CAR-T Cell Persistence Research Articles

Incidence of pre-existing B-cell aplasia in B-ALL: Implications for post-CAR T-cell monitoring

Ongoing B-cell aplasia (BCA) post-CAR T-cell infusion is increasingly utilized as a surrogate for functional CAR T-cell persistence in patients with relapsed/refractory B-ALL. We sought to evaluate the incidence of pre-treatment BCA—which may impact post-infusion BCA monitoring.

AMPK agonism optimizes the in vivo persistence and anti-leukemia efficacy of chimeric antigen receptor T cells.

Chimeric antigen receptor T cell (CART) therapy has seen great clinical success. However, up to 50% of leukemia patients relapse and long-term survivor data indicate that CART cell persistence is key to enforcing relapse-free survival. Unfortunately, ex vivo expansion protocols often drive metabolic and functional exhaustion, reducing in vivo efficacy. Preclinical models have demonstrated that redirecting metabolism ex vivo can improve in vivo T cell function and we hypothesized that exposure to an agonist targeting the metabolic regulator AMP-activated protein kinase (AMPK), would create CARTs capable of both efficient leukemia clearance and increased in vivo persistence. CART cells were generated from healthy human via lentiviral transduction. Following activation, cells were exposed to either Compound 991 or DMSO for 96 hours, followed by a 48-hour washout. During and after agonist treatment, T cells were harvested for metabolic and functional assessments. To test in vivo efficacy, immunodeficient mice were injected with luciferase+ NALM6 leukemia cells, followed one week later by either 991- or DMSO-expanded CARTs. Leukemia burden and anti-leukemia efficacy was assessed via radiance imaging and overall survival. Human T cells expanded in Compound 991 activated AMPK without limiting cellular expansion and gained both mitochondrial density and improved handling of reactive oxygen species (ROS). Importantly, receipt of 991-exposed CARTs significantly improved in vivo leukemia clearance, prolonged recipient survival, and increased CD4+ T cell yields at early times post-injection. Ex vivo, 991 agonist treatment mimicked nutrient starvation, increased autophagic flux, and promoted generation of mitochondrially-protective metabolites. Ex vivo expansion processes are necessary to generate sufficient cell numbers, but often promote sustained activation and differentiation, negatively impacting in vivo persistence and function. Here, we demonstrate that promoting AMPK activity during CART expansion metabolically reprograms cells without limiting T cell yield, enhances in vivo anti-leukemia efficacy, and improves CD4+ in vivo persistence. Importantly, AMPK agonism achieves these results without further modifying the expansion media, changing the CART construct, or genetically altering the cells. Altogether, these data highlight AMPK agonism as a potent and readily translatable approach to improve the metabolic profile and overall efficacy of cancer-targeting T cells.

Efficacy of NKG2D CAR-T cells with IL-15/IL-15Rα signaling for treating Epstein-Barr virus-associated lymphoproliferative disorder

Epstein-Barr virus (EBV) related post-transplant lymphoproliferative disorder (EBV-PTLD) is a life-threatening complication after hematopoietic stem cell transplantation (HSCT) or solid organ transplantation (SOT), for which no standard therapeutic means have been developed. Significant increase expression of natural killer group 2 member D ligands (NKG2DLs) was observed on B-lymphoblastoid cells of EBV-PTLD, indicating NKG2DLs as potential therapeutic targets for treatment of EBV-PTLD. In this study, the recombinant constructs of NKG2D CAR and IL-15/IL-15Rα-NKG2D CAR were generated with a retroviral vector and then transduced to human T cells to produce NKG2D CAR-T and IL-15/IL-15Rα-NKG2D CAR-T cells, respectively. B-lymphoblastoid cell lines (B-LCLs) and the xenografted mouse models were established to evaluate the efficacy of these CAR-T cells. IL-15/IL-15Rα-NKG2D CAR-T cells exhibited superior proliferation and antigen-specific cytotoxic effect compared to NKG2D CAR-T, as IL-15/IL-15Rα signaling promoted the expansion of less differentiated central memory T cells (TCM) and increased expression of CD107a and IFN-γ. Moreover, EBV DNA load was dramatically reduced, and 80% B-LCL cells were eliminated by IL-15/IL-15Rα-NKG2D CAR-T cells after co-culturing. In-vivo study confirmed that IL-15/IL-15Rα-NKG2D CAR-T cell therapy significantly enhanced antiviral efficacy in mice, as the serum load of EBV after IL-15/IL-15Rα-NKG2D CAR-T cell infusion was 1500 times lower than the untreated control (P < 0.001). The enhanced efficacy of IL-15/IL-15Rα-NKG2D CAR T cells was probably due to the IL-15/IL-15Rα signaling improved homing and persistence of NKG2D CAR-T cells in vivo, and increased the production of IFN-γ, Perforin, and Granulysin. In conclusion, NKG2D CAR-T cells co-expressing IL-15/IL-15Rα promoted the central memory CAR T cell proliferation and improved the homing and persistence of CAR T cells in vivo, resulting in enhanced anti-tumor and anti-viral effects in treating EBV-PTLD.

