Autologous CAR Research Articles

Summary of US Food and Drug Administration Chimeric Antigen Receptor (CAR) T-Cell Biologics License Application Approvals From a Statistical Perspective.

The approval of tisagenlecleucel and axicabtagene ciloleucel in 2017 marked a milestone in the development of oncology therapies. Since 2017, the breakthrough in treatment or even cure of previously intractable diseases represented by this new class of cancer treatments has continued with subsequent chimeric antigen receptor T (CAR T)-cell approvals. To date, the US Food and Drug Administration has approved five autologous CAR T-cell products for seven indications. A feature of autologous CAR T-cell products that differentiates them from traditional oncology drugs is that they need to be manufactured specifically for each patient. This feature has implications in study design, statistical analyses, and interpretation of study results. In this article, we share our experiences in the statistical review of CAR T-cell products and provide considerations for the design and statistical analyses of CAR T-cell trials. We also describe how the newly adopted estimand framework for clinical trials can help clarify nuanced issues in CAR T-cell trial design.

Trafficking and persistence of alloantigen-specific chimeric antigen receptor regulatory T cells in Cynomolgus macaque

SummaryAdoptive transfer of chimeric antigen receptor regulatory T cells (CAR Tregs) is a promising way to prevent allograft loss without the morbidity associated with current therapies. Non-human primates (NHPs) are a clinically relevant model to develop transplant regimens, but manufacturing and engraftment of NHP CAR Tregs have not been demonstrated yet. Here, we describe a culture system that massively expands CAR Tregs specific for the Bw6 alloantigen. In vitro, these Tregs suppress in an antigen-specific manner without pro-inflammatory cytokine secretion or cytotoxicity. In vivo, Bw6-specific CAR Tregs preferentially traffic to and persist in bone marrow for at least 1 month. Following transplant of allogeneic Bw6+ islets and autologous CAR Tregs into the bone marrow of diabetic recipients, CAR Tregs traffic to the site of islet transplantation and maintain a phenotype of suppressive Tregs. Our results establish a framework for the optimization of CAR Treg therapy in NHP disease models.

Sequencing of Novel Therapies for Mantle Cell Lymphoma.

There is no standard approach to sequencing novel therapies in mantle cell lymphoma (MCL). For initial treatment, intensive induction chemotherapy followed by autologous stem cell transplant and rituximab maintenance remains our preferred approach in young, fit patients. We consider bendamustine plus rituximab or lenalidomide plus rituximab in patients who are ineligible for intensive chemotherapy-based approaches. Bruton's tyrosine kinase inhibitors are our preferred class of agents to use in the second-line setting. When patients inevitably relapse on one of these agents, we proceed with chimeric antigen receptor T-cell (CAR T) therapy in eligible patients, often with the use of bridging therapy with corticosteroids, lenalidomide, or venetoclax. We treat patients who are ineligible for CAR T or clinic trial with venetoclax, lenalidomide, or proteosome inhibitor-based regimens, although efficacy is expected to be limited in this setting with a shortened duration of response to each subsequent line of therapy. Allogeneic stem cell transplant remains an option for carefully selected patients who progress after autologous stem cell transplant and CAR T. Clinical trials involving combinations of novel agents in early lines of therapy are ongoing, and new compounds with unique mechanisms of action are in development. The results of ongoing clinical trials with novel agents will further change the treatment landscape for patients with MCL in the coming years.

Absolute Lymphocyte Count Expansion Kinetics Can be Utilized to Assess Response to CAR T Cell Products

IntroductionCAR T-cell therapies are utilized to treat relapsed/refractory B-lymphoblastic leukemia (B-ALL), diffuse large B cell lymphoma, mantle cell lymphoma, and multiple myeloma. CAR T cell expansion kinetics after infusion impact response. However, these CAR T cell products vary in their target epitope and constituent molecules that makes it difficult to validate broad molecular or flow cytometric assays for use in the clinical setting. The lack of commercially available reagents also limits the ability of clinical laboratories to validate separate CAR T cell specific assays. We investigated the utility of common hematology laboratory parameters to measure CAR T cell expansion and response.MethodsClinical hematology laboratory parameters after infusion of autologous and allogeneic CAR T cell products directed were assessed. Concurrent CBC and cell population data (CPD) parameters from the Sysmex XN 3000 automated hematology analyzer were available in 82 patients. Absolute lymphocyte count (ALC) kinetics after infusion of autologous CD19, allogeneic CD19, CD22, CD33, allogeneic CD123-directed CAR T cell products were analyzed. Patients who received bone marrow transplant served as controls. CPD parameters included X (lateral light scatter-granularity), Y (fluorescence-nuclei acid content), Z (forward scatter-size), and their distribution widths WX, WY, WZ. Archived CellaVision cell morphology images from 118 patients who received CD19-directed CAR T cell products and 25 patients who received other CAR T cell products were analyzed. Response was determined from 1 month post-CAR bone marrow disease assessment.ResultsAbsolute Lymphocyte Counts, lymphocyte morphology and cell population data after infusion of CAR T cell productsCD19-CAR, UCAR19, and CD22-CAR all showed a distinct lymphocyte expansion phase post-infusion in responders (Figure 1A) that was absent in non-responders and controls(Figure 1B). ALC showed characteristic lag, expansion, and contraction phases in responders. CD19-CAR had a peak at day 8 while CD22-CAR and allogenic Universal(U)CAR19 had relatively delayed peak times occurring near day 15 (Figure 1B). The stem cell transplant control patients did not show ALC expansion in the first two weeks and instead showed normal lymphocyte regeneration that occurs in the third to fourth weeks. CD33-CAR and allogeneic UCAR123 non responders did not show ALC expansions.CAR T cell responders showed a distinct sequence of changes in lymphocyte morphology that was absent in non-responders and stem cell transplant controls (Figure 1C). This pattern was noted uniformly across various CAR T cell products (Figure 1D-1F). The morphological changes were categorized as: early, mid, and late. Early atypical cells were noted around days 4-8 after infusion and showed immunoblastic morphology that was present in 89% (n=105) of patients. Mid atypical cells were noted around days 5-14 after infusion and showed atypical large granular lymphocyte morphology that were seen in 95% (n=112) of patients. Late atypical cells showed the typical LGL morphology and was seen in 82% (n=97) of patients.WY fluorescence, which is a measure of nucleic acid content, was most useful in assessing changes in lymphocytes after CAR T cell infusion. WY was low (mean 402, n=57) at baseline pre-infusion timepoint and peaked (mean 1207) approximately 1 week after infusion (mean 7.9 days, n = 59). Peak WY was observed 3.7 days prior to peak ALC (mean day 11.6, n = 59).ConclusionWe demonstrate for the first time that common clinical laboratory parameters can be used to follow CAR T cell expansion after infusion in various autologous and allogeneic CAR T cell products. ALC expansion is a measure of CAR T cell expansion after infusion and correlates with response. Responders showed higher peak ALC compared to non-responders in all CAR T cell products. Timing of peak ALC expansion was determined by other factors such as expression of target antigen and CAR T-cell product used. Lymphocyte morphology followed ALC changes and showed a consistent sequence of changes that was seen across multiple CAR T cell products. Finally, CPD parameter WY which is a measure of nuclei acid content and activation, was an early harbinger of ALC expansion. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Engineered Hypoimmune Allogeneic CAR T Cells Exhibit Innate and Adaptive Immune Evasion Even after Sensitization in Humanized Mice and Retain Potent Anti-Tumor Activity

