Chimeric Antigen Receptor T-cell Efficacy Research Articles

Mitochondrial Isocitrate Dehydrogenase Inhibition Enhances CAR T-Cell Function By Restraining Antioxidant Metabolism and Histone Acetylation

Introduction: The efficacy of chimeric antigen receptor (CAR) T-cell therapy is hampered by relapse in hematologic malignancies and by hyporesponsiveness in solid tumors. Mitochondria are vital for the regulation of memory T-cell formation or exhaustion. A mitochondria-related compound screening was performed and we found that the FDA-approved isocitrate dehydrogenase 2 (IDH2) inhibitor enasidenib enhances long-lived memory CAR T-cell formation, and improves tumor clearance in vivo. IDH2 as the key component of the tricarboxylic acid (TCA) cycle, we hypothesized that IDH2 inhibition might promote CAR T-cell persistence by reprogramming the metabolism. The study aims to systematically evaluate the role and the mechanism of IDH2 inhibition on CAR T cells, and explore the application of enasidenib in CAR T-cell therapy. Methods and Results: To identify mitochondrial components that affect the long-term efficacy of CAR T-cells, we performed an in vitro screening using a mitochondria-related compound library based on the enrichment of the CD62L + CAR T-cell subset, which mainly contains T memory stem cells (T SCM) and central memory T cells (T CM). Among several candidate compounds that promoted memory CAR T-cell formation, enasidenib (ENA), an inhibitor of both wild-type and mutant IDH2 enzymes, was the most effective one. The proportion of CD62L has increased by over 20%. To determine the effect of ENA on exhaustion induced by tonic CAR signaling and tumor antigen stimulation, we measured the expression of inhibitory receptors PD-1, TIM-3, and LAG-3 and the level of apoptosis in freshly expanded CAR T cells and B-ALL encountered CAR T cells. CAR T cells treated with ENA exhibited reduced surface levels of those inhibitory receptors. We measured the production of granzyme B and IFNγ, and tumor rechallenge assay in CAR T cells after ENA treatment to assess the effector function, ENA treated CAR T cells exerted enhanced and sustained cytotoxicity in a tumor rechallenge assay at an extreme E:T ratio of 1:10. These results were observed not only in CD19-41BBζ CAR T cells, but also in CD19-28ζ and GD2-28ζ CAR T cells. CAR T cells expanded in the presence of ENA significantly prolonged survival of recipients after Nalm-6 infusion (p < 0.0001), extended in vivo ENA treatment further enhanced CAR T-cell expansion and tumor suppression. The median survival was extended from 45 to 67.5 days. Consistent with the effect of ENA treatment, IDH2 knockdown increased the proportions of the T scm/T n and T cm subsets, and alleviated CAR T-cell exhaustion. IDH2-knockdown CAR T cells had sustained cytotoxicity and higher CD62L expression after rounds of killing B-ALL cells in vitro. To systematically explore the effects of IDH2 inhibition on the metabolism of CAR T cells, relative metabolite amounts was measured using mass spectrometry (MS). IDH2-inhibited CAR T cells exhibited a substantial reduction of metabolites in the TCA cycle, including succinate, fumarate, and malate, and in the glycolysis pathway, including lactate, phosphoenolpyruvate. Mechanistically, IDH2 inhibition reprogram central carbon metabolism of CAR T cells by redirects glucose carbon utilization from glycolysis to the pentose phosphate pathway. In addition, IDH2 limits cytosolic acetyl-CoA level to prevent histone acetylation that promotes memory cell formation. Significance: Our study indicates that metabolic intervention in CAR T cells with the FDA-approved IDH2 inhibitor enasidenib can advance current treatment, with better tumor eradication and CAR T-cell persistence.

Efficacy of Chimeric Antigen Receptor T-Cell Therapy Is Not Impaired By Previous Bispecific Antibody Treatment in Patients with Large B-Cell Lymphoma