NR4A ablation improves mitochondrial fitness for long persistence in human CAR-T cells against solid tumors

BackgroundAntitumor effect of chimeric antigen receptor (CAR)-T cells against solid tumors is limited due to various factors, such as low infiltration rate, poor expansion capacity, and exhaustion of T cells...

Good manufacturing practice-grade generation of CD19 and CD123-specific CAR-T cells using piggyBac transposon and allogeneic feeder cells in patients diagnosed with B-cell non-Hodgkin lymphoma and acute myeloid leukemia.

The non-viral production of CAR-T cells through electroporation of transposon DNA plasmids is an alternative approach to lentiviral/retroviral methods. This method is particularly suitable for early-phase clinical trials involving novel types of CAR-T cells. The primary disadvantage of non-viral methods is the lower production efficiency compared to viral-based methods, which becomes a limiting factor for CAR-T production, especially in chemotherapy-pretreated lymphopenic patients. We describe a good manufacturing practice (GMP)-compliant protocol for producing CD19 and CD123-specific CAR-T cells based on the electroporation of transposon vectors. The lymphocytes were purified from the blood of patients undergoing chemotherapy for B-NHL or AML and were electroporated with piggyBac transposon encoding CAR19 or CAR123, respectively. Electroporated cells were then polyclonally activated by anti-CD3/CD28 antibodies and a combination of cytokines (IL-4, IL-7, IL-21). The expansion was carried out in the presence of irradiated allogeneic blood-derived mononuclear cells (i.e., the feeder) for up to 21 days. Expansion in the presence of the feeder enhanced CAR-T production yield (4.5-fold in CAR19 and 9.3-fold in CAR123). Detailed flow-cytometric analysis revealed the persistence of early-memory CAR-T cells and a low vector-copy number after production in the presence of the feeder, with no negative impact on the cytotoxicity of feeder-produced CAR19 and CAR123 T cells. Furthermore, large-scale manufacturing of CAR19 carried out under GMP conditions using PBMCs obtained from B-NHL patients (starting number=200x10e6 cells) enabled the production of >50x10e6 CAR19 in 7 out of 8 cases in the presence of the feeder while only in 2 out of 8 cases without the feeder. The described approach enables GMP-compatible production of sufficient numbers of CAR19 and CAR123 T cells for clinical application and provides the basis for non-viral manufacturing of novel experimental CAR-T cells that can be tested in early-phase clinical trials. This manufacturing approach can complement and advance novel experimental immunotherapeutic strategies against human hematologic malignancies.

Novel OX40 and 4-1BB derived spacers enhance CD30 CAR activity and safety in CD30 positive lymphoma models

The chimeric antigen receptor (CAR) derived from the CD30 specific murine antibody, HRS-3, has produced promising clinical efficacy with a favorable safety profile in the treatment of relapsed or refractory CD30-positive lymphomas. However, persistence of the autologous CAR-T cells was brief, and many patients relapsed a year after treatment. The lack of persistence may be attributed to the use of a wild-type immunoglobulin (Ig)G1 spacer that can associate with Fc receptors. We first identified the cysteine-rich domain (CRD) 5 of CD30 as the primary binding epitope of HRS-3 and armed with this insight, attempted to improve the HRS-3 CAR functionality with a panel of novel spacer designs. We demonstrate that HRS-3 CARs with OX40 and 4-1BB derived spacers exhibited similar anti-tumor efficacy, circumvented interactions with Fc receptors, and secreted lower levels of cytokines invitro than a CAR employing the IgG1 spacer. Humanization of the HRS-3 scFv coupled with the 4-1BB spacer preserved potent on-target, on-tumor efficacy, and on-target, off-tumor safety. In a lymphoma mouse model of high tumor burden, Tcells expressing humanized HRS-3 CD30.CARs with the 4-1BB spacer potently killed tumors with low levels of circulating inflammatory cytokines, providing a promising candidate for future clinical development in the treatment of CD30-positive malignancies.