Engineered Hypoimmune Allogeneic CAR T Cells Exhibit Innate and Adaptive Immune Evasion Even after Sensitization in Humanized Mice and Retain Potent Anti-Tumor Activity

Analysis of Factors Associated with Conversion to CR in Patients with Large B-Cell Lymphoma Achieving Day 30 PR after CAR T-Cell Therapy

Analysis of Factors Associated with Conversion to CR in Patients with Large B-Cell Lymphoma Achieving Day 30 PR after CAR T-Cell Therapy

Results from a Pilot Study of ARI0002h, an Academic BCMA-Directed CAR-T Cell Therapy with Fractionated Initial Infusion and Booster Dose in Patients with Relapsed and/or Refractory Multiple Myeloma

Results from a Pilot Study of ARI0002h, an Academic BCMA-Directed CAR-T Cell Therapy with Fractionated Initial Infusion and Booster Dose in Patients with Relapsed and/or Refractory Multiple Myeloma

Industrialization of an Academic Miltenyi Prodigy-Based CAR T Process

INTRODUCTIONWe have previously described AUTO1, a CD19 CAR with a fast off-rate binding domain, designed to reduce CAR T-cell immune toxicity and improve engraftment. Clinical testing in two academic studies in relapsed/refractory (r/r) paediatric [NCT02443831; CARPALL] and adult B-ALL, B-NHL and B-CLL [NCT02935257; ALLCAR19] confirmed the intended function of the receptor, with low levels of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) and long-term engraftment of CAR T-cell 1,2. Based on data in adult B-ALL, we initiated a phase Ib/II registration study in r/r adult B-ALL [NCT04404660; FELIX]. To facilitate this study and future commercialization, industrialization of the manufacturing process was required.METHODS & RESULTSThe original process in the academic studies was based on the Miltenyi CliniMACS Prodigy T cell transduction process. Leukapheresis was performed at the same site as manufacture. T cells were isolated from pheresis by CD4/CD8 positive selection and seeded onto the Prodigy to be activated using the Miltenyi CD3/CD28 targeting activating reagent, TransAct. The following day, transduction was carried out using a lentiviral vector. Cells were cryopreserved after an expansion phase of up to day 10 of the process.To facilitate industrialization of the AUTO1 manufacture in the multi-center, multi-regional FELIX study, we first explored the use of cryopreserved pheresis (81.3% median viability pre-selection (range 71.9 - 94.3), 1.0 days median doubling time (range 0.9 - 1.5) and 47.6% median CD19 CAR expression (range 19.1-62.1)). We concluded that optimal manufacture includes the use of fresh pheresis and the initiation of manufacture within 72 hours (99.0% median viability pre-selection (range 92.5 - 99.7), 1.3 days median doubling time (range 1.1 - 2.1) and 69.3% median CD19 CAR expression (range 22.9-86.2)).To further simplify the process, we explored removal of the pre-selection step. Full-scale runs using starting material from 4 healthy donors were conducted to compare CD4/CD8 selected with unselected cells. On the day following activation, selected cells displayed a higher percentage of viable cells, defined as cPARP-FVS780- (median: 76.1%, range: 84.5-66.4) as compared to unselected cells (median: 52.2%, range: 43.6-59.0). In addition, selected cells demonstrated a median of 23-fold expansion (range: 20.0 - 29.1) compared to a 13.3-fold expansion for unselected cells (range 6.1-17.4). Median transduction efficiencies of viable CAR+ T-cells were 53.9% (range: 43.2-56.9) and 78.0% (range: 64.5-81.1) in selected and unselected cells, respectively. CD4/8 pre-selection was determined to be a critical part of the process.A comparison of phenotype between 18 batches manufactured using the academic process and 5 batches produced from fresh material using the industrial process was carried out. No significant differences, as determined by 2-way ANOVA, were observed between the percentage of CAR+ CD3+ cells, the memory phenotype (% TSC/naive, % TCM, % TEM and % TEMRA) and the percentage expression of PD1 (figure 1). The CD4/CD8 ratio was also comparable between products of the two processes.Data from the initial 6 fresh in patients show that engraftment in the FELIX study is consistent with ALLCAR19 engraftment results. Additional patients, updated clinical data and longer follow-up will be presented at the conference.CONCLUSIONIndustrialization of an autologous Miltenyi CAR T process is feasible, leading to a comparable product to that manufactured in an academic setting. We have now opened the pivotal multi-center phase II part of the FELIX study in r/r adult B-ALL patients.REFERENCES 1.Ghorashian S et al. (2019) Enhanced CAR T cell expansion and prolonged persistence in pediatric patients with ALL treated with a low-affinity CD19 CAR. Nat Med, 25(9):1408-1414.2.Roddie C et al. (2021) Durable responses and low toxicity after fast off-rate CD19 CAR-T therapy in adults with relapsed/ refractory B-ALL. J Clin Oncol, in pressFigure 1. Comparison of phenotype between 18 CAR T cell batches manufactured using the academic process and 5 batches produced using the industrial process. Boxes represent median, 25th and 75th percentiles and whiskers represent minimum and maximum. [Display omitted] DisclosuresCulshaw: Autolus Ltd.: Current Employment. Arce Vargas: Autolus Ltd.: Current Employment. Santiago Toledo: Autolus Ltd.: Current Employment. Roddie: Novartis: Consultancy; Celgene: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau. Shaughnessy: BMS: Honoraria, Speakers Bureau; Sanofi: Honoraria, Speakers Bureau; Kite: Honoraria, Speakers Bureau. Cerec: Autolus Ltd.: Current Employment. Duffy: Autolus Ltd.: Current Employment. Perna: Autolus Ltd.: Current Employment. Brugger: Autolus Ltd.: Current Employment. Merges: Autolus Ltd.: Current Employment. Pule: Autolus Ltd: Current Employment.

