Generation ◽

Advisory Board ◽

Advisory Committees ◽

Equity Ownership ◽

Cells Cultured

Introduction: We have pioneered a personalized cancer vaccine in which patient derived tumor cells are fused with autologous dendritic cells (DCs) such that a broad array of shared and neo-tumor antigens is presented in the context of DC mediated co-stimulation, limiting the risk of antigen escape. In clinical trials of patients with hematologic malignancies, vaccination with DC/tumor fusions induced an expansion of tumor-specific T cells, and resulted in prolonged remissions in a subset of patients. In the current study, we have developed a novel second generation vaccine, whereby a DC/lymphoma fusion vaccine is presented in the context of a unique biomatrix that expresses high levels of the 41BB costimulatory molecule, to further accentuate T cell activation and prevent the establishment of tumor tolerance. In this study, we demonstrate efficacy of DC/lymphoma fusion cell vaccination in a preclinical lymphoma model, and show enhanced potency of the second-generation vaccine. Methods/Results: We first demonstrated the potency of the DC/tumor fusion vaccine in generating anti-tumor immunity in the A20 lymphoma model. Murine DC/A20 fusions were generated from bone marrow derived mononuclear cells cultured with GM-CSF and IL-4 then fused to syngeneic A20 lymphoma cells. DC/A20 fusion cells effectively induced tumor specific immunity as manifested by potent lysis of A20 T cells in vitro as compared to unstimulated T cells in a standard CTL assay. Consistent with this observation, vaccination with DC/A20 fusions effectively induced lymphoma specific immunity in an immunocompetent murine model. Balb/C mice (30 animals) underwent IV inoculation with 750,000 syngeneic, luciferase and mCherry transduced, A20 cells. 24 hours after tumor cells challenge, 15 mice were treated subcutaneously with 105 DC/A20 fusions. Tumor burden was detected using BLI imaging. 10 days post inoculation, within the untreated cohort all 15/15 mice had detectable tumor whereas within the treated group, 5 mice did not demonstrate any evidence of disease and 5 mice demonstrated minimal disease. We subsequently demonstrated that patient derived autologous DC/lymphoma fusions stimulated T cell mediated lysis of primary lymphoma cells. DC were generated from patient derived peripheral blood mononuclear cells cultured with GM-CSF and IL-4 and matured with TNFa. Primary lymphoma cells were isolated from resected tumor and fused with DC at a ratio of 10:1. Fusion stimulated T cells potently lysed autologous tumor cells as compared to unstimulated T cells (25.7% as compared to 12.66%) in a standard CTL assay. To further enhance vaccine potency, we developed a biomatrix substrate expressing the costimulatory molecule 41BB. Using carbodiimide chemistry we covalently bonded RGD peptide and 41BBL protein to an alginate (Alg)-based scaffold. The Alg/RGD/41BBL scaffold can serve as a supporting microenvironment for the co-culture of T cells and fusion vaccine. We cultured syngeneic T cells with DC/A20 fusion vaccine within a scaffold with or without bound 41BBL and examined the T cells cytotoxicity by a CTL assay as described above. Vaccine mediated stimulation of T cells in the context of the Alg/RGD/41BBL scaffold demonstrated higher levels of tumor lysis as compared to the percent T cells cultured within an Alg/RGD scaffold (22.95% and 13.95% respectively). Conclusion: In the current study we assessed the efficacy of the DC/Lymphoma fusion vaccine to elicit a tumor specific immune response. We succeeded in demonstrating the capacity of DC/Lymphoma fusion vaccine to generate tumor specific T cell cytotoxicity in vitro as well as in vivo in an immunocompetent murine model. Accordingly, we presented patient derived primary tumor results supporting the applicable nature of the DC/Lymphoma vaccine in lymphoma patients. In addition, we developed a second-generation fusion vaccine comprised of the original DC/Tumor vaccine presented to the T cells in an Alg/RGD/41BBL scaffold acting as a nurturing microenvironment for T cell immune specific response against the tumor cells. Our initial results exhibit promising potential and an in vivo experiment with the second-generation fusion vaccine is ongoing. Disclosures Arnason: Celgene/Juno: Consultancy; Regeneron Pharmaceuticals, Inc.: Consultancy. Kufe:Nanogen Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Genus Oncology: Equity Ownership; Reata Pharmaceuticals: Consultancy, Equity Ownership, Honoraria; Hillstream BioPharma: Equity Ownership; Victa BioTherapeutics: Consultancy, Equity Ownership, Honoraria, Membership on an entity's Board of Directors or advisory committees; Canbas: Consultancy, Honoraria. Rosenblatt:Dava Oncology: Other: Education; BMS: Research Funding; Partner Tx: Other: Advisory Board; Merck: Other: Advisory Board; Parexel: Consultancy; Imaging Endpoint: Consultancy; Celgene: Research Funding; BMS: Other: Advisory Board ; Amgen: Other: Advisory Board. Avigan:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pharmacyclics: Research Funding; Juno: Membership on an entity's Board of Directors or advisory committees; Partners Tx: Membership on an entity's Board of Directors or advisory committees; Partner Tx: Membership on an entity's Board of Directors or advisory committees; Karyopharm: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy; Parexel: Consultancy; Takeda: Consultancy.

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Venetoclax Enhances Anti-Leukemia Activity of CD123-Specific BiTE-Secreting T-Cells in AML

Blood ◽

10.1182/blood-2020-139625 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 12-13

Author(s):

Hong Mu-Mosley ◽

Lauren B Ostermann ◽

Ran Zhao ◽

Challice L. Bonifant ◽

Stephen Gottschalk ◽

...

Keyword(s):