IMMU-02. MODIFYING CAR T CELL EPIGENETIC PROGRAMS TO IMPROVE THEIR PERSISTENCE AGAINST GROUP 3 MEDULLOBLASTOMAS

Abstract BACKGROUND Safe, effective therapies are desperately needed to improve outcomes for patients with medulloblastoma (MB), a malignant pediatric brain cancer. Chimeric antigen receptor (CAR)-T cells are a promising therapeutic option as they target T-cell cytotoxicity exclusively to tumor associated antigens. B7-homolog 3 (B7-H3) is an ideal target for CAR-T cell therapy as all MB subtypes express B7-H3 and healthy tissues do not. However, a roadblock to tumor clearance is the inability of B7-H3 CAR-T cells to persist, suggesting that improving persistence will benefit anti-tumor efficacy. The goal of this study was to compare head-to-head knocking out TET2 or DNMT3A negative epigenetic regulators of CAR-T cell persistence against group 3 MB (G3MB), the most malignant MB subtype. METHODS We generated B7-H3 CAR-T cells with CD28ζ signaling domain and performed CRISPR/Cas9 knockout (KO) of TET2, DNMT3A, and AAVS1 as a control. We compared resulting CAR-T cell persistence via repeat stimulation assays in vitro against G3MB cell lines with varying B7-H3 antigen density (D341low, HDMB03mid, and D425high). We further compared KO CAR-T cells in vivo against D341low, HDMB03mid, and D425high orthotopic xenografts. RESULTS Our data shows that DNMT3A KO, but not TET2 KO, consistently improves the persistence and expansion of CAR-T cells against G3MB in vitro. In vivo, KO of epigenetic regulators moderately improves CAR-T cell therapy against highly aggressive D341low, HDMB03mid, and D425high but is insufficient to elicit curative responses. CONCLUSIONS Our study demonstrates that genetic KO of negative epigenetic regulators of CAR-T cell persistence can improve anti-tumor function against G3MB. We conclude that for the B7-H3.CD28ζ CAR, DNMT3A KO is superior for improving persistence over TET2 KO, but that DNMT3A KO is insufficient in vivo. We believe this is due to the aggressive nature of G3MB and we are optimizing in vivo studies for better representation of CAR-T cell persistence.

Co-stimulation of CD28/CD40 signaling molecule potentiates CAR-T cell efficacy and stemness

CD19 chimeric antigen receptor T (CD19CAR-T) cells have achieved promising outcomes in relapsed/refractory B-cell malignancies. However, recurrences occur due to the loss of CAR-T cell persistence. We developed dual T/B-cell co-stimulatory molecules (CD28 and CD40) in CAR-T cells to enhance intense tumoricidal activity and persistence. CD19.28.40z CAR-T cells promoted pNF-κB and pRelB downstream signaling while diminishing NFAT signaling upon antigen exposure. CD19.28.40z CAR-T cells demonstrated greater proliferation which translated into effective anti-tumor cytotoxicity in long-term co-culture assay. Repetitive weekly antigen stimulation unveiled continuous CAR-T cell expansion while preserving central memory T-cell subset and lower expression of exhaustion phenotypes. The intrinsic genes underlying CD19.28.40z CAR-T cell responses were compared to conventional CARs and demonstrated the up-regulated genes associated with T-cell proliferation and memory as well as down-regulated genes related to apoptosis, exhaustion, and glycolysis pathway. Enrichment of genes toward T-cell stemness, particularly SELL, IL-7r, TCF7, and KLF2, was observed. Effective and continuing anti-tumor cytotoxicity in vivo was exhibited in both B-ALL and B-NHL xenograft models while demonstrating persistent T-cell memory signatures. The functional enhancement of CD37.28.40z CAR-T cell activities against CD37+ tumor cells was further validated. The modification of dual T/B-cell signaling molecules remarkably maximized the efficacy of CAR-T cell therapy.

Fully equipped CARs to address tumor heterogeneity, enhance safety, and improve the functionality of cellular immunotherapies.

