Allogeneic Chimeric Antigen Receptor T-cell Research Articles

Clinical Manufacture of FT819: Use of a Clonal Multiplexed-Engineered Master Induced Pluripotent Stem Cell Line to Mass Produce Off-the-Shelf CAR T-Cell Therapy

FT819 is a first-of-kind, allogeneic, off-the-shelf CAR T-cell therapy derived from a clonal master induced pluripotent stem cell (iPSC) line precisely engineered to insert a novel 1XX anti-CD19 chimeric antigen receptor (CAR) under the regulation of the T-cell receptor alpha constant (TRAC) locus for optimized control of anti-tumor activity and to completely delete T-cell receptor (TCR) expression to eliminate the potential of graft-versus-host disease (GvHD). Unlike conventional allogeneic CAR T-cell therapies which require repeatedly sourcing of T cells from various donors as the starting material, the use of a clonal master engineered iPSC line serves as a renewable starting cell source and ensures routine mass production of a uniformly engineered, homogenous CAR T-cell product for broad patient access.T cell-derived iPSCs were generated using a proprietary non-integrating cellular reprogramming system and genetically modified to integrate a novel anti-CD19 1XX CAR into both alleles of the TRAC gene. After single cell subcloning, each engineered iPSC clone was screened for multiple critical quality attributes including pluripotency, identity, genomic stability, cassette integration, on/off-target integration, T-cell differentiation propensity, and CAR T-cell function. Accordingly, the ideal single cell-derived engineered iPSC clone was selected as the clonal master iPSC line for FT819 and was converted into a master cell bank (MCB).The iPSC MCB serves as a renewable source for the routine GMP manufacture of FT819 drug product. The FT819 production process consists of three stages: 1) generation of CD34-expressing hematopoietic progenitor cells from iPSCs (>90% CD34+ cells post enrichment); 2) lineage-specification to T cells followed by T-cell expansion (>5e5 fold expansion); and 3) fill/finish and cryopreservation of the drug product. As an example, in an initial small-scale manufacturing campaign, a total of 2.5 × 10 10 FT819 CAR T-cells were generated and filled and finished starting from one vial of the MCB.The FT819 drug product was tested on safety, identity, purity, and potency. The final product was comprised of CD45+CD7+ lymphocytes (>99%), with homogeneous CAR expression (>99% CAR+) and lacking expression of TCRαβ (not detected) on the cell surface. Importantly, there were no residual iPSCs detected in the FT819 drug product. The FT819 drug product exhibited potent and consistent effector function against NALM6 leukemia cells. The FT819 drug product is currently being used in a landmark Phase I study (NCT04629729), the first-ever iPSC-derived T-cell therapy to undergo clinical investigation, for the treatment of patients with relapsed/refractory B-cell lymphoma, chronic lymphocytic leukemia and precursor B-cell acute lymphoblastic leukemia.In summary, FT819 is a first-of-kind, off-the-shelf, CAR T-cell therapy uniquely derived from a clonal multiplexed-engineered master iPSC line. The novel manufacturing paradigm enables mass production of a uniformly engineered, homogenous cell therapy product that is available on-demand for broad patient access. A multi-center Phase 1 study of FT819 is currently ongoing for the treatment of B-cell malignancies.Key Words: cancer immunotherapy, cell therapy, CAR-T, CD19, allogeneic, induced pluripotent stem cell, iPSC, clonal master iPSC line, engineered, off-the-shelf, cGMP, production, manufacturing, FT819 DisclosuresYuan: Fate Therapeutics, Inc.: Current Employment. Clarke: Fate Therapeutics, Inc.: Current Employment. Lai: Fate Therapeutics, Inc.: Current Employment. Chang: Fate Therapeutics, Inc.: Current Employment. Yang: Fate Therapeutics, Inc.: Current Employment. Hsia: Fate Therapeutics, Inc.: Current Employment. Abujarour: Fate Therapeutics, Inc.: Current Employment. Lee: Fate Therapeutics, Inc.: Current Employment. van der Stegen: Fate Therapeutics, Inc.: Current Employment. Shaked: Fate Therapeutics, Inc.: Current Employment. Jalloh: Fate Therapeutics, Inc.: Current Employment. Moreno: Fate Therapeutics, Inc.: Current Employment. ORourke: Fate Therapeutics, Inc.: Current Employment. Sung: Fate Therapeutics, Inc.: Current Employment. Gutierrez: Fate Therapeutics, Inc.: Current Employment. Rezner: Fate Therapeutics, Inc.: Current Employment. Eberhart: Fate Therapeutics, Inc.: Current Employment. Magdaleno: Fate Therapeutics, Inc.: Current Employment. Farnan: Fate Therapeutics, Inc.: Current Employment. Plavsic: Fate Therapeutics, Inc.: Current Employment. Bressi: Fate Therapeutics, Inc.: Current Employment. Rivière: Centre for Commercialization of Cancer Immunotherapy: Other: Provision of Services; Fate Therapeutics: Other: Provision of Services, Patents & Royalties; The Georgia Tech Research Corporation (GTRC): Other: Provision of Services (uncompensated); FloDesign Sonics: Other: Provision of Services; Juno Therapeutics: Patents & Royalties. Valamehr: Fate Therapeutics, Inc.: Current Employment.