Introduction: Potential T-cell exhaustion after bispecific antibody (BsAb) treatment remains an open question, raising the theoretical concern that prior BsAb exposure could affect subsequent chimeric antigen receptor (CAR) T-cell efficacy. Clinical data on CAR T-cell outcomes after prior BsAb treatment in the setting of large B-cell lymphoma (LBCL) are scarce and highly awaited to better define treatment sequencing in relapsed/refractory (R/R) patients. Methods: We conducted a retrospective, international study including R/R LBCL patients treated with CD19-targeted CAR T-cells at 15 centers between July 2018 and January 2023 who had been exposed to BsAbs prior to apheresis. Then, we identified a control cohort from patients included in the DESCAR-T Registry (n=764). We carried out a 1:1 propensity score matching (PSM) to achieve balance between cohorts; 13 baseline covariates were included in the PSM. We compared response rates, survival outcomes and toxicity after CAR T-cell therapy, according to previous BsAb exposure. Results: We identified 47 LBCL patients who received BsAb therapy prior to CAR T-cell apheresis. Median age was 65 years (range 31-82), with a male predominance (66%), and median prior lines of therapy before BsAb were 2 (IQR 2-3) (Table). The BsAbs targeted CD20/CD3 (91%) or CD22/CD3 (9%), either in monotherapy (n=41, 87%) or in combination with other agents (n=6, 13%) (lenalidomide [n=2], polatuzumab [n=1], chemotherapy [n=2], missing [n=1]). The median time on BsAb treatment was 98 days (IQR 56-160) with a best overall (complete) response rate (ORR [CRR]) of 47% (19%). Median progression-free survival (PFS) and duration of response (DOR) were 3.1 months (95% CI 2.7-4.4 months) and 8.8 months (95% CI 2.2-NR), respectively. Cytokine release syndrome (CRS) occurred in 59% of patients (grade 3 in 4%). No neurologic toxicity (NT) was reported. In 26 (55%) patients, bispecific antibody was the last line before CAR T-cell therapy. Median washout between the last BsAb dose and lymphocyte apheresis for CAR T-cell manufacturing was 43 days (range 34-103 days). In terms of the subsequent CAR T-cell therapy, patients received axi-cel (n=22, 47%), tisa-cel (n=20, 43%) or liso-cel (n=5, 11%). Most patients developed CRS after infusion (79%, 6% grade >2), with a low rate of NT (23%, 2% grade >2). Neutropenia and thrombocytopenia grade >2 were reported in 66% and 45% of patients, respectively. Regarding efficacy, ORR after infusion was 83% (CR 43%). Median PFS and overall survival (OS) were 6.6 months (95% CI 2.6-not reached [NR]) and NR (95% CI 9.0-NR), respectively. The rate of overall (complete) response was similar between patients who had previously responded (CR or PR) or not (SD or PD) to BsAb therapy (82% [41%] vs 84% [44%], respectively, p=0.64). However, all 9 patients achieving CR after BsAb achieved subsequent response to CAR T-cells. Given the wide variability in the washout between last BsAb dose and lymphocyte apheresis, we evaluated the impact of this interval on CAR T-cell efficacy. The 6-month PFS and OS of patients previously exposed to BsAb within 45 days of lymphocyte apheresis was similar to patients who had a longer washout (59% vs 47% [p=0.25] and 83% vs 67% [p=0.21], respectively). In the second part of the analysis, we matched our cohort with a control group of CAR T-cell recipients not previously exposed to BsAbs. The final analysis included 2 sets of 42 patients with comparable characteristics. Median follow-up from CAR T-cell infusion was 11.5 months for the BsAb cohort (CI 95% 6.4-19.0 months) and 18.8 months for the control cohort (CI 95% 10.9-23.0 months). Patients with previous BsAb exposure showed a similar PFS (p=0.10, Figure) and OS (p=0.08) after CAR T-cell infusion in comparison to the control group. In terms of toxicity, there were no differences in the incidence of CRS (p=0.41) or NT (p=1.0) after infusion. Conclusions: Previous exposure to bispecific antibody treatment targeting different antigens does not have a negative impact on survival outcomes after CAR T-cell therapy. Lack of response to a previous BsAb does not predict for lower response rates after CAR T-cell infusion.

Outsmart™ IL-2/15, a Novel Cytokine Designed to Enhance ROR1-Specific CAR T Anti-Tumor Activity While Minimizing Treg Activation and Systemic Cytokine Exposure

Introduction: Effective treatment with chimeric antigen receptor T (CAR-T) cells against solid and some liquid tumors will require the safe production of immune-modulating cytokines to promote CAR-T cell expansion and to stimulate endogenous anti-tumor immune responses within the tumor microenvironment. OutSmart™ IL-2/15 is a computationally designed, CD8α-targeted, IL-2-based cytokine produced by engineered T cells via a T cell activation-dependent promoter. Here, we demonstrate that inducible production of CD8-targeted IL-2/15 drives proliferation and anti-tumor efficacy of ROR1-specific CAR-T cells, stimulates bystander CD8 + T and NK cells, and minimizes activation of immune suppressive T regulatory cells (Tregs). Methods and Results: Wild-type (wt) IL-2 was modified using Rosetta protein design software package to eliminate IL-2Rα binding while retaining native IL-2Rβγ binding interfaces. Out of 10,355 designs, 38 were prioritized based on in silico analysis and ML-guided structure prediction, and evaluated for IL-2R binding as recombinant proteins. Consistent with the design criteria, none of the designs bound IL-2Rα, and 33 (87%) retained IL-2Rβγ binding and signaling activity. pSTAT5 analysis showed wt IL-2 highly activated CD4 +CD25 +FoxP3 + Treg cells, whereas the novel IL-2 designs showed a >3-log reduction Treg stimulation. These designs were iteratively optimized to generate a version exhibiting improved thermostability and IL-2Rβγ binding affinity equivalent to wt IL-2. To increase the potency against immune effector cells, but not Tregs, an anti-CD8α VHH was tethered to the modified IL-2 molecules (CD8-IL-2/15) to mimic high-affinity IL-2Rα binding and selectively activate CD8 + T and NK cells. This prosthetic binding interaction dramatically increased CD8 + T cell stimulation and CD8α + NK cell activation (>2-logs and 1-log by pSTAT5, respectively), while retaining its reduced capacity to stimulate Tregs. CD8-IL-2/15 gene expression was subsequently placed under the control of a T cell activation-dependent promoter and integrated into a lentiviral construct with a constitutively expressed ROR1-specific CAR. T cells transduced with a lentivirus expressing CD8-IL-2/15 and a ROR1-targeting CAR showed inducible cytokine production following exposure to ROR1 + tumor cells (H1975) leading to enhanced CAR-T cell proliferation and anti-tumor killing during repeat tumor challenge assays in vitro. Using immune-deficient mice (NSG) engrafted with H1975 tumors, inducible CD8-IL-2/15 enhanced ROR1-specific CAR-T cells showed durable tumor control at low doses (1e6 - 4e6 CAR T cells/animal), which was comparable to wt IL-2, whereas mock T cells and ROR1 CAR only T cells failed to control tumor growth ( Figure 1). In addition, CAR-T expansion with CD8-IL-2/15 increased >4-fold over wt IL-2 (p<0.0001), measured by cell counts in peripheral blood. Conclusions: In summary, OutSmart™ IL-2/15 is a genetic module that produces CD8-IL-2/15 in response to T cell activation, promoting robust CAR-T expansion and enhanced anti-tumor efficacy. Furthermore, local production of a CD8-IL-2/15 enhances the effector function of bystander CD8 + T cells and NK cells, but only minimally activates Treg cells due to removing the IL-2Rα binding interface. Inducible production of CD8-IL-2/15 dramatically improves the potency of a ROR1 CAR for treating ROR1 + solid and liquid cancers. More generally, OutSmart™ protein design methods and control technologies can be applied to create other designed cytokines for oncology and beyond.