Although adoptive transfer of chimeric antigen receptor (CAR)-engineered T cells has achieved unprecedented response rates in patients with certain hematological malignancies, this therapeutic modality is still far from fulfilling its remarkable potential, especially in the context of solid cancers. Antigen escape variants, off-tumor destruction of healthy tissues expressing tumor-associated antigens (TAAs), poor CAR-T cell persistence, and the occurrence of functional exhaustion represent some of the most prominent hurdles that limit CAR-T cell ability to induce long-lasting remissions with a tolerable adverse effect profile. In this review, we summarize the main approaches that have been developed to face such bottlenecks, including the adapter CAR (AdCAR) system, Boolean-logic gating, epitope editing, the modulation of cell-intrinsic signaling pathways, and the incorporation of safety switches to precisely control CAR-T cell activation. We also discuss the most pressing issues pertaining to the selection of co-stimulatory domains, with a focus on strategies aimed at promoting CAR-T cell persistence and optimal antitumor functionality.

Updated results from first-in-human phase 1 dose-escalation trial of TAK-102, a GPC3-targeted armored CAR T cells, in patients with advanced solid tumors.

2543 Background: Glypican 3 (GPC3) is a member of the glypican family of heparan sulfate proteoglycans that are attached to the cell surface by a glycosylphosphatidylinositol anchor. High GPC3 expression rates are reported in numerous cancer types with a high unmet medical need, including hepatocellular carcinoma (HCC). TAK-102 is a GPC3-targeted autologous chimeric antigen receptor T cell (CAR-T) immunotherapy armored with IL-7 and CCL19. The addition of IL-7 and CCL19 to the construct was designed to support the expansion of memory subsets and persistence of CAR-T cells. We hypothesized TAK-102 would help overcome the challenges associated with an immunosuppressive tumor microenvironment that limit the activity of nonarmored CAR-T therapies in solid tumors. Methods: The first-in-human, Phase 1 dose escalation study evaluated TAK-102 in patients (pts) with GPC3-expressing solid tumors who were refractory or intolerant to standard treatments. TAK-102 was administered via a single infusion to 3 dose cohorts after lymphodepleting chemotherapy (LDC; consisting of fludarabine and cyclophosphamide): dose level (DL) 1 (starting cohort), 1x107 CAR+ cells/body; DL2, 1x108 CAR+ cells/body; DL3, 5x108 CAR+ cells/body. Objectives included evaluation of safety, dose-limiting toxicity (DLT), recommended phase 2 dose, cellular kinetic (CK) parameters, tumor markers, cytokine/chemokine and antitumor activity based on RECIST 1.1. Results: Eleven pts were enrolled and infused TAK-102 (DL1: 3 pts, DL2: 3 pts, DL3: 5 pts): 1 gastric neuroendocrine carcinoma, 2 liposarcoma, 8 HCC. Five pts achieved stable disease (SD), HCC (GPC3 H-Score: 36) . In patients achieving SD, the greatest reduction in tumor size was 26.4%. No DLTs or neurotoxicity were observed. Six pts experienced cytokine release syndrome (Grade1: 5 pts, Grade2: 1 pt); all cases were manageable. AFP was measured as a tumor marker for HCC. Among 8 pts with HCC, 4 had SD after treatment with TAK-102 and 3 showed a decrease or stabilization of AFP levels corresponding to their clinical status. CK profiles for pts were assessed by flow cytometry and qPCR-based assays. Overall, there was improvement in TAK-102 exposure (Cmax, AUC) when escalating from DL1 to DL2. There was a slight decrease in Tmax from DL2 to DL3. Homeostatic cytokine (IL-7) spiked post-LDC and showed no further increase after TAK-102 infusion across all the DLs. There was dose-dependency observed in peak CCL19, IFN-γ and IL-6 levels. Conclusions: TAK-102, an armored CAR-T, is well tolerated and has a manageable safety profile with some early signs of anti-tumor activity. For CK, TAK-102 exposure (Cmax, AUC) showed improvement from DL1 to DL2, and slight decrease in Tmax from DL2 to DL3. Dose-dependency was observed in peak CCL19, IFN-γ and IL-6 levels, which may point towards increased signal of activity from DL1 to DL3. Clinical trial information: NCT04405778 .

First-in-human autologous CAR-T for metastatic breast cancers to target growth factor receptor MUC1*.