Optimizing the Clinical Impact of CAR-T Cell Therapy in B-Cell Acute Lymphoblastic Leukemia: Looking Back While Moving Forward.

Chimeric antigen receptor T-cell (CAR-T) therapy has been successful in creating extraordinary clinical outcomes in the treatment of hematologic malignancies including relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). With several FDA approvals, CAR-T therapy is recognized as an alternative treatment option for particular patients with certain conditions of B-ALL, diffuse large B-cell lymphoma, mantle cell lymphoma, follicular lymphoma, or multiple myeloma. However, CAR-T therapy for B-ALL can be surrounded by challenges such as various adverse events including the life-threatening cytokine release syndrome (CRS) and neurotoxicity, B-cell aplasia-associated hypogammaglobulinemia and agammaglobulinemia, and the alloreactivity of allogeneic CAR-Ts. Furthermore, recent advances such as improvements in media design, the reduction of ex vivo culturing duration, and other phenotype-determining factors can still create room for a more effective CAR-T therapy in R/R B-ALL. Herein, we review preclinical and clinical strategies with a focus on novel studies aiming to address the mentioned hurdles and stepping further towards a milestone in CAR-T therapy of B-ALL.

Selecting the Optimal CAR-T for the Treatment of B-Cell Malignancies.

Chimeric antigen receptor T-cell (CAR-T) therapy is a form of adoptive cellular therapy that has revolutionized the treatment landscape in hematologic malignancies, especially B-cell lymphomas. In this review, we will discuss some of the landmark data behind these therapies and then lay out our approach to utilizing this new therapy. CD19-directed CAR-Ts are the most common type currently used in treatment of relapsed B-cell lymphoid neoplasms. There are currently three FDA-approved products: axicabtagene ciluecel and tisagenlecleucel for the treatment of relapsed/refractory large B-cell lymphoma and pediatric B-cell acute lymphocytic leukemia (tisagenlecleucel only) and brexucabtagene autoleucel for the treatment of relapsed/refractory mantle cell lymphoma. These therapies are associated with distinctive acute toxicities such as cytokine release syndrome and neurotoxicity and chronic toxicities such as cytopenias and hypogammaglobulinemia. CAR-T therapy provides significant potential in the treatment of relapsed B-cell lymphomas despite current limitations. Several novel CAR cell designs are currently being studied in clinical trials which include tandem CAR-Ts, allogeneic CAR-Ts, and CAR-NK cells.

Updated data from alloSHRINK phase I first-in-human study evaluating CYAD-101, an innovative non-gene edited allogeneic CAR-T in mCRC.