Flow Cytometry ◽

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Vehicle Control ◽

Advisory Committees ◽

Cellular Therapies

Background: CD123 is frequently expressed in hematologic malignancies including AML. CD123 has been a potential immunotherapeutic target in AML due to its association with leukemic stem cells that play an essential role in disease progression and relapse. Our previous study using T-cells secreting CD123/CD3-bispecific T-cell engagers (BiTEs) (CD123-ENG T-cells) has shown activity in preclinical studies, recognizing and killing acute myeloid leukemia (AML) blasts in vitro and in vivo. CD123-ENG T-cells secrete bispecific molecules that recognize CD3 (T-cells) and CD123 (AML blasts), and are able to direct transduced T-cells and recruit bystander T-cells to kill CD123-positive blasts. Venetoclax is a BCL-2 inhibitor that can restore functional apoptosis signaling in AML cells, and has been FDA approved for the treatment of AML patients in combination with hypomethylating agents. To improve the efficacy of CD123-ENG T-cells we explored efficacy in AML by combining targeted immunotherapy (CD123-ENG T cells) with targeted inhibition of anti-apoptotic BCL-2 (venetoclax) in vitro and in vivo models of AML. Methods : CD123-ENG T-cells were generated by retroviral transduction and in vitro expansion. Non-transduced (NT) T-cells served as control. In vitro, GFP+ MOLM-13 AML cells were pretreated with venetoclax (0, 10µM, and 20µM) for 24 hours prior to co-culture with CD123-ENG or NT T-cells at an effector/target ratio of 1:10. After 16 hours, MOLM-13 AML cells were analyzed by flow cytometry and quantitated using counting beads; cytotoxicity was calculated relative to untreated MOLM-13 control. The anti-AML activity of the combination was further evaluated in a MOLM-13-luciferase xenograft AML mouse model. Leukemia progression was assessed by bioluminescence imaging. The frequency of MOLM13 AML and human T cells in periphera blod (PB) was determined by flow cytometry. Results: In vitro, we demonstrated that pretreatment of Molm13 AML cells with venetoclax enhanced the cytolytic activity of CD123-ENG T-cells compared to NT- or no T-cell controls. Interestingly, venetoclax sensitized Molm13 to CD123-ENG T-cell killing in a dose-dependent manner (Fig.1; 50%/31% killing by CD123-ENG T-cells versus 27%/14% of killing by NT T cells post pretreatment with 10µM or 20µM ventoclax, p<0.001). In the Molm13 luciferase xenograft model, NSGS mice were randomized into 5 groups after AML engraftment was confirmed: 1) vehicle control, 2) Venetoclax (Ven) only, 3) CD123-ENG T-cells only, 4) Ven+CD123-ENG T-cells, 5) Ven+CD123-ENG T-cells/2-day-off Ven post T-cell infusion (Ven[2-day-off]+CD123-ENG). Venetoclax treatment (100 µg/kg daily via oral gavage) was started on day 4 post Molm13 injection, and on day 7, mice received one i.v. dose of CD123-ENG T-cells (5x106 cells/mouse). Venetoclax or CD123-ENG T-cell monotherapy reduced leukemia burden compared to the control group, and combinational treatments further inhibited leukemia progression as judged by BLI and circulating AML cells (%GFP+mCD45-/total live cells) by flow cytometry on day 15 post MOLM-13 injection: vehicle control: 19.6%; Ven+: 3.4%; CD123-ENG T-cells:1.2 %; Ven+CD123-ENG T-cells: 0.3%; Ven[2-day-off]+CD123-ENG T-cells (p<0.01 Ven+ or CD123-ENG T-cells versus control; p<0.001 Ven+CD123-ENG or Ven[2-day-off]+CD123-ENG T cells versus CD123-ENG T cells, n=5). The enhanced anti-AML activity of combining venetoclax and CD123-ENG T-cells translated into a significant survival benefit in comparison to single treatment alone (Fig. 2). However, while Ven+CD123-ENG and Ven[2-day-off]+CD123-ENG T-cell treated mice had a survival advantage, they had reduced circulating numbers of human CD3+ T cells on day 8 post T-cells infusion compared to mice that received CD123-ENG T-cells, indicative of potential adverse effect of venetoclax on T-cell survival in vivo. Conclusion: Our data support a concept of combining pro-apoptotic targeted and immune therapy using venetoclax and CD123-ENG T-cells in AML. While it has been reported that venetoclax does not impair T-cell functionality, more in-depth analysis of the effect of Bcl-2 inhibition on T-cell function and survival appears warranted, as it could diminish survival not only of AML blasts but also of immune cells. Disclosures Bonifant: Patents filed in the field of engineered cellular therapies: Patents & Royalties: Patents filed in the field of engineered cellular therapies. Gottschalk:Patents and patent applications in the fields of T-cell & Gene therapy for cancer: Patents & Royalties; Inmatics and Tidal: Membership on an entity's Board of Directors or advisory committees; Merck and ViraCyte: Consultancy; TESSA Therapeutics: Other: research collaboration. Velasquez:Rally! Foundation: Membership on an entity's Board of Directors or advisory committees; St. Jude: Patents & Royalties. Andreeff:Amgen: Research Funding; Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees.

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CD20-TCB, a Novel T-Cell-Engaging Bispecific Antibody, Induces T-Cell-Mediated Killing in Relapsed or Refractory Non-Hodgkin Lymphoma: Biomarker Results From a Phase I Dose-Escalation Trial

Blood ◽

10.1182/blood-2019-123979 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5319-5319 ◽

Cited By ~ 2

Author(s):

