scholarly journals Establishment and validation of in-house cryopreserved CAR/TCR-T cell flow cytometry quality control

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yihua Cai ◽  
Michaela Prochazkova ◽  
Chunjie Jiang ◽  
Hannah W. Song ◽  
Jianjian Jin ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
Quality Control ◽  
T Cells ◽  
T Cell ◽  
Critical Role ◽  
Transduction Efficiency ◽  
Quality Controls ◽  
Car T Cells ◽  
Car T ◽  
Vector Identity

Abstract Background Chimeric antigen receptor (CAR) or T-cell receptor (TCR) engineered T-cell therapy has recently emerged as a promising adoptive immunotherapy approach for the treatment of hematologic malignancies and solid tumors. Multiparametric flow cytometry-based assays play a critical role in monitoring cellular manufacturing steps. Since manufacturing CAR/TCR T-cell products must be in compliance with current good manufacturing practices (cGMP), a standard or quality control for flow cytometry assays should be used to ensure the accuracy of flow cytometry results, but none is currently commercially available. Therefore, we established a procedure to generate an in-house cryopreserved CAR/TCR T-cell products for use as a flow cytometry quality control and validated their use. Methods Two CAR T-cell products: CD19/CD22 bispecific CAR T-cells and FGFR4 CAR T-cells and one TCR-engineered T-cell product: KK-LC-1 TCR T-cells were manufactured in Center for Cellular Engineering (CCE), NIH Clinical Center. The products were divided in aliquots, cryopreserved and stored in the liquid nitrogen. The cryopreserved flow cytometry quality controls were tested in flow cytometry assays which measured post-thaw viability, CD3, CD4 and CD8 frequencies as well as the transduction efficiency and vector identity. The long-term stability and shelf-life of cryopreserved quality control cells were evaluated. In addition, the sensitivity as well as the precision assay were also assessed on the cryopreserved quality control cells. Results After thawing, the viability of the cryopreserved CAR/TCR T-cell controls was found to be greater than 50%. The expression of transduction efficiency and vector identity markers by the cryopreserved control cells were stable for at least 1 year; with post-thaw values falling within ± 20% range of the values measured at time of cryopreservation. After thawing and storage at room temperature, the stability of these cryopreserved cells lasted at least 6 h. In addition, our cryopreserved CAR/TCR-T cell quality controls showed a strong correlation between transduction efficiency expression and dilution factors. Furthermore, the results of flow cytometric analysis of the cryopreserved cells among different laboratory technicians and different flow cytometry instruments were comparable, highlighting the reproducibility and reliability of these quality control cells. Conclusion We developed and validated a feasible and reliable procedure to establish a bank of cryopreserved CAR/TCR T-cells for use as flow cytometry quality controls, which can serve as a quality control standard for in-process and lot-release testing of CAR/TCR T-cell products.

109 Dominant-negative TGFβ receptor 2 enhances GPC3-targeting CAR-T cell efficacy against hepatocellular carcinoma

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A121-A121
Author(s):  
Nina Chu ◽  
Michael Overstreet ◽  
Ryan Gilbreth ◽  
Lori Clarke ◽  
Christina Gesse ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Dominant Negative ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

BackgroundChimeric antigen receptors (CARs) are engineered synthetic receptors that reprogram T cell specificity and function against a given antigen. Autologous CAR-T cell therapy has demonstrated potent efficacy against various hematological malignancies, but has yielded limited success against solid cancers. MEDI7028 is a CAR that targets oncofetal antigen glypican-3 (GPC3), which is expressed in 70–90% of hepatocellular carcinoma (HCC), but not in normal liver tissue. Transforming growth factor β (TGFβ) secretion is increased in advanced HCC, which creates an immunosuppressive milieu and facilitates cancer progression and poor prognosis. We tested whether the anti-tumor efficacy of a GPC3 CAR-T can be enhanced with the co-expression of dominant-negative TGFβRII (TGFβRIIDN).MethodsPrimary human T cells were lentivirally transduced to express GPC3 CAR both with and without TGFβRIIDN. Western blot and flow cytometry were performed on purified CAR-T cells to assess modulation of pathways and immune phenotypes driven by TGFβ in vitro. A xenograft model of human HCC cell line overexpressing TGFβ in immunodeficient mice was used to investigate the in vivo efficacy of TGFβRIIDN armored and unarmored CAR-T. Tumor infiltrating lymphocyte populations were analyzed by flow cytometry while serum cytokine levels were quantified with ELISA.ResultsArmoring GPC3 CAR-T with TGFβRIIDN nearly abolished phospho-SMAD2/3 expression upon exposure to recombinant human TGFβ in vitro, indicating that the TGFβ signaling axis was successfully blocked by expression of the dominant-negative receptor. Additionally, expression of TGFβRIIDN suppressed TGFβ-driven CD103 upregulation, further demonstrating attenuation of the pathway by this armoring strategy. In vivo, the TGFβRIIDN armored CAR-T achieved superior tumor regression and delayed tumor regrowth compared to the unarmored CAR-T. The armored CAR-T cells infiltrated HCC tumors more abundantly than their unarmored counterparts, and were phenotypically less exhausted and less differentiated. In line with these observations, we detected significantly more interferon gamma (IFNγ) at peak response and decreased alpha-fetoprotein in the serum of mice treated with armored cells compared to mice receiving unarmored CAR-T, demonstrating in vivo functional superiority of TGFβRIIDN armored CAR-T therapy.ConclusionsArmoring GPC3 CAR-T with TGFβRIIDN abrogates the signaling of TGFβ in vitro and enhances the anti-tumor efficacy of GPC3 CAR-T against TGFβ-expressing HCC tumors in vivo, proving TGFβRIIDN to be an effective armoring strategy against TGFβ-expressing solid malignancies in preclinical models.Ethics ApprovalThe study was approved by AstraZeneca’s Ethics Board and Institutional Animal Care and Use Committee (IACUC).