TPS2683 Background: MUC1 has been one of the most important therapeutic targets for solid tumor cancers for the past 20+ years. However, no MUC1 targeted therapeutic has yet succeeded or has been granted FDA approval. Although MUC1 is overexpressed on cancer cells, it is also widely expressed on normal epithelial cells. We previously reported that a MUC1 transmembrane cleavage product, MUC1* (muk 1 star), is a Class I growth factor receptor activated by ligand-induced dimerization of its truncated extra cellular domain. We generated monoclonal antibodies that recognize the specific conformation that is created when MUC1 is cleaved by specific enzymes expressed in the tumor microenvironment. 93% of human breast cancer tissues are recognized by one of these antibodies, huMNC2, which importantly does not bind to normal MUC1. We have incorporated this antibody into two CARs, wherein one bears the “1XX” mutations in CD3z that greatly increase CAR-T cell persistence, inhibit exhaustion and enable the killing of low antigen expressing cancer cells. Methods: Phase I for huMNC2-CAR44, an autologous frozen product, opened January, 2020, but as a 1st-in-human trial was paused during COVID. All patients receive 300 mg/m2 cyclophosphamide and 30 mg/m2 fludarabine for 3 days prior to CAR-T treatment. Dose escalation from 3.3x105 – 1x107 CAR+ cells/kg follows a standard 3 + 3 design. In addition to standard organ function inclusion criteria, the trial was first open to breast cancer patients whose cancer had progressed after at least 2 or 3 prior therapies while metastatic, yet there was no limit on the number of prior therapies. A recent patient biopsy had to be at least 30% positive for MUC1* in a CLIA validated IHC assay. Importantly, there were no limits on the vein-to-vein time. Dose levels 1 and 2 for huMNC2-CAR44 were completed without DLTs. Phase I for huMNC2-CAR22, which bore the 1XX mutations in CD3z to increase persistence and increase the killing of low antigen expressing cells opened September, 2023. Based on responses of initial huMNC2-CAR44 patients, inclusion criteria were amended to an Enrichment Trial Design. The number of prior therapies was limited to less than or equal to 10. Anticipated survival at the time of product infusion should be at least 3 months. Vein-to-vein time, which historically had been 15-16 days at one site and as high as 83 days at another site, would be targeted to 16- 22 days. The tumors of eligible patients need to have a MUC1* membrane positive H-score equal to or greater than 120 out of a possible 300, defined as high MUC1* positivity. Based on IHC analysis of human breast cancer TMAs, the H-score restriction would include roughly 40% of breast cancers. The increased ability of huMNC2-CAR22 to kill low antigen expressing cancer cells may support future studies of patients expressing low levels of MUC1*. Clinical trial information: NCT04020575 .

Nanomaterials Boost CAR-T Therapy for Solid Tumors.

T cell engineering, particularly via chimeric antigen receptor (CAR) modifications for enhancing tumor specificity, has shown efficacy in treating hematologic malignancies. The extension of CAR-T cell therapy to solid tumors, however, is impeded by several challenges: The absence of tumor-specific antigens, antigen heterogeneity, a complex immunosuppressive tumor microenvironment, and physical barriers to cell infiltration. Additionally, limitations in CAR-T cell manufacturing capacity and the high costs associated with these therapies restrict their widespread application. The integration of nanomaterials into CAR-T cell production and application offers a promising avenue to mitigate these challenges. Utilizing nanomaterials in the production of CAR-T cells can decrease product variability and lower production expenses, positively impacting the targeting and persistence of CAR-T cells in treatment and minimizing adverse effects. This review comprehensively evaluates the use of various nanomaterials in the production of CAR-T cells, genetic modification, and in vivo delivery. It discusses their underlying mechanisms and potential for clinical application, with a focus on improving specificity and safety in CAR-T cell therapy.

Arming Vδ2 T Cells with Chimeric Antigen Receptors to Combat Cancer.

Immunotherapy has emerged as a promising approach in the field of cancer treatment, with chimeric antigen receptor (CAR) T-cell therapy demonstrating remarkable success. However, challenges such as tumor antigen heterogeneity, immune evasion, and the limited persistence of CAR-T cells have prompted the exploration of alternative cell types for CAR-based strategies. Gamma delta T cells, a unique subset of lymphocytes with inherent tumor recognition capabilities and versatile immune functions, have garnered increasing attention in recent years. In this review, we present how arming Vδ2-T cells might be the basis for next-generation immunotherapies against solid tumors. Following a comprehensive overview of γδ T-cell biology and innovative CAR engineering strategies, we discuss the clinical potential of Vδ2 CAR-T cells in overcoming the current limitations of immunotherapy in solid tumors. Although the applications of Vδ2 CAR-T cells in cancer research are relatively in their infancy and many challenges are yet to be identified, Vδ2 CAR-T cells represent a promising breakthrough in cancer immunotherapy.