Ann-Marie E Bröske ◽

Ian James ◽

Anton Belousov ◽

Enrique Gomez ◽

Marta Canamero ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cells ◽

Board Of Directors ◽

T Cell Activation ◽

Research Funding ◽

Cell Activation ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership

Introduction: CD20-TCB (RG6026) is a novel T-cell-engaging bispecific (TCB) antibody with a '2:1' molecular format that comprises two fragment antigen binding regions that bind CD20 (on the surface of B cells) and one that binds CD3 (on the surface of T cells). CD20-TCB offers the potential for increased tumor antigen avidity, rapid T-cell activation, and enhanced tumor cell killing versus other bispecific formats. The safety, tolerability, pharmacokinetics, biomarkers, and antitumor activity of CD20-TCB are currently being investigated in a multicenter Phase I dose-escalation trial (NP30179; NCT03075696). We recently presented preliminary clinical data demonstrating promising clinical activity in relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) patients with indolent or aggressive disease (Dickinson et al. ICML 2019). Here, we present preliminary blood and tissue biomarker analyses to explore modes of action, support optimal biological dose selection, and identify potential outcome predictors. Methods: For biomarker analyses, we performed immune profiling of peripheral blood by flow cytometry, analyzed plasma cytokine levels by ELISA, and characterized baseline and on-treatment tumor biopsies by immunohistochemistry/immunofluorescence assays and RNA sequencing. Biomarker data were obtained from 122 patients dosed with 0.005-25mg CD20-TCB. Results: CD20-TCB infusion led to a rapid and transient reduction in T cells in the peripheral circulation (T-cell margination) in all patients. T-cell margination reached nadir 6 hours after the first CD20-TCB infusion, and showed a strong association with CD20-TCB dose and receptor occupancy (RO%; as determined by Djebli et al. ASH 2019). Interestingly, rebound of T cells 160 hours after the first CD20-TCB infusion was associated with response to treatment. Responding patients showed long-term T-cell activation after the first infusion of CD20-TCB at doses from 0.6mg and above. T-cell activation was demonstrated by 2-4-fold elevation of T-cell activation markers such as Ki67, HLA-DR, PD-1, ICOS, OX40, and 4-1BB, which was sustained up to Cycle 5 (105 days). Analysis of paired pre- and on-treatment tumor biopsies (n=6) obtained before and 2-3 weeks after the first dose of CD20-TCB showed evidence of T-cell-mediated tumor cell killing. Analysis of archival and pre-treatment tumor biopsies (n=80) revealed that clinical responses were achieved irrespective of the amount of tumor T-cell infiltration at baseline. In contrast, preliminary baseline bulk tumor RNA sequencing data (n=46) showed upregulation of gene signatures associated with cell proliferation/Myc and T-cell subsets (effector vs exhausted-like) in non-responding patients. Conclusions: In this study, we demonstrated the mode of action of CD20-TCB, a novel bispecific antibody with promising clinical activity in R/R NHL. We also demonstrated that biomarker data on T-cell activation can support dose finding in conjunction with pharmacokinetics. Additional analysis is ongoing to evaluate response predictors and better characterize the population that will benefit most from T-cell mediated therapies. Disclosures Bröske: Roche: Employment, Equity Ownership. James:A4P Consulting Ltd: Consultancy. Belousov:Roche: Employment. Gomez:F. Hoffmann-La Roche Ltd: Employment. Canamero:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Ooi:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Grabole:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Wilson:F. Hoffmann-La Roche Ltd: Employment. Korfi:F. Hoffmann-La Roche Ltd: Consultancy. Kratochwil:F. Hoffmann-La Roche Ltd: Employment. Morcos:Roche: Employment, Equity Ownership. Ferlini:Roche: Employment, Equity Ownership. Thomas:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Dimier:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Moore:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Bacac:Roche: Employment, Equity Ownership, Patents & Royalties: Patents, including the one on CD20-TCB. Weisser:Pharma Research and Early Development Roche Innovation Center Munich: Employment, Equity Ownership, Patents & Royalties. Dickinson:Merck Sharpe and Dohme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; GlaxoSmithKline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. OffLabel Disclosure: CD20-TCB (also known as RG6026, RO7082859) is a full-length, fully humanized, immunoglobulin G1 (IgG1), T-cell-engaging bispecific antibody with two fragment antigen binding (Fab) regions that bind to CD20 (on the surface of B cells) and one that binds to CD3 (on the surface of T cells) (2:1 format). The 2:1 molecular format of CD20-TCB, which incorporates bivalent binding to CD20 on B cells and monovalent binding to CD3 on T cells, redirects endogenous non-specific T cells to engage and eliminate malignant B cells. CD20-TCB is an investigational agent.

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Ibrutinib-Based Therapy Improves Anti-Tumor T Cell Killing Function Allowing Effective Pairing with Anti-PD-L1 Immunotherapy Compared to Traditional FCR Chemoimmunotherapy; Implications for Therapy and Correlative Immune Functional Data from the Phase III E1912 Trial

Blood ◽

10.1182/blood-2018-99-118333 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 236-236 ◽

Cited By ~ 2

Author(s):

Despoina Papazoglou ◽

Connie E. Lesnick ◽

Victoria Wang ◽

Neil E. Kay ◽

Tait D. Shanafelt ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cells ◽

Board Of Directors ◽

Research Funding ◽

Phase Iii ◽

Advisory Committees ◽

Time Points ◽

Killing Function ◽

Time Point

Abstract The targeted therapy ibrutinib inhibits B cell receptor signaling (BTK inhibitor) and has yielded high response rates and durable remissions in patients with chronic lymphocytic leukemia (CLL). However, it is widely believed that the addition of immune therapies to targeted drugs will be required to activate anti-tumor immunity and work towards curative therapy. Identifying effective combinations of targeted drugs and/or standard chemotherapy with immunotherapy is a priority research area and particularly relevant for CLL, as patients' T cells have been shown to exhibit profound tolerance/exhaustion and notably, no activity was reported in a recent trial of anti-PD-1 immunotherapy for relapsed disease. Ibrutinib has shown beneficial immunomodulatory activity in CLL by inhibiting IL-2-inducible T cell kinase (ITK) as well BTK that is associated with increased effector CD4+and CD8+ T cell numbers and decreased expression of inhibitory checkpoint receptors such as PD-1 on patient T cells. Here we have performed comparative immune bioassays from a randomized phase III trial comparing ibrutinib-based therapy to traditional FCR chemoimmunotherapy to assess the effects of treatments on anti-tumor T cell function. Viable peripheral blood mononuclear cell samples were collected serially (baseline, 6 months and 12 months) from CLL patients on the randomized phase III E1912 trial of ibrutinib and rituximab versus FCR for previously untreated disease to allow longitudinal batched immune analysis. Cytotoxicity assays revealed that highly purified CD3+ T cells from the FCR treated patients at 6 and 12-month time-points did not change their activated killing function against autologous baseline CD19+ CLL tumor B cells (acting as target antigen-presenting cells pulsed with superantigen, sAg) compared to pre-treatment/baseline exhausted T cells (n=22). In contrast, patients treated with ibrutinib-based therapy had a significant increase in activated anti-tumor T cell killing function (P<.01, n=22) at both 6-month (66% increase) and 12-month (89% increase) time-points. Flow cytometric analysis of circulating immune subsets revealed that the percentage of PD-1 and PD-L1 positive cells among CD8+ and CD4+ T cells (particularly effector compartments) were reduced with ibrutinib-based therapy, whereas only a partial reduction was detected following FCR treatment. However, patients' T cells from both treatment arms responded normally to T cell receptor engagement by upregulating these checkpoint molecules. This led us to explore ex vivo treatment of highly purified CD3+ T cells and CD19+ CLL B cells from both treatment arms with anti-PD-L1 or anti-PD-1 immunotherapy prior to cytotoxicity assays. Our functional data revealed that the T cells from both FCR time-points (6 and 12-months) were not sensitive to either anti-PD-L1 (n=14) or anti-PD-1 (n=14) treatment. In contrast, ibrutinib-based treatment sensitized anti-tumor T function (23% increase in killing) following anti-PD-L1 treatment (n=14) at the 6-month time-point only (P<.01) but not with anti-PD-1. To investigate the mechanism underlying these effector function differences, we compared the ability of highly purified CD3+ T cells from each treatment arm (n=45) time-point to form F-actin immunological synapses with baseline autologous CLL tumor B cells. Quantitative confocal image analysis revealed that ibrutinib-based therapy significantly (P<.01) enhanced polarization of F-actin, tyrosine-phosphorylated proteins and granzyme B at immune synapses with tumor cells at both 6 and 12-month time-points, whereas FCR treated patient T cells failed to mobilize these lytic synapse molecules. Importantly, our assays have revealed that T cells from both FCR treatment time-points formed "non-polarized" immune synapses with tumor cells, in keeping with cytotoxic dysfunction and insensitivity to additional checkpoint immunotherapy. In contrast, our functional correlative bioassays have revealed that ibrutinib-based therapy can reactivate exhausted cytolytic T cell function and suggest to us, a potential therapeutic window for anti-PD-L1 immunotherapy at the earlier 6-month time-point. We believe this data supports the concept of incorporating functional bioassays to immune-monitoring assays associated to clinical trials that should aid knowledge-led design of future combination immunotherapy. Disclosures Kay: Janssen: Membership on an entity's Board of Directors or advisory committees; Agios Pharm: Membership on an entity's Board of Directors or advisory committees; Acerta: Research Funding; Cytomx Therapeutics: Membership on an entity's Board of Directors or advisory committees; Infinity Pharm: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Morpho-sys: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Tolero Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding. Shanafelt:Pharmacyclics: Research Funding; Genentech: Research Funding; GlaxoSmithKline: Research Funding; Jansen: Research Funding. Ramsay:Celgene Corporation: Research Funding; Roche Glycart AG: Research Funding; MedImmune: Research Funding.