scholarly journals P08.05 Combined pharmacological targeting of adenosine 2a- and 2b-receptor enhances CAR T cell function

2021 ◽  
Vol 9 (Suppl 1) ◽  
pp. A26.2-A27
Author(s):  
M Seifert ◽  
M Benmebarek ◽  
B Cadilha ◽  
J Jobst ◽  
J Dörr ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Combination Therapy ◽  
Cell Function ◽  
Cytokine Secretion ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Cell Effector

BackgroundDespite remarkable response rates mediated by anti-CD19 chimeric antigen receptor (CAR) T cells in selected B cell malignancies, CAR T cell therapy still lacks efficacy in the vast majority of tumors. A substantial limiting factor of CAR T cell function is the immunosuppressive tumor microenvironment. Among other mechanisms, the accumulation of adenosine within the tumor can contribute to disease progression by suppressing anti-tumor immune responses. Adenosine 2a- and 2b-receptor (A2A and A2B)-mediated cAMP build-up suppresses T cell effector functions. In the present study we hypothesize, that combination therapy with the selective A2A/A2B dual antagonist AB928 (etrumadenant) enhances CAR T cell efficacy.Materials and MethodsSecond generation murine (anti-EPCAM) and human (anti-MSLN) CAR constructs, containing intracellular CD28 and CD3ζ domains, were fused via overlap extension PCR cloning. Murine or human T cells were retrovirally transduced to stably express the CAR constructs. A2A/A2B signaling in CAR T cells was analyzed by phospho-specific flow cytometry of CREB (pS133)/ATF-1 (pS63). CAR T cell activation was quantified by flow cytometry and enzyme-linked immunosorbent assay (ELISA) of IFN-γ, IL-2 and TNF-α. CAR T cell proliferation was assessed by flow cytometry. CAR T cell cytotoxicity was assessed by impedance based real-time cell analysis.ResultsAB928 protected murine CAR T cells from cAMP response element-binding protein (CREB) phosphorylation in the presence of stable adenosine analogue 5′-N-ethylcarboxamidoadenosine (NECA). NECA inhibited antigen-dependent CAR T cell cytokine secretion in response to four murine tumor cell lines. CAR T cell-mediated tumor cell lysis as well as proliferation were decreased in the presence of NECA or adenosine. Importantly, AB928 fully restored CAR T cell cytotoxicity, proliferation, and cytokine secretion in a dose dependent manner. Further, AB928 also restored antigen dependent cytokine secretion of human CAR T cells in the presence of NECA.ConclusionsHere we used the A2A/A2B dual antagonist AB928 to overcome adenosine-mediated suppression of CAR T cells. We found that AB928 enhanced important CAR T cell effector functions in the presence of the adenosine analogue, suggesting that combination therapy with AB928 may improve CAR T cell efficacy. This study was limited to in vitro experiments. To confirm the relevance of our findings, this combination therapy must be further investigated in an in vivo setting.Disclosure InformationM. Seifert: None. M. Benmebarek : None. B. Cadilha : None. J. Jobst: None. J. Dörr: None. T. Lorenzini: None. D. Dhoqina: None. J. Zhang: None. J. Zhang: None. U. Schindler: E. Ownership Interest (stock, stock options, patent or other intellectual property); Modest; Amgen Inc., Arcus Biosciences. Other; Significant; Arcus Biosciences. S. Endres: None. S. Kobold: B. Research Grant (principal investigator, collaborator or consultant and pending grants as well as grants already received); Significant; Arcus Biosciences.

scholarly journals B-CLL Mediated Resistance to CAR T Cell Therapy Via Insufficient Activation Is CAR-Independent