Stealth transgenes enable CAR-T cells to evade host immune responses

BackgroundAdoptive cell therapy, such as chimeric antigen receptor (CAR)-T cell therapy, has improved patient outcomes for hematological malignancies. Currently, four of the six FDA-approved CAR-T cell products use the FMC63-based...

Abstract LB236: Metabolically armed CD19 CAR-T cells for safe and effective treatment of relapsed or refractory CD19+ B cell hematological malignancies at extremely low doses

Abstract Background: The undeniable success of CD19 CAR-T cell therapy in managing relapsed or refractory (r/r) B-cell hematological malignancies, such as diffuse large B-cell lymphoma (DLBCL) and B-cell acute lymphoblastic leukemia (B-ALL), underscores its significance. Despite the favorable complete remission (CR) rates of around 50% for r/r DLBCL and up to 90% for r/r B-ALL, a notable challenge persists as more than half of patients experiencing CR after CD19 CAR-T cells treatment encounter relapse within a year, attributed to inadequate CAR-T persistence in both indications. Urgent attention is required to devise innovative strategies to overcome these challenges. Recently, we developed metabolically armed CD19 CAR-T cells expressing IL-10 can enhance OXPHOS metabolism, proliferation, and persistence of CAR-T cells in vivo. Significantly, these IL-10-expressing CAR-T cells trigger stem-like memory responses in various lymphoid organs, leading to robust tumor eradication and durable protection. Motivated by these promising findings, an open-label, single arm, investigator-initiated trial (IIT, ClinicalTrials.gov identifier: NCT05715606, NCT05747157) was conducted to assess the safety and efficacy of newly developed metabolically armed IL-10-expressing CD19 CAR-T (product name: Meta10-19 infusion) for treating patients with r/r DLBCL or r/r B-ALL. Method: From Feb 2023 to Dec 2023, this IIT clinical trial evaluated Meta10-19 infusion in adult patients with r/r DLBCL or r/r B-ALL. The patients were recruited and treated at the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China. Patients in 3 dose cohorts (2.0 × 104, 5.0 × 104, or 1.0 × 105 CAR-T cells/kg, corresponding to 1%, 2.5%, or 5% doses of commercialized CAR-T infusion) underwent lymphodepleting chemotherapy with cyclophosphamide and fludarabine before Meta10-19 infusion. The primary endpoint was the incidence of dose-limiting toxicities. The secondary endpoint was the response and survival. Results: The treatment with Meta10-19 infusion has successfully induced CR in all 12 cases of r/r DLBCL (n=6) or r/r B-ALL (n=6), as evaluated by PET-CT scan, NMR spectroscopy or minimal residual disease assessment of bone marrow. No server cytokine storm syndrome or neurotoxicity was observed. All treated patients achieved CR at 3 months post treatment, with the first patient maintaining continuous remission up to 9 months until now. Notably, these metabolically armed CD19 CAR-T cells demonstrated efficacy even for patients with bulky mass (≥7.5 cm) of DLBCL at extremely low infusion dose (1~5% doses of commercialized CAR-T). Conclusion: Preliminary findings suggest that Meta10-19 infusion exhibits promising breakthrough efficacy and safety profile, and active enrollment is ongoing to validate the initial results. Citation Format: Yugang Guo, Qianwen Xu, Lei Xue, Erling Chen, Chonglin Liu, Min Gao, Youjia Li, Jingjing Ren, Jinping Li, Li Tang, Xingbing Wang. Metabolically armed CD19 CAR-T cells for safe and effective treatment of relapsed or refractory CD19+ B cell hematological malignancies at extremely low doses [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB236.

Placental circulating T cells: a novel, allogeneic CAR-T cell platform with preserved T-cell stemness, more favorable cytokine profile, and durable efficacy compared to adult PBMC-derived CAR-T

BackgroundChimeric antigen receptor (CAR)-T cell quality and stemness are associated with responsiveness, durability, and memory formation, which benefit clinical responses. Autologous T cell starting material across patients with cancer is...