Phase I Study of FT516, an Off-the-Shelf iPSC-Derived NK Cell Therapy, in Combination with Rituximab in Patients with Relapsed/Refractory B-Cell Lymphoma

Phase I Study of FT516, an Off-the-Shelf iPSC-Derived NK Cell Therapy, in Combination with Rituximab in Patients with Relapsed/Refractory B-Cell Lymphoma

CD4-Targeted Fusosomes Are Capable of Transducing Resting T Helper Cells to Generate Highly Potent CAR-T Cells

Introduction: Chimeric antigen receptor T cell therapy (CAR T) is a successful treatment for B cell malignancies; however, the time, complexity and cost of manufacturing autologous CAR T products limits the availability of these therapies to patients. Furthermore, ex vivo manipulation of T cells is likely to have a negative impact on quality. In vivo gene delivery of CAR T transgenes by systemic infusion of standard lentiviral vectors may increase therapeutic accessibility but is limited by off-target transduction and the requirement for T cell activation. Here, we demonstrate that a paramyxovirus-based integrating vector (fusosome) engineered with a CD4 re-targeted envelop (CD4 fusogen) can efficiently and specifically transduce resting and activated CD4+ T cells to generate functional CD4+ CD19-specific CAR T cells capable of eliminating CD19+ lymphoma cells.Methods: Anti-CD4 single chain variable fragments () and single variable domain (VHHs) were screened for CD4 binding, specificity, and NHP cross-reactivity and inserted into receptor binding paramyxovirus fusogen. CD4-targeted fusosomes expressing GFP were screened for high on-target titer against the CD4+ SupT1 cell line and low off-target transduction on non-CD4 expressing cells. Subsequently, a CD19-specific CAR encoding 4-1BB and the CD3z endo-domains (CD19 CAR) was generated to examine CD4+ CAR T transduction efficiency and functionality. PBMCs were thawed and activated with anti-CD3/anti-CD28 beads and exposed to GFP, CD4-targeted fusosomes and specificity of targeting CD4+ T cells was measured by flow cytometry. Subsequently, CD19 CAR fusosomes targeting CD4 were used to test transduction efficiency against activated (CD3/CD28 or IL-7 treated) or resting T cells, and to measure T cell function against CD19+ and CD19 knockout (CRISPR/Cas9-edited) Nalm-6 lymphoma cells (e.g., tumor co-culture and rechallenge assays and cytokine production) in vitro. Vector copy number (VCN) was determined by a multiplex ddPCR assay and reported as copies per diploid genome (c/dg).Results: To target CD4+ T cells, we generated fusogens encoding scFvs and VHHs specific to the CD4 T cell co-receptor (n = 399). Using fusosomes carrying the GFP transgene, NHP cross-reactive CD4-targeted fusogens that efficiently transduced CD4+ SupT1 cells were selected (n = 12 with crude SupT1 titers >1E6). Activated PBMCs transduced with a CD4-targeted fusosomes exhibited specific CD4 T cell transduction whereas VSV-G pseudotyped vectors showed broad transduction including CD4+ and CD8+ T cells. CD4-targeted CD19 CAR fusosomes could efficiently transduce both activated (34% ± 1.5% CD4+CAR+; 0.54 ± 0.18 c/dg) and resting T cells, albeit at a lower expression and integration rate (20% ± 0.5% CD4+CAR+; 0.28 ± 0.14 c/dg). Resting CD4-transduced CAR T cells demonstrated specific cytotoxicity and cytokine production (GM-CSF, IFN-g, TNF-a, IL-2, IL-6, and IL-10) against CD19+ Nalm-6 but did not recognize CD19 knockout tumor cells. In long-term co-culture assays with repetitive stimulation with fresh tumor cells, resting CD4+ CD19 CAR T cells continued to show potent tumor cell killing. Future experiments will evaluate the efficacy of CD4 fusosomes against CD19+ tumors in vivo.Summary: CD4-specific fusosomes can efficiently deliver an integrating CAR payload to resting and activated CD4+ T cells. Modified CD4+ CAR T cells demonstrate potent anti-tumor activity against CD19+ tumor cells. These data suggest that targeting the CD4 co-receptor through in vivo delivery using a novel pseudotyped integrating vector can produce functional CAR T cells to target cancer. DisclosuresCiarlo: Sana Biotechnology: Current Employment. Frye: Sana Biotechnology: Current Employment. DeGroot: Sana Biotechnology: Current Employment. Flores: Sana Biotechnology: Current Employment. Elpek: Sana Biotechnology: Current Employment. Pepper: Sana Biotechnology: Current Employment. Johnson: Sana Biotechnology: Current Employment. Shah: Sana Biotechnology: Current Employment. Foster: Sana Biotechnology: Current Employment, Current equity holder in publicly-traded company. Fry: Sana Biotechnology: Current Employment, Current equity holder in publicly-traded company.