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 44-44
Author(s):  
McKensie Collins ◽  
Weimin Kong ◽  
Inyoung Jung ◽  
Stefan M Lundh ◽  
J. Joseph Melenhorst
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Research Funding ◽  
Cytokine Production ◽  
Cell Function ◽  
T Cell Therapy ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Chronic Lymphocytic Leukemia (CLL) is a B cell malignancy that accounts for nearly 1/3rd of adult leukemia diagnoses in the Western world. Conventional chemo-immunotherapies initially control progression, but in the absence of curative options patients ultimately succumb to their disease. Chimeric Antigen Receptor (CAR) T cell therapy is potentially curative, but only 26% of CLL patients have a complete response. CLL-stimulated T cells have reduced effector functions and B-CLL cells themselves are believed to be immunosuppressive. Our work demonstrates that insufficient activation of CAR T cells by CLL cells mediates some of these effects and that the results are conserved between ROR1- and CD19-targeting CARs. Results: In this study we used an in vitro system to model the in vivo anti-tumor response in which CAR T cells serially engage with CLL cells. Multiple stimulations of CD19 or ROR1-targeting CAR T cells with primary CLL cells recapitulated many aspects of known T cell dysfunction including reduced proliferation, cytokine production, and activation. While the initial stimulation induced low level proliferation, subsequent stimulations failed to elicit additional effector functions. We further found that these functional defects were not permanent, and that CAR T cell function could be restored by switching to a stimulus with an aAPC (artificial Antigen Presenting Cell) control cell line. The aAPCs are well-characterized as potent stimulators of CAR T cell effector responses. Flow cytometry revealed that CLL-stimulated CAR T cells retained a non-activated, baseline differentiation profile, suggesting that CLL cells fail to stimulate CAR T cells rather than rendering them non-functional. One mechanism that could dampen activation is immune suppression. We assessed this at a high level by stimulating CAR T cells with CLL cells and aAPCs mixed at known ratios. However, even cultures containing 75% CLL cells stimulated proliferation and cytokine production. Extensive immune-phenotyping revealed high level expression of the IL-2 Receptor on 90% (18/20) of the B-CLL cells tested. Since cytokine sinking via IL-2 receptor expression is a well-known mechanism of regulatory T cell suppression, we hypothesized that CLL cells similarly sink IL-2, blunting T cell activation. To test this, we supplemented IL-2 into CLL/CAR T cell co-cultures and showed that this rescued proliferation but only partially restored cytokine production. In contrast to our hypothesis, analysis of cytokine production by flow cytometry showed that CLL-stimulated CAR T cells did not produce IL-2 following a 6- or 12-hour stimulus, but TNFα was expressed after 12-hours. Similarly, CAR T cell degranulation, a prerequisite for target cell lysis was triggered after CLL recognition. These data again suggested that CLL cells insufficiently stimulate CAR T cell cytokine production, but also showed that cytolytic activity against CLL cells is intact. We further proposed that CLL cells express insufficient levels of co-stimulatory and adhesion molecules to activate CAR T cells. Flow cytometry showed that most CLL cells expressed co-stimulatory and adhesion molecules at low levels; we hypothesized that up-regulating these molecules would enhance CAR T cell targeting of CLL cells. CLL cells were activated with CD40L and IL-4, which increased expression of CD54, CD58, CD80, and CD86. Stimulating CAR T cells with activated CLL cells enhanced CAR T cell proliferation and induced cell conjugate formation, indicating cell activation. Therefore, improving CLL stimulatory capacity can rescue T cell dysfunctions. To assess whether IL-2 addition and CD40 ligation were synergistic, we combined the two assays; however, we saw no additional improvement over IL-2 addition alone, suggesting that the two interventions may act upon the same pathway. Importantly, we also showed that rescue of CAR T cell function via IL-2 addition or CD40 ligation was not CAR-specific, as we observed the functional defects and subsequent rescue with both a ROR1-targeting CAR and the gold standard CD19-targeting CAR. Conclusions: Together, these data show that CAR T cell "defects" in CLL are actually insufficient activation, and improving the stimulatory capacity of CLL cells may enable better clinical responses. Further, this effect is not CAR-specific and these results may therefore be broadly applicable to multiple therapies for this disease. Disclosures Melenhorst: IASO Biotherapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Kite Pharma: Research Funding; Novartis: Other: Speaker, Research Funding; Johnson & Johnson: Consultancy, Other: Speaker; Simcere of America: Consultancy; Poseida Therapeutics: Consultancy.

scholarly journals Piggybac Transposon Mediated CD19 CAR-T Cells Derived from CD45RA-Positive PBMCs Possess Potent and Sustained Antileukemic Function

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2807-2807
Author(s):  
Masaya Suematsu ◽  
Shigeki Yagyu ◽  
Nobuyoshi Nagao ◽  
Susumu Kubota ◽  
Yuto Shimizu ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Cells ◽  
Research Funding ◽  
Stress Test ◽  
Transduction Efficiency ◽  
Antigen Stimulation ◽  
Car T Cells ◽  
Car T