A Phase 1 Dose Escalation Trial of Third-Generation CD19-Directed CAR T-Cells Incorporating CD28 and Toll-like Receptor 2 (TLR2) Intracellular Domains for Relapsed or Refractory B-Cell Non-Hodgkin Lymphomas (ENABLE)

Introduction: Chimeric antigen receptor (CAR) T cell therapies directed against CD19 and incorporating either CD28 or 4-1BB intracellular co-stimulatory domains are a standard of care for relapsed or refractory (r/r) B-cell lymphomas. CD19-directed CAR T-cell products employing CD28 co-stimulation yield high response rates, but have been associated with higher rates of immune effector cell-associated neurotoxicity syndrome (ICANS) and severe cytokine release syndrome (CRS) than 4-1BB co-stimulated products. There is a need for CAR T-cell products that combine high efficacy with low toxicity. Toll-like receptor 2 (TLR2) is expressed by T-cells, and its engagement enhances T-cell expansion, modulates cytokine production, and promotes long-lived T-cell memory. In preclinical studies, interposition of an intracellular domain from TLR2 between CD28 and CD3ζ resulted in reduced CAR T-cell production of ICANS-associated cytokines GM-CSF and IFN-γ, while maintaining production of the homeostatic cytokine IL-7. We investigated the safety and efficacy of a novel third generation CD19-directed CAR T-cell product, which combines CD28 and TLR2 co-stimulatory domains ( Figure). Methods: We completed a first-in-human phase 1 dose escalation trial of WZTL-002, comprising autologous 1928T2z CAR T-cells (‘ENABLE’, NCT04049513) for patients with r/r B-cell non-Hodgkin lymphomas (B-NHL). A 3+3 dose escalation design was used, with doses from 5 × 10 4 to 1 × 10 6 viable CAR T-cells/kg body weight. Eligible participants had radiologically assessable disease, satisfactory organ function and no central nervous system (CNS) involvement by lymphoma. Bridging therapy was permitted after leukapheresis and pending CAR T-cell manufacture and release. WZTL-002 CAR T-cells were administered intravenously after 3 days of fludarabine (30mg/m 2/day) and cyclophosphamide (500mg/m 2/day) lymphodepletion. Adverse events (AEs) were graded by CTCAE 5.0 except CRS and ICANS (graded by American Society for Transplantation and Cellular Therapy criteria). Response assessment was by PET/CT at month 3, per Lugano 2014 criteria. Pharmacokinetic analyses were by droplet digital PCR for CAR transgenes in blood mononuclear cells. Results: Of 21 patients treated within the dose escalation trial, median age was 57 years (range 23 - 70); 10 (48%) were female; 4 (19%) Māori. Lymphomas were of large cell histology in 17 (81%, Table). Participants had received a median of 4 prior lines of therapy, including autograft in 11 (52%) and allograft in 1. Product phenotyping showed WZTL-002 CAR T-cells were median 49% CD4 +, 41% CD8 + and 34% CD62L +. As of June 14 2023, all patients had reached the primary follow-up timepoint (3 months after WZTL-002 administration). Grade ≥ 3 AEs occurring in ≥ 10% of recipients were: neutropenia (95%), lymphopenia (57%), hypogammaglobulinemia (57%), anaemia (43%), febrile neutropenia (43%), thrombocytopenia (24%) and tumor pain (19%). Grade 1 - 2 CRS occurred in 13 patients (62%); 6 received tocilizumab and 3 dexamethasone. No CRS of grade ≥ 3, and no ICANS of any grade, occurred. Two grade 4 cytopenia dose limiting toxicities occurred at day 21 (one each at 5 × 10 5 and 1 × 10 6 cells/kg), both resolved to grade 2 by day 90. Maximum tolerated dose was not reached. Responses were seen at all dose levels with complete metabolic response in 11 (52%) at month 3. WZTL-002 CAR T-cells expanded at all dose levels. Among recipients of 0.5 - 1.0 × 10 6 CAR T-cells/kg (n = 12), median peak CAR T-cell level (C max) was 93,950 transgene copies/μg genomic DNA (reached at median day 10) and CAR T-cells persisted in 9 of 11 assessed (82%) at day 90. A recommended phase 2 dose (RP2D) range of 0.5 - 1 × 10 6/kg was selected. Conclusions: In this dose escalation trial of a novel third-generation CD19-directed CAR T-cell product that combines CD28 and TLR2 co-stimulatory domains for r/r B-NHL, we observed no severe CRS, no ICANS of any grade and complete responses at all dose levels. At RP2D, in vivo CAR T-cell expansion was similar to or greater than other CD19-directed products. In conjunction with preclinical findings, this study suggests interposition of a TLR2 domain between CD28 and CD3ζ domains may reduce CAR T-cell-related ICANS risk while retaining efficacy. Enrolment to a dose expansion cohort has commenced and will assess outpatient management and the safety and efficacy of WZTL-002 CAR T-cells manufactured using a closed automated process.

Torque Teno Virus plasma DNA load: a novel prognostic biomarker in CAR-T therapy.