Relmacabtagene Autoleucel CD19 CART Therapy for Adults with Heavily-Pretreated Relapsed/Refractory Large B-Cell Lymphoma in China

IntroductionPrognosis for relapsed and refractory large B-cell lymphoma (r/r LBCL) is poor, and treatment remains challenging. Relmacabtagene autoleucel (relma-cel) is a CD19-directed 4-1BB/CD3z chimeric antigen receptor T cell (CAR-T) product manufactured in China. RELIANCE study is the first CAR-T study with CD19 as target that got IND approved by the authority in China. Initial findings of the pivotal Phase 2 single-arm, multicenter RELIANCE trial demonstrated high response rates and low rates of CAR-T-associated toxicity with relma-cel treatment in heavily pretreated patients (pts) with r/r LBCL (NCT04089215; Ying et al. Cancer Med 2020;10:999-1011). Long-term follow-up data for the RELIANCE study are presented.Materials & MethodsFifty-nine adults (age ≥18 years) with heavily pretreated (≥2 prior therapies), measurable and histologically confirmed r/r LBCL were randomized to receive lymphodepletion chemotherapy (LDC: fludarabine 25 mg/m 2 + cyclophosphamide 250 mg/m 2 daily×3) followed by a single infusion of autologous CAR+ T cells at a dose of 100×10 6 or 150×10 6. Pts were evaluated for efficacy using Lugano criteria and for toxicity using Common Terminology Criteria for Adverse Events v4.03 and for cytokine release syndrome (CRS) using Lee et al. (Blood 2014;124(2):188-95). Primary endpoint was 3-month objective response rate (ORR); key secondary endpoints included complete response rate (CRR) at 3 months, duration of response (DOR), progression-free survival (PFS), overall survival (OS) and treatment-emergent adverse event (TEAE) profile. The data cutoff date was December 31, 2020.ResultsAt the time of analysis, all 59 pts (median age 56.0 years, range 18-75 years) were at least 15 months post-treatment with relma-cel (7 pts completed trial, 34 pts on study, 18 pts withdrew). Among the modified intent-to-treat (mITT) population of 58 efficacy-evaluable pts, best ORR was 77.6%, with a best CRR of 51.7%; ORR and CRR at 3-month-postdose landmark were 60.3% and 44.8%, respectively. With a median follow-up of 17.9 months (range 0.3-25.6 months), median PFS (mITT) was 7.0 months (95% CI 4.8-not reached [NR]). Median PFS was NR (95% CI 8.8 months-NR) for pts with compete response (CR) at 3 months, the 6-, 12-, 18- and 24-month PFS rates were 80.8%, 69.2%, 69.2% and 69.2%, respectively (Figure). PFS was associated with objective response or CR at 1, 3, 6, and 12 months (log-rank test, p≤0.002). Median OS was NR (95% CI NR-NR) for both the mITT population and pts with CR at 3 months (12-month OS rate, 76.8% and 92.3%, respectively). Median DOR was NR (95% CI 4.9 months-NR) for the mITT population and (95% CI 8.0 months-NR) for pts with CR at 3 months. Levels of CAR-T cells declined to below the level of quantification (BLQ) in 41 (69.5%) pts, among whom nearly 40% had sustained response. Median time from documentation of CAR-T BLQ to disease progression was 6.1 months (95% CI 1.8-NR). Treatment-related TEAEs were reported in 93.2% of pts and were primarily grade 1-2 (89.8% pts); 54.2% of pts had grade ≥3 TEAEs. Pyrexia was the most common TEAE, reported in 59.3% of pts (all grade 1-2). The most common grade ≥3 treatment-related TEAEs were neutrophil count decrease (30.5%) and white blood cell (WBC) count decrease (13.6%). Presence of cytopenia at day 29 (78.0%) was significantly associated with WBC count after LDC, change in serum albumin between days 1 and 4 and serum interleukin 8 after LDC (p<0.05). The incidence of CRS and neurotoxicity (NT) was 47.5% and 20.3%, respectively, both primarily grade 1-2. There were no CRS- or NT-related deaths. Occurrence of grade ≥2 CRS or NT (11.9% and 6.8%, respectively) was significantly associated with fold-change of platelet count on day 4 compared with baseline and day 1 absolute neutrophil count (p<0.03). There were no treatment-related deaths.ConclusionsThese are the first data of long-term follow-up CD19 CAR-T study with IND approval in China reported. With nearly 18 months of median follow-up, the RELIANCE pivotal registered study demonstrated durable responses, high rates of OS and PFS, and no new safety profile found in r/r LBCL pts. Based on these data, relma-cel is undergoing approval in China. Figure: Kaplan-Meier estimates of (A) PFS and (B) OS by 3-month tumor responsePR, partial response [Display omitted] DisclosuresZhang: JW Therapeutics: Current Employment. Yang: JW Therapeutics: Current Employment. Zhou: JW Therapeutics: Current Employment. Zheng: JW Therapeutics: Current Employment.