Abstract Background: The quality of chimeric antigen receptor (CAR)-T cell products, including the expression of memory and exhaustion markers, has been shown to influence their long-term functionality. We previously demonstrated that piggyBac (PB) transposon-mediated CD19 CAR-T cells exhibit memory-rich phenotype that is characterized by a high proportion of CD45RA+/CCR7+ T cell fraction. To further investigate the favorable phenotype of PB-CD19 CAR-T cells, we generated PB-CD19 CAR-T cells from CD45RA+ and CD45RA− peripheral blood mononuclear cells (PBMCs) (RA+ CAR and RA− CAR, respectively), and compared their phenotype and antitumor function. Methods: CD45RA+ and CD45RA− PBMCs were isolated by magnetic selection from whole PBMCs, then the CD19-CAR transgene was transduced into these cells using the PB transposon system, as described previously. Transduction efficiency of CD19 CAR transgene was determined 24 hours by flow cytometry after transduction. The phenotype of CD19 CAR-T was evaluated by flow cytometry on day 14. High throughput RNA sequencing was performed to see the T cell activation/exhaustion profile upon antigen stimulation. Sequential killing assays were performed by adding fresh tumor cells into CAR-T cells co-cultured with tumor cells every three days by restoring an effector target ratio of 1:1. To see the durable antitumor efficacy in vivo, we performed in vivo stress test, in which CAR T-cells dosage was lowered to the functional limits, so that these CAR-T cells should be maintained and expanded in vivo, to achieve the antitumor efficacy. We injected 5 x 10 5 of firefly luciferase-labeled CD19+ tumor cells (REH) into NSG mice via tail vein, then these mice were treated with 1 x 10 5 of CD19 RA+ CAR-T, RA− CAR-T, or control CAR-T cells, respectively, at day 6 after the tumor injection. Results: RA+ CAR T cells demonstrated better transient transduction efficiency 24 h after transduction (RA+ CAR-T: 77.5 ± 9.8% vs RA− CAR-T: 39.7 ± 3.8%), and superior expansion capacity after 14 days of culture than RA− CAR-T cells (RA+ CAR-T: 32.5 ± 9.3-fold vs RA− CAR-T: 11.1 ± 5.4-fold). RA+ CAR-T cells exhibited dominant CD8 expression (RA+ CAR-T: 84.0 ± 3.4% vs RA− CAR-T: 34.1 ± 10.6%), less expression of exhaustion marker PD-1 (RA+ CAR-T: 3.1 ± 2.5% vs RA− CAR-T: 19.2 ± 6.4%) and T cell senescence marker CD57 (RA+ CAR-T: 6.8 ± 3.6% vs RA− CAR-T: 20.2 ± 6.9%), and enrichment of naïve/stem cell memory fraction (CAR+/CD45RA+CCR7+ fraction; RA+ CAR-T: 71.9 ± 9.7% vs RA− CAR-T: 8.0 ± 5.3%), which were associated with longevity of CAR-T cells. Transcriptome analysis revealed that RA+ CAR-T cells exhibited the enrichment of naïve/memory phenotype and less expression of canonical exhaustion markers, and these exhaustion profiles even maintained after the antigen stimulation. RA+ CAR-T cells demonstrated sustained killing activity even after multiple tumor rechallenges in vitro, without inducing exhaustion marker expression of PD-1. Although antigen stimulation could increase CAR expression, leading to tonic CAR signaling and exhaustion, in our study, the expression of CAR molecule on the cell surface following antigen stimulation in RA+ CAR was controlled at a relatively lower level that in RA− CAR-T cells. RA+ CAR-T cells achieved prolonged tumor control with expansion of CAR-T cells than RA− CAR-T cells in in vivo stress test (Fig.1A-C). On day15, bone marrow studies in RA+ CAR group exhibited abundant human CD3 positive T cells with less expression of PD-1, and relatively smaller amount of REH cells than RA− CAR group (Fig.1D). Furthermore, in two of long-lived mice in RA+ CAR group, human CD3 positive T cells were expanded even day 50 after treatment as confirmed by sequential bone marrow studies (Fig.1E), which indicated the antigen-induced proliferation and long-term functionality of RA+ CAR-T cells in vivo. Conclusion: Our results suggest that PB-mediated RA+ CAR-T cells exhibit memory-rich phenotype and superior antitumor function, thereby indicating the usefulness of CD45RA+ PBMC as a starting material of PB-CAR-T cells. Figure 1 Figure 1. Disclosures Yagyu: AGC Inc.: Research Funding. Nagao: AGC Inc.: Current Employment. Kubota: AGC Inc.: Current Employment. Shimizu: AGC Inc.: Current Employment. Nakazawa: AGC Inc.: Research Funding; Toshiba Corporation: Research Funding.

scholarly journals Advanced Flow Cytometry Assays for Immune Monitoring of CAR-T Cell Applications

2021 ◽  
Vol 12 ◽  
Author(s):  
Ulrich Blache ◽  
Ronald Weiss ◽  
Andreas Boldt ◽  
Michael Kapinsky ◽  
André-René Blaudszun ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
B Cell ◽  
B Cell Lymphoma ◽  
Cytotoxic Agents ◽  
Clinical Staging ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

Adoptive immunotherapy using chimeric antigen receptor (CAR)-T cells has achieved successful remissions in refractory B-cell leukemia and B-cell lymphomas. In order to estimate both success and severe side effects of CAR-T cell therapies, longitudinal monitoring of the patient’s immune system including CAR-T cells is desirable to accompany clinical staging. To conduct research on the fate and immunological impact of infused CAR-T cells, we established standardized 13-colour/15-parameter flow cytometry assays that are suitable to characterize immune cell subpopulations in the peripheral blood during CAR-T cell treatment. The respective staining technology is based on pre-formulated dry antibody panels in a uniform format. Additionally, further antibodies of choice can be added to address specific clinical or research questions. We designed panels for the anti-CD19 CAR-T therapy and, as a proof of concept, we assessed a healthy individual and three B-cell lymphoma patients treated with anti-CD19 CAR-T cells. We analyzed the presence of anti-CD19 CAR-T cells as well as residual CD19+ B cells, the activation status of the T-cell compartment, the expression of co-stimulatory signaling molecules and cytotoxic agents such as perforin and granzyme B. In summary, this work introduces standardized and modular flow cytometry assays for CAR-T cell clinical research, which could also be adapted in the future as quality controls during the CAR-T cell manufacturing process.

scholarly journals CAR2.0 Therapy for the Management of Post-Transplantation Relapse of B-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 7-7
Author(s):  
Rui Zhang ◽  
Juan Xiao ◽  
Zhouyang Liu ◽  
Yuan Sun ◽  
Sanfang Tu ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Lymphoblastic Leukemia ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Cell Acute Lymphoblastic Leukemia