74 Background: CYAD-101 is a first-in-class, non-gene edited allogeneic CAR T-cell product that combines the broad breadth of tumor targeting of the NKG2D-based chimeric antigen receptor (CAR) with a peptide-based approach that controls graft versus host disease (GvHD). NKG2D binds eight ligands commonly over-expressed across many tumors while the co-expressed T-cell receptor (TCR) inhibitory (TIM) peptide interferes with signaling by the endogenous TCR. A bank of CYAD-101 cells was produced from a single donor and evaluated in the AlloSHRINK phase 1 study (NCT03692429) in patients with unresectable metastatic colorectal cancer (mCRC). Methods: Three CYAD-101 infusions, each administered following a FOLFOX standard cycle as preconditioning chemotherapy, were tested in a 3+3 dose-escalation study (dose-levels (DL): 108, 3x108 and 109 T-cells per infusion) in patients with relapsed/refractory mCRC who progressed after previous treatment with oxaliplatin-based chemotherapy, with or without irinotecan-based chemotherapy. Results: Fifteen patients (pts) were enrolled (3 pts at DL-1, 3 pts at DL-2, 9 pts at DL-3). No dose-limiting toxicity (DLT), Grade ≥ 3 related adverse events or GvHD were reported after any of the CYAD-101 infusions, thus confirming the overall good safety profile of CYAD-101 post FOLFOX. Encouraging anti-tumor activity was observed with 2 confirmed partial responses (PR), including one response in a KRAS mutated patient. In addition, 9 pts achieved stable disease (SD), with 7 SD lasting at least 3 months. The median progression-free survival in this heavily pre-treated population was 3.9 months (95% CI). Whilst engraftment of the CYAD-101 cells was observed after each infusion, the relative level of systemic cytokines appeared to be primarily modulated by cell dose with some suggestion that the magnitude of modulation might be associated with clinical response. Interestingly, preliminary analysis of the T-cell repertoire identified some evidence of TCR diversity after therapy in the patient showing the most durable partial response. Conclusions: These clinical results demonstrate the safety and tolerability of a fist-in-human non-gene edited allogeneic CAR T-cell treatment with early promising anti-tumor activity in advanced mCRC pts. Preliminary translational analysis present intriguing observations that the modulation of systemic cytokine levels may be associated with dose which is uncommon in CAR T-cell therapies reported to date while limited T-cell clonal diversification in the best responding patient underscores the likely central role of the adoptively transferred T-cell in driving therapeutic response in this particular patient. Extension cohort evaluating CYAD-101 following other preconditioning chemotherapy is expected to be initiated end 2020. Clinical trial information: NCT03692429.

Efficacy and safety of chimeric antigen receptor T cell immunotherapy in B-cell non-Hodgkin lymphoma: asystematic review and meta-analysis.

Aim: The aim was to evaluate the efficacy and safety of chimeric antigen receptor T (CAR-T) cell in B-cell non-Hodgkin lymphoma (B-NHL). Materials & methods: A meta-analysis was conducted using eligible clinical trials, which were obtained from electronic medical literature databases. Results: A total of 24 clinical trials with 590 patients were included. The best overall response rate was 66% and complete remission rate was 46%. The incidence rates of cytokine-release syndrome and neurotoxicity (grade≥3) were 9and 5%, respectively. The various clinical factors were analyzed. Autogenic CAR-T cell may lead to improved efficacy than allogeneic CAR-T cell. CD20 CAR-T cell may show increased efficacy than CD19 CAR-T cell. Conclusion: CAR-T immunotherapy has remarkable efficacy and low toxicity in relapsed/refractory B-NHL.

Sequential CD19 and BCMA-specific CAR T-cell treatment elicits sustained remission of relapsed and/or refractory myeloma.

The low rate of durable response against relapsed and/or refractory multiple myeloma (RRMM) in recent studies indicates that chimeric antigen receptor T‐cell (CART) treatment is yet to be optimized. This study aims to investigate the safety and efficacy of sequential infusion of CD19‐CART and B‐cell maturation antigen (BCMA)‐CARTs for RRMM with a similar 3 + 3 dose escalation combined with a toxicity sentinel design. We enrolled 10 patients, among whom 7 received autologous infusion and 3 received allogeneic infusion. The median follow‐up time was 20 months. The most common grade 3/4 treatment‐emergent toxicities were hematological toxicities. Cytokine‐release syndrome (CRS) adverse reactions were grade 1/2 in 9 out of 10 subjects. No dose‐limited toxicity (DLT) was observed for BCMA‐CAR‐positive T cells ≤5 × 107/kg), while two patients with dose‐levels of 5–6.5 × 107/kg experienced DLTs. The overall response rate was 90% (five partial responses and four stringent complete responses). Three out of four patients with stringent complete responses to autologous CART had progression‐free survival for over 2 years. The three patients with allogeneic CART experienced disease progression within 2 months. These results evidence the sequential infusion's preliminarily tolerability and efficacy in RRMM, and present a simple and safe design applicable for the establishment of multiple CART therapy.