Torque Teno Virus (TTV) is a single-stranded circular DNA virus which has been identified as a surrogate marker of immune competence in transplantation. In this study we investigated the dynamics of plasma TTV DNAemia in 79 adult patients undergoing chimeric antigen receptor T-cell (CAR-T) therapy for relapsed or refractory large B-cell lymphoma, also evaluating the impact of TTV on immunotoxicities, response and survival outcomes. After lymphodepleting therapy, TTV DNA load was found to decrease slightly until reaching nadir around day 10, after which it increased steadily until reaching maximum load around day 90. TTV DNA load < 4.05 log10 copies/ml at immune effector cell-associated neurotoxicity syndrome (ICANS) onset identified patients at risk of progressing to severe forms of ICANS (OR 16.68, P = 0.048). Finally, patients who experienced falling or stable TTV DNA load between lymphodepletion and CAR-T infusion had better progression-free survival than those with ascending TTV DNA load (HR 0.31, P = 0.006). These findings suggest that TTV monitoring could serve as a surrogate marker of immune competence, enabling predictions of CAR-T efficacy and toxicity. This could pave the way for the development of TTV-guided therapeutic strategies that modulate clinical patient management based on plasma TTV load, similar to suggested strategies in solid organ transplant recipients.

Efficacy and safety of fourth-generation CD19 CAR-T expressing IL7 and CCL19 along with PD-1 monoclonal antibody for relapsed or refractory large B-cell lymphoma

Objective: This study systematically explore the efficacy and safety of fourth-generation chimeric antigen receptor T-cells (CAR-T), which express interleukin 7 (IL7) and chemokine C-C motif ligand 19 (CCL19) and target CD19, in relapsed or refractory large B-cell lymphoma. Methods: Our center applied autologous 7×19 CAR-T combined with tirelizumab to treat 11 patients with relapsed or refractory large B-cell lymphoma. The efficacy and adverse effects were explored. Results: All 11 enrolled patients completed autologous 7×19 CAR-T preparation and infusion. Nine patients completed the scheduled six sessions of tirolizumab treatment, one completed four sessions, and one completed one session. Furthermore, five cases (45.5%) achieved complete remission, and three cases (27.3%) achieved partial remission with an objective remission rate of 72.7%. Two cases were evaluated for disease progression, and one died two months after reinfusion because of uncontrollable disease. The median follow-up time was 31 (2-34) months, with a median overall survival not achieved and a median progression-free survival of 28 (1-34) months. Two patients with partial remission achieved complete remission at the 9th and 12th months of follow-up. Therefore, the best complete remission rate was 63.6%. Cytokine-release syndrome and immune effector cell-associated neurotoxicity syndrome were controllable, and no immune-related adverse reactions occurred. Conclusion: Autologous 7×19 CAR-T combined with tirelizumab for treating relapsed or refractory large B-cell lymphoma achieved good efficacy with controllable adverse reactions.

Tislelizumab augment the efficacy of CD19/22 dual-targeted chimeric antigen receptor T cell in advanced stage relapsed or refractory B-cell non-Hodgkin lymphoma.

Dual-targeted chimeric antigen receptor T (CAR-T) cell is an important strategy to improve the efficacy of CD19 CAR-T cell against refractory or relapsed B cell non-Hodgkin lymphoma (R/R B-NHL). However, durable responses are not achieved in most patients, in part owing CAR-T cell exhaustion caused by PD-1/PD-L1 pathway.We conducted a prospective, single-arm study of dual-targeted CD19/22 CAR-T cell combined with anti-PD-1 antibody, tislelizumab, in R/R B-NHL (NCT04539444). Tislelizumab was administrated on +1day after patients received infusion of CD19/22 CAR-T cell. Responses, survival and safety were evaluated. From 1 August 2020 to 30 March 2023, 16 patients were enrolled. The median follow-up time is 16.0 (range: 5.0-32.0months) months. Overall response was achieved in 14 of 16 (87.5%) patients, and the complete response (CR) was achieved in 11 of 16 (68.8%) patients. The 1-year progression-free survival and overall survival rates were 68.8% and 81.3%, respectively. Of the 14 patients responded, 9 patients maintained their response until the end of follow-up. Among the 15 out of 16 (93.8%) patients who had extranodal involvement, 14 (93.3%) patients achieved overall response rate with 11 (73.3%) patients achieving CR. Eight (50%) patients experienced cytokine release syndrome. No neurologic adverse events were reported. Gene Ontology-Biological Process enrichment analysis showed that immune response-related signaling pathways were enriched in CR patients. Our results suggest that CD19/22 CAR-T cell combined with tislelizumab elicit a safe and durable response in R/R B-NHL and may improve the prognosis of those patients.

Targeted glycan degradation potentiates cellular immunotherapy for solid tumors

Immune cell-based cancer therapies, such as chimeric antigen receptor T (CAR-T)-cell immunotherapy, have demonstrated impressive potency against hematological tumors. However, the efficacy of CAR-T cells against solid tumors remains limited. Herein, we designed tumor-targeting molecule-sialidase conjugates that potently and selectively stripped different sialoglycans from a variety of cancer cells. Desialylation enhanced induced pluripotent stem cell-derived chimeric antigen receptor-macrophage (CAR-iMac) infiltration and activation. Furthermore, the combination of cancer cell desialylation and CAR-iMac adoptive cellular therapy exerted a dramatic therapeutic effect on solid tumors and significantly prolonged the survival of tumor-bearing mice; these effects were mainly dependent on blockade of the checkpoint composed of sialic acid-binding immunoglobulin-like lectin (Siglec)-5 and Siglec-10 on the macrophages, and knockout of the glycoimmune checkpoint receptors could construct a CAR-iMac cell with stronger anticancer activity. This strategy that reverts the immune escape state ("cold tumor") to a sensitive recognition state ("hot tumor") has great significance for enhancing the effect of cellular immunotherapy on solid tumors. Therefore, desialylation combined with CAR-iMac cellular immunotherapy is a promising approach to enhance treatment with cellular immunotherapy and expand the valid indications among solid tumors, which provides inspiration for the development of cellular immunotherapies with glycoimmune checkpoint inhibition for the treatment of human cancer.