BACKGROUND: Allogeneic haematopoietic stem cell transplantation (allo-HCT) is a standard treatment for relapsed/refractory B-cell acute lymphoblastic leukemia (r/r B-ALL). However ~30-40% of patients (pts) still relapse after HCT. We report a cohort of 20 r/rB-ALL pts, who relapsed after HCT, and enrolled in the CAR2.0 study receiving one or two types of CAR-T cells targeting various B-ALL antigens. METHOD: Pts with r/r B-ALL who relapsed after allo-HCT and did not have significant active comorbiditeis, were enrolled in the study. The target antigens were determined based on immunostaining of each pt's leukemia cells, and CAR-T infusions included a single, or a combination of CAR-Ts targeting the following antigens: CD19, CD22, CD123 and CD38. T cells were collected from pts (N=4) or their allogeneic donors (N=16) and transduced with an apoptosis-inducible, safety-engineered lentiviral CAR with the following intracellular signaling domains: CD28/CD27/CD3ζ-iCasp9 (4SCAR). Pts received cyclophosphamide/fludarabine lymphodepleting therapy before infusion of 0.2-5.8x106 CAR-T/kg per infusion. In addition to disease response, we carefully monitored the quality of apheresis cells, efficiency of gene transfer, T cell proliferation rate, CAR-T infusion dose, and the CAR-T copy number in peripheral blood. RESULTS: Among the 20 enrolled pts, 11 were <18 years of age, and 7 were BCR- ABL (P190) positive. Before CAR-T treatment, 7 pts had ≤grade 2 active graft-versus-host disease (GVHD), and 13 pts received chemotherapy or targeted therapy after their relapse post HCT. Six pts had extramedullary relapse and 2 of them also had bone marrow relapse. The tumor burden in bone marrow ranged from minimal residual disease (MRD) negative to 66% of blasts, based on flow cytometry before CAR-T therapy. Five pts had >10% blasts in bone marrow, 8 pts had <3% blasts, and 7 pts had MRD negative bone marrow (summarized in the Table below). Based on the GVHD history, chimerism state and the available T-cell sources, 16 pts used allogeneic HCT donor T-cells for CAR-T preparation. All pts were full donor chimeras prior to CAR-T infusion, except one pt who had 41% donor cells in bone marrow. Eleven pts received a single CD19 CAR-T infusion, with a mean dose of 1.6x106 CAR-T/kg, and ten achieved an MRD remission and one had progressive disease (PD) within 60 days by flow cytometry. The remaining 9 pts received 2 CAR-Ts (CD19 plus CD22, CD123 or CD38 CAR-Ts) given on the same day, and resulted in 8 CR and 1 PD within 60 days. After CAR-T infusion, no cytokine release syndrome (CRS) was observed in 8 pts, and 12 pts experienced CRS of grade 1, which was consistent with the previously described low toxicity profile of the 4SCAR design. Acute GVHD ≤ grade 2 developed in 5 pts within one month following CAR-T cell infusion but all responded well to supportive care and/or cyclosporine infusion. The 2 pts who developed PD after CAR-T infusion included the one with 41% donor chimerism and had grade 2 GVHD and active infections before CAR-T infusion. The other pt with PD following CAR-T had severe bone marrow suppression, low leukocyte count, infections and was transfusion dependent before enrollment. This emphasizes the need for controlling comorbidities before infusion of CAR-T cells. In summary, total 18 patients (90%) achieved negative MRD remission within 2 months of therapy with acceptable CRS. Four pts relapsed (after being in remission for 3 months) and 14 pts are in continued remission, 6 of which for > 1 year. None of these 20 pts received a second HCT after CAR-T infusion. GVHD developed in 5/16 (31%) pts after donor source CAR-T cell infusion within one month, but all responded well to treatment. CONCLUSION: This study focuses on CAR-T cell therapy following relapse after HCT. While the expanded study is ongoing, we present results of the first 20 pts. Use of donor-derived or recipient-derived CAR-T products in pts who relapsed after allo-HCT is well tolerated and it may prolong life expectancy of these pts while maintaining good quality of life. Table Disclosures No relevant conflicts of interest to declare.

scholarly journals Foamy Virus Based Vectors for CAR-T Cell Development

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 4646-4646
Author(s):  
Emmanouil Simantirakis ◽  
Vassilis Atsaves ◽  
Ioannis Tsironis ◽  
Margarita Gkyzi ◽  
Kostas Konstantopoulos ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Gene Transfer ◽  
Peripheral Blood ◽  
Transduction Efficiency ◽  
Target Cells ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Ifn Γ