Demonstrating the Manufacture of Human CAR-T Cells in an Automated Stirred-Tank Bioreactor.

Chimeric antigen receptor T-cell (CAR-T) therapies have proven clinical efficacy for the treatment of hematological malignancies. However, CAR-T cell therapies are prohibitively expensive to manufacture. The authors demonstrate the manufacture of human CAR-T cells from multiple donors in an automated stirred-tank bioreactor. The authors successfully produced functional human CAR-T cells from multiple donors under dynamic conditions in a stirred-tank bioreactor, resulting in overall cell yields which were significantly better than in static T-flask culture. At agitation speeds of 200 rpm and greater (up to 500 rpm), the CAR-T cells are able to proliferate effectively, reaching viable cell densities of >5 × 106 cells ml-1 over 7 days. This is comparable with current expansion systems and significantly better than static expansion platforms (T-flasks and gas-permeable culture bags). Importantly, engineered T-cells post-expansion retained expression of the CAR gene and retained their cytolytic function even when grown at the highest agitation intensity. This proves that power inputs used in this study do not affect cell efficacy to target and kill the leukemia cells. This is the first demonstration of human CAR-T cell manufacture in stirred-tank bioreactors and the findings present significant implications and opportunities for larger-scale allogeneic CAR-T production.

Allogeneic FLT3 CAR T Cells with an Off-Switch Exhibit Potent Activity against AML and Can Be Depleted to Expedite Bone Marrow Recovery

Patients with relapsed or refractory acute myeloid leukemia (AML) have a dismal prognosis and limited treatment options. Chimeric antigen receptor (CAR) Tcells have achieved unprecedented clinical responses in patients with B cell leukemias and lymphomas and could prove highly efficacious in AML. However, a significant number of patients with AML may not receive treatment with an autologous product due to manufacturing failures associated with low lymphocyte counts or rapid disease progression while the therapeutic is being produced. We report the preclinical evaluation of an off-the-shelf CAR Tcell therapy targeting Fms-related tyrosine kinase 3 (FLT3) for the treatment of AML. Single-chain variable fragments (scFvs) targeting various epitopes in the extracellular region of FLT3 were inserted into CAR constructs and tested for their ability to redirect Tcell specificity and effector function to FLT3+ AML cells. A lead CAR, exhibiting minimal tonic signaling and robust activity invitro and invivo, was selected and then modified to incorporate a rituximab-responsive off-switch in cis. We found that allogeneic FLT3 CAR Tcells, generated from healthy-donor Tcells, eliminate primary AML blasts but are also active against mouse and human hematopoietic stem and progenitor cells, indicating risk of myelotoxicity. By employing a surrogate CAR with affinity to murine FLT3, we show that rituximab-mediated depletion of FLT3 CAR Tcells after AML eradication enables bone marrow recovery without compromising leukemia remission. These results support clinical investigation of allogeneic FLT3 CAR Tcells in AML and other FLT3+ hematologic malignancies.

Role of Donor-Derived CD19.CAR-T Cells in Treating Patients That Relapsed after Allogeneic Hematopoietic Stem Cell Transplantation

