scholarly journals A Novel CD19-Anti-CD20 Bridging Protein Prevents and Reverses CD19-Negative Relapse from CAR19 T Cell Treatment In Vivo

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 252-252 ◽  
Author(s):  
Paul Rennert ◽  
Lihe Su ◽  
Fay Dufort ◽  
Alyssa Birt ◽  
Tom Sanford ◽  
...  

Introduction CAR T cells that recognize the antigen CD19 (CAR19s) have achieved remarkable success in otherwise untreatable B cell malignancies including refractory and relapsed ALL and NHL. However, clinical data from diverse CAR19 trials, and real-world experience with the approved CAR19 therapeutics (tisagenlecleucel and axicabtagene ciloleucel), highlight a critical issue, that of patient relapse due to the loss of expression of the target antigen (CD19) or the antigenic epitope. Antigen loss relapse rate of up to 50% have been reported across indications (adult ALL, pediatric ALL, adult NHL) irrespective of the specific CAR19 used. Attempts to treat patients who have relapsed from CAR19 treatment include provision of a CAR T cell to a second antigen, for example CD22. Such attempts have met with limited success, further, many patients cannot tolerate a second regimen of apheresis, consolidation, lymphodepletion and CAR T infusion. Importantly, many of the patients relapsing with CD19-negative malignancies still have detectable levels of CAR19 T cells in circulation, since the CAR19s persist in the presence of normal B cells being produced by the bone marrow (these B cells are CD19-positive). Therefore, a technology that reactivates the patient-resident CAR19s to attack the relapsing tumor cell would be a highly attractive alternative to subsequent CAR T therapy. Here we present this technology and illustrate its' ability to prevent relapses and importantly, to reverse relapses in vivo. Experimental Procedures A stabilized form of the CD19 extracellular domain (ECD) was cloned in frame with an anti-CD20 scFv and an anti-albumin VHH, to create a monomeric CD19-ECD-anti-CD20 bridging protein with extended circulating half-life characteristics. The protein was purified from a mammalian cell expression system. Protein stability, binding affinities, and cytotoxic activity were analyzed in vitro. We utilized CD19-positive, CD20-positive and double positive cell lines to assess single and dual antigen activity. We utilized patient derived CD20-positive/CD19-negative cells to demonstrate translational relevance. Finally, we used single and dual flank in vivo models to assess the potency of the bridging protein in the relapse setting and in the prevention setting. Results and Discussion The CD19-anti-CD20 bridging protein was shown to be expressed at high levels, readily purified and highly stable (no aggregation or clipping, thermostable, and stable in media/serum at 37oC for extended periods). The purified bridging protein directed CAR19 cytotoxicity against CD19-negative/CD20-positive cells with superb potency (IC50 = 23pM = 1.6 ng/ml). CAR19 T cells that were previously activated by a CD19-positive tumor cell could subsequently be activated by a CD19-negative tumor cell in the presence of the CD19-anti-CD20 bridging protein. In vitro, a CAR19 T cells found and eliminated CD19-negative cells "hidden" in a population of dual-positive cells in a mixing experiment but only if the bridging protein was present, otherwise, the CD19-negative cells invariably escaped from CAR19 T cells. The activity of the CD19-anti-CD20 bridging protein extended to CD19-negative/CD20-positive patient-derived cells tested in vitro. In vivo, using a dual flank model, CAR19 T cells plus the injected bridging protein controlled both CD19-positive/CD20-positive and CD19-negative/CD20-positive tumors, while CAR19 alone did not impact the latter tumor. In a relapse setting the growth of a mixture of CD19-positive and CD19-negative cells was merely delayed by CAR19 T cells alone but was eradicated when CAR19 cells were given along with the CD19-anti-CD20 bridging protein injected systemically. Importantly, CAR19 cells that had "lost" control over the mixed population could be restimulated to eliminate the CD19-negative population when the CD19-anti-CD20 bridging protein was added after those cells have begun to escape the initial (CAR19-only) treatment in vivo. These results have led to the identification of a development candidate for the treatment of CD19-negative relapse from CAR19 treatment. The GMP production campaign is underway. The first-in-human trial will enroll patients relapsing from CAR19 therapy with CD19-negative malignancy, in whom CAR19 T cells are shown to still be present. Disclosures Rennert: Aleta Biotherapeutics: Employment, Equity Ownership. Su:Aleta Biotherapeutics: Employment. Dufort:Aleta Biotherapeutics: Employment. Birt:Aleta Biotherapeutics: Employment. Sanford:Aleta Biotherapeutics: Employment. Wu:Aleta Biotherapeutics: Employment. Ambrose:Aleta Biotherapeutics: Employment. Lobb:Aleta Biotherapeutics: Consultancy, Equity Ownership.

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1934-1934 ◽  
Author(s):  
Eduardo Huarte ◽  
Roddy S O'Connor ◽  
Melissa Parker ◽  
Taisheng Huang ◽  
Michael C. Milone ◽  
...  