Introduction A novel approach that can cover the therapeutic gap in NHL treatment are the autologous T cells, expressing Chimeric Antigen Receptors (CAR-T cells) against tumor markers. Such clinical-grade products based on Lenti (LV) or Retro- vectors have hit the market. An alternative vector system for CAR gene transfer in T-cells are Foamy Viruses (FV). To evaluate the potential of FV vectors in CAR-T cell development, we synthesized an antiCD19 scFv cDNA and cloned it in both an FV and an LV backbone; both vectors were tested in paired experiments Material and Methods The anti-CD19 CAR was under the control of the EF1a promoter; EGFP expression was under the control of an IRES2 element. The anti-CD19 CAR sequence was deduced from published data. FV vectors were made with a 4-plasmid vector system in 293T cells. 2nd generation LV vectors were purchased from Addgene. Cord blood (CB), healthy donor peripheral blood (PB) and CLL patients' PB was used as a source for CD3+ cells using immunomagnetic enrichment. Informed consent has been obtained in all cases of human sample use. T cells were activated by antiCD3/CD28 beads and transduced with antiCD19 LV or FV vectors. Transduction efficiency was assayed by flow cytometry (FCM) using a PE-conjugated anti-mouse Fab antibody. FV and LV CAR-T cells were expanded with Rapid Expansion Protocol (REP) and their cytotoxicity assays was evaluated against the CD19+ cell lines Raji and Daudi. The CLL patient derived CAR-Ts were evaluated against autologous B cells. Cytotoxicity was evaluated with an FCM protocol using CFSE-stained target cells vs unstained effector CARTs in different ratios. At the end of the incubation cells were stained with 7AAD to discriminate against live/dead cells. CAR-T cell activation was also assayed by INF-γ ELISA, following cocultures with target cells at a ratio of 1:1 for 24h. Results Vector titers: LV vector titers were between 3-5x10^5 TU/ml for both LV vectors (with or without EGFP cassette). FV vector titers were between 2-4x10^5 TU/ml regardless of the presence of the EGFP cassette. Tx efficiency: FV can mediate efficient gene transfer on T cells in the presence of heparin at an effective dose of 20-40 U/ml using a spinoculation technique. Transduction efficiency ranged from 40-65% at MOI=3-5, and was comparable to the transduction efficiency of LV vectors at a much higher MOI (10 to 30). Cytotoxicity data on lines: Following REP, the cell population consisted mostly (close to 96% purity) of CAR-T cells regardless of the vector used or of the T cell source. Effector cells were cocultured with the CD19+ cell lines, Daudi and Raji at varying ratios. With cord blood derived FV-CAR-T cells, at 4h post coculture we observed a 39.4% cell lysis at a ratio of 10:1 effector to target (n=1). Similar results were obtained for LV vectors. Peripheral blood derived CAR-T cells at THE same ratio (10:1), demonstrated 83.9% and 93.1% cell lysis for FV-CART and LV-CART cells respectively (n=2). Cytotoxicity data on CLL cells: T-cells from peripheral blood of CLL patients were used to generate LV- and FV-CAR-T cells. At the ratio of 10:1, we observed 73.1% and 69,8% cytotoxicity for FV-CAR-Ts and 70.1% and 70.7% with LV-CAR-Ts, in 2 independent paired experiments. IFN as activation marker: In two paired activation experiments, CB-derived FV-CAR-T cells secrete 560 and 437pg/ml of IFN-γ; similarly, LV-CAR-Ts secrete 534 and 554pg/ml IFN-γ. Untransduced control cells, produced 68pg/ml and 12pg/ml for FV-CAR-T and LV-CAR-T experimental arm respectively. Conclusion In the current work, we developed and tested FV vectors for anti- CD19 CAR-T cell production. We proved that FV viral vectors are capable of mediating efficient gene transfer to human T cells. We developed a method to efficiently transfer FV vectors into T-cells, using a clinically relevant protocol with heparin. The FV-derived CAR T cells demonstrate the same cytotoxic properties in vitro as their LV-derived counterpart and the same activation levels in the presence of CD19 expressing target cells as measured by IFN-γ secretion. FV CARTs derived from PB of CLL patients were capable of mediating comparable cytotoxicity levels as their LV-derived counterparts. Overall, we provide a proof of concept that FVs could be a safe and efficient alternative to LV derived vectors for CAR-T cells. Disclosures No relevant conflicts of interest to declare.

scholarly journals P06.02 Enhancing CAR T cell persistence and memory through modulating mitochondrial function

2020 ◽  
Vol 8 (Suppl 2) ◽  
pp. A42.1-A42
Author(s):  
A Hosseini Rad ◽  
G Min Yi Tan ◽  
A Poudel ◽  
A McLellan
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Cell Viability ◽  
T Cell Activation ◽  
Mitochondrial Function ◽  
Luciferase Reporter ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T

BackgroundCAR T cell therapy for solid tumours has achieved limited success compared to its application to B cell malignancies. One reason for this failure is the low differentiation rate to memory subsets and low persistence of CAR T cells due to activation-induced cell death (AICD) in lymphoid tissue and the tumour microenvironment. In this study, we have expressed the MCL1 gene within CAR T cells to overcome losses by AICD in adoptively transferred T cells. The MCL1 gene expresses two isoforms; the long isoform localises to the outer membrane of mitochondria and inhibits the CD95 signalling death pathway, while the short isoform localises to the inner membrane of mitochondria to enhance mitochondrial oxidation, phosphorylation and fusion. In addition, we have also utilized a microRNA (miR) 429 to promote memory T cell formation through the suppression of genes such as T-cell-restricted intracellular antigen-1 (TIA-1), T cell activation inhibitor, mitochondrial (TCAIM) and mitochondrial fission factor (MFF).Materials and MethodsOverexpression of MCL1 was confirmed at both mRNA and protein level by real time RT-PCR (qPCR) and western blot. Similarly, overexpression of miR-429 was measured by qPCR and specific binding of miR-429 to the 3′ UTR of target genes was confirmed by luciferase reporter assay. Mitochondrial depolarization and cell viability were assessed by TMRE mitochondrial membrane potential assay (flow-cytometry) and resazurin assay. The effect of MCL1 or miR429 overexpression on HER2-CAR T cells was determined by flow cytometry. Soluble leucine-zipper CD95L (https://www.addgene.org/104349/) was expressed and purified from Expi293 cells.ResultsOverexpression of MCL1 in both Jurkat T cells and primary human T cells protected cells against mitochondria depolarization as well as the loss of cell viability in response to CD95L-triggering. Expression of miR429 downregulated TIA1, TCAIM and MFF. A HER2-CAR construct with either MCL1 or miR429 in a lentiviral system was successfully designed and transduced into primary T cells. Mitochondria in transduced T demonstrated enlarged and fusion morphology - a classic feature of memory T cells.ConclusionsOverexpressing MCL1 or miR429 significantly improves mitochondrial function in T cells. This approach will be used to increase persistence of adoptively transferred CAR T cells.Disclosure InformationA. Hosseini Rad: None. G. Min Yi Tan: None. A. Poudel: None. A. McLellan: None.