Correlative Biological Studies Related to the Response, Peak and Persistence of ARI0002h, an Academic BCMA-Directed CAR-T Cell, with Fractionated Initial Infusion and Booster Dose for Patients with Relapsed and/or Refractory Multiple Myeloma (RRMM)

Correlative Biological Studies Related to the Response, Peak and Persistence of ARI0002h, an Academic BCMA-Directed CAR-T Cell, with Fractionated Initial Infusion and Booster Dose for Patients with Relapsed and/or Refractory Multiple Myeloma (RRMM)

CD22-CAR T-Cell Therapy Mediates High Durable Remission Rates in Adults with Large B-Cell Lymphoma Who Have Relapsed after CD19-CAR T-Cell Therapy

CD22-CAR T-Cell Therapy Mediates High Durable Remission Rates in Adults with Large B-Cell Lymphoma Who Have Relapsed after CD19-CAR T-Cell Therapy

TT52CAR19: Phase 1 Trial of CRISPR/Cas9 Edited Allogeneic CAR19 T Cells for Paediatric Relapsed/Refractory B-ALL

Background‘Off-the-shelf’ CAR T cell therapies are being investigated as alternatives to autologous CAR therapy, and can be generated using genome editing from allogeneic donors. Strategies to address HLA barriers include disruption of T cell receptor expression to prevent GVHD and removal of cell surface HLA expression to obviate host mediated rejection, as well as removal of CD52 to create a survival advantage in the presence of Alemtuzumab. In this study, lentiviral mediated CAR19 expression is linked to CRISPR editing through the incorporation of CRISPR guide RNA sequences within the vector 3'Long terminal repeat (LTR). The trial is in progress using pre-manufactured batches of TT52CAR19 T cells.Investigational medicinal product (IMP)Three allogeneic non-HLA matched donor derived CAR19 T cell banks were manufactured from steady state apheresis harvests from registry volunteer donors, using a semi-automated process under compliant conditions. Cells were activated with anti-CD3/CD28 (Transact) reagent and transduced with a lentiviral vector, TT52CAR19, and dual guide sgRNA cassettes targeting the T cell receptor alpha chain (TRAC) and CD52 loci. Next electroporation of Cas9 mRNA elicited transient genome editing, and automated magnetic bead depletion removed remaining TCRαβ+ T cells (mean 0.7%) and enriched CAR19+ T cells (mean 92.8%). Cells were cryopreserved in aliquots suitable for dose-banding and subjected to release testing, including flow cytometry, quantification of copy number (mean 3.83) and exclusion of replication competent lentivirus. Potency of each bank was confirmed in human:murine chimera experiments.Trial sponsorship & approvalsThe study is open at a single site and is sponsored by Great Ormond Street Hospital NHS trust and is supported by the Medical Research Council and National Institute for Health Research. Clinical trial authorisation was awarded by the MHRA after expert review, and ethical approval including gene therapy advisory committee (GTAC) review, and health research authority (HRA) approval. The study is open label, single arm and non-randomised.Study aims and ObjectivesThe study aims to establish the safety and feasibility of TT52CAR19 for the induction of molecular remission in children with relapsed /refractory CD19-positive B-cell acute lymphoblastic leukaemia (B-ALL) within 28 days, ahead of planned allogeneic haematopoietic stem cell transplantation (allo-SCT). Assessments include time to remission, duration of remission, disease-free survival and overall survival. Expansion, persistence and elimination of TT52CAR19 cells and tracking of immune recovery after allo-SCT is monitored. Recording of complications and toxicities, including possible genotoxic side effects from CRISPR/Cas9 modification provides safety profile information.Eligibility, infusion and outcomesThe study plans to treat 10 children aged between 6 months and < 18 years with CD19+ B-ALL quantified at >10 -4 in marrow (by flow or PCR) who are ineligible for autologous therapy. To date 2/4 children screened were found eligible and proceeded to lymphodepletion comprising Fludarabine, Cyclophosphamide and Alemtuzumab followed by a single infusion of 0.8-2.0x10 6 CAR19 T cells and a maximum of 5x10 4/kg TCRαβ T cells. In both cases, there was no GVHD or CRS >grade 1 and recovery of neutrophil counts by d28. Molecular remission was achieved in one child, where TT52CAR19 cells persistence was tracked by chimerism and copy number until further conditioning and allo-SCT. This child remains in remission >6 months later.ConclusionsFeasibility of pre-manufacturing off-the-shelf CRISPR/Cas9 edited CAR19 T cells is demonstrated and the trial has provided first in human safety data and preliminary indications of potent anti-leukaemic activity in one of two subjects dosed. DisclosuresQasim: Autolus: Current equity holder in publicly-traded company; Novartis: Honoraria; Servier: Research Funding; Tessa: Membership on an entity's Board of Directors or advisory committees.