Background The Chimeric Antigen Receptor T (CAR-T) cells with strong anti-leukemia role can treat relapsed/refractory CD19-positive acute lymphoblastic leukemia (CD19+-ALL) with good outcome. The allogeneic CAR-T cells receives activation signals from both T cell receptor (TCR) and CAR, which may possess stronger activity in anti-leukemia cells. However, the infusion of allogeneic CAR-T cells may cause graft-versus-host disease, which could limit its application after allogeneic hematopoietic stem cell transplantation (allo-HSCT). It is still unclear that the role of the donor-derived CAR-T cells in treating relapsed patients after allo-HSCT. In this study, the prospective study was performed to investigate the role of donor-derived CAR-T cells on relapsed patients after allo-HSCT. Methods From April 2016 to March 2019, relapsed patients after allo-HSCT with CD19+-ALL and a Karnofsky score greater than or equal to 60 were enrolled in this study. The donor underwent apheresis for mononuclear cells to construct the CAR-T cells. The bone marrow aspiration every month after CART- cells infusion was carried out for the assessment of disease status by follow cytometry. The chimerism was detected every month after CAR-T cells treatment. Results Eighteen patients enrolled in this study. The median number of infused CAR-T cells was 1.825Í106/Kg. Thirteen patients (13/18=72.22%) reached complete remission (CR) after CAR-T cells treatment. Four patients (4/18=22.22%) had ineffectiveness. One patient died from b uncontrolled bleeding because of low platelet. The patients with blast cells <5% had higher CR. The full chimerism achieved after CART- cells treatment for all patients with the decrease of chimerism at the time of relapse. The median time of follow-up was seven months (ranged from three months to twenty-five months). Three patients with decreased CAR-T cells or chimerism was underwent allogeneic hematopoietic stem cell transplantation or relapsed within six months. The other eleven patients were complete remission with full chimerism or the continual proliferation of CAR-T cells without the second allo-HSCT during our follow-up period. Seventeen patients observed cytokine release syndrome in which six patients with degree III-IV. Two patients developed GVHD in skin and intestinal tract. All patients recovered after management. No other severe complications and death were observed. Conclusion Our results showed that the treatment by donor-derived CAR-T cells for relapsed patients after allo-HSCT is safe and effective. No second transplantation was needed for relapsed patients after allo-HSCT with the treatment of donor-derived CAR-T cells that with good chimerism and continual proliferation of CAR-T cells. However, further clinical trials should be performed to investigate this protocol with larger cases. Disclosures No relevant conflicts of interest to declare.

Lower T cell inhibitory receptor level in mononuclear cells from cord blood compared with peripheral blood.

T cell inhibitory receptors play important role in maintaining T cell homeostasis. The feature of such negative costimulator signal transduction pathway in cord blood (CB) T cells remains unclear. In this study, the expression levels of T cell inhibitory receptors including programmed death-1 (PD-1), cytotoxic T lymphocyte antigen-4 (CTLA-4), T cell immunoglobulin mucin-3 (Tim-3), lymphocyte activation gene-3 (LAG-3) and B and T lymphocyte attenuator (BTLA) were characterized in CB and compared with peripheral blood (PB). Significant lower expression of PD-1, CTLA-4, LAG-3 and BTLA was found in CB, while similar expression level of Tim-3 was showed between CB and PB. Together, different expression pattern of such T cell inhibitory receptor in CB is worthy to further discuss their role on immune response when CB is used in cord blood stem cell transplantation as well as allogeneic chimeric antigen receptor T-cell producing.

Abstract 1428: Allogeneic CRISPR/Cas9 gene-edited CAR-T cells targeting CD33 show potent preclinical activity against AML cells

Abstract Acute myelogenous leukemia (AML) has a high mortality rate and remains difficult to treat, making new treatment approaches critical. Chimeric antigen receptor T (CAR-T) cell therapies have shown impressive clinical responses in B-cell neoplasia. However, comparable successes have not been reported to date in myeloid malignancies, potentially due to difficulty in manufacturing efficacious CAR-T cells from AML patients and lack of a suitable tumor antigen for AML. To address these issues, we have developed allogeneic CAR-T cells from healthy donors targeting the CD33/Siglec-3 antigen, a protein expressed on most AML cells and subpopulations in the majority of AML patients at presentation and relapse. Allogeneic anti-CD33 CAR-T cells were produced from healthy donor-derived T cells using CRISPR/Cas9 gene editing. In these cells, the TRAC locus was disrupted to reduce the risk of graft versus host disease (GvHD). At the same time, a CAR construct targeting CD33 was inserted site-specifically into the TRAC locus. In addition, the beta-2-microglobulin locus was disrupted to prevent clearance of the allogeneic CAR-T cells by the host immune system. These allogeneic anti-CD33 CAR-T cells showed potent effector activity in vitro against human AML-derived cell lines, as measured by both tumor cell lysis and effector cytokine secretion. The allogeneic anti-CD33 CAR-T cells also potently reduced AML tumors in vivo in xenograft mouse models. Citation Format: Brigid McEwan, Zinkal Padalia, Ashley Porras, Jason Sagert, Jonathan A. Terrett, Tony Ho, Demetrios Kalaitzidis. Allogeneic CRISPR/Cas9 gene-edited CAR-T cells targeting CD33 show potent preclinical activity against AML cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1428.