Recombinant oncolytic adenovirus armed with CCL5, IL-12, and IFN-γ promotes CAR-T infiltration and proliferation in vivo to eradicate local and distal tumors

The efficacy of chimeric antigen receptor T (CAR-T) cells for solid tumors remains unsatisfactory due to the limited tumor infiltration and immunosuppressive microenvironment. To overcome these limitations, the genetically engineered recombinant oncolytic adenoviruses (OAVs) that conditionally replicate in tumor cells were developed to modify the tumor microenvironment (TME) to facilitate CAR-T-mediated tumor eradication. Here in the present study, a novel recombinant OAV carrying CCL5, IL12, and IFN-γ controlled by Ki67 promoter was constructed (named AdKi67-C3). The antitumor activity of AdKi67-C3 was tested in vitro and in vivo by using mono administration or combing with CAR-T cells targeting B7H3. It proved that CCL5 expressed by AdKi67-C3 indeed induced more CAR-T migration in vitro and CAR-T infiltration in tumor mass in vivo. Meanwhile, cytokines of IFN-γ and IL12 secreted by AdKi67-C3-infected tumor cells significantly promoted proliferation and persistence of CAR-T cells in vitro and in vivo. In tumor-bearing xenograft mouse models of kidney, prostate or pancreatic cancer, local pretreatment with AdKi67-C3 dramatically enhanced CAR-T cell efficacy and eliminated local and distant tumors. More importantly, mice achieving complete tumor regression resisted to re-challenge with the same tumor cells, suggesting establishment of long-term antitumor immune response. Therefore, OAVs armored with cytokines could be developed as a bioenhancer to defeat the immunosuppressive microenvironment and improve therapeutic efficacy of CAR-T in solid tumors.

Tumor-Targeted Nonablative Radiation Promotes Solid Tumor CAR T-cell Therapy Efficacy.

Infiltration of tumor by T cells is a prerequisite for successful immunotherapy of solid tumors. In this study, we investigate the influence of tumor-targeted radiation on chimeric antigen receptor (CAR) T-cell therapy tumor infiltration, accumulation, and efficacy in clinically relevant models of pleural mesothelioma and non-small cell lung cancers. We use a nonablative dose of tumor-targeted radiation prior to systemic administration of mesothelin-targeted CAR T cells to assess infiltration, proliferation, antitumor efficacy, and functional persistence of CAR T cells at primary and distant sites of tumor. A tumor-targeted, nonablative dose of radiation promotes early and high infiltration, proliferation, and functional persistence of CAR T cells. Tumor-targeted radiation promotes tumor-chemokine expression and chemokine-receptor expression in infiltrating T cells and results in a subpopulation of higher-intensity CAR-expressing T cells with high coexpression of chemokine receptors that further infiltrate distant sites of disease, enhancing CAR T-cell antitumor efficacy. Enhanced CAR T-cell efficacy is evident in models of both high-mesothelin-expressing mesothelioma and mixed-mesothelin-expressing lung cancer-two thoracic cancers for which radiotherapy is part of the standard of care. Our results strongly suggest that the use of tumor-targeted radiation prior to systemic administration of CAR T cells may substantially improve CAR T-cell therapy efficacy for solid tumors. Building on our observations, we describe a translational strategy of "sandwich" cell therapy for solid tumors that combines sequential metastatic site-targeted radiation and CAR T cells-a regional solution to overcome barriers to systemic delivery of CAR T cells.

Biomaterials for chimeric antigen receptor T cell engineering.

Chimeric antigen receptor T (CAR-T) cells have achieved breakthrough efficacies against hematological malignancies, but their unsatisfactory efficacies in solid tumors limit their applications. The prohibitively high prices further restrict their access to broader populations. Novel strategies are urgently needed to address these challenges, and engineering biomaterials can be one promising approach. The established process for manufacturing CAR-T cells involves multiple steps, and biomaterials can help simplify or improve several of them. In this review, we cover recent progress in engineering biomaterials for producing or stimulating CAR-T cells. We focus on the engineering of non-viral gene delivery nanoparticles for transducing CAR into T cells ex vivo/in vitro or in vivo. We also dive into the engineering of nano-/microparticles or implantable scaffolds for local delivery or stimulation of CAR-T cells. These biomaterial-based strategies can potentially change the way CAR-T cells are manufactured, significantly reducing their cost. Modulating the tumor microenvironment with the biomaterials can also considerably enhance the efficacy of CAR-T cells in solid tumors. We pay special attention to progress made in the past five years, and perspectives on future challenges and opportunities are also discussed. STATEMENT OF SIGNIFICANCE: Chimeric antigen receptor T (CAR-T) cell therapies have revolutionized the field of cancer immunotherapy with genetically engineered tumor recognition. They are also promising for treating many other diseases. However, the widespread application of CAR-T cell therapy has been hampered by the high manufacturing cost. Poor penetration of CAR-T cells into solid tissues further restricted their use. While biological strategies have been explored to improve CAR-T cell therapies, such as identifying new cancer targets or integrating smart CARs, biomaterial engineering provides alternative strategies toward better CAR-T cells. In this review, we summarize recent advances in engineering biomaterials for CAR-T cell improvement. Biomaterials ranging from nano-, micro-, and macro-scales have been developed to assist CAR-T cell manufacturing and formulation.