GSNOR overexpression enhances CAR-T cell stemness and anti-tumor function by enforcing mitochondrial fitness

Chimeric antigen receptor T cell (CAR-T) has been developed as a promising agent for patients with refractory or relapsed lymphoma and leukemia, but not all the recipients could achieve a long-lasting remission. The limited capacity of in vivo expansion and memory differentiation post activation is one of the major reasons for suboptimal CAR-T therapeutic efficiency. Nitric oxide (NO) plays multifaceted roles in mitochondrial dynamics and T-cell activation, but its function on CAR-T cell persistence and anti-tumor efficacy remains unknown. Herein, we found the continuous signaling from CAR not only promotes excessive NO production, but also suppressed S-nitrosoglutathione reductase (GSNOR) expression in T cells, which collectively led to increased protein S-nitrosylation, resulting in impaired mitochondrial fitness and deficiency of T cell stemness. Intriguingly, enforced expression of GSNOR promoted memory differentiation of CAR-T cell after immune activation, rendered CAR-T better resistance to mitochondrial dysfunction, further enhanced CAR-T cell expansion and anti-tumor capacity in vitro and in mouse tumor model. Thus, we revealed a critical role of NO in restricting CAR-T cell persistence and functionality, and defined that GSNOR overexpression may provide a solution to combat NO stress and render patients with more durable protection from CAR-T therapy.

Abstract 6322: CCTx-001 CAR T-cells targeting the AML specific antigen IL-1RAP show robust pre-clinical anti-tumor efficacy

Abstract Despite significant advancements in acute myeloid leukemia (AML) treatment, patients with relapsed/refractory (r/r) AML have limited therapeutic options. Novel approaches are urgently needed. CAR T-cell therapy has shown remarkable success in hematological malignancies. However, its application in AML has been hampered by the absence of highly AML-specific antigens, making current CAR T-cell AML therapies under development poorly tolerated and effective. This pre-clinical study introduces a novel CAR T-cell therapy, CCTx-001, specifically designed to target IL-1RAP, a 78-kDa transmembrane glycoprotein. IL-1RAP, is highly expressed on AML cells but not on healthy hematopoietic stem and progenitor cells (CD34+ HSPC). Additionally, transcriptomic analyses reveal a correlation between high IL-1RAP expression and poor prognosis in AML patients. IL-1RAP's predominant presence on myeloid leukemia cells, coupled with their dependence to IL-1RAP-related pathways for their survival, presents a promising avenue for CAR T-cell therapy without the risk of treatment-induced antigen loss. CCTx-001, an autologous CAR T-cell therapy, was developed to target IL-1RAP on AML cells. It comprises CD8+ and CD4+ T-cells transduced with a highly specific anti-IL-1RAP Single-Chain Variable Fragment (scFv), an IgG1 hinge region, CD28, 4-1BB co-stimulatory domains, and a CD3ζ activation domain. In vitro experiments confirmed CCTx-001's efficacy in killing AML cell lines and primary AML cells of varying IL-1RAP expression levels, also demonstrating cytotoxicity and cytokine release that was dependent on the (E:T) ratio and target expression. Furthermore, in vivo studies using immunocompromised NCG mice confirmed CCTx-001's ability to target IL-1RAP and inhibit the growth of IL-1RAP-positive human AML tumor xenografts, leading to increased survival time. Biodistribution analyses confirmed the successful adoptive transfer, expansion and persistence of CCTx-001 CAR T-cells in vivo, only when injected into IL-1RAP-expressing tumor-bearing mice, which correlated with reduced levels of circulating AML cells. The promising preclinical data presented herein warrant the evaluation of CCTx-001 CAR T-cell therapy in clinical trials for r/r AML patients. CCTx-001 CAR T-cell therapy offers a potential breakthrough in addressing the unmet medical needs of AML patients with resistant or refractory disease. Citation Format: Edouard De Dreuzy, Soha Reda El Sayed, Delphine Genin, Clementine Primus, Lucie Bouquet, Alexis Collette, Olivier Favre-Bulle, Erik Rutjens, Jens Hasskarl, Ksenija Pavletic, Marina Deschamps, Christophe Ferrand, Richard C. A. Sainson. CCTx-001 CAR T-cells targeting the AML specific antigen IL-1RAP show robust pre-clinical anti-tumor efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6322.

Abstract 28: A CRISPR/Cas9 screening platform ImmuT Finder® enables in vivo T cell functional screening and identification of potent immunoregulatory targets for next-generation T cell therapy