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CLL B Cells Develop Resistance to Ibrutinib By Reinvigorating the IL-4R - IL-4 Axis Blocked By Bruton's Tyrosine Kinase Inhibitors Including Acalabrutinib and Zanubrutinib

Blood ◽

10.1182/blood-2019-127255 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 477-477

Author(s):

Shih-Shih Chen ◽

Constantine S. Tam ◽

Alan G. Ramsay ◽

Priyadarshini Ravichandran ◽

Natalia C. Couto-Francisco ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cells ◽

B Cell ◽

Board Of Directors ◽

Research Funding ◽

Cell Subset ◽

Advisory Committees

Bruton's tyrosine kinases inhibitors (BTKis) represent major advances in CLL therapy. However resistance to this form of therapy is emerging, and such patients often progress more rapidly. Hence there is an important need for therapies that address resistance. Microenvironmental input like IL-4 is critical for CLL disease progression. Compared with normal B cells, CLL cells exhibit significantly higher levels of surface membrane (sm) IL-4 receptor (IL4-R) and contain increased amounts of pSTAT6, a downstream mediator of IL-4R signaling. IL-4 stimulation of CLL B cells suppresses smCXCR4 and increases smIgM, thus promotes CLL cell retention and expansion. In this study, we aimed to examine if smIL-4R expression, IL4R signaling, and IL-4-producing cells are altered in patients sensitive or resistant to BTKis. To do so, T and B cell subset changes were studied overtime in 12 acalabrutinib-treated CLL patients, 6 zanubrutinib-treated CLL patients, 30 ibrutinib-sensitive and 5 ibrutinib-resistant CLL patients, 4 of which exhibited BTK mutations. Consistent with only ibrutinib inhibiting T-cell kinase (ITK), T-cell subset analyses revealed no changes in Th1, Th2, Th17, Th9, and Th22 cells after zanubrutinib or acalabrutinib treatment. In contrast, a Th1-biased T-cell immunity was observed in patients responsive to ibrutinib. In patients progressing on ibrutinib, significantly reduced Th2 T cells were found during the resistant as well as sensitive periods. In an in vitro T-cell function assay using T cells collected before and after the treatment with each BTKi, only ibrutinib treated patients exhibited a reduced ability of T cells to support CLL B cell survival. We next studied changes in CLL B cells, including numbers of IL-4, -10 and -13 producing B cells after BTKi treatment. IL-13 producing CLL B cells were not changed. IL-10 producing CLL B cells were reduced in both ibrutinib sensitive and resistant patients, but not in zanubrutinib or acalabrutinib treated patients. Importantly, IL-4 producing CLL B cells were significantly decreased in patients treated with all 3 BTKi. Significantly reduced smIL-4R levels, impaired IL-4R signaling, decreased smIgM and increased smCXCR4 were also seen in patients treated with each BTKi. To understand the mechanism responsible for inhibition of IL-4 production in CLL cells treated with BTKis, we stimulated CLL cells through IgM, Toll-like receptor and CD40L, finding that only anti-IgM stimulation significantly increased IL-4 production and p-STAT6 induction. We then explored the function of IL-4. IL-4 enhanced CLL B cell survival in vitro and this action was blocked by all 3 BTKis. Moreover, adhesion of CLL B cells to smIL-4R expressing stromal cells was decreased by IL-4 and IL-4R neutralizing antibodies, especially in M-CLL cases. In in vivo studies transferring autologous T cells and CLL PBMCs into alymphoid mice, we found less CLL B cells in mouse spleens post ibrutinib than zanubrutinib or acalabrutinib treatment. This might be due to the suppressed Th2 cells found only in ibrutinib, while IL-4 producing B cells were reduced in all 3 BTKi treated mice. These results support the idea that IL-4 promotes CLL B cell adhesion and growth in tissues. Finally, we investigated the IL-4/IL-4R axis in ibrutinib-resistant patients. Although IL-4 producing T cells remain reduced during the sensitive and resistant phases, CLL B cell production of IL-4 and expression of and signaling through smIL-4R returned when patients developed ibrutinib-resistance. When comparing paired ibrutinib-sensitive and -resistant CLL B cells collected from 3 patients in a xenograft model that requires T cell help, we found ibrutinib-resistant CLL B cells grew in vivo with only minimal (~15%) numbers of autologous T cells compared to B cells collected from ibrutinib-sensitive phase; this suggested a reduced requirement for T-cell help for growth of ibrutinib-resistant CLL cells. In summary, we found IL-4 is a key survival factor in the CLL microenvironment that also improves leukemia cell adhesion to stromal cells expressing smIL-4R. IL-4 production and signaling can be stimulated in CLL B cells through the B-cell receptor, and are consistently blocked by BTKis. Moreover, the recovered ability of ibrutinib-resistant CLL B cells to produce and respond to IL-4 leads to disease progression, suggesting blocking the IL-4/IL-4R axis is a potential treatment for ibrutinib-resistant CLL patients. Disclosures Chen: Pharmacyclics: Research Funding; Beigene: Research Funding; Verastem: Research Funding; ArgenX: Research Funding. Tam:Abbvie, Janssen: Research Funding; Abbvie, Janssen, Beigene, Roche, Novartis: Honoraria. Ramsay:Celgene Corporation: Research Funding; Roche Glycart AG: Research Funding. Kolitz:Boeringer-Ingelheim: Research Funding; Roche: Research Funding; Astellas: Research Funding. Zhou:BeiGene: Employment. Barrientos:Genentech: Consultancy; Gilead: Consultancy; Janssen: Consultancy; Abbvie: Consultancy, Research Funding; Pharmacyclics: Consultancy, Research Funding. Rai:Pharmacyctics: Membership on an entity's Board of Directors or advisory committees; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; Cellectis: Membership on an entity's Board of Directors or advisory committees; Genentech/Roche: Membership on an entity's Board of Directors or advisory committees.