scholarly journals Novel CD19t T-Antigen Presenting Cells Designed to Re-Activate and Expand CD19 CAR T Cells In Vivo: Early Demonstration of Feasibility and Safety

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 4021-4021 ◽  
Author(s):  
Colleen Annesley ◽  
Rebecca Gardner ◽  
Olivia Finney ◽  
Corinne Summers ◽  
Adam J. Lamble ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Pilot Study ◽  
Antigen Presenting Cells ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Antigen Presenting

Abstract Background: Immunotherapy with CD19 specific chimeric antigen receptor (CAR) T cells for relapsed/refractory acute lymphoblastic leukemia (ALL) demonstrated a minimal residual disease (MRD) negative remission rate of 93% on the phase 1 portion of Pediatric Leukemia Adoptive Therapy (PLAT)-02. However, the 1-year event free survival (EFS) was 50.8%, largely due to recurrence of disease which was frequently associated with early loss of CAR T cell persistence. Subjects on PLAT-02 with <15% CD19 antigen burden in the bone marrow prior to lymphodepletion had a decreased magnitude of CAR T cell expansion and were less likely to have durable persistence of CAR T cells. Also, subjects with a rapid contraction of CAR T cells in the blood between Day +10 and Day+14, as measured by flow cytometry, had inferior long term persistence. These findings led to the hypothesis that loss of persistence may be due to decreased antigen stimulation and subsequent quiescence of CAR+ effector T cells. Episodic target exposure using T cell antigen presenting cells (T-APCs) expressing a truncated human CD19 (CD19t) could trigger CD19 CAR T cell proliferation and re-activation in vivo, resulting in more durable CAR T cell persistence and diminished risk of CD19+ relapse. Methods: Eligible subjects for PLAT-03 (NCT03186118), a pilot study of CD19t T-APCs, must have previously enrolled on the phase 2 portion of PLAT-02 and have a stored apheresis product available. Cohorts include subjects that have an identified predictive factor to lose CAR T cell persistence early, or have already experienced early loss of CAR T cell persistence before 6 months and can receive a reinfusion of CD19 CAR T cells prior to planned T-APCs. Patient-derived T-APC products are manufactured with selected and cryopreserved CD4 and CD8 cells from the subject's original apheresis product. The T cells are activated and transduced with a lentiviral vector to express the CD19t transgene. Transduced cells are expanded in culture for 10-14 days, cryopreserved and release-tested. Subjects <25kg receive 10x106 T-APCs/kg and those ≥25kg receive a flat dose of 5x108 T-APCs. Subjects receive at least one, and up to six total doses of T-APCs at monthly intervals. Results: Seven subjects (ages 9-23 years) have enrolled on PLAT-03; 5 enrolled based on low CD19 antigen burden at the time of lymphodepletion, and 2 based on rapid CAR T cell contraction between Days 10 and 14. T-APC products were successfully manufactured in 5/5 subjects, with two products pending manufacture. One of 5 subjects was unable to receive his planned T-APCs, as he lost CAR T cell persistence prior to T-APC infusion and failed to engraft a second infusion of CD19 CAR T cells. Of the 4 subjects that have received at least one dose of T-APCs, there have been no related adverse events (AEs) > grade 2, and no fever or cytokine release syndrome (CRS) has been observed. Grade 1-2 AEs that are at least possibly related to T-APCs have included hypogammaglobulinemia, nausea, vomiting and headache. Two subjects have completed T-APC treatment; one received all 5 available T-APC doses (subject S001), and one experienced loss of CAR T cell persistence after two T-APC doses and therefore was not eligible for further doses. Data is shown for subject S001, a 20 year old man with multiply relapsed B-ALL. He enrolled on PLAT-03 due to a low CD19 antigen burden of 4.79% by flow cytometry (inclusive of both normal and malignant CD19+ cells) just prior to lymphodepletion. He had minimal toxicity (grade 1 CRS) following CD19 CAR T cell infusion, and subsequently received 5 monthly doses of T-APCs. An increase in the quantity of detectable CAR T cells (EGFRt+ cells) was observed following T-APCs as shown below, and the subject has ongoing CAR T cell persistence at 8 months, as evidenced by B cell aplasia. Conclusion: The first-in-human, pilot study PLAT-03 introduces CD19t T-APCs in an attempt to enhance durable CAR T cell persistence and leukemia remission following CD19 CAR T cell immunotherapy. T-APCs have been successfully manufactured from stored apheresis products collected for CAR T cell production. Four subjects have been successfully treated with at least one T-APC infusion to date, without any significant toxicity and with early evidence of efficacy. Accrual of subjects is ongoing to further assess the safety and feasibility of administering CD19t T-APCs, and to examine the impact of T-APCs on CD19 CAR T cell efficacy. Figure. Figure. Disclosures Park: Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees. Jensen:Juno Therapeutics, Inc.: Consultancy, Patents & Royalties, Research Funding.

scholarly journals Eight-Day Point of Care CAR T-Cell Manufacturing on Clinimacs Prodigy from Healthy Donors As a Proof-of-Concept Study

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 2851-2851
Author(s):  
Kim G. Hankey ◽  
Tim Luetkens ◽  
Stephanie Avila ◽  
John McLenithan ◽  
John Braxton ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Board Of Directors ◽  
Point Of Care ◽  
Transduction Efficiency ◽  
Advisory Committees ◽  
Car T Cells ◽  
Car T Cell ◽  
Car T ◽  
Experimental Runs

Abstract Introduction Chimeric Antigen Receptor (CAR) T-cell therapy has emerged as a powerful immunotherapy for various forms of cancer, especially hematologic malignancies. However, several factors limit use of CAR T-cells to a wider number of patients. Long manufacturing time (usually 3-4 weeks with standard of care products) poses a big challenge in treating these chemorefractory patients in a timely fashion. Thus, we evaluated the feasibility of a fresh in and fresh out, short, eight-day manufacturing process performed locally to expedite CAR T-cell drug product delivery. Herein we report the results of two experimental runs using this modified short eight-day culture process. Methods We used the CliniMACS Prodigy® closed manufacturing system and modified the 12-day T Cell Transduction (TCT) activity matrix protocol to produce anti-CD19 CAR T-cells in eight days. Normal donor mononuclear cells were collected by leukapheresis and enriched for CD4 and CD8 cells by immunomagnetic bead selection in three stages. Enriched T-cells were activated with MACS GMP T Cell TransACT and cultured at 37°C with 5% CO 2 for 16-24 hours in media supplemented with 12.5mcg/L each of IL-7 and IL-15, and 3% heat-inactivated human AB serum. On day 1 of the process, activated T-cells were transduced with lentiviral vector encoding the anti-CD19 CAR (Lentigen, LTG1563) at a multiplicity of infection (MOI) of 7-10. On day 3, the cells were washed twice and the media volume adjusted to feed the expanding cells. The culture was again fed on day 5 by exchanging half the volume of spent media with fresh supplemented media. Media supplemented with cytokines alone was used for the remaining four washes on day 6, 7 and 8. Transduction efficiency and T-cell subset frequencies were assessed by flow cytometry on the MACSQuant-10 and CAR-T Express Mode package on days 3, 6 and 8. Subsequently, we performed ELISPOT assay for CAR T-cell potency testing and in-vivo efficacy testing in NSG mice bearing Raji B cell lymphoma. Results Refer to Table 1 for details on cell populations of interest for experiment number 1 and 2. The total number of CD3 T-Cells increased from 97% on day 0 to &gt;99.5% on the harvest day (day 8). CD3 T-cells expanded 11.6- and 34.2-fold on day 8 when compared to day 0. Transduction efficiency of ~40% was observed in both experimental runs. Final CD19 CAR T-cells numbers ranged from 9.3-13.3 x 10e8 with viability of CD3+ cells &gt;93% for both the runs. Day 3 of the culture is an important day since a clinical decision to proceed with lymphodepletion must be made to facilitate the fresh in and fresh out approach. Here we observed reliable transduction of T-cells on day 3 with an average efficiency of 15.9%. Day 3 data reliably provided information to proceed with lymphodepletion. A total of 100,000 CD19 CAR T-cells produced in experiment #1 were exposed to beads coated with CD19 protein, BCMA control protein, or T cell-activating beads coated with anti-CD3 and anti-CD28 antibodies in an ELISPOT plate. Spots in figure 1 represents individual CAR T-cells producing IFN-gamma. This novel ELISPOT assay shows high IFN-gamma by CD19 CAR T-cells in response to the target antigen or unspecific stimulation using CD3/CD28 beads. Subsequently, NSG mice received injections of 5x10e5 Raji B cell lymphoma cells stably expressing luciferase into the tail vein. One week later, 4 mice per group received individual i.v. injections of 4x10e6 CD19 CAR T-cells, 0.3x10e6 CD19 CAR T-cells, 4x10e6 mock-transduced CAR T-cells, or media. Survival curves in figure 2 represent survival of the mice after receiving the treatment with best survival seen with 4x10e6 dose. Conclusions In these experimental runs, we were able to generate CD19 CAR+ T-cells in a short eight-day manufacturing process. The final product characteristics (viability, transduction efficiency and doses) were comparable to clinical formulations. Further, point-of-care potency assay suggests high IFN-gamma production and elimination of CD19 tumor in the in vivo murine model. The point-of-care CAR T-cell production allows for shorter vein-to-vein time and offers dramatic reduction in the product cost. Lastly, the novel potency assay via ELISPOT testing allows for rapid and visual functional analysis of the CAR T-cell product. Figure 1 Figure 1. Disclosures Hardy: Kite/Gilead: Membership on an entity's Board of Directors or advisory committees; American Gene Technologies, International: Membership on an entity's Board of Directors or advisory committees; InCyte: Membership on an entity's Board of Directors or advisory committees. Abramowski-Mock: Miltenyi Biotec: Current Employment. Mittelstaet: Miltenyi Biotec: Current Employment. Dudek: Miltenyi Biotec: Current Employment.

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