Use of chimeric antigen receptor T cells in allogeneic hematopoietic stem cell transplantation.

The chimeric antigen receptor T (CAR-T) cells play an antileukemia role, and can be used to treat or prevent relapse by targeting minimal residual disease for patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, the infusion of allogeneic CAR-T cells may also cause graft-versus-host disease, which limited their applications during and after allo-HSCT. In this review, we discuss the clinical trials that applying CAR-T cells before allo-HSCT and the use of donor-derived CAR-T cells as conditioning regimen during allo-HSCT. At last, we analyzed the effect of donor-derived CAR-T cells on preventive infusion after allo-HSCT.

A Protein-Based Method to Develop Allogeneic Chimeric Antigen Receptor T-Cells

▪IntroductionAnti-CD19 chimeric antigen receptor (CAR) T-cells are highly effective against B-cell malignancies. However, significant problems associated with autologous T-cells preclude more widespread adoption, including manufacturing failures, poor T-cell quality and cost/logistic issues. A solution could be allogeneic CAR T-cells generated from healthy donors, if these could be prevented from causing graft versus host disease (GvHD). GvHD is mediated by T-cell receptors (TCR) of donor T-cells. Previous approaches have used genome-editing to delete TCR expression, introducing complexity, expense and unpredictable genotoxicity. We developed an alternative, protein-based strategy: TCR-knockdown using an anti-TCR ScFv fused to a KDEL endoplasmic reticulum (ER)-retention domain.ResultsWe cloned anti-TCR/CD3 ScFvs with C-terminal KDEL motifs, and introduced these to TCR-positive cell lines or primary T-cells. While clones OKT3 and BMA031 had no effect on TCR expression, cells expressing UCHT1-KDEL demonstrated loss of surface TCR.We subsequently generated constructs in which UCHT1-KDEL, a 2ndgeneration anti-CD19 CAR and RQR8 (a sort-suicide gene containing CD34 epitope) were co-expressed. We demonstrated obligate linkage of CAR expression and TCR downregulation in transduced T-cells. Following positive CD34 bead selection for RQR8, purity of RQR8+TCR-CAR+ T-cells was >99.8%. In addition, we demonstrated that positive selection for RQR8 was routinely more stringent than depletion of TCR-positive cells.We demonstrated that CAR19-KDEL and conventional CAR19 cells demonstrated equivalent specificity, cytokine release and cytotoxicity in 48hr co-cultures with a panel of CD19-positive and CD19-negative cell lines. In addition, in long-term co-culture assays, no differences in proliferative capacity, markers of differentiation or exhaustion were seen. However, while conventional CAR19 cells proliferated in mixed lymphocyte reactions with irradiated allogeneic peripheral blood mononuclear cells (PBMCs), CAR19-KDEL cells did not.We compared CAR19 and CAR19-KDEL cells in vivo using the NSG-NALM6 tumour xenograft model. Both CAR19 and CAR19-KDEL were able to substantially delay tumour progression relative to control CAR or mock-transduced T-cells in a low-dose (0.2M) model. Finally, we developed a xeno-GvHD model in which irradiated NSG mice were injected with a high dose (5M) of CAR19 or CAR19-KDEL cells. While 100% of mice in the CAR19 group died of xeno-GvHD by D65, all CAR19-KDEL recipients were alive and healthy at D180.ConclusionsWe have developed a protein-based method which avoids genome editing for the rapid, simple and cost-effective generation of allogeneic CAR T-cells. Our positive selection strategy allows a highly stringent selection of TCR-negative cells. This process may bring the generation of ‘off the shelf’ CAR T-cells closer to clinical application. DisclosuresMaciocia:Autolus: Equity Ownership, Patents & Royalties: UCLB. Pule:UCLB: Patents & Royalties; Autolus: Employment, Equity Ownership.