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Duobody-CD3xCD20 Induces Potent Anti-Tumor Activity in Malignant Lymph Node B Cells from Patients with DLBCL, FL and MCL Ex Vivo, Irrespective of Prior Treatment with CD20 Monoclonal Antibodies

Blood ◽

10.1182/blood-2019-125765 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 4066-4066

Author(s):

Hilma J Van Der Horst ◽

A. Vera de Jonge ◽

Ida H Hiemstra ◽

Anne T Gelderloos ◽

Daniella RAI Berry ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Tumor Microenvironment ◽

Tumor Cell ◽

Cytotoxic Activity ◽

Board Of Directors ◽

Tumor Cells ◽

T Cell Activation ◽

Research Funding ◽

Advisory Committees

DuoBody-CD3xCD20 (GEN3013) is a novel clinical-stage CD3 bispecific antibody (bsAb) targeting CD20-positive tumor cells. GEN3013 was previously shown to induce potent T cell-mediated cytotoxicity towards B cell Non-Hodgkin lymphoma (B-NHL) cell lines in vitro and in vivo. Here, we investigated the cytotoxic activity of GEN3013 in tumor cells obtained from lymph node (LN) biopsies of B-NHL patients, who were newly diagnosed (ND) or relapsed from/refractory to (RR) treatment regimens containing CD20 monoclonal antibodies. Moreover, we explored whether specific tumor microenvironment characteristics could be associated with sensitivity to GEN3013. To test the intrinsic susceptibility of B-NHL cells to GEN3013, independent of interpatient variation in tumor T cell frequency or activation status, single cell suspensions obtained from LN of B-NHL patients were incubated with GEN3013 in the presence of allogeneic PBMC from a single donor, at an effector to target (E:T) ratio 10:1. GEN3013 (30 ng/mL) induced median tumor cell lysis of 64% in Diffuse Large B Cell Lymphoma (DLBCL, n=14), 69% in Follicular Lymphoma (FL, n=14) and 84% in Mantle Cell Lymphoma (MCL, n=8) samples, with EC50 values ranging from 0.01-3.9 ng/ml. Importantly, cytotoxic activity of GEN3013 was comparable in ND (n=24) and RR (n=12) patients (Figure 1). In these assays considerable heterogeneity in T cell activation, as assessed by expression of CD25, CD69 and granzyme B release, was observed. Furthermore, high expression of T cell activation markers was not always associated with high levels of GEN3013 cytotoxic activity, suggesting tumor-intrinsic resistance mechanisms. In parallel, in all B-NHL samples GEN3013-mediated cytotoxicity was assessed without the addition of allogeneic PBMCs, thus purely relying on T cells present in the LN biopsy. In this setting, median tumor cell lysis was lower; 18% in DLBCL (range 0-46%), 17% in FL (range 0-46%) and 0% in MCL (range 0-11%), but strongly correlated with the number of T cells present in the single cell suspensions. Analysis of the tumor microenvironment by 7 color immunohistopathology of matched FFPE-embedded tumor biopsies (n=24), confirmed that the T cell frequency in the tumor biopsies was the major determinant of GEN3013 cytotoxic activity in DLBCL, FL and MCL. Moreover, experiments using (MACS) purified T cells from 4 DLBCL and 5 FL LN biopsies demonstrated that the intrinsic capacity of tumor LN T cells to induce GEN3013 mediated cytotoxicity was comparable to healthy donor T cells. Detailed tumor microenvironment analysis based on 7 color immunohistopathology staining, including relative frequency and spatial distribution of CD4 and CD8 T cells and macrophages, as well as the T cell activation status, in relation to sensitivity to GEN3013 mediated tumor cell lysis is ongoing and results will be presented. In conclusion, GEN3013 induced potent cytotoxicity in tumor cells of DLBCL, FL and MCL patients ex vivo, irrespective of prior treatment with CD20 monoclonal antibodies. Autologous T-cells at the tumor site were able to mediate GEN3013-induced cytotoxicity, and cytotoxic activity was enhanced in presence of PBMCs suggesting that optimal tumor cell kill by GEN3013 is dependent on T-cells in the tumor microenvironment. The cytotoxic capacity of B-NHL patient T cells within the tumor microenvironment was comparable to healthy donor peripheral blood T cells, emphasizing the therapeutic potential of CD3 bsAb in B-NHL. A First-in-Human trial to assess the safety and preliminary efficacy of GEN3013 in B-NHL patients is currently ongoing (NCT03625037). Figure 1 Cytotoxic activity induced by GEN3013 compared to CD3xcontrol bsAb (both 30ng/ml) towards tumor cells obtained from lymph node (LN) biopsies of newly diagnosed (ND) versus relapse or refractory (RR) DLBCL, FL and MCL patients. GEN3013 achieved comparable lysis in ND versus RR patients (Mann-Whitney U test; not significant). Error bars represent median ± interquartile range. Figure 1 Disclosures Van Der Horst: Genmab: Other: Financial Support. Hiemstra:Genmab: Employment, Equity Ownership, Other: Warrants. de Jong:Genmab: Research Funding; BMS: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Chamuleau:Genmab: Research Funding. Zweegman:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees, Research Funding. Breij:Genmab: Employment, Other: Warrants. Roemer:Genmab: Research Funding. Mutis:Celgene: Research Funding; Janssen Research and Development: Research Funding; Onkimmune: Research Funding; Genmab: Research Funding.

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High-Parameter Mass Cytometry (CyTOF) Evaluation of Relapsed/Refractory Multiple Myeloma (MM) Pts (Pts) Treated with Daratumumab Supports Immune Modulation As a Novel Mechanism of Action

Blood ◽

10.1182/blood.v128.22.4521.4521 ◽

2016 ◽

Vol 128 (22) ◽

pp. 4521-4521 ◽

Cited By ~ 6

Author(s):

Homer Adams ◽

Frederik Stevenaert ◽

Jakub Krejcik ◽

Koen Van der Borght ◽

Tineke Casneuf ◽

...