Immunicy-1: Targeting BCMA with Cyad-211 to Establish Proof of Concept of an shRNA-Based Allogeneic CAR T Cell Therapy Platform

Off-the-shelf allogeneic CAR T cells derived from healthy donor cells have the potential to overcome many of the issues associated with the time-consuming manufacturing of autologous CAR T cells. However, adoptive transfer of allogeneic T cells carries the risk of graft-versus-host disease (GvHD). Most of the clinical experience with allogeneic CAR T cells is based on gene editing to eliminate T cell receptor (TCR) to mitigate the risk of GvHD. While clearly effective, the downsides of gene editing include multiple manufacturing steps requiring multiple clinical grade reagents, thus extending culture times, which can be associated with T cell exhaustion.As an alternative, we have explored short hairpin RNA (shRNA) as a means to knockdown TCR expression at the mRNA level. This shRNA is co-expressed along with the CAR in a single clinical grade vector, therefore requiring just one step of genetic modification.CYAD-211 is an allogeneic anti-BCMA CAR T that co-expresses a shRNA targeting CD3z which results in reduction of cell surface TCR expression. IMMUNICY-1 is an ongoing open-label Phase 1 trial (NCT04613557) designed to evaluate CYAD-211 in adult patients with refractory or relapsed multiple myeloma (MM) following at least two prior MM regimens. Patients receive non-myeloablative preconditioning (cyclophosphamide 300 mg/m²/day and fludarabine 30 mg/m²/day, for 3 days) followed by a single CYAD-211 infusion in a 3+3 dose escalation design evaluating three dose-levels (DL): 30x10 6, 100x10 6 and 300x10 6 cells/infusion.As of July 29, 2021, nine patients were enrolled across the 3 DLs. Patients had received a median of four prior lines of treatment. Seventy-eight percent of patients were previously exposed to all three major MM drug classes (proteasome inhibitors, immunomodulatory drugs, and anti-CD38 antibody therapy). Eight patients had prior autologous stem cell transplantation.CYAD-211 was well tolerated. One patient developed grade 1 cytokine release syndrome. Two patients had Grade ≥ 3 hematologic toxicities possibly related to the experimental treatment. Two patients experienced infectious adverse events (1 grade 1 rhinitis and 1 grade 2 upper respiratory infection). There was no neurologic toxicity and no GvHD. There was no dose-limiting toxicity.Eight patients were evaluated for activity per IMWG criteria. Two patients achieved partial response at dose-levels 1 and 2 while 5 patients had stable disease (SD). One patient with an ongoing SD (3 months +) showed evidence of reduction in size of plasmacytomas.Analysis of peripheral blood samples by molecular methods confirmed the engraftment of CYAD-211. All patients had detectable CAR T cells. However, the engraftment was short lasting (3-4 weeks). There was a correlation between the depth of lymphodepletion and engraftment. There was also a dose-response in terms of CYAD-211 kinetics with a level neighboring 8,000 copies of CAR T per microgram of input DNA in patients at DL3.These early data indicate that CYAD-211 is well tolerated with a good safety profile. While further study is required to fully understand the anti-BCMA potency of the CAR used in this trial, the lack of observed GvHD despite engraftment of CYAD-211 provides proof of concept of the safe administration of CAR T using a shRNA-allogeneic platform. The lack of sustained engraftment of CYAD-211 can be explained by rejection of the allogeneic cells by the recovering immune system of the recipient and calls for exploring the role of augmented lymphodepletion. Furthermore, given the ability to include multiple shRNA within the single CAR vector, future strategies will also examine knocking down other molecules that are important in driving immune rejection. DisclosuresAl-Homsi: BMS: Other: Independent Medical Education Grant; Daichii Sankyo: Consultancy; Celyad Oncology: Other: Advisory Board. Deeren: Alexion: Consultancy; BMS: Consultancy; Incyte: Consultancy; Novartis: Consultancy; Sanofi: Consultancy, Research Funding; Sobi: Consultancy; Takeda: Consultancy. Nishihori: Karyopharm: Research Funding; Novartis: Research Funding. Meuleman: iTeos Therapeutics: Consultancy. Abdul-Hay: Amgen: Membership on an entity's Board of Directors or advisory committees; Takeda: Speakers Bureau; Abbvie: Consultancy; Jazz: Other: Advisory Board, Speakers Bureau; Servier: Other: Advisory Board, Speakers Bureau. Braun: Celyad Oncology: Current Employment. Lonez: Celyad Oncology: Current Employment. Dheur: Celyad Oncology: Current Employment. Alcantar-Orozco: Celyad Oncology: Current Employment. Gilham: Celyad Oncology: Current Employment. Flament: Celyad Oncology: Current Employment. Lehmann: Celyad Oncology: Current Employment.

Efficacy and Safety of Chimeric Antigen Receptor T Cells in Acute Lymphoblastic Leukemia With Post-Transplant Relapse.