Study on Use of CAR-T Cells in Allogeneic Hematopoietic Stem Cell Transplantation

Background: The chimeric antigen receptor T (CAR-T) cells have showed strong anti-leukemia role, which can treat or prevent relapse by targeting minimal residual disease for patients undergone allogeneic hematopoietic stem cell transplantation (allo-HSCT). The infusion of allogeneic CAR-T cells may cause the graft-versus-host disease, which could limit its use during and after allo-HSCT. It is still unclear whether CAR-T cells can be used during and after allo-HSCT. In this study, the use of CAR-T cells in these situation was explored.Methods: Two patients with relapsed/refractory acute lymphoblastic leukemia (ALL) received allo-HSCT, the CAR-T cells was used as a reduced-intensity conditioning regimen. Another three patients with high-risk ALL received preventive infusion of CAR-T cells on days +60 after allo-HSCT.Results: For patients undergone allo-HSCT, the time of peak CAR-T cell proliferation was detected after the first infusion of CAR-T cells on day 7. The engraftment and full donor cell engraftment were established. The disease was in complete remission with negative minimal residual disease, which was undetectable by flow cytometry. No graft-versus-host disease and serious cytokine release syndrome was found. For patients received preventive infusion of CAR-T cells, the CAR-T cells continually survival. No graft-versus-host disease and serious cytokine release syndrome was found. The disease is complete remission for 1-6 months.Conclusion: It is safety and effective for CAR-T cells used in allogeneic hematopoietic stem cell transplantation. DisclosuresNo relevant conflicts of interest to declare.

Allogeneic CAR-T Cells: More than Ease of Access?

Patient derived anti-CD19 chimeric antigen receptor-T (CAR-T) cells are a powerful tool in achieving a complete remission in a range of B-cell malignancies, most notably B-acute lymphoblastic leukaemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL). However, there are limitations, including inability to manufacture CAR-T cells from the patient’s own T cells, disease progression and death prior to return of engineered cells. T cell dysfunction is known to occur in cancer patients, and several groups have recently described differences in CAR-T cells generated from chronic lymphocytic leukaemia (CLL) patients compared with those from a healthy donor. This is thought to contribute to the low response rate in this disease group. Healthy donor, gene-edited CAR-T cells which do not require human leucocyte antigen (HLA) matching have the potential to provide an ‘off the shelf’ product, overcoming the manufacturing difficulties of producing CAR-T cells for each individual patient. They may also provide a more functional, potent product for malignancies such as CLL, where T cell dysfunction is common and frequently cannot be fully reversed during the manufacturing process. Here we review the potential benefits and obstacles for healthy donor, allogeneic CAR-T cells.

Next-Generation Chimeric Antigen Receptor T-Cell Therapy: Going off the Shelf.

Autologous, patient-specific chimeric antigen receptor T-cell (CART) therapy has emerged as a powerful and potentially curative therapy for cancer, especially for CD19-positive hematological malignancies. Indeed, on August 30, 2017, the University of Pennsylvania-designed CD19-directed CART (CART-19) cell therapy (CTL019, tisagenlecleucel-t, Kymriah - Novartis) became the first CART therapy approved by the Food and Drug Administration (FDA) for acute lymphoblastic leukemia. However, the development of CART technology and its wider application is partly limited by the patient-specific nature of such a platform and by the time required for manufacturing. The efficacious generation of universal allogeneic CART cells would overcome these limitations and represent a major advance in the field. However, several obstacles in the generation of universal CART cells need to be overcome, namely the risk of CART rejection and the risk of graft-versus-host disease mediated by the allogeneic CART. In this review, we discuss the different strategies being employed to generate universal CART and provide our perspective on the successful development of a truly off-the-shelf CART product.

A Multidrug-resistant Engineered CAR T Cell for Allogeneic Combination Immunotherapy

The adoptive transfer of chimeric antigen receptor (CAR) T cell represents a highly promising strategy to fight against multiple cancers. The clinical outcome of such therapies is intimately linked to the ability of effector cells to engraft, proliferate, and specifically kill tumor cells within patients. When allogeneic CAR T-cell infusion is considered, host versus graft and graft versus host reactions must be avoided to prevent rejection of adoptively transferred cells, host tissue damages and to elicit significant antitumoral outcome. This work proposes to address these three requirements through the development of multidrug-resistant T cell receptor αβ-deficient CAR T cells. We demonstrate that these engineered T cells displayed efficient antitumor activity and proliferated in the presence of purine and pyrimidine nucleoside analogues, currently used in clinic as preconditioning lymphodepleting regimens. The absence of TCRαβ at their cell surface along with their purine nucleotide analogues-resistance properties could prevent their alloreactivity and enable them to resist to lymphodepleting regimens that may be required to avoid their ablation via HvG reaction. By providing a basic framework to develop a universal T cell compatible with allogeneic adoptive transfer, this work is laying the foundation stone of the large-scale utilization of CAR T-cell immunotherapies.

In Vivo Proof of Concept of Activity and Safety of UCART19, an Allogeneic “Off-the-Shelf” Adoptive T-Cell Immunotherapy Against CD19+ B-Cell Leukemias

Chimeric antigen receptor (CAR)-redirected T-cells have given rise to long-term durable remissions and remarkable objective response rates in patients with refractory leukemia, raising hopes that a wider application of CAR technology may lead to a new paradigm in cancer treatment. A limitation of the current autologous approach is that CAR T-cells must be manufactured on a "per patient basis". We have developed a standardized platform for manufacturing T-cells from third-party healthy donors to generate allogeneic "off-the-shelf" engineered CD19-CAR+ T-cell–based frozen products. Our platform involves the use of transcription activator-like effector nucleases (TALEN™), which mediate the simultaneous inactivation of two genes through genome editing. The knockout of the TCR alpha gene eliminates TCR expression and is intended to abrogate the donor T-cell’s potential for graft-versus-host disease (GvHD), while knocking out the CD52 gene makes donor T-cells resistant to the lymphodepleting agent alemtuzumab. In addition, our T-cells are engineered to coexpress the RQR8 gene as a safety feature, with the aim of rendering them sensitive to the monoclonal antibody rituximab.We previously provided proof-of-concept for the application of this approach by manufacturing TCR/CD52-deficient RQR8+ and CD19-CAR+ T-cells (UCART19) using a good manufacturing practice–compatible process, and we also demonstrated that the resulting UCART19 cells were functional using in vitro assays. Here we report the ability of UCART19 cells to engraft into an orthotopic human CD19+ lymphoma xenograft immunodeficient mouse model. UCART19 cells exhibited antitumor activity equivalent to that of standard CD19 CAR T-cells. We also demonstrated that UCART19 cells did not mediate alloreactivity in a xeno-GvHD mouse model. Furthermore, the effectiveness of the rituximab-induced depletion mechanism of RQR8+ cells was shown in an immunocompetent mouse model.In conclusion, our work significantly enlarges upon previous results by showing in vivo that (1) concomitant inactivation of a second gene has no deleterious effects on T-cells, (2) the antitumor potency of manufactured TCR/CD52-deficient CD19–CAR+ T-cells is similar to that of standard CD19-CAR+ T-cells, (3) TCR gene inactivation is efficient at preventing potential graft-versus-host reaction, and (4) allogeneic T-cells can be depleted by the use of rituximab. This valuable dataset supports the development of allogeneic CAR T-cells, and UCART19 will be investigated in an exploratory, first-in-human, clinical trial where refractory/relapsed CD19+ B-cell leukemia patients are to be enrolled. DisclosuresGouble:Cellectis SA: Employment. Poirot:Cellectis SA: Employment. Schiffer-Mannioui:Cellectis SA: Employment. Galetto:Cellectis SA: Employment. Derniame:Cellectis SA: Employment. Arnould:Cellectis SA: Employment. Desseaux:Cellectis SA: Employment. Smith:Cellectis SA: Employment.