Enhancing CAR T-cell Therapy Using Fab-Based Constitutively Heterodimeric Cytokine Receptors.

Adoptive T-cell therapy aims to achieve lasting tumor clearance, requiring enhanced engraftment and survival of the immune cells. Cytokines are paramount modulators of T-cell survival and proliferation. Cytokine receptors signal via ligand-induced dimerization, and this principle has been hijacked utilizing nonnative dimerization domains. A major limitation of current technologies resides in the absence of a module that recapitulates the natural cytokine receptor heterodimeric pairing. To circumvent this, we created a new engineered cytokine receptor able to constitutively recreate receptor-heterodimer utilizing the heterodimerization domain derived from the IgG1 antibody (dFab_CCR). We found that the signal delivered by the dFab_CCR-IL2 proficiently mimicked the cytokine receptor heterodimerization, with transcriptomic signatures like those obtained by activation of the native IL2 receptor. Moreover, we found that this dimerization structure was agnostic, efficiently activating signaling through four cytokine receptor families. Using a combination of in vivo and in vitro screening approaches, we characterized a library of 18 dFab_CCRs coexpressed with a clinically relevant solid tumor-specific GD2-specific chimeric antigen receptor (CAR). Based on this characterization, we suggest that the coexpression of either the common β-chain GMCSF or the IL18 dFab_CCRs is optimal to improve CAR T-cell expansion, engraftment, and efficacy. Our results demonstrate how Fab dimerization is efficient and versatile in recapitulating a cytokine receptor heterodimerization signal. This module could be applied for the enhancement of adoptive T-cell therapies, as well as therapies based on other immune cell types. Furthermore, these results provide a choice of cytokine signal to incorporate with adoptive T-cell therapies.

An exploratory clinical trial on intra-lumbar injection of B7H3-specific allogeneic universal CAR-T cells in patients with recurrent high-grade gliomas.

2043 Background: No standard-of-care treatment was established for recurrent high-grade gliomas (rHGGs) yet. Intrathecal infusion of autologous chimeric antigen receptor-T (CAR-T) cells has displayed potent anti-tumor activity in one patient (Brown et al. N Engl J Med 2016). We evaluated the safety, efficacy, pharmacokinetic (PK) and pharmacodynamic (PD) characteristics of B7H3-specific allogeneic universal CAR-T (B7H3 UCAR-T) cells in patients with rHGGs. Methods: Eligible patients who had received standard treatment for newly-diagnosed high-grade gliomas but failed were treated with 2.5×107 B7H3 UCAR-T cells via intra-lumbar injection every month. Eligibility criteria included histologic and/or cytologic rHGGs, B7H3-positive antigen expression rate of &gt;50% in tumor tissue and Karnofsky performance status (KPS) ≥ 40. The primary endpoint was treatment-related adverse events (TAEs); secondary endpoints include overall survival (OS) and objective response rate (ORR); exploratory endpoints were PK and PD characteristics of B7H3 UCAR-T cells. Results: In the 7 patients enrolled, 4 (57.1%) were female, 5 (71.4%) glioblastoma (WHO Grade IV) and 2 (28.6%) diffuse midline glioma (WHO Grade IV), and the mean age was 40.4 years. The most common reported TAEs were increased cerebrospinal fluid (CSF) IL-6 (7/7, 100%), headache (7/7, 100%), increased blood IL-6 (6/7, 86%) and fever (6/7, 86%). No adverse events of grade 3 or greater related to B7H3 UCAR-T cells were reported. All the adverse events recovered or relieved after treatment. No typical or severe systemic cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS) or graft versus host disease (GvHD) were observed during the study period. Based on Immunotherapy Response Assessment in Neuro-Oncology (iRANO), 3 of 7 patients had response to therapy (42.9%; 95% CI: 15.8 to 75.0) and 7 of 7 patients were stable disease (100%; 95% CI: 64.6 to 100). As of cutoff date (January 30, 2023), two patients died. The median OS was not reached (95% CI: 12.9 to could not be estimated). The median follow-up for OS was 15.6 months (95% CI: 14.7 to 16.1). OS rate at 12 months was 85.7% (95% CI: 48.7 to 97.4). The CAR DNA copy numbers increased 1 day after each administration and persist at least 1 month in cerebrospinal fluid. IL-6 concentrations in CSF and peripheral blood increased after each administration while the change and concentration values in peripheral blood were much lower than those in CSF. Conclusions: In patients with rHGGs, B7H3 UCAR-T cells was not associated with any toxic effects of grade 3 or higher. B7H3 UCAR-T cells resulted in a significantly longer overall survival and a higher objective response rate than history data. B7H3 UCAR-T cells persist well in patients. Clinical trial information: ChiCTR2100047968 .

Impact of fludarabine exposure on the depth and duration of lymphopenia and CAR T-cell outcomes.

10033 Background: Chimeric antigen receptor (CAR) T-cells are highly effective for patients with relapsed or refractory B-ALL. Lymphodepletion has been paramount to CAR T-cell expansion and efficacy. Recent data identified an association of fludarabine exposure with reduced relapse rates, longer leukemia free survival, and more prolonged B-cell aplasia following tisagenlecleucel. However, the relationship of fludarabine exposure to lymphopenia and the mechanism by which dosing impacts outcomes following CAR T-cells remains unknown. Methods: We conducted a retrospective review of children and young adults with B-ALL who received fludarabine for lymphodepletion (LD) prior to infusion of anti-CD19, anti-CD22, or anti-CD19/22 bispecific CAR T-cells. The primary objective of this study was to investigate the impact of fludarabine on the depth and duration of lymphopenia. Secondary objectives included examining the impact of fludarabine exposure on: 1) overall clinical response, and 2) CAR T-cell expansion. All patients in the analysis cohort received fludarabine 25 mg/m2/day x 3 days ( = 75 mg/m2 cumulative dosing). Fludarabine exposure (AUC per dose) for each patient was predicted using a validated population PK model and analyzed with various responses/endpoints using the 3-day cumulative exposure/patient. Results: Of 137 children and young adults, the median cumulative AUC was 8.3 mg*hr/mL (range, 3.00-13.83 mg*hr /mL). The overall complete response (CR) rate was: 67.9% (93/137). The median duration of lymphopenia (defined as an absolute lymphocyte count (ALC) £ 150 K/uL) was 5 days (range, 0-15); and the median ALC on Day 0 was 80 K/uL (range, 0-1250 K/uL). When stratified by the median fludarabine exposure, there was no difference in depth or duration of lymphopenia or CAR T-cell expansion collectively or per trial. The median fludarabine exposure also did not differ between responders and non-responders. However, depth and duration of lymphopenia did differ in the CD22 CAR T-cell trial. Specifically, in those achieving CR, the duration of lymphopenia was longer than in non-responders (7 days versus 4 days, p = 0.030). Similarly, CAR T-cell expansion was higher if lymphopenia duration was greater than 5 days (p = 0.019). These findings were not seen across our less persistent CD19 or CD19/22 CAR T-cell trials. Conclusions: Although lymphodepletion impacts CAR T-cell response, we did not find an association between CR rate, depth of lymphopenia, or duration of lymphopenia with varying fludarabine exposures. This raises additional questions regarding the impact of LD therapy on CAR T-cell outcomes—especially since a more prolonged lymphopenia was associated with high CR rates and greater peak expansion in at least one of our studies (CD22 CAR T-cells). Future analysis will evaluate the impact of fludarabine on Day 0 cytokines and other immune parameters. Clinical trial information: NCT03448393 .

Early granulocyte colony stimulating factor administration increases the risk of cytokine release syndrome in acute lymphoblastic leukemia patients receiving anti-CD19 chimeric antigen receptor T-cell therapy.

Cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS) and neutropenia are common toxicities associated with chimeric antigen receptor T (CAR-T) cell therapy. The role of granulocyte colony stimulating factor (G-CSF) in CAR-T-cell-treated patients remains unclear. To explore the efficacy and safety of early G-CSF administration in patients with relapsed/refractory B-cell acute lymphoblastic leukemia (R/R B-ALL) who were receiving autologous anti-CD19 CAR-T cells, we retrospectively collected and summarized clinical data to compare patients receiving G-CSF within 14days (early G-CSF group) to patients receiving later or no G-CSF (control group) after their CART infusion. The results showed that there was no significant difference in the incidence and duration of neutropenia between the early G-CSF group and the control group (77% vs. 63%, p=0.65; 8 vs. 4days, p=0.37, respectively). However, the incidence and duration of CRS were significantly higher in the early G-CSF group than in the control group (81% vs. 38%, p=0.03; 3 vs. 0days, p=0.004, respectively). Moreover, early G-CSF application had no significant effect on the expansion and efficacy of CAR-T cells. In conclusion, our study suggested that early G-CSF administration did not reduce the incidence and duration of neutropenia but rather increased the incidence and duration of CRS.

Tumor-intrinsic sensitivity to the pro-apoptotic effects of IFN-γ is a major determinant of CD4+ CAR T-cell antitumor activity

CD4+ T cells and CD4+ chimeric antigen receptor (CAR) T cells display highly variable antitumor activity in preclinical models and in patients; however, the mechanisms dictating how and when CD4+ T cells promote tumor regression are incompletely understood. With the help of functional intravital imaging, we report that interferon (IFN)-γ production but not perforin-mediated cytotoxicity was the dominant mechanism for tumor elimination by anti-CD19 CD4+ CAR T cells. Mechanistically, mouse or human CD4+ CAR T-cell-derived IFN-γ diffused extensively to act on tumor cells at distance selectively killing tumors sensitive to cytokine-induced apoptosis, including antigen-negative variants. In anti-CD19 CAR T-cell-treated patients exhibiting elevated CAR CD4:CD8 ratios, strong induction of serum IFN-γ was associated with increased survival. We propose that the sensitivity of tumor cells to the pro-apoptotic activity of IFN-γ is a major determinant of CD4+ CAR T-cell efficacy and may be considered to guide the use of CD4+ T cells during immunotherapy.

Screening and characterization of the scFv for chimeric antigen receptor T cells targeting CEA-positive carcinoma.

Chimeric antigen receptor T (CAR-T) cell therapy presents a promising treatment option for various cancers, including solid tumors. Carcinoembryonic antigen (CEA) is an attractive target due to its high expression in many tumors, particularly gastrointestinal cancers, while limited expression in normal adult tissues. In our previous clinical study, we reported a 70% disease control rate with no severe side effects using a humanized CEA-targeting CAR-T cell. However, the selection of the appropriate single-chain variable fragment (scFv) significantly affects the therapeutic efficacy of CAR-T cells by defining their specific behavior towards the target antigen. Therefore, this study aimed to identify the optimal scFv and investigate its biological functions to further optimize the therapeutic potential of CAR-T cells targeting CEA-positive carcinoma. We screened four reported humanized or fully human anti-CEA antibodies (M5A, hMN-14, BW431/26, and C2-45), and inserted them into a 3rd-generation CAR structure. We purified the scFvs and measured the affinity. We monitored CAR-T cell phenotype and scFv binding stability to CEA antigen through flow cytometry. We performed repeated CEA antigen stimulation assays to compare the proliferation potential and response of the four CAR-T cells, then further evaluated the anti-tumor efficacy of CAR-T cells ex vivo and in vivo. M5A and hMN-14 CARs displayed higher affinity and more stable CEA binding ability than BW431/26 and C2-45 CARs. During CAR-T cell production culture, hMN-14 CAR-T cells exhibit a larger proportion of memory-like T cells, while M5A CAR-T cells showed a more differentiated phenotype, suggesting a greater tonic signal of M5A scFv. M5A, hMN-14, and BW431/26 CAR-T cells exhibited effective tumor cell lysis and IFN-γ release when cocultured with CEA-positive tumor cells in vitro, correlating with the abundance of CEA expression in target cells. While C2-45 resulted in almost no tumor lysis or IFN-γ release. In a repeat CEA antigen stimulation assay, M5A showed the best cell proliferation and cytokine secretion levels. In a mouse xenograft model, M5A CAR-T cells displayed better antitumor efficacy without preconditioning. Our findings suggest that scFvs derived from different antibodies have distinctive characteristics, and stable expression and appropriate affinity are critical for robust antitumor efficacy. This study highlights the importance of selecting an optimal scFv in CAR-T cell design for effective CEA-targeted therapy. The identified optimal scFv, M5A, could be potentially applied in future clinical trials of CAR-T cell therapy targeting CEA-positive carcinoma.

Chimeric antigen receptor-T cell efficacy can be evaluated on an Organ-Chip model system

Abstract Objective: The need for human-centric model systems that can test the efficacy of chimeric antigen receptor (CAR) therapies is expanding rapidly, as these hold great promise for cancer treatment. We recently developed a system for inflammatory immune cell recruitment on the human Colon Intestine-Chip as a model for inflammatory bowel disease (IBD). The goal of the current study was to develop a novel system for measuring the recruitment and killing capacity of CAR-T cells in an Organ-Chip system. Methods: We seeded a representative human HER2 +non-small cell lung carcinoma cell line (A549) into the top channel and human lung microvascular endothelial cells into the vascular (bottom) channel of Emulate’s S1 Organ-Chips. HER2-specific or CD19-specific (negative control) CAR-T cells were perfused through the vascular channel. Total CAR-T cell recruitment from the vasculature channel to the carcinoma-containing (top) channel and CAR-T-mediated killing (caspase activity, and IFN-g production) were measured over 72 hours. This system is further being used to monitor CAR-T cell exhaustion and efficacy of co-therapies (e.g., that might support CAR-T recruitment and killing efficacy). Results: HER2 CAR-T cells were recruited to the top channel, which was supported by the addition of known cancer chemokines (e.g. CXCL10), and induced significant killing and response to co-therapies as measured by caspase activity compared to controls. Conclusion: These early findings suggest that the human-centric Organ-Chip model can evaluate the efficacy of CAR-T cell therapies, and in particular, provide a system that integrates both the recruitment and killing aspects of CAR-T function.

Crystal Structure of a Chimeric Antigen Receptor (CAR) scFv Domain Rearrangement Forming a VL-VL Dimer

Chimeric Antigen Receptor T-cell (CAR-T) immunotherapies are dependent upon designed transmembrane proteins to bind target antigens and stimulate an immune response. The success or failure of these CARs is only partially predictable, yet recent work has highlighted the importance of antigen binding scFvs driving distinct oligomerization states with varied CAR-T efficacy. Here, we sought to determine the extracellular structure of the anti-CD19 CAR 47G4-CD828Z. Unexpectedly, the resolved crystal structure revealed an IgVL homodimer bound along an inverted VL|VL interface. We found that the VL-VH linker, designed to be cleavage resistant, was cleaved, and the VH and CAR hinge domains were absent from the crystal structure lattice. Molecular Dynamics simulations revealed that the inverted VL|VL interface was more stable than the canonical VL|VL configuration. Our work substantiates the need to interrogate the scFv structure and CAR oligomerization state for optimal CAR-T design.

CAR T-Cells for the Treatment of Refractory or Relapsed Large B-Cell Lymphoma: A Single-Center Retrospective Canadian Study.

Chimeric antigen receptor (CAR) T-cells are an important new third-line treatment option for large B-cell lymphoma (LBCL). The objective response rates in pivotal early phase clinical trials with CAR T-cells were very promising. The objective of this study was to describe the efficacy results obtained with CAR T-cells infusions in our institution and to compare the toxicities of our cohort with those of pivotal trials and studies conducted in a real-life setting. Efficacy and safety data were retrospectively collected from 25 patients with LBCL treated with CAR T-cells therapy at CHU de Québec-Université Laval. A literature search was then performed to identify other efficacy or safety data from a real-life setting. At 3 months post infusion, the objective response rate (ORR) in our population with tisagenlecleucel and axicabtagene-ciloleucel were 20% and 47%, respectively. Bulky disease was the only negative predictor of poor response at 3 months (0% vs. 53%, P=.03). Bulky disease was associated with a median PFS of 2 months compared to 5 months for non-bulky disease (P=.0009). Grade ≥ 3 hematological toxicities were greater in patients treated with axi-cel (60% vs. 20%, P=.048), without bone marrow involvement (55% vs. 0%, P =.046), without stage IV disease (72% vs. 21%, P =.02), with refractory disease (67% vs. 10%, P =.01) or having been affected by cytokine release syndrome (58% vs. 0%, P =.02). The poor response rate at 3 months after infusion in our cohort was influenced mainly by bulky disease. Further studies are needed to better characterize the loss of efficacy of CAR T-cells because the majority of patients will relapse over time.