Background: T-cells engineered to express a chimeric antigen receptor (CAR-T-cells) are a promising cancer immunotherapy. Such targeted therapies have shown long-term relapse survival in patients with B cell leukemia and lymphoma. However, cytokine release syndrome (CRS) represents a serious, potentially life-threatening, side effect often associated with CAR-T cells therapy. The Janus kinase (JAK) tyrosine kinase family is pivotal for the downstream signaling of inflammatory cytokines, including interleukins (ILs), interferons (IFNs), and multiple growth factors. CRS manifests as a rapid (hyper)immune reaction driven by excessive inflammatory cytokine release, including IFN-g and IL-6. Itacitinib is a potent, selective JAK1 inhibitor which is being clinically evaluated in several inflammatory diseases. Aims: To evaluate in vitro and in vivo the potential of itacitinib to modulate CRS without impairing CAR-T cell anti-tumor activity. Materials and Methods: In vitro proliferation and cytotoxic activity of T cells and CAR-T cells was measured in the presence of increasing concentrations of itacitinib or tocilizumab (anti-IL-6R). To evaluate itacitinib effects in vivo, we conducted experiments involving adoptive transfer of human CD19-CAR-T-cells in immunodeficient animals (NSG) bearing CD19 expressing NAMALWA human lymphoma cells. The effect of itacitinib on cytokine production was studied on CD19-CAR-T-cells expanded in the presence of itacitinib or tocilizumab. Finally, to study whether itacitinib was able to reduce CRS symptoms in an in vivo setting, naïve mice were stimulated with Concanavalin-A (ConA), a potent T-cell mitogen capable of inducing broad inflammatory cytokine releases and proliferation. Results: In vitro, itacitinib at IC50 relevant concentrations did not significantly inhibit proliferation or anti-tumor killing capacity of human CAR-T-cells. Itacitinib and tocilizumab (anti-IL-6R) demonstrated a similar effect on CAR T-cell cytotoxic activity profile. In vivo, CD19-CAR-T-cells adoptively transferred into CD19+ tumor bearing immunodeficient animals were unaffected by oral itacitinib treatment. In an in vitro model, itacitinib was more effective than tocilizumab in reducing CRS-related cytokines produced by CD19-CAR-T-cells. Furthermore, in the in vivo immune hyperactivity (ConA) model, itacitinib reduced serum levels of CRS-related cytokines in a dose-dependent manner. Conclusion: Itacitinib at IC50 and clinically relevant concentrations did not adversely impair the in vitro or in vivo anti-tumor activity of CAR-T cells. Using CAR-T and T cell in vitro and in vivo systems, we demonstrate that itacitinib significantly reduces CRS-associated cytokines in a dose dependent manner. Together, the data suggest that itacitinib may have potential as a prophylactic agent for the prevention of CAR-T cell induced CRS. Disclosures Huarte: Incyte corporation: Employment, Equity Ownership. Parker:Incyte corporation: Employment, Equity Ownership. Huang:Incyte corporation: Employment, Equity Ownership. Milone:Novartis: Patents & Royalties: patents related to tisagenlecleucel (CTL019) and CART-BCMA; Novartis: Research Funding. Smith:Incyte corporation: Employment, Equity Ownership.


2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A143-A143
Author(s):  
Jonathan Terrett ◽  
Brigid Mcewan ◽  
Daniel Hostetter ◽  
Luis Gamboa ◽  
Meghna Kuppuraju ◽  
...  

BackgroundCD33 is the most consistently expressed antigen in AML, with high levels and homogeneous expression observed in malignant AML cells from most patients, including those with relapsed disease. Normal myelomonocytic cell lineages and a percentage of hematopoietic progenitors also express CD33, and the extreme myeloablation caused by the CD33-targeted antibody-drug conjugate (ADC) gemtuzumab ozogamicin reinforced concerns about targeting this antigen with more potent agents such as T-cell engaging bispecific antibodies and CAR-T cells. We have shown previously that allogeneic CRISPR/Cas9 gene-edited CAR-T cells targeting CD33 with TRAC disruption to reduce GvHD and B2M disruption to reduce allogeneic host rejection could eliminate tumors in xenograft models of AMLMethodsGiven that off-target activity of the toxin could contribute to the myeloablation seen with CD33-targeted ADCs, we created in vitro and in vivo models to examine reconstitution of the myeloid compartment following treatment of CD33-targeted allogeneic CAR-T cells.ResultsAlthough co-culture of CD34+ stem cells in vitro with our CD33-targeted allogeneic CAR-T cells did significantly deplete the cell population, colonies still formed after removal of the CAR-T cells as the presumably CD33-negative stem/progenitor cells expanded and differentiated. A similar phenomenon was observed in vivo with CD34 humanized mice bearing an AML tumor (THP-1 cells) and treated with the CD33-targeted allogeneic CAR-T cells. The CAR-T cells completely eradicated the THP-1 tumor but did not lead to long-term myelosuppression or B cell aplasia.ConclusionsThus, allogeneic CRISPR/Cas9 multiplex gene-edited CD33-targeted CAR-T cell therapy may be both efficacious and tolerable in AML.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3222-3222
Author(s):  
Kathy Karasiewicz ◽  
Shuyang He ◽  
Mary Ng ◽  
Kristina Tess ◽  
Weifang Ling ◽  
...  

Celularity, Inc. is developing a CD19 CAR-T Cell therapy using an allogeneic platform derived from postpartum human placental cells. T cells isolated from placenta/ umbilical cord blood and genetically modified to express CD19 chimeric antigen receptor (CAR), termed Placental-derived (P-) CD19 CAR T cells, are in development for the treatment of B cell malignancies. Unlike adult peripheral blood mononuclear cell (PBMC)-derived T cells, P-T cells are mostly naïve (CD45RA+) and can be readily expanded while maintaining an earlier differentiation phenotype such as greater expression of naïve/ memory markers, lower expression of effector/ exhaustion markers, allowing for greater proliferative potential of these cells ex vivo. These cells are also known to have greater immune tolerance to HLA mismatch and display impaired allogeneic activation, contributing to lower incidences of severe graft-verse-host disease (GvHD) (Barker, et. al. Blood, 2001; Chen, et al. Biology of Blood and Marrow Transplantation, 2006), making them an attractive cell population for use as an allogeneic, adoptive cell therapy. A robust process for the isolation, transduction, and expansion of placental-derived T cells to generate "off-the-shelf" allogeneic P-CD19 CAR T cells was developed. Twenty-One day expanded, non-modified P-T cells (N=3) were compared to adult PBMCs for their allo-reactivity in a Xenogeneic GvHD model in NCG mice. P-T cells did not induce xeno-GvHD whereas PBMCs did, as evidenced by significant weight loss and death of all mice (N=5) by Day 28 post infusion. Despite expanded P-T cells demonstrating lack of in vivo GvHD, current manufacture of P-CD19 CAR T cells does include a CRISPR-mediated T-cell receptor a constant (TRAC) knockout (KO) step as an additional risk-mitigation strategy to circumvent any potential GvHD stemming from expression of endogenous T cell receptor. CD19 CAR transduction using a retrovirus provided by Sorrento Therapeutics, Inc., followed by TRAC knockout with CRISPR results in both high efficiency of CD19 CAR expression (~30% CD19 Fc+) and TCR KO (>96% CD3-/ TCR a/b-). In vitro, the functional activity of P-CD19 CAR-TRAC KO T cells against CD19+ Burkitt's Lymphoma (Daudi) and Acute lymphoblastic Leukemia (NALM6) cell lines was assessed in cytotoxicity and cytokine release assays. P-CD19 CAR T cells specifically lyse CD19+ Daudi/ Nalm6 targets in both 4-hour endpoint FACS and ACEA kinetic cytotoxicity assays, and in most cases at levels equivalent to or greater than PBMC-derived CD19 CAR T cells. When P-CD19 CAR T cells were co-cultured with CD19+ Daudi/ Nalm6 target cells for 24-hours, they secreted pro-inflammatory cytokines and effector proteins in an antigen-specific manner. In vivo, the anti-tumor activity of P-CD19 CAR T cells was assessed using a disseminated lymphoma xenograft model in NSG mice. Luciferase expressing Daudi cells (3×106) were intravenously (IV) injected on Day 0, followed by IV injection of P-CD19 CAR T cells (14×106) on Day 7. Bioluminescence Imaging (BLI) and survival were used as primary study endpoints. P- CD19 CAR T cells were well tolerated and safe. P-CD19 CAR T cells significantly reduced tumor burden, and improved survival. Four weeks after treatment, the vehicle group had a 100% mortality rate, while all animals from P-CD19 CAR T-treated group (N=5) remained alive without clinical symptoms including weight loss or changes in their fur. In summary, Celularity has defined a robust process for the generation and expansion of CD19 CAR T cells from human placenta. These cells exhibit potent anti-tumor activity both in vitro and in vivo with little evidence of acute GvHD induction, highlighting their potential as an allogeneic, adoptive cell therapeutic agent. Future in vivo GvHD studies will include assessment of both CD19 CAR and TRAC KO genetically modified P-T cells. Disclosures Karasiewicz: Celgene: Equity Ownership; Celularity, Inc.: Employment, Equity Ownership, Patents & Royalties: Patent Inventor. He:Celularity Inc: Employment. Ng:Celularity, Inc.: Employment. Tess:Celularity, Inc.: Employment. Ling:Celularity Inc: Employment. Kaufmann:Sorrento Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties. Zeldis:Sorrento Therapeutics Inc: Employment, Equity Ownership. Ji:Celularity, Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Sorrento Therapeutics Inc: Employment, Equity Ownership, Patents & Royalties. Hariri:Celularity Inc: Employment. Zhang:Celularity Inc: Employment.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2772-2772
Author(s):  
Tom Leedom ◽  
Alexander S. Hamil ◽  
Somayeh Pouyanfard ◽  
Jennifer Govero ◽  
Rachel Langland ◽  
...  

Abstract Background T-cell Acute Lymphoblastic Leukemia (T-ALL) / Lymphoblastic Lymphoma (LBL) represent a class of devastating hematologic cancers with high rates of relapse and mortality in both children and adults. Development of CAR-T cell therapies for T-cell cancers has been complicated by induction of fratricide and the high risk of malignant cell contamination of the drug product in the autologous setting. Previously, Cooper et. al., demonstrated that CRISPR/Cas9 gene-editing to delete CD7 prevented self-killing, and deletion of the T-cell receptor alpha constant (TRAC) enabled the use of healthy donor-derived T-cells to manufacture CD7-targeted CAR-T cells without risk of malignancy and mitigating the risk of GvHD. Here we present preclinical data supporting the safety and efficacy of WU-CART-007, an IND ready, off-the-shelf, and fratricide resistant CD7-targeted CAR-T cell for the treatment of CD7+ T-cell malignancies. Methods WU-CART-007 was manufactured using T cells isolated from healthy donors by deletion of CD7 and TRAC, followed by CAR transduction, cell expansion, depletion of residual TCRa/b+ cells and cryopreservation. Donors were confirmed negative for a panel of adventitious viruses. CD7/TRAC deletion and CAR transduction were confirmed by flow cytometry. Off-target editing profile was assessed by GUIDE-Seq. The binding kinetics to human CD7 were conducted by bio-layer interferometry and CD7 selectivity was confirmed by cell microarray with a library of HEK-293 cells expressing approximately 6000 human proteins. The in vitro activity of WU-CART-007 was interrogated by co-culture with human CD7+ CCRF-CEM T-ALL cells and the potential on-target, off-tumor activity was assessed by co-culture with a panel of immune and non-immune primary human cells. In vivo anti-tumor functionality was confirmed in immunocompromised NSG mice after the establishment of low or high tumor burden CCRF-CEM xenografts engineered to express green fluorescent protein (GFP) and click beetle red (CBR) luciferase. The impact of WU-CART-007 on normal hematopoiesis was assessed using CD34+ humanized NCG mice. Results Several successful full-scale manufacturing runs were completed with consistently high dual CD7/TRAC deletion, transduction efficiency, and cell viability. Drug product was primarily composed of a T cell memory phenotype. Off- target nuclease analysis by GUIDE-seq and targeted NGS confirmed no evidence of off-target editing events. The WU-CART-007 scFv exhibited high affinity and exquisite specificity for human CD7. In vitro co-incubation experiments confirmed strong cytotoxicity against CD7-expressing cells including CCRF-CEM T-ALL cells, primary T and NK cells, but not CD7- cells such as myeloid cells, B cells, hepatocytes, astrocytes, cardiomyocytes, epithelial cells, and endothelial cells. Importantly, no cytotoxicity was observed against hematopoietic progenitor cells in human bone marrow or cord blood following co-incubation with WU-CART-007. Similarly, WU-CART-007 treatment of a non-tumor bearing humanized mouse model resulted in transient reductions in CD7+ cells (T-cells and NK cells) but not CD7- cells (myeloid and B cells), and the impacted cells recovered after circulating WU-CART-007 cells were no longer detectable. Assessment of in vivo anti-tumor efficacy revealed that WU-CART-007 effectively inhibited tumor progression (>99% TGI) in both low and high burden CCRF-CEM tumor models and improved survival in a dose-dependent manner, while CAR- cells were inactive, confirming CD7-dependent activity. Conclusions These preclinical studies support the use of WU-CART-007 in clinical trials and highlight the potential of WU-CART-007 to be a well-tolerated and active therapy for patients with CD7+ T-cell malignancies. A first in human Phase 1/2 trial in patients with R/R T-ALL/LBL is currently open for enrollment (NCT# 04984356). Disclosures No relevant conflicts of interest to declare.


Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 729-729
Author(s):  
Cedric Menard ◽  
Joelle Dulong ◽  
Tien Tuan Nguyen ◽  
Nadège Bescher ◽  
Maelle Latour ◽  
...  

Abstract The immunostimulatory properties of lenalidomide have been mostly described in vitro while in vivo studies performed in multiple myeloma or chronic lymphocytic leukemia have reported a poorly characterized T-cell activation. A better understanding of lenalidomide kinetics and mechanisms of action is mandatory to optimize its combination with other immunotherapeutic agents in particular for the treatment of non Hodgkin lymphomas. We undertook a thorough immune monitoring of patients enrolled in the French multicenter clinical trial GALEN (ClinicalTrials.gov: NCT01582776) addressing the tolerance and efficacy of the association of lenalidomide and obinutuzumab, a glycoengineered type II anti-CD20 monoclonal antibody, in relapsed/refractory B-cell lymphomas. A 1-week interval between the start of lenalidomide and the first infusion of obinutuzumab was planned, allowing an assessment of the effect of lenalidomide alone on immune-related parameters separately from the combinatorial therapy. Serial blood samples were collected in 44 patients (16 DLBCL and 28 FL) to investigate T, B, NK, and myeloid subsets. In addition, in vitro functional assays were designed to address T cell functional features (proliferation, immune synapse, activity of regulatory T cells (Treg)). In the context of the association with obinutuzumab, we first checked that CD20 expression was not affected on circulating malignant and normal B cells (p=0.43 and 0.8; respectively). Interestingly, upon 1 week of lenalidomide treatment, normal B cells, unlike malignant B cells, upregulated MHC class II (p<0.001 versus 0.16; respectively) while both increased the expression of the costimulatory molecule CD86 (p=0.001 and 0.002; respectively). More importantly, the T-cell capacity to mount a functional immune synapse with malignant B cells was restored in 5/6 relapsed/refractory patients (p<0.001) and we confirmed that this stood true for 6 FL patients at diagnosis (p<0.001). In addition, T cell proliferation was strongly increased in vivo as measured by Ki67 staining (p<0.001) but also upon TCR stimulation ex vivo (p=0.002). This immunostimulatory effect could not be ascribed to a blockade of Treg inhibitory potential by lenalidomide as effector T-cell proliferation was similarly enhanced upon in vitro Treg depletion before and after lenalidomide treatment (p=0.02). In addition, T-cell activation was associated with a reshaping of memory T-cell distribution with the central memory subset dropping in favor of effector cells (p<0.001 and 0.002 respectively). This restoration of T-cell functions was paralleled by the induction of activation markers on T cells such as HLA-DR, CD137, PD-1, and Tim-3 (p<0.001 for all markers). Finally, immune stimulation was not confined to T cells as NK cells also upregulated CD137 (p<0.001) but not PD-1 (p=0.53) expression. We also investigated the myeloid compartment including circulating MDSC and monocytes, both being putative precursors of tumor-associated macrophages. Within 1 week of lenalidomide, patients experienced a decrease of monocytes subsets count and an upregulation of the activation marker and Fcg receptor CD64 (p=0.006). Of note, preliminary experiments showed that, at least in some cases, in vitro exposure of macrophages to lenalidomide could enhance anti-CD20-mediated phagocytosis of tumor cells. Some of these immunological parameters were transiently modulated and returned to baseline levels upon lenalidomide washout but others were restored long term in particular the immune synapse score and memory T cell counts. We herein report for the first time early in vivo T cell activation by lenalidomide in relapse FL/DLBCL through a detailed phenotypic analysis strengthened by innovative functional assays. The study of T cells heterogeneity at the transcriptomic level is underway and the correlation of these immunomodulatory properties with clinical data is also currently being addressed. Our results will help build new and more relevant lenalidomide-based immunotherapeutic approaches. (This study was supported by research grants from Celgene and Roche companies) Disclosures Menard: Celgene: Consultancy; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy. Lamy: Roche: Consultancy, Honoraria. Morschhauser: Roche: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Servier: Consultancy; Gilead: Consultancy. Tarte: Celgene: Consultancy, Research Funding; Novimmune: Research Funding; Roche: Consultancy.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 3912-3912 ◽  
Author(s):  
Pinar Ataca Atilla ◽  
Haruko Tashiro ◽  
Mary Kathryn McKenna ◽  
Madhuwanti Srinivasan ◽  
Brian Wesley Simons ◽  
...  

Introduction: C-type lectin 1 (CLL-1, CD371) is highly expressed on the malignant cells from many patients with AML, and CAR T cells directed to this antigen can selectively target both leukemic progenitor cells (LSC) as well as AML blasts whilst sparing normal tissues. We previously showed (1) that such CAR-Ts can recognize and eliminate both AML blasts and primitive AML colony-forming cells in a low tumor-burden model. We have now modified the structure of the CLL-1 CAR and added transgenic expression of IL15 to enhance performance sufficiently for activity even against more extensive disease. Material and Methods: We assessed the phenotype and cytolytic ability of T cells transduced with 5 CLL-1 CAR constructs, varying in their spacer, transmembrane and costimulatory sequences (CD28z-CD8, CD28z-sh, CD28z-CH3, 4-1BBz-sh, 4-1BBz-CH3), and compared these with the effects of our published construct (4-1BBz-CD8)(1). We used flow cytometry to determine the effects of each construct on T cell phenotype and differentiation, and sequential (recursive) co-culture assays with tumor-cell targets to determine the durability of the anti-tumor activity. The most active constructs (CD28z-CD8 and 4-1BBz-CD8) were then evaluated in NOD.SCID IL-2Rg-/- (NSGS) mice engrafted with 1.5x10ˆ6 FFLuc-modified HL 60 AML cells, which received 2x10ˆ6 CLL-1 CAR T cells on day 3. To determine if we could further potentiate the in vivo expansion, persistence and anti-tumor activity of the CLL-1 CAR-T cells, we used a second retroviral vector to co-express transgenic IL15, measuring the effects in vitro and in vivo. Mice engrafted with 1.5x10ˆ6 tumor cells and received 2.5x10ˆ6 CLL-1 CAR T cells on week 3 in patient derived xenograft (PDX) model. We determined antitumor activity by bioluminescence imaging and weekly bleeding and measured serum cytokines by multiplex analysis (Luminex, TX). After euthanasia, we examined formalin-fixed/paraffin embedded sections. Results: Modified CLL-1 CAR constructs were expressed by 70-80% of cells irrespective of CAR sequence, but CD28z-CD8 CAR T cell expansion was significantly higher than CAR T cells with 4-1BBz endodomains (p<0.001), in part because of a higher death rate/lower viability in 4-1BBz cells (p<0.001). Consistent with these differences, both CD4 and CD8 T cell populations had more terminally differentiated cells (CCR7-CD45RA+) in CD28z versus 41BBz CAR T cells. In sequential co-culture assays against HL 60 (E:T=1:4) and THP-1 (E:T=1:4), CD28z-CD8 CAR T cells continued to expand well producing the greatest antitumor effect. In vivo models showed reduction in tumor signal in mice receiving either CD28z-CD8 CAR T or 4-1BBz-CD8 CAR T cells, but that only CD28z-CD8 CAR T cells prolonged survival (p<0.01). Nonetheless, all mice ultimately relapsed, usually with extramedullary disease, in association with limited CAR T persistence. We therefore incorporated transgenic IL15 as a "signal 3" for CD28z-CD8 CAR T cells, and determined the effects of forced IL15 expression on T cell phenotype, expansion, and antitumor activity in vitro and in vivo. In vitro, CD28z-CD8 CAR T cells with IL15 were less terminally differentiated and had superior expansion compared to CD28z-CD8 CAR T cells without IL15 (p<0.001). In both AML PDX and AML cell line animal models, CD28z-CD8 CAR T co-expressing transgenic IL15 initially (week 1) expanded better than CD28z-CD8 CAR T without IL15 (p<0.001) (Fig 1a), but produced severe acute toxicity associated with high level production of human IL15, TNF alpha and IFN gamma (Fig 1b). Histopathology showed marked inflammatory changes with tissue damage in lung and liver. This acute toxicity could be managed by 2 strategies, individually or in combination. The excessive TNF alpha secretion could be blocked with anti-TNF alpha antibody (1mg/kg/mouse) (BioLegend, CA USA) weekly, while excessive T cell expansion could be arrested by activation of an inducible caspase 9 safety switch by administration of dimerizing drug (2). Both strategies successfully prolonged tumor free survival (Fig 2,b). Conclusion: Addition of transgenic IL15 to CLL-1-CD28z-CD8 CAR augmented activity against AML in a range of cell line and PDX models, and toxicity associated with exuberant CART expansion could be prevented by cytokine blockade and/or an inducible safety switch. References: 1. Tashiro H, et al. Mol Ther. 2017 2.Straathof KC et al. Blood. 2005 Disclosures Brenner: T Scan: Membership on an entity's Board of Directors or advisory committees; Marker Therapeutics: Equity Ownership; Allovir: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Tessa Therapeutics: Equity Ownership; Memgen: Membership on an entity's Board of Directors or advisory committees; Allogene: Membership on an entity's Board of Directors or advisory committees.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 1974-1974 ◽  
Author(s):  
Adam D. Cohen ◽  
J. Joseph Melenhorst ◽  
Alfred L. Garfall ◽  
Simon F Lacey ◽  
Megan Davis ◽  
...  

Abstract Background: Relapsed/refractory (rel/ref) MM is associated with progressive immune dysfunction, including reversal of CD4:CD8 T cell ratio and acquisition of terminally-differentiated T cell phenotypes. BCMA-directed CAR T cells have promising activity in MM, but the factors that predict for robust in vivo expansion and responses are not known. In a phase 1 study of CART-BCMA (autologous T cells expressing a human BCMA-specific CAR with CD3ζ/4-1BB signaling domains) in refractory MM patients (median 7 priors, 96% high-risk cytogenetics), we observed partial response (PR) or better in 12/25 (47%) (Cohen et al, ASH 2017, #505). Recently, we demonstrated in CLL pts receiving CD19-directed CAR T cells that certain T cell phenotypes prior to generation of the CAR T product were associated with improved in vivo expansion and clinical outcomes (Fraietta et al, Nat Med 2018). We thus sought to identify pre-treatment clinical or immunological features associated with CART-BCMA expansion and/or response. Methods: Three cohorts were enrolled: 1) 1-5 x 108 CART cells alone; 2) cyclophosphamide (Cy) 1.5 g/m2 + 1-5 x 107 CART cells; and 3) Cy 1.5 g/m2 + 1-5 x 108 CART cells. Phenotypic analysis of peripheral blood (PB) and bone marrow (BM) mononuclear cells, frozen leukapheresis aliquots, and phenotype and in vitro kinetics of CART-BCMA growth during manufacturing were performed by flow cytometry. CART-BCMA in vivo expansion was assessed by flow cytometry and qPCR. Responses were assessed by IMWG criteria. Results: Responses (≥PR) were seen in 4/9 pts (44%, 1 sCR, 2 VPGR, 1 PR) in cohort 1; 1/5 (20%, 1 PR) in cohort 2; and 7/11 (64%, 1 CR, 3 VGPR, 3 PR) in cohort 3. As of 7/9/18, 3/25 (12%) remain progression-free at 11, 14, and 32 months post-infusions. As previously described, responses were associated with both peak in vivo CART-BCMA expansion (p=0.002) as well as expansion over first month post-infusion (AUC-28, p=0.002). No baseline clinical or MM-related characteristic was significantly associated with expansion or response, including age, isotype, time from diagnosis, # prior therapies, being quad- or penta-refractory, presence of del 17p or TP53 mutation, serum hemoglobin, BM MM cell percentage, MM cell BCMA intensity, or soluble BCMA concentration. Treatment regimen given before leukapheresis or CART-BCMA infusions also had no predictive value. We did find, however, that higher CD4:CD8 T cell ratios within the leukapheresis product were associated with greater in vivo CART-BCMA expansion (Spearman's r=0.56, p=0.005) and clinical response (PR or better; p=0.014, Mann-Whitney). In addition, and similar to our CLL data, we found that a higher frequency of CD8 T cells within the leukapheresis product with an "early-memory" phenotype of CD45RO-CD27+ was also associated with improved expansion (Spearman's r=0.48, p=0.018) and response (p=0.047); Analysis of manufacturing data confirmed that higher CD4:CD8 ratio at culture start was associated with greater expansion (r=0.41, p=0.044) and, to a lesser degree, responses (p=0.074), whereas absolute T cell numbers or CD4:CD8 ratio in final CART-BCMA product was not (p=NS). In vitro expansion during manufacturing did associate with in vivo expansion (r=0.48, p=0.017), but was not directly predictive of response. At the time of CART-BCMA infusion, the frequency of total T cells, CD8+ T cells, NK cells, B cells, and CD3+CD56+ cells within the PB or BM was not associated with subsequent CART-BCMA expansion or clinical response; higher PB and BM CD4:CD8 ratio pre-infusion correlated with expansion (r=0.58, p=0.004 and r=0.64, p=0.003, respectively), but not with response. Conclusions: In this study, we found that CART-BCMA expansion and responses in heavily-pretreated MM patients were not associated with tumor burden or other clinical characteristics, but did correlate with certain immunological features prior to T cell collection and manufacturing, namely preservation of normal CD4:CD8 ratio and increased frequency of CD8 T cells with a CD45RO-CD27+ phenotype. This suggests that patients with less dysregulated immune systems may generate more effective CAR T cell products in MM, and has implications for optimizing patient selection, timing of T cell collection, and manufacturing techniques to try to overcome these limitations in MM patients. Disclosures Cohen: Celgene: Consultancy; Novartis: Research Funding; Oncopeptides: Consultancy; Janssen: Consultancy; Poseida Therapeutics, Inc.: Research Funding; Bristol Meyers Squibb: Consultancy, Research Funding; Kite Pharma: Consultancy; GlaxoSmithKline: Consultancy, Research Funding; Seattle Genetics: Consultancy. Melenhorst:Parker Institute for Cancer Immunotherapy: Research Funding; novartis: Patents & Royalties, Research Funding; Casi Pharmaceuticals: Consultancy; Incyte: Research Funding; Shanghai UNICAR Therapy, Inc: Consultancy. Garfall:Amgen: Research Funding; Kite Pharma: Consultancy; Bioinvent: Research Funding; Novartis: Research Funding. Lacey:Novartis Pharmaceuticals Corporation: Patents & Royalties; Parker Foundation: Research Funding; Tmunity: Research Funding; Novartis Pharmaceuticals Corporation: Research Funding. Davis:Novartis Institutes for Biomedical Research, Inc.: Patents & Royalties. Vogl:Karyopharm Therapeutics: Consultancy. Pruteanu:Novartis: Employment. Plesa:Novartis: Research Funding. Young:Novartis: Patents & Royalties, Research Funding. Levine:Novartis: Consultancy, Patents & Royalties, Research Funding; CRC Oncology: Consultancy; Incysus: Consultancy; Tmunity Therapeutics: Equity Ownership, Research Funding; Brammer Bio: Consultancy; Cure Genetics: Consultancy. June:Novartis Pharmaceutical Corporation: Patents & Royalties, Research Funding; Immune Design: Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding; Novartis Pharmaceutical Corporation: Patents & Royalties, Research Funding; Immune Design: Membership on an entity's Board of Directors or advisory committees; Celldex: Consultancy, Membership on an entity's Board of Directors or advisory committees; Tmunity Therapeutics: Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties, Research Funding. Stadtmauer:Takeda: Consultancy; Celgene: Consultancy; Amgen: Consultancy; AbbVie, Inc: Research Funding; Janssen: Consultancy. Milone:Novartis: Patents & Royalties.


Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4463-4463
Author(s):  
Xiao He ◽  
Yanliang Zhang ◽  
Yun Wei Lai ◽  
Stephanie Baguley ◽  
Yan Li ◽  
...  

Introduction: Multiple Myeloma (MM) and Non-Hodgkin Lymphoma (NHL) are hematologic malignancies that remain difficult to treat. While autologous CAR-T cell therapies have shown promise in treating these diseases, these therapies are not without issues, including lack of response in many patients, lengthy time to produce CAR-T cells, occasional production failures, as well as high manufacturing costs. As an alternative approach, protein-based T cell engaging and redirecting bispecific antibodies (BsAbs) have been developed. We have generated anti-CD38/CD3 BsAbs to redirect T cells against CD38, a clinically validated antigen in MM and studied their ability to elicit target-dependent tumor cell lysis. The lead molecule is a humanized, stability-engineered CD3-engaging and CD38 antigen affinity-optimized BsAb with reduced effector function to mitigate antigen-independent T cell toxicity. Preclinical data demonstrate potent anti-tumor activity in vitro assays and in vivo studies against CD38-expressing lymphoma and MM cell lines. Methods: Anti-CD38/CD3 BsAbs were generated by CH3 Fc domain interface engineering for heterodimerization of a CD38-targeting Fab arm and anti-CD3-scFv-Fc fusion chain with hinge mutations for reduced FcR affinities. Novel bispecific molecules that bind to CD38 with various affinities/binding kinetics were evaluated in a series of in vitro and in vivo studies, including target-specific redirected T cell cytotoxicity (RTCC) against cancer cell lines. T cell response profiles, and cytokine release. The lead CD38/CD3 BsAb was selected and further evaluated for its ability to inhibit tumor growth and prolong survival in a disseminated luciferase-expressing Raji xenograft mouse model co-implanted with primary human peripheral blood mononuclear cells (hPBMC). Results: Our lead CD38/CD3 BsAb possesses the desired CD38 and CD3, affinities resulting in effective tumor antigen and T cell engagement for RTCC. The CD38/CD3 BsAb induced potent T cell-dependent lysis of CD38-positive cancer cells in vitro, with the CD38 antigen density positively correlating with the cytotoxicity potency. Antigen dependent and dose-dependent T cell activation and cytokine release were studied in vitro, with the level of T cell activation and cytokine release being indicative of the anti-tumor potency but not necessarily anti-CD3 affinity. In an in vivo study, we evaluated the impact of CD38 affinity of the BsAb on anti-tumor activity of the BsAbs. The data showed that a balanced CD38 vs CD3 affinity was shown to be preferred for T cell stimulation and prolonged anti-tumor activity. In preclinical cytotoxicity assays against a cancer cell line panel using hPBMC from healthy donors, our lead CD38/CD3 BsAb was benchmarked against daratumumab, a marketed anti-CD38 antibody for MM, and demonstrated more potent tumor cell killing. These data suggest a more robust anti-tumor activity exerted by the CD38/CD3 BsAb through RTCC than daratumumab through antibody-dependent cellular cytotoxicity (ADCC). In Raji tumor cell-bearing NSG mice implanted with previously unstimulated hPBMCs, our CD38/CD3 BsAb induced tumor growth inhibition and prolonged survival compared to control BsAb or hPBMCs-only treated animals. Conclusions: Our preclinical data demonstrate that our lead CD38/CD3 BsAb recruits T cells against CD38-positive tumor MM and lymphoma cells in a potent target and dose-dependent manner in preclinical studies. These preclinical characterizations support the rationale for clinical investigation of the lead BsAb in selected CD38-positive malignancies. Disclosures He: Sorrento Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties. Zhang:Sorrento Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties. Lai:Sorrento Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties. Baguley:Sorrento Therapeutics, Inc.: Employment, Equity Ownership. Li:Sorrento Therapeutics, Inc.: Employment, Equity Ownership. Cao:Sorrento Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties. Yan:Sorrento Therapeutics, Inc.: Employment, Equity Ownership. Takeshita:Sorrento Therapeutics, Inc.: Employment, Equity Ownership. Zeldis:Sorrento Therapeutics Inc: Employment, Equity Ownership. Ji:Sorrento Therapeutics Inc: Employment, Equity Ownership, Patents & Royalties; Celularity, Inc.: Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Kaufmann:Sorrento Therapeutics, Inc.: Employment, Equity Ownership, Patents & Royalties.


2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A109-A109
Author(s):  
Jiangyue Liu ◽  
Xianhui Chen ◽  
Jason Karlen ◽  
Alfonso Brito ◽  
Tiffany Jheng ◽  
...  

BackgroundMesothelin (MSLN) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein with high expression levels in an array of malignancies including mesothelioma, ovaria, non-small cell lung cancer, and pancreatic cancers and is an attractive target antigen for immune-based therapies. Early clinical evaluation of autologous MSLN-targeted chimeric antigen receptor (CAR)-T cell therapies for malignant pleural mesothelioma has shown promising acceptable safety1 and have recently evolved with incorporation of next-generation CAR co-stimulatory domains and armoring with intrinsic checkpoint inhibition via expression of a PD-1 dominant negative receptor (PD1DNR).2 Despite the promise that MSLN CAR-T therapies hold, manufacturing and commercial challenges using an autologous approach may prove difficult for widespread application. EBV T cells represent a unique, non-gene edited approach toward an off-the-shelf, allogeneic T cell platform. EBV-specific T cells are currently being evaluated in phase 3 trials [NCT03394365] and, to-date, have demonstrated a favorable safety profile including limited risks for GvHD and cytokine release syndrome.3 4 Clinical proof-of-principle studies for CAR transduced allogeneic EBV T cell therapies have also been associated with acceptable safety and durable response in association with CD19 targeting.5 Here we describe the first preclinical evaluation of ATA3271, a next-generation allogeneic CAR EBV T cell therapy targeting MSLN and incorporating PD1DNR, designed for the treatment of solid tumor indications.MethodsWe generated allogeneic MSLN CAR+ EBV T cells (ATA3271) using retroviral transduction of EBV T cells. ATA3271 includes a novel 1XX CAR signaling domain, previously associated with improved signaling and decreased CAR-mediated exhaustion. It is also armored with PD1DNR to provide intrinsic checkpoint blockade and is designed to retain functional persistence.ResultsIn this study, we characterized ATA3271 both in vitro and in vivo. ATA3271 show stable and proportional CAR and PD1DNR expression. Functional studies show potent antitumor activity of ATA3271 against MSLN-expressing cell lines, including PD-L1-high expressors. In an orthotopic mouse model of pleural mesothelioma, ATA3271 demonstrates potent antitumor activity and significant survival benefit (100% survival exceeding 50 days vs. 25 day median for control), without evident toxicities. ATA3271 maintains persistence and retains central memory phenotype in vivo through end-of-study. Additionally, ATA3271 retains endogenous EBV TCR function and reduced allotoxicity in the context of HLA mismatched targets. ConclusionsOverall, ATA3271 shows potent anti-tumor activity without evidence of allotoxicity, both in vitro and in vivo, suggesting that allogeneic MSLN-CAR-engineered EBV T cells are a promising approach for the treatment of MSLN-positive cancers and warrant further clinical investigation.ReferencesAdusumilli PS, Zauderer MG, Rusch VW, et al. Abstract CT036: A phase I clinical trial of malignant pleural disease treated with regionally delivered autologous mesothelin-targeted CAR T cells: Safety and efficacy. Cancer Research 2019;79:CT036-CT036.Kiesgen S, Linot C, Quach HT, et al. Abstract LB-378: Regional delivery of clinical-grade mesothelin-targeted CAR T cells with cell-intrinsic PD-1 checkpoint blockade: Translation to a phase I trial. Cancer Research 2020;80:LB-378-LB-378.Prockop S, Doubrovina E, Suser S, et al. Off-the-shelf EBV-specific T cell immunotherapy for rituximab-refractory EBV-associated lymphoma following transplantation. J Clin Invest 2020;130:733–747.Prockop S, Hiremath M, Ye W, et al. A Multicenter, Open Label, Phase 3 Study of Tabelecleucel for Solid Organ Transplant Subjects with Epstein-Barr Virus-Driven Post-Transplant Lymphoproliferative Disease (EBV+PTLD) after Failure of Rituximab or Rituximab and Chemotherapy. Blood 2019; 134: 5326–5326.Curran KJ, Sauter CS, Kernan NA, et al. Durable remission following ‘Off-the-Shelf’ chimeric antigen receptor (CAR) T-Cells in patients with relapse/refractory (R/R) B-Cell malignancies. Biology of Blood and Marrow Transplantation 2020;26:S89.


Leukemia ◽  
2021 ◽  
Author(s):  
Kinan Alhallak ◽  
Jennifer Sun ◽  
Katherine Wasden ◽  
Nicole Guenthner ◽  
Julie O’Neal ◽  
...  

AbstractT-cell-based immunotherapy, such as CAR-T cells and bispecific T-cell engagers (BiTEs), has shown promising clinical outcomes in many cancers; however, these therapies have significant limitations, such as poor pharmacokinetics and the ability to target only one antigen on the cancer cells. In multiclonal diseases, these therapies confer the development of antigen-less clones, causing tumor escape and relapse. In this study, we developed nanoparticle-based bispecific T-cell engagers (nanoBiTEs), which are liposomes decorated with anti-CD3 monoclonal antibodies (mAbs) targeting T cells, and mAbs targeting the cancer antigen. We also developed a nanoparticle that targets multiple cancer antigens by conjugating multiple mAbs against multiple cancer antigens for T-cell engagement (nanoMuTEs). NanoBiTEs and nanoMuTEs have a long half-life of about 60 h, which enables once-a-week administration instead of continuous infusion, while maintaining efficacy in vitro and in vivo. NanoMuTEs targeting multiple cancer antigens showed greater efficacy in myeloma cells in vitro and in vivo, compared to nanoBiTEs targeting only one cancer antigen. Unlike nanoBiTEs, treatment with nanoMuTEs did not cause downregulation (or loss) of a single antigen, and prevented the development of antigen-less tumor escape. Our nanoparticle-based immuno-engaging technology provides a solution for the major limitations of current immunotherapy technologies.


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