Abstract Insufficient tumor infiltration and the presence of various immunosuppressive mechanisms in tumor microenvironment (TME) are two major challenges compromising the anti-tumor efficacy of T cell therapy post infusion. PD-1/PD-L1 blockade has been proven to benefit a portion of late-stage solid tumor patients, however KO of PD-1 may impact the long-term persistence of CAR-T cells, indicating target selection strategies for gene editing of cell therapy products may differ from antibody drugs. To discover potent and/or novel immunoregulatory targets that could maximize the function of T cell therapy, we established an in vivo CRISPR/Cas9 screening platform, ImmuT Finder®, to identify functional gene targets in primary mouse T cells. Notably, T cells carrying sgRNA library have been collected at different harvest time points post transfer based on different screening purposes; library size has been rationally designed to ensure good coverage of the whole library in harvest samples. We selected top targets from in vivo screening and quickly validated their function in primary human T cells in a 96-well array. Then, the top targets that showed significant enhancement in proliferation and function of human T cells were further selected, and their combinational effects on human peripheral T cells and TIL were tested both in vitro and in vivo. Finally, GT307 stands out as the most potent KO combination, which significantly improves serial tumor killing of TCR-T and CAR-T as well as autologous tumor cytotoxicity of TIL in vitro. Furthermore, GT307 KO TCR-T and TIL demonstrated significantly improved tumor control in mouse models than their unedited counterparts and promoted long-term persistence with low support of IL-2. In summary, these data demonstrated that our ImmuT Finder® platform enables discovery of potent and/or novel targets for the development of T cell product and supports the clinical assessment of GT307 as a next-generation T cell therapy. Citation Format: Jingwei Sun, Jiahui Jin, Jingman Wang, Yao Sheng, Fei Li, Lingyun Chen, Yongchao Tan, Zhao Xu, Yanbin Liu, Ke Liu, Yarong Liu. A CRISPR/Cas9 screening platform ImmuT Finder® enables in vivo T cell functional screening and identification of potent immunoregulatory targets for next-generation T cell therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 28.

Abstract 3636: Myeloid cell rebound associated with GD2-CAR-T cell therapy in solid tumor patients

Abstract GD2 is a validated cancer immunotherapy target with highly restricted normal tissue expression. Promising activity of GD2-CAR-T cell therapy in diffuse midline glioma and neuroblastoma has promoted interest in this therapy. We initiated three phase 1 clinical trials of escalating doses of intravenously administered autologous GD2-CAR-T cells in patients with advanced GD2-positive solid tumors. Emerging evidence suggests that CAR-T cells may increase circulating myeloid derived suppressor cells (MDSCs) and that this event may be mediated and/or triggered by CAR-T cell-derived cytokines and chemokines. These findings may help to explain the limited persistence of CAR-T cell therapy in solid tumor patients. Hence, we sought evidence of MDSC generation and secretion of relevant cytokines and chemokines in our clinical trial patients. The CARPETS trial (www.anzctr.org.au: ACTRN12620000622909) recently closed to recruitment after enrolling 12 patients (7 melanoma, 4 colorectal cancer, and 1 sarcoma). No significant adverse events were attributable to CAR-T cell therapy. We opened two other GD2-CAR-T cell therapy trials in 2023: LEVI’S-CATCH (ACTRN12622000675729) in patients with diffuse midline glioma at Sydney Children’s Hospital and KARPOS (ACTRN12622001514796) in adult patients with recurrent glioblastoma at Royal Adelaide Hospital. To date, 3 patients have enrolled to LEVI’S-CATCH with the first patient clearing the dose limiting (DLT) evaluation period. Three patients completed enrolment to the first dose cohort of KARPOS without DLTs. In all CARPETS patients, CAR-T cell expansion, which was measured by by DNA quantitative PCR and flow cytometry, peaked during the 6-week post-CAR-T infusion DLT evaluation period. In 6 CARPETS patients for whom peripheral blood samples were available, we found by flow cytometry, newly formed or increased size of pre-existing subpopulations of non-classical monocytes and/or MDSCs of mononuclear and/or polymorphonuclear class, which peaked at or after the time of peak CAR-T cell expansion. Typically, serum levels of inflammatory cytokines and chemokines such as TNF, IL-6, IL-8, CCL2, GM-CSF, and CXCL10, were detected only after the CAR-T cell infusion with variable patterns of the timing and concentration of analyte observed among the 12 patients. At the time of writing, blood samples from the first KARPOS patient showed CAR-T cell expansion and the subsequent increases in circulating myeloid derived suppressor cells and inflammatory cytokines. We expect that full data sets for these parameters will be presented for current and future enrolled patients to both studies. To improve CAR-T cell persistence in solid tumor patients, these data indicate the need for new therapeutic strategies to mitigate effects of CAR-T cell induced myeloid cells with antitumor activity. Citation Format: Michael P. Brown, Tessa Gargett, Nga T. Truong, Orazio Vittorio, David S. Ziegler. Myeloid cell rebound associated with GD2-CAR-T cell therapy in solid tumor patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3636.