Keyword(s):

Flow Cytometry ◽

T Cells ◽

T Cell ◽

Nk Cells ◽

Board Of Directors ◽

Research Funding ◽

Granzyme B ◽

Advisory Committees ◽

Activation Markers ◽

Equity Ownership

Abstract Introduction: Daratumumab (DARA) is a human CD38-targeting monoclonal antibody that induces deep clinical responses in MM pts through multifaceted mechanisms of action (MOA) including complement-dependent cytotoxicity, antibody-dependent cellular cytotoxicity, antibody-dependent cellular phagocytosis and induction of apoptosis. Flow cytometry analysis revealed a previously unknown immunomodulatory role of DARA, via T-cell induction expansion, T-cell activity enhancement, and reduction of immune suppressive cell populations including CD38+ myeloid-derived suppressor cells, CD38+ regulatory T cells (TRegs), and CD38+ regulatory B cells (BRegs). Next-generation mass cytometry (CyTOF), which allows high parameter evaluation of the immune system, was used to assess the effects of DARA alone or in combination on a more comprehensive profile of immune cell subpopulations. Methods: Relapsed/refractory MM pt samples from a subset of single agent studies; SIRIUS (32 pts; whole blood [WB] only; Lonial S et al. The Lancet, 2016) and GEN501 (5 pts; WB and bone marrow [BM], Lokhorst HM et al. NEJM, 2015) along with GEN503, a study of DARA plus lenalidomide and dexamethasone (9 pts; WB and BM; Plesner T et al. ASH 2015) were analyzed. Fluorochrome or metal-conjugated antibody panel stained samples were evaluated by flow cytometry or cytometry by time-of-flight (CyTOF®) platforms, respectively. FACS analyses were performed and analyzed by FACS Canto II flow cytometers and FACSDiva software. For CyTOF analysis, events were clustered by phenotype by a spanning tree progression of density normalized events (SPADE) algorithm, and each cluster was associated with an immune population via Cytobank® software. Differential analysis of population fractions and marker intensity, over time and between response groups, derived raw P values from t-tests and single cell level bootstrap adjusted P values corrected for multiple dependent hypothesis testing. Results were visualized using SPADE trees (Figure) and Radviz projections, a new method that allows for the comparison of populations and conditions while preserving the relation to original dimensions. Results: Flow cytometry and high-dimensional CyTOF analyses confirmed previous findings including higher CD38 expression on plasma cells compared with other immune populations of natural killer (NK), monocytes, B and T cells, and depletion of both plasma cells and NK cells upon DARA treatment. Interestingly, while NK cells were significantly reduced with DARA treatment, remaining active NK cells (CD16+CD56dim) demonstrated increased expression of activation markers CD69, CD25 and CD137 while also decreasing granzyme B and increasing naive marker CD27. Though functionality tests weren't performed, the ability to evaluate several markers simultaneously suggests these cells possess limited cytotoxicity. Additionally, these studies indicated depletion of CD38 positive immune suppressive subsets of Tregs and Bregs. CD38+ basophil reductions occurred independent of response and may provide insight to short-lived infusion related reactions. Several observations within the T-cell compartment were indicative of a DARA-mediated adaptive response in both WB and BM samples. T cells displayed increases in total numbers and shifted towards higher CD8:CD4 and effector:naïve ratios after 2 months of DARA treatment. Responders had higher expression levels of several activation markers including CD69 and HLA-DR along with increased production of cytolytic enzyme granzyme B in CD8+ T cells following DARA treatment. Interestingly, in the GEN503 sample set, pts who achieved a complete response presented with a distinct BM CD4 T-cell phenotype of high granzyme B positivity versus those that achieved a partial response or very good partial response. This observation suggests pts with an active immune phenotype may achieve deeper responses to DARA in combination with standard of care agents lenalidomide and dexamethasone. Conclusion: CyTOF analysis of pt samples from both single agent and combination DARA studies agree with flow cytometry and support the pharmacodynamics and immune modulatory MOA of DARA while providing additional insight into changes in T-cell subtypes and activation status. Future CyTOF analyses of clinical samples from phase 3 combination studies aim to confirm these observations and expand the understanding of the MOA of DARA. Disclosures Adams: Janssen Research & Development, LLC: Employment. Stevenaert:Janssen: Employment. Van der Borght:Janssen: Employment. Casneuf:Janssen R&D, Beerse, Belgium: Employment; Johnson & Johnson: Equity Ownership. Smets:Janssen: Employment. Bald:Janssen: Employment. Abraham:Janssen: Employment. Ceulemans:Janssen: Employment. Vanhoof:Janssen: Employment; Johnson & Johnson: Equity Ownership. Ahmadi:Janssen: Employment. Usmani:Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sanofi: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Array: Research Funding; BioPharma: Research Funding; Pharmacyclics: Research Funding; Takeda: Consultancy, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Janssen: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Research Funding; Millenium: Membership on an entity's Board of Directors or advisory committees; Skyline: Membership on an entity's Board of Directors or advisory committees. Plesner:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Lonial:Janssen: Consultancy; BMS: Consultancy; Merck: Consultancy; Novartis: Consultancy; Janssen: Consultancy; Onyx: Consultancy; Onyx: Consultancy; Millenium: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy; Celgene: Consultancy. Lokhorst:Genmab: Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding. Mutis:Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Genmab: Research Funding; Celgene: Research Funding. van de Donk:Janssen: Research Funding; BMS: Research Funding; Amgen: Research Funding; Celgene: Research Funding. Sasser:Janssen Pharmaceuticals R&D: Employment; Johnson & Johnson: Equity Ownership.

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Abstract Title Submitted by Hollie Pegram to the 2012 ASH Annual Meeting: Expansion and Modification of Umbilical Cord Blood T Cells with a Chimeric Antigen Receptor and IL-12

Blood ◽

10.1182/blood.v120.21.1907.1907 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1907-1907

Author(s):

Hollie J. Pegram ◽

Juliet Barker ◽

Sergio Giralt ◽

Renier J Brentjens

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

Tumor Cells ◽

Chimeric Antigen Receptor ◽

Umbilical Cord Blood ◽

Cell Expansion ◽

Research Funding ◽

Advisory Committees

Abstract Abstract 1907 Transplantation of unrelated umbilical cord blood (CB) derived stem cells is often used to treat adult patients with B-cell acute lymphoblastic leukemia (B-ALL). However, patients can relapse post transplant and prognosis of those with advanced or refractory disease is poor. We hypothesize that additional therapy involving adoptive transfer of CB derived T cells modified to express a CD19-specific chimeric antigen receptor (CAR) could improve patient outcome following CB transplantation in this population. We have previously demonstrated that human T cells which express the anti-CD19 1928z CAR, containing the signaling domains of the co-stimulatory CD28 receptor and CD3z chain, effectively eradicate CD19+ tumors in SCID-Beige mice, and have shown promise in early clinical trials. In this study, we demonstrate the ability to effectively isolate and expand T cells from CB, necessary for application of adoptive CB T cell therapy. We compared T cell expansion in in vitro cultures with the addition of exogenous stimulatory cytokines, including IL-2, IL-7, IL-12, IL-15 or combinations thereof. We demonstrate that in vitro culture in the context of exogenous IL-12 combined with IL-15 resulted in optimal expansion of CB T cells (over 150-fold). In addition, expansion of T cells in the context of exogenous IL-12 and IL-15 resulted in a favorable phenotype, with maximal expression of memory T cell markers, CD62L and CCR7. Furthermore, these cells were shown to produce high levels of IFNγ and express high levels of CD107a following stimulation with PHA. CB T cells expanded in IL-12 and IL-15 were therefore shown to have a unique memory cell phenotype combined with effector T cell function. Previous studies in our laboratory have demonstrated that expression of IL-12 in tumor targeted T cells resulted in increased anti-tumor function. Given these studies and the favorable effect of IL-12 on CB T cell expansion we used retroviral modification to express both 1928z CAR and IL-12 in CB T cells. CB T cells modified with both IL-12 and 1928z were shown to have increased cytokine secretion when cultured with CD19+ tumor cells, compared to UCB T cells modified with a CAR alone. Additionally, these cells were demonstrated to have increased lytic function, resulting in increased specific lysis of CD19+ tumor cells in a 51Cr release assay. Our data suggest that CB T cells modified to express both CAR and IL-12 will have improved anti-tumor function, and could therefore decrease relapse and improve overall survival following CB transplant for the treatment of B-ALL. Disclosures: Giralt: Millenium: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Onyx: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Manufacture and Immunological Characterization of GMP-Compliant Functional Sars-COV-2 Cytotoxic T Lymphocytes (CTLs) Utilizing the Clinimacs ® Cytokine Capture System

Blood ◽

10.1182/blood-2021-145620 ◽

2021 ◽

Vol 138 (Supplement 1) ◽

pp. 476-476

Author(s):

Yaya Chu ◽

Jordan Milner ◽

Margaret Lamb ◽

Elena Maryamchik ◽

Olivia Rigot ◽

...

Keyword(s):

Flow Cytometry ◽

T Cells ◽

T Cell ◽

Board Of Directors ◽

Cd8 T Cells ◽

Research Funding ◽

Cytotoxic T Cell ◽

Advisory Committees ◽

Ifn Γ

Abstract Background: The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a pandemic that has taken millions of lives around the globe. Treatment of patients with moderate and severe COVID-19 disease has included dexamethasone, tocilizumab, Remdesivir, convalescent plasma, and targeted antibodies, however, currently, there are no FDA approved targeted cellular therapies in the treatment of mild or moderate SARS-CoV-2 disease. Virus-specific cytotoxic T cell lymphocytes (vCTLs) have shown therapeutic efficacy in immunocompromised patients with viral infections. We developed a multicenter and multidisciplinary Viral Cytotoxic T-Cell Consortium (VIRCTLC) to investigate the use of vCTLs manufactured by direct enrichment using the Cytokine Capture System (CCS) on the CliniMACS® Prodigy device. SARS-CoV-2 specific PepTivator Peptides consist of overlapping peptides that span the entire sequence of the protein (Protein N and M), or the length of its immunodominant domain (Protein S). The peptides can bind to either MHC class I or MHC class II molecules and are therefore able to target both CD4 and CD8 T cells. Objective: To screen, manufacture, and characterize SARS-CoV-2 vCTLs generated from convalescent COVID-19 donors using the CliniMACS® Cytokine Capture System on the CliniMACS® Prodigy device. Methods: Donor screening was done utilizing PBMNCs from 15 convalescent COVID-19 donors after informed consent. PBMNCs were stimulated with a mix of PepTivator peptides (Miltenyi Biotech®) contained in the S, M and N proteins. IFN-γ levels were examined in CD3, CD4, and CD8 T cells by flow cytometry analysis. After informed consent, PBMNCs from three convalescent COVID-19 donors who screened positively to the PepTivator® peptide pools of SARS-CoV-2 Proteins M, N and S were collected by apheresis using the SPECTRA Optia® apheresis instrument. PBMNCs were incubated with the PepTivator® peptide pools for 4 hours. After incubation, the SARS-CoV-2 vCTLs were enriched using the CliniMACS Cytokine Capture System as we have previously described (Flower/Cairo, et al, ASTCT, 2020). Samples were taken from the enriched vCTLs and tested in gram stains, sterility cultures, cell counts, viability and IFN-γ cytokine staining (CD3/CD4/CD8/IFN-γ marker panel) by flow cytometry. Amplification and sequencing of TCRβ CDR3 regions of pre-stimulated PBMNC, stimulated PBMNCs samples taken from the QC bag (QC samples) and the enriched SARS-CoV-2 vCTLs were performed on the ImmunoSEQ platform using ImmunoSEQ® TCRB Assay kit (Adaptive Biotechnologies, Seattle, WA, USA). Characterization of immune subsets was done by mass cytometry analysis with 41 Immunophenotypic markers. Transcriptome of the immune landscape of QC samples, and enriched vCTLs was compared with the pre samples using the human nCounter PanCancer Immune Profiling Panel on the nCounter system. Results: We demonstrate that 93.3% of convalescent donor blood samples passed the screening criteria for clinical manufacture. Three validation runs resulted in enriched T cells that consisted of 79% + 21% (mean + SEM) IFNγ + T cells (Fig.1). TCRβ sequencing showed that convalescent COVID-19 donors have a highly diverse TCR repertoire and we identified TCRβ CDR3 clones that are known to be associated with SARS-CoV-2 T cell responses. Immunophenotyping analysis demonstrated more CD4 T cells than CD8 T cells in the SARS CoV-2 vCTLs, an increase in memory CD8 and CD4 cells, especially CD8 T EM, CD4 T cm and CD4 T EMRA cells (Fig.2) and an increase DC cells in the SARS CoV-2 vCTL products as compared to pre-stimulated PBMNCs. Expression of the exhaustion markers was not enhanced in the SARS CoV-2 vCTLs as compared to pre-stimulated PBMNCs. Transcriptome analysis showed increased gene expression in T-cell function, interleukin, pathogen defense, and TNF superfamily pathway genes in the SARS CoV-2 vCTLs as compared to pre-stimulated PBMNCs. Conclusion: Our study demonstrates that highly functional SARS-CoV-2 vCTLs can be rapidly generated by direct cytokine enrichment from convalescent donor peripheral blood mononuclear cells. These data serve as pre-clinical validation for an ongoing clinical trial utilizing related HLA-matched and haplo-identical SARS CoV-2 vCTLs for the treatment of patients with mild and moderate SARS-CoV-2 disease (IND #27260, NCT# 04896606). Figure 1 Figure 1. Disclosures Lee: Kiadis Pharma: Divested equity in a private or publicly-traded company in the past 24 months, Honoraria, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Courier Therapeutics: Current holder of individual stocks in a privately-held company. Johnson: Miltenyi Biotec: Research Funding. Cairo: Jazz Pharmaceutical: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Speakers Bureau; Sanofi: Speakers Bureau; Servier: Speakers Bureau; Sobi: Speakers Bureau; Omeros: Membership on an entity's Board of Directors or advisory committees; Nektar: Membership on an entity's Board of Directors or advisory committees.

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Immunotherapy with T-Cells Engineered with a Chimeric Antigen Receptor Bearing a Human CD19-Binding Single Chain Variable Fragment for Relapsed or Refractory Acute Lymphoblastic Leukemia and B-Cell Non-Hodgkin Lymphoma

Blood ◽

10.1182/blood-2018-99-111528 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 1415-1415 ◽

Cited By ~ 3

Author(s):

Jordan Gauthier ◽

Alexandre V. Hirayama ◽

Kevin A. Hay ◽

Alyssa Sheih ◽

Barbara S. Pender ◽

...

Keyword(s):

Flow Cytometry ◽

T Cells ◽

T Cell ◽

Board Of Directors ◽

Research Funding ◽

Advisory Committees ◽

Car T Cell ◽

Car T ◽

Equity Ownership ◽

Grade 3

Abstract Background We previously reported high response rates and durable remissions in patients (pts) with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (ALL; Turtle, JCI 2016) and non-Hodgkin lymphoma (NHL; Turtle, Sci Transl Med 2016) treated with CD19-specific chimeric antigen receptor T (CD19 CAR-T) cells. In a subset of pts, we identified CD8+ T cell responses to epitopes in the murine CD19-binding single chain variable fragment (scFv) of the CAR that could limit CAR-T cell persistence and responses to subsequent infusions. In an effort to reduce the potential for immune CAR-T cell rejection, the murine CD19-binding scFv of the CAR was replaced with a fully human scFv linked to 4-1BB and CD3z signaling domains (JCAR021; Sommermeyer, Leukemia 2017). Here we report the initial clinical results of immunotherapy with JCAR021. Methods We initiated a phase I trial investigating lymphodepletion with cyclophosphamide 300 mg/m2/d and fludarabine 30 mg/m2/d for 3 days (Cy/Flu) followed by infusion of JCAR021 in pts with R/R ALL and aggressive NHL (NCT03103971). Pts were enrolled into 1 of 3 cohorts: high marrow burden ALL (HMB; > 5% blasts in bone marrow [BM] before lymphodepletion); low marrow burden ALL (LMB; ≤ 5% blasts in BM before lymphodepletion); and NHL. The starting dose was 7x104 JCAR021 cells/kg for the HMB ALL cohort, and 7x105 JCAR021 cells/kg in both the LMB ALL and NHL cohorts. Dose escalation/de-escalation follows a modified toxicity probability interval algorithm (Guo, Contemp Clin Trials 2017). Responses in the NHL cohort and in the HMB/LMB ALL cohorts were determined by the Lugano criteria (Cheson, JCO 2014) and the 2018 NCCN guidelines, respectively. Cytokine release syndrome (CRS) was graded according to consensus criteria (Lee, Blood 2014) and neurotoxicity was graded according to CTCAE v4.03. Results Pt characteristics are detailed in Table 1. As of June 15, 2018, 9 pts were enrolled on the trial. Two pts did not receive JCAR021: one pt was excluded after aggressive NHL was reclassified as indolent after pathology review and one pt had no detectable disease upon pre-treatment restaging. The 7 pts who received JCAR021 had a median age of 63 years (range: 29 - 69). Both pts in the LMB ALL cohort had bulky extramedullary disease (> 5 cm diameter). One patient (LMB ALL cohort) had failed two allogeneic transplants and one patient (HMB ALL cohort) had failed an allogeneic transplant prior to treatment with JCAR021. Four of 4 pts in the NHL cohort and 2 of 2 pts in the LMB ALL cohort received 7x105 JCAR021 cells/kg. The pt treated in the HMB ALL cohort received 7x104 JCAR021 cells/kg. No pt in any cohort developed grade ≥ 3 CRS. All ALL pts developed grade 2 CRS. No pts with NHL developed CRS; one pt in the NHL cohort who had CNS disease prior to CAR-T cell immunotherapy developed grade 3 neurotoxicity in the absence of CRS. We did not observe other neurologic events. No other grade ≥ 3 non-hematopoietic organ toxicity was observed and all 7 treated pts have completed response evaluation. Four weeks after infusion of a low dose of JCAR021, both patients in the LMB ALL cohort had undetectable marrow disease by high resolution flow cytometry and regression of bulky extramedullary disease (1 complete response [CR] and 1 partial response [PR] by PET-CT). One pt treated with a low dose (7x104 cells/kg) of JCAR021 in the HMB ALL cohort did not achieve CR (decrease in BM blasts from 79.8% to 29.5%) but CNS disease was cleared by flow cytometry. In the NHL cohort, we observed objective responses in 2 of 4 patients (1 CR, 1 PR). JCAR021 was detected in blood by flow cytometry and/or quantitative PCR for up to 112 days after infusion. Conclusion JCAR021 appears to have a favorable toxicity profile in R/R ALL and NHL pts. JCAR021 cells expanded in vivo and have persisted in all pts. We observed responses at very low doses of CAR-T cells in ALL pts with bulky disease. This trial continues to enroll to define optimal dosing and determine the safety and efficacy of JCAR021. Disclosures Hirayama: DAVA Oncology: Honoraria. Hay:DAVA Oncology: Honoraria. Till:Mustang Bio: Patents & Royalties, Research Funding. Kiem:Homology Medicine: Consultancy; Magenta: Consultancy; Rocket Pharmaceuticals: Consultancy. Shadman:TG Therapeutics: Research Funding; Mustang: Research Funding; Gilead: Research Funding; Pharmacyclics: Research Funding; AstraZeneca: Consultancy; Qilu Puget Sound Biotherapeutics: Consultancy; Acerta: Research Funding; Abbvie: Consultancy; Verastem: Consultancy; Genentech: Consultancy, Research Funding; Beigene: Research Funding; Celgene: Research Funding. Cassaday:Amgen: Consultancy, Research Funding; Seattle Genetics: Other: Spouse Employment, Research Funding; Adaptive Biotechnologies: Consultancy; Incyte: Research Funding; Pfizer: Consultancy, Research Funding; Merck: Research Funding; Kite Pharma: Research Funding; Jazz Pharmaceuticals: Consultancy. Acharya:Teva: Honoraria; Juno Therapeutics: Research Funding. Riddell:NOHLA: Consultancy; Adaptive Biotechnologies: Consultancy; Cell Medica: Membership on an entity's Board of Directors or advisory committees; Juno Therapeutics: Equity Ownership, Patents & Royalties, Research Funding. Maloney:Juno Therapeutics: Research Funding; Seattle Genetics: Honoraria; Janssen Scientific Affairs: Honoraria; GlaxoSmithKline: Research Funding; Roche/Genentech: Honoraria. Turtle:Aptevo: Consultancy; Nektar Therapeutics: Consultancy, Research Funding; Caribou Biosciences: Consultancy; Gilead: Consultancy; Juno Therapeutics / Celgene: Consultancy, Patents & Royalties, Research Funding; Bluebird Bio: Consultancy; Eureka Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Consultancy; Precision Biosciences: Equity Ownership, Membership on an entity's Board of Directors or advisory committees.

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