Twenty patients with relapsed B-ALL after HSCT were treated with CAR T cell therapy and were evaluated for efficacy and safety. Twelve patients previously received haploidentical transplantation, while 8 patients received HLA-matched transplantation. The median relapse time was 12 months (range, 4 to 72). Thirteen patients received autologous CAR T cells, and 7 patients received allogeneic CAR T cells, which were derived from transplant donors. The median infusion dose was 2.9×106/kg (range, 0.33 to 12×106/kg). Nineteen patients were evaluated for efficacy, among which 17 patients (89.5%) achieved MRD negative. The CR rates in the HLA-matched transplantation group and haploidentical transplantation group were 100% (7/7) and 83.3% (10/12), respectively. The median follow-up time was 9.80 months (range, 2.40 to 64.97). Ten patients (50%) died of relapse, 3 patients (15%) died of infection, and 1 patient (5%) died of aGVHD. Fifteen patients (75%) developed CRS, including 3 (20%) grade 1 CRS, 6 (40%) grade 2 CRS, and 6 (40%) grade 3 CRS. Ten patients (50%) developed aGVHD, including 1 (10%) grade I aGVHD, 6 (60%) grade II aGVHD, and 3 (30%) grade III aGVHD. The log rank test showed that CAR T cell origin was correlated with aGVHD occurrence in the haploidentical transplantation group (P = 0.005). The authors’ study indicated that the initial efficacy and safety of CAR T cell therapy for patients with post-transplant relapse were satisfactory. However, aGVHD was a concern in patients with a history of haploidentical transplantation occupied with allogeneic CAR T cells, which warrants clinical attention.

CAR T-Cells for T-cell Lymphoma

Introduction Developing CAR T-cells for T-lineage malignancies requires minimizing fratricide of engineered T-cells and mitigating the risk of T-cell aplasia, which may be caused by the off-tumor activity of CAR T-cells. We have developed and optimized for clinical evaluation a CAR targeting pan-T-cell antigen CD5, which is highly expressed in peripheral T-cell lymphoma. Expression of an optimized CD5 CAR produces only transient and limited fratricide as T-cells rapidly internalize and degrade CD5 protein in a CAR-dependent manner. Resulting CD5 CAR T-cells are fratricide-resistant and produce strong anti-tumor activity in mouse xenograft models of human T-cell malignancies.1 Based on this preclinical work, we initiated a Phase I clinical trial at Baylor College of Medicine with autologous CD5 CAR T-cells in patients with refractory or relapsed T-cell malignancies as a bridge to allogeneic HSCT (NCT03081910).

Abstract CT031: GD2 CAR T cells mediate clinical activity and manageable toxicity in children and young adults with DIPG and H3K27M-mutated diffuse midline gliomas

Abstract Background: Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMGs) are universally lethal central nervous system tumors. We previously discovered that the disialoganglioside GD2 is highly and homogenously expressed on H3K27M+ gliomas and demonstrated that GD2 CAR T cells are effective in preclinical models (Mount/Majzner et al., Nat Med, 2018). Methods: Four subjects (3 DIPG, 1 spinal cord DMG; 4-25 yr; 1M/3F) were enrolled at DL1. Three subjects with H3K27M+ DIPG received 1e6 autologous GD2 CAR T cells/kg intravenously (IV) on study. One patient, a 25 y/o with spinal cord DMG, developed rapidly progressive disease after enrollment, resulting in complete paraparesis that led to removal from the study prior to cell infusion; she was treated on a single patient eIND with the same treatment regimen as DL1. We utilized a retroviral vector expressing a 14g2a.4-1BB.z CAR construct and an inducible iCasp9 safety switch. Manufacturing was performed in the Miltenyi Prodigy on CD4/CD8 enriched apheresis product. CAR T cells were cultured in the presence of dasatinib to improve T cell fitness (Weber et al., Science, 2021). An Ommaya reservoir was placed in all patients for monitoring of intracranial pressure (ICP). Results: We generated GD2 CAR T cell products meeting release criteria for all four patients. All subjects received lymphodepletion with cyclophosphamide and fludarabine and remained inpatient for 14+ days after infusion. All patients developed cytokine release syndrome (Grade 1-3) manifested by fever, tachycardia and hypotension, beginning 6-7 days after infusion. Due to concern for tumoral edema and increased ICP, patients were managed with conservative fluid resuscitation, and early intervention with tocilizumab and anakinra +/- corticosteroids. Other toxicities included ICANS (Grade 1-2) and neurotoxicity mediated by inflammation in sites of disease which we have termed Tumor Inflammation-Associated Neurotoxicity (TIAN). TIAN most often manifested as worsening of existing deficits, but one patient developed symptoms of increased ICP which quickly resolved upon removal of CSF via the Ommaya. No evidence of on-target, off-tumor toxicity was observed in any patients. No dose-limiting toxicities occurred.CAR T cells trafficked to the CNS and were detected in both the CSF and peripheral blood. Inflammatory cytokines including IL-6 were elevated in the CSF and blood. 3/4 patients exhibited marked improvement or resolution of neurological deficits and some radiographic improvement. The patient treated on a single patient eIND exhibited a &amp;gt;90% reduction in her spinal cord DMG tumor volume at two months post-infusion. Durability of the therapeutic benefit remains to be determined. Conclusions: This is the first report of GD2 CAR T cell therapy for DIPG and spinal cord DMG. Toxicities are similar to other CAR T cells with additional, manageable complications due to inflammation at CNS sites of tumor. Treatment at DL1 demonstrated a tolerable safety profile and clear signs of T cell expansion and activity including clinical responses. This approach has the potential to transform therapy for patients with H3K27M+ DIPG/DMG. Further correlative studies, including single-cell RNAseq, longer-term outcomes and results from patients on subsequent dose levels will also be presented. Citation Format: Robbie G. Majzner, Sneha Ramakrishna, Aaron Mochizuki, Shabnum Patel, Harshini Chinnasamy, Kristen Yeom, Liora Schultz, Rebecca Richards, Cynthia Campen, Agnes Reschke, Jasia Mahdi, Angus Martin Shaw Toland, Christina Baggott, Sharon Mavroukakis, Emily Egeler, Jennifer Moon, Kayla Landrum, Courtney Erickson, Lindsey Rasmussen, Valentin Barsan, John S. Tamaresis, Anne Cunniffe Marcy, Michael Kunicki, Michelle Fujimoto, Zach Ehlinger, Sreevidya Kurra, Timothy Cornell, Sonia Partap, Paul Fisher, Gerald Grant, Hannes Vogel, Bita Sahaf, Kara Davis, Steven Feldman, Crystal L. Mackall, Michelle Monje. GD2 CAR T cells mediate clinical activity and manageable toxicity in children and young adults with DIPG and H3K27M-mutated diffuse midline gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT031.

Anti-CD123 CAR T-Cell Therapy for the Treatment of Myelodysplastic Syndrome

INTRODUCTIONMyelodysplastic syndrome (MDS) is a group of heterogeneous disorders caused by ineffective hematopoiesis characterized by bone marrow dysplasia resulting in cytopenias. Currently, treatment options for MDS are limited to supportive care and hypomethylating agents with most patients eventually succumbing to the disease (anemia, infection or hemorrhage) or progressing to leukemia. Previously it have been demonstrated that CD123 is an important target for the treatment of MDS due to its aberrantly high expression in high-risk MDS cells compared to low-risk MDS cells and normal cells. As such, CD123-directed therapy may be useful in treating patients with high-risk MDS. METHODSChimeric antigen receptor (CAR) vector containing a CD123-specific single-chain variable fragment in combination with a CD28 costimulatory domain, CD3ζ signaling domain and tEGFR was expressed on healthy donor and patient derived T lymphocytes utilizing lentiviral vector delivery to target high-risk MDS cells. An anti-CD19 CAR was used as a negative control. CAR expressing or control T-cells were cocultured with MDS cell line (MDS-L) or primary MDS cells from patient bone marrow to examine in vitro anti-tumor function. Eradication of MDS cells was analyzed by flow cytometry 48hr after coculture. Intracellular TNF-α and cell surface CD107A were examined in effector cells 5 hours after cocultured with MDS cells. For in vivo analysis of CD123 CAR T cells, NSG-S mice were engrafted with 1.5x106 primary high-risk MDS cells for eight weeks, and were infused with autologous anti-CD123 CAR T-cells or control. Tumor burden was then analyzed on day 28. RESULTSHealthy donor derived anti-CD123 CAR T-cells effectively eliminated MDS cell line (MDS-L) (>99%), and primary bone marrow derived MDS cells (>70%) in vitro . The killing was associated with increased cytokine release and degranulation by anti-CD123 CAR T-cells, which did not occur with control anti-CD19 CAR T-cells. In addition, anti-CD123 CAR T-cells generated from patients with high-risk MDS showed 50~70% transduction efficiency. These cells successfully eradicated autologous CD123+ MDS cells at >99.9% in vitro compared to untransduced control T-cells (Figure 1A). The killing was also confirmed by increased intracellular TNF-α expression (Figure 1B). Furthermore, a patient derived xenograft system (PDX) was utilized to examine the killing ability of autologous anti-CD123 CAR T-cells in vivo . High-risk MDS bone marrow cells were engrafted in NSG-S mice. Eight weeks following engraftment, 7x104 autologous EGFRt+ anti-CD123 CAR T-cells or mock T-cells were infused via tail vein. On day 28 after autologous anti-CD123 CAR T-cell infusion, we observed significant decreases in both CD34+/CD38-/CD123+ MDS cells and MDS bulk (hCD45+/EGFRt-) while mice infused with mock CAR T-cells were unable to reduce tumor burden (Figure 1C and 1D). To extend the utility of our approach, we performed drug screening to identify the agents that increase expression of CD123 on MDS cells. We hypothesize that drugs inducing increased expression of CD123 will increase efficacy of anti-CD123 CAR T cell and avoid resistance arising from CD123 low/dim MDS progenitor cells. 134 various oncologic drugs were dosed at multiple concentrations (1nM, 100nM, 1uM, 0uM) and incubated with MDS-L cell line for 6hr, 16hr or 48hr. MDS-L cells were then analyzed for CD123 expression (Mean fluorescence) and cell viability (%live out of total) by flow cytometry. Eight drugs with low cytotoxicity significantly increased CD123 expression, including trifluridine (1uM), sunitinib (100nM), metoxantrone (1nM), dasatinib (10uM), imatinib (1uM), regorafenib (10uM), dabrafenib (100nM) and DEAB (100nM). These drug candidates will be examined further in primary MDS bone marrow samples and in combination with anti-CD123 CAR T-cells. CONCLUSIONThese results demonstrate that anti-CD123 CAR T-cells exhibit activity against high-risk MDS, and represent an effective therapeutic option for patients with high-risk MDS. [Display omitted] DisclosuresBudde:Mustang Therapeutics: Research Funding; Merck: Research Funding, Speakers Bureau; Amgen: Research Funding; KITE Pharmaceutical: Speakers Bureau; Precision Biosciences: Consultancy.

A Comparison of One Year Outcomes in ZUMA-1 (axicabtagene ciloleucel) and SCHOLAR-1 in Patients with Refractory, Aggressive Non-Hodgkinlymphoma (NHL)

A Comparison of One Year Outcomes in ZUMA-1 (axicabtagene ciloleucel) and SCHOLAR-1 in Patients with Refractory, Aggressive Non-Hodgkinlymphoma (NHL)