Characteristics of anti-CD19 CAR T cell infusion products associated with efficacy and toxicity in patients with large B cell lymphomas

Single-cell dynamics of breakthrough toxicities after anakinra prophylaxis for axicabtagene ciloleucel in lymphoma

ABSTRACT

Chimeric antigen receptor (CAR) T-cell (CAR-T) therapy is limited by cytokine release syndrome (CRS) and neurotoxicity (NT). We sought to use once-daily prophylactic anakinra, an interleukin-1 (IL-1) receptor antagonist, to prevent CRS/NT that would require hospitalization (grade ≥2) in patients receiving axicabtagene ciloleucel for large-cell lymphoma, with the goal of facilitating outpatient therapy and management. Our study, in line with others, demonstrates that once-daily prophylactic anakinra is insufficient to prevent the development of toxicities that would require hospitalization in most patients. As part of the initial study design, we prospectively incorporated single-cell RNA sequencing to gain insight into the molecular immune signaling associated with breakthrough CRS and NT despite anakinra prophylaxis. In patients who developed breakthrough CRS or NT, we found that interferon gamma (IFN-γ) pathways and ligand-receptor activities were significantly enriched, as were cytokine levels of IFN-γ and CXCL10 in CD14+ monocytes. This correlated with increased IFN-γ and other cytokines in the peripheral blood. In infused CAR-T products, IL-4 and IL-10 anti-inflammatory pathways were negatively associated with grade ≥2 toxicities, regardless of anakinra treatment. These data identify IFN-γ as a potential key mechanism in CAR-T-associated toxicities, which is not inhibited by anakinra but may be otherwise targetable. This trial was registered at www.ClinicalTrials.gov as #NCT04150913.

Library-based single-cell analysis of CAR signaling reveals drivers of in vivo persistence

The anti-tumor function of engineered T cells expressing chimeric antigen receptors (CARs) is dependent on signals transduced through intracellular signaling domains (ICDs). Different ICDs are known to drive distinct phenotypes, but systematic investigations into how ICD architectures direct T cell function-particularly at the molecular level-are lacking. Here, we use single-cell sequencing to map diverse signaling inputs to transcriptional outputs, focusing on a defined library of clinically relevant ICD architectures. Informed by these observations, we functionally characterize transcriptionally distinct ICD variants across various contexts to build comprehensive maps from ICD composition to phenotypic output. We identify a unique tonic signaling signature associated with a subset of ICD architectures that drives durable in vivo persistence and efficacy in liquid, but not solid, tumors. Our findings work toward decoding CAR signaling design principles, with implications for the rational design of next-generation ICD architectures optimized for in vivo function.

Allogeneic off-the-shelf CAR T-cell therapy for relapsed or refractory B-cell malignancies

ABSTRACT

Despite clinical benefit with the use of chimeric antigen receptor (CAR) T cells, the need to manufacture patient-specific products limits its clinical utility. To overcome this barrier, we developed an allogeneic "off-the-shelf" CAR T-cell product using Epstein-Barr virus (EBV)-specific T cells (EBV-VSTs) genetically modified with a CD19-specific CAR (19-28z). Patients with relapsed/refractory (R/R) B-cell malignancies were stratified into 3 treatment cohorts: cohort 1 (n = 8; disease recurrence after allogeneic or autologous hematopoietic cell transplantation [HCT]), cohort 2 (n = 6; consolidative therapy after autologous HCT), or cohort 3 (n = 2; consolidative therapy after allogeneic HCT). The primary objective of this trial was to determine the safety of multiple CAR EBV-VST infusions. Most patients (n = 12/16) received multiple doses (overall median, 2.5 [range, 1-3]) with 3 × 106 T cells per kg determined to be the optimal dose enabling multiple treatments per manufactured cell line. Severe cytokine release syndrome or neurotoxicity did not occur after infusion, and no dose-limiting toxicity was observed in the trial. Median follow-up was 48 months (range, 4-135) with 4 deaths due to disease progression. Overall survival of all patients was 81% at 12 months and 75% at 36 months. Postinfusion expansion and persistence were limited, and CAR EBV-VSTs demonstrated a unique T-cell phenotype compared with autologous 19-28z CAR T cells. Our study demonstrates the feasibility and safety of an allogeneic "off-the-shelf" CAR EBV-VST product with favorable outcomes for patients with CD19+ R/R B-cell malignancies. This trial was registered at www.ClinicalTrials.gov as #NCT01430390.

Glofitamab in refractory or relapsed diffuse large B cell lymphoma after failing CAR-T cell therapy: a phase 2 LYSA study

Persons with diffuse large B cell lymphoma (DLBCL) refractory or in first progression/relapsed (R/R) after chimeric antigen receptor T (CAR-T) cell therapy exhibit dramatic outcomes. We enrolled such persons in a phase 2 single-arm, nonblinded trial ( NCT04703686 ) to evaluate the efficacy and safety of glofitamab, a CD20-CD3 T cell-engaging bispecific antibody, using a short ramp-up regimen to reach full dose within 1 week. A total of 46 participants received at least one glofitamab infusion following obinutuzumab (anti-CD20 monoclonal antibody) pretreatment. The primary endpoint was overall survival (OS). Secondary endpoints included independent-assessed best overall metabolic response rate (OMRR) and complete metabolic response rate (CMRR), progression-free survival (PFS), duration of response, safety and tolerability and health-related quality of life. After a median follow-up of 15.3 months (95% confidence interval (CI), 10.1-17.7), the primary endpoint was met, achieving a median OS of 14.7 months (90% CI, 8.8-not reached). The best OMRR was 76.1%. The best CMRR was 45.7%. The median PFS was 3.8 months (95% CI, 2.4-19.6). Despite the shortened setup dosing, no excess cytokine release syndrome or neurotoxicity events were observed (grade ≥ 3, 0% for both). In conclusion, glofitamab improved OS in participants with R/R DLBCL after CAR-T cell therapy, with a favorable safety profile.

Effects of an Initial Anti-CD19 CAR T-cell Therapy on Subsequent Anti-CD22 CAR T-cell Manufacturing and Clinical Outcomes in Patients with Relapsed/Refractory LBCL

SIGNIFICANCE

Late leukapheresis (>6 months after CAR19) resulted in less residual CAR19, higher CAR22 CD4+ naïve T and TCM cells, less TEM cells, and higher CD8+ TCM cells, but similar clinical outcomes to those with early leukapheresis. CAR22 responses were associated with higher transduction efficiency and CD8+ TCM and less CD8+ TEM cells.

The Bidirectional Interplay between T Cell-Based Immunotherapies and the Tumor Microenvironment

T cell-based therapies, including tumor-infiltrating lymphocyte therapy, T-cell receptor-engineered T cells, and chimeric antigen receptor T cells, are powerful therapeutic approaches for cancer treatment. Whereas these therapies are primarily known for their direct cytotoxic effects on cancer cells, accumulating evidence indicates that they also influence the tumor microenvironment (TME) by altering the cytokine milieu and recruiting additional effector populations to help orchestrate the antitumor immune response. Conversely, the TME itself can modulate the behavior of these therapies within the host by either supporting or inhibiting their activity. In this review, we provide an overview of clinical and preclinical data on the bidirectional influences between T-cell therapies and the TME. Unraveling the interactions between T cell-based therapies and the TME is critical for a better understanding of their mechanisms of action, resistance, and toxicity, with the goal of optimizing efficacy and safety.

CD8+ T cell-based immunotherapy: Promising frontier in human diseases

The abundant cell components of the adaptive immune system called T lymphocytes (T cells) play important roles in mediating immune responses to eliminate the invaders and create the memory of the germs to form a new immunity for the next encounter. Among them, cytotoxic T cells expressing cell-surface CD8 are the most critical effector cells that directly eradicate the target infected cells by recognizing antigens presented by major histocompatibility complex class I molecules to protect our body from pathological threats. In the continuous evolution of immunotherapy, various CD8+ T cell-based therapeutic strategies have been developed based on the role and molecular concept of CD8+ T cells. The emergence of such remarkable therapies provides promising hope for multiple human disease treatments such as autoimmunity, infectious disease, cancer, and other non-infectious diseases. In this review, we aim to discuss the current knowledge on the utilization of CD8+ T cell-based immunotherapy for the treatment of various diseases, the molecular basis involved, and its limitations. Additionally, we summarize the recent advances in the use of CD8+ T cell-based immunotherapy and provide a comprehensive overview of CD8+ T cells, including their structure, underlying mechanism of function, and markers associated with CD8+ T cell exhaustion. Building upon these foundations, we delineate the advancement of CD8+ T cell-based immunotherapies with fundamental operating principles followed by research studies, and challenges, as well as illustrate human diseases involved in this development.

Outcome correlates of approved CD19-targeted CAR T cells for large B cell lymphoma

CD19-targeted chimeric antigen receptor (CAR) T cells have provided a breakthrough in the treatment of patients with relapsed and/or refractory large B cell lymphoma (LBCL). Currently, three CD19-targeted CAR T cell products are approved by the FDA and various other regulators for the treatment of patients with LBCL: axicabtagene ciloleucel, tisagenlecleucel and lisocabtagene maraleucel. Response rates following infusion of these CD19-targeted CAR T cells have been promising; however, approximately half of treated patients show relapse within 2 years. Furthermore, receiving these agents can be associated with serious toxicities, including cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome. In this Review, we summarize the factors associated with the efficacy, including response and survival outcomes, and toxicity of CD19-targeted CAR T cells in pivotal clinical trials and large real-world datasets describing the outcomes of patients with LBCL who received treatment with these products.

CAR T cell-driven induction of iNOS in tumor-associated macrophages promotes CAR T cell resistance in B cell lymphoma

Chimeric antigen receptor (CAR) T cell therapies have revolutionized B cell malignancy treatment, but subsets of patients with large B cell lymphoma (LBCL) experience primary resistance or relapse after CAR T cell treatment. To uncover tumor microenvironment (TME)-induced resistance mechanisms, we examined patients' intratumoral immune infiltrates and observed that elevated levels of immunoregulatory macrophages in pre-infusion tumor biopsies are correlated with poor clinical responses. CAR T cell-produced interferon-gamma (IFN-γ) promotes the expression of inducible nitric oxide synthase (iNOS, NOS2) in immunoregulatory macrophages, impairing CAR T cell function. Mechanistically, iNOS-expressing macrophages upregulated the p53 pathway, mediating apoptosis and cell cycle arrest in CAR T cells, while downregulating the MYC pathway involved in ribosome biogenesis and protein synthesis. Furthermore, CAR T cell metabolism is compromised by depletion of glycolytic intermediates and rewiring of the TCA cycle. Pharmacological inhibition of iNOS enhances the CAR T cell treatment efficacy in B cell tumor-bearing mice. Notably, elevated levels of iNOS+CD14+ monocytes were observed in leukaphereses of patients with non-durable response to CAR T cell therapy. These findings suggest that mitigating iNOS in tumor-associated macrophages (TAMs) by blocking IFN-γ secretion from CAR T cells will improve outcomes for LBCL patients.

Measurable Residual Disease Testing During Treatment with Bispecific Antibodies for Lymphoma

The introduction of bispecific antibodies (BsAbs) has led to significant improvements in survival for patients with relapsed and refractory B-cell lymphomas. Despite these advances, there remains a significant number of patients who experience disease progression after these novel therapies. Predicting which patients may respond to certain treatments and the durability of their responses remains challenging. Measurable residual disease (MRD) has become easier to detect and quantify through the use of genomic next-generation sequencing tools and has been studied as a possible biomarker to predict long-term outcomes and risk-stratify patients after BsAb therapy in several lymphoma subtypes. Here, we review recent data demonstrating that MRD negativity is associated with radiographic response and improved progression-free survival. Because of heterogeneity in assay choice, assessment timing, and technical parameters, further work is needed before MRD testing is ready to be incorporated into clinical practice in the context of BsAb treatment for B-cell lymphomas.

Enrichment of CD7+CXCR3+ CAR T-cells in infusion products is associated with durable remission in relapsed or refractory diffuse large B-cell lymphoma

BACKGROUND

Chimeric antigen receptor (CAR) T-cell therapy is the standard of care for relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL). However, more than half of patients fail to achieve durable remission. Identifying predictive biomarkers within the CAR T-cell infusion product (IP) may guide strategies to improve clinical outcomes.

PATIENTS AND METHODS

This single-center observational study, conducted at Lausanne University Hospital (CHUV), Switzerland, analyzed IPs from 13 patients with R/R DLBCL who underwent standard-of-care CAR T-cell therapy. A 39-marker mass cytometry panel was used to compare phenotypic and functional markers between long-term responders (R) and nonresponders (NR). Unsupervised and supervised analytic approaches were applied to IP data, and longitudinal peripheral blood samples were collected over 30 days after infusion to track CAR T-cell subpopulation dynamics.

RESULTS

At a median follow-up of 13.5 months, median progression-free survival (PFS) was 13.3 months [95% confidence interval (CI) 9.7-24.3 months] in R (n = 8) versus 3.5 months (95% CI 0.5-5.4 months) in NR (n = 5) (hazard ratio 56.67, 95% CI 7.3-439.3, P = 0.0001). A CD3+CXCR3+CD7+ CAR T-cell subpopulation-found in both CD4+ and CD8+ compartments-was significantly enriched in R. These cells showed increased expression of perforin, granzyme B, and NKG2D (restricted to CD8+ cells). In contrast, NR had a higher frequency of CXCR3+CD7+LAG3+ CAR T-cells. Surface expression of CD3, CD7, CXCR3, and NKG2D were higher in R, whereas LAG3, Ki67, and CD71 were elevated in NR. A predictive cut-off ratio of CD3+CXCR3+CD7+LAG3+CAR+ T-cells <0.83 and CD3+CXCR3+CD7+NKG2D+CAR+ T-cells >1.034 yielded a predictive accuracy of 0.92. Serum CXCL9 and CXCL10 concentrations did not differ between groups.

CONCLUSIONS

Enrichment of CD7+CXCR3+ CAR T-cells alongside elevated NKG2D expression in R, in contrast to higher LAG3 and CD71 in NR, emerged as potentially robust correlates of therapeutic outcome. Although derived from a small, hypothesis-generating cohort, these findings suggest that targeted analysis of IP composition may inform the development of biomarker-driven strategies to optimize CAR T-cell products and improve the likelihood of durable remission in R/R DLBCL.

New player in CAR-T manufacture field: comparison of umbilical cord to peripheral blood strategies

One of the most successful treatments in hematologic cancer is chimeric antigen receptor (CAR)-T cell-based immunotherapy. However, CAR-T therapy is not without challenges like the costly manufacturing process required to personalize each treatment for individual patients or graft-versus-host disease. Umbilical cord blood (UCB) has been most commonly used for hematopoietic cell transplant as it offers several advantages, including its rich source of hematopoietic stem cells, lower risk of graft-versus-host disease, and easier matching for recipients due to less stringent HLA requirements compared to bone marrow or peripheral blood stem cells. In this review, we have discussed the advantages and disadvantages of different CAR-T cell manufacturing strategies with the use of allogeneic and autologous peripheral blood cells. We compare them to the UCB approach and discuss ongoing pre-clinical and clinical trials in the field. Finally, we propose a cord blood bank as a readily available source of CAR-T cells.

Two-Stage CD8+ CAR T-Cell Differentiation in Patients with Large B-Cell Lymphoma

Chimeric antigen receptor (CAR) T-cell therapy has expanded therapeutic options for patients with diffuse large B-cell lymphoma (DLBCL). However, progress in improving clinical outcomes has been limited by an incomplete understanding of CAR T-cell differentiation in patients. To comprehensively investigate CAR T-cell differentiation in vivo, we performed single-cell, multimodal, and longitudinal analyses of CD28-costimulated CAR T cells from infusion product and peripheral blood (day 8-28) of patients with DLBCL who were successfully treated with axicabtagene ciloleucel. Here, we show that CD8+ CAR T cells undergo two distinct waves of clonal expansion. The first wave is dominated by CAR T cells with an exhausted-like effector memory phenotype during the peak expansion period (day 8-14). The second wave is dominated by CAR T cells with a terminal effector phenotype during the post-peak persistence period (day 21-28). Importantly, the two waves have distinct ontogeny and are biologically uncoupled. Furthermore, lineage tracing analysis via each CAR T cell's endogenous TCR clonotype demonstrates that the two waves originate from different effector precursors in the infusion product. Precursors of the first wave exhibit more effector-like signatures, whereas precursors of the second wave exhibit more stem-like signatures. These findings suggest that pre-infusion heterogeneity mediates the two waves of in vivo clonal expansion. Our findings provide evidence against the intuitive idea that the post-peak contraction in CAR abundance is solely apoptosis or extravasation of short-lived CAR T cells from peak expansion. Rather, our findings demonstrate that CAR T-cell expansion and persistence are mediated by clonally, phenotypically, and ontogenically distinct CAR T-cell populations that serve complementary clinical purposes.

Immunophenotype of CAR T cells and apheresis products predicts response in CD22 CAR T cell trial for B cell acute lymphoblastic leukemia

Although CAR T cell therapy is increasingly used to treat relapsed B cell acute lymphoblastic leukemia (ALL), 20%-30% of patients do not respond, and few clinical predictors of response have been established, especially in the pediatric population. A deeper analysis of CAR T cell infusion products, along with the apheresis product used as the starting material for CAR T cell manufacturing, provides valuable insights for predicting clinical outcomes. We analyzed infusion products and CD4/8-selected T cell starting materials from pediatric and young adult patients on a single-center study with relapsed/refractory B cell ALL who were undergoing treatment with CD22 CAR T cells and evaluated differences between T cells from responders and non-responders (NCT023215612). We found that CAR T cells from non-responders had a more differentiated T cell phenotype and overexpressed genes associated with cytotoxicity and exhaustion compared with those of responders. Furthermore, we found that these differences could be tracked back to the apheresis materials prior to CAR T cell manufacturing. Using flow cytometry-based immunophenotypic markers, we developed a scoring system that distinguished non-responders based on T cell phenotype at the time of apheresis. These findings can help inform outcomes for patients and providers as well as provide insights into targeted manufacturing changes to optimize CAR T cell efficacy.

RHOA Loss of Function Impairs the IFNγ Response and Promotes CD19 Antigen Escape to Drive CAR-T Resistance in Diffuse Large B-cell Lymphoma

CD19-directed chimeric antigen receptor (CAR)-T cells are breakthrough therapies for aggressive B-cell lymphomas, but less than half of patients achieve durable responses. We previously showed through whole-genome sequencing of tumors from CAR-T-treated patients that deletions of RHOA (3p21.31) are enriched in cases progressing after treatment. RHOA 's roles in resistance and pathogenesis are poorly defined, despite loss-of-function alterations that occur in ~20% of newly diagnosed diffuse large B-cell lymphoma (DLBCL) cases. To evaluate mechanisms of CAR-T resistance, we created RHOA-deficient DLBCL systems and confirmed cell-intrinsic loss of response to CAR-19 in vitro and in vivo. RHOA loss promotes AKT activation that impairs cell-intrinsic responses to interferon gamma (IFNγ). Moreover, expression of the CAR target CD19 is consistently down-regulated accompanied by a drive toward plasmablast differentiation. RHOA deficient tumors demonstrate greatly increased sensitivity to AKT-pathway inhibitors, which reverse impaired IFNγ responses. Lymphoma microenvironments in vivo in immunocompetent mice reveal that RHOA loss promotes decreased infiltration by cytotoxic T cells and enrichment of M2-polarized macrophages, known markers of CAR-T resistance in lymphoma clinical cases. Overall, we characterize RHOA deficiency as an AKT-mediated CAR-T resistance driver and implicate avoidance of T-cell mediated killing as a likely reason for RHOA's frequent loss in DLBCL pathogenesis.

A Checkpoint Reversal Receptor Mediates Bipartite Activation and Enhances CAR T-cell Function

SIGNIFICANCE

Enhancing CART function and persistence while balancing immune effector-mediated inflammation is crucial. Using our clinically relevant HER2-CAR platform, we demonstrate that tumor-intrinsic signals like the PD-1/PD-L1 immune checkpoint can be leveraged in CART design to modulate immune synapse and metabolic parameters, improving antitumor function without increasing cytokine production.

Mapping variant effects on anti-tumor hallmarks of primary human T cells with base-editing screens

Single-nucleotide variants (SNVs) in key T cell genes can drive clinical pathologies and could be repurposed to improve cellular cancer immunotherapies. Here, we perform massively parallel base-editing screens to generate thousands of variants at gene loci annotated with known or potential clinical relevance. We discover a broad landscape of putative gain-of-function (GOF) and loss-of-function (LOF) mutations, including in PIK3CD and the gene encoding its regulatory subunit, PIK3R1, LCK, SOS1, AKT1 and RHOA. Base editing of PIK3CD and PIK3R1 variants in T cells with an engineered T cell receptor specific to a melanoma epitope or in different generations of CD19 chimeric antigen receptor (CAR) T cells demonstrates that discovered GOF variants, but not LOF or silent mutation controls, enhanced signaling, cytokine production and lysis of cognate melanoma and leukemia cell models, respectively. Additionally, we show that generations of CD19 CAR T cells engineered with PIK3CD GOF mutations demonstrate enhanced antigen-specific signaling, cytokine production and leukemia cell killing, including when benchmarked against other recent strategies.

Is there a place for engineered immune cell therapies in autoimmune diseases?

The ability to engineer immune cells yielded a transformative era in oncology. Early clinical trials demonstrated the efficacy of chimeric antigen receptor (CAR) T cells in resetting the immune system, motivating the expansion of this treatment beyond cancer, including autoimmune conditions. In this review, we discuss the current state of CAR T cell research in autoimmune diseases, examining the main challenges that limit widespread adoption of this therapy, such as complex isolation protocols, stringent immunosuppression, risk of secondary malignancies, and variable efficacy. We also review the studies addressing these limitations by development of off-the-shelf allogeneic CAR T cells, tunable safety systems, and antigen-specific therapies, which hold the potential to improve safety and accessibility of this treatment in clinical practice.

Enhanced conversion of T cells into CAR T cells by modulation of the MAPK/ERK pathway

Delivery of chimeric antigen receptors (CARs) to T cells is usually mediated by lentiviral vectors (LVs), which can have broad tropism or be T cell targeted. To better understand the molecular events during CAR T cell generation, T cell transduction with four different LVs is followed by single-cell multi-omics analysis, distinguishing between transduced T cells and T cells with vector signal but no CAR. We find that only a fraction of the T cells that encounter vectors convert into CAR T cells. Single-cell transcriptome data reveal that interferon-stimulated genes are upregulated in non-transduced cells, whereas extracellular signal-regulated kinase (ERK)2 phosphatases are upregulated in CAR T cells. This expression pattern is evident in CAR T cells from healthy donors and patients. The role of the mitogen-activated protein kinase (MAPK)/ERK pathway in CAR T cell generation is confirmed by chemical inhibitors. These data provide molecular insights into T cell transduction with implications for improving CAR T cell generation.

Genetic disruption of Blimp-1 drastically augments the antitumor efficacy of BCMA-targeting CAR T cells

ABSTRACT

Chimeric antigen receptor (CAR) T cells directed against B-cell maturation antigen (BCMA) are an effective treatment for multiple myeloma (MM), but short persistence and frequent relapses are challenges for this immunotherapy. This lack of durability has been attributed to the premature terminal differentiation of CAR T cells, which prevents the formation of long-lived memory cells that maintain antitumor responses. To improve long-term efficacy, we used CRISPR/CRISPR-associated protein 9-mediated gene editing to ablate the expression of the transcription factor Blimp-1. Blimp-1 knockout (KO) CAR T cells displayed a memory-like phenotype compared with control (Mock) CAR T cells, but had reduced effector function, with a striking loss of granzyme B. However, in a murine model of advanced MM, Blimp-1 KO CAR T cells effectively slowed or even prevented disease progression, significantly outperforming Mock CAR T cells in improving survival (P = .006). To understand this enhanced in vivo effectiveness, Blimp-1 KO CAR T cells were characterized after being repeatedly challenged with tumor cells in vitro. In this setting, Blimp-1 KO CAR T cells maintained a highly active state with high expression of memory markers, but, crucially, demonstrated enhanced effector function and increased energetic capacity. RNA-sequencing analysis of tumor-exposed Blimp-1 KO CAR T cells confirmed the presence of a memory-like transcriptomic signature and, additionally, revealed enhanced ribosome biogenesis and repressed CAR T-cell dysfunction as mechanisms that could contribute to improved antitumor activity. Put together, our findings show that dampening Blimp-1 expression altered the phenotype and function of anti-BCMA CAR T cells, leading to augmented therapeutic efficacy in MM.

TBK1 Targeting Is Identified as a Therapeutic Strategy to Enhance CAR T-Cell Efficacy Using Patient-Derived Organotypic Tumor Spheroids

Novel therapeutic strategies are needed to improve the efficacy of chimeric antigen receptor (CAR) T cells as a treatment of solid tumors. Multiple tumor microenvironmental factors are thought to contribute to resistance to CAR T-cell therapy in solid tumors, and appropriate model systems to identify and examine these factors using clinically relevant biospecimens are limited. In this study, we examined the activity of B7-H3-directed CAR T cells (B7-H3.CAR-T) using 3D microfluidic cultures of patient-derived organotypic tumor spheroids (PDOTS) and then confirmed the activity of B7-H3.CAR T cells in PDOTS. Although B7-H3 expression in PDOTS was associated with B7-H3.CAR-T sensitivity, mechanistic studies revealed dynamic upregulation of co-inhibitory receptors on CAR T-cells following target cell encounter that led to CAR T-cell dysfunction and limited efficacy against B7-H3-expressing tumors. PD-1 blockade restored CAR T-cell activity in monotypic and organotypic tumor spheroids with improved tumor control and upregulation of effector cytokines. Given the emerging role of TANK-binding kinase 1 (TBK1) as an immune evasion gene, we examined the effect of TBK1 inhibition on CAR T-cell efficacy. Similar to PD-1 blockade, TBK1 inhibition restored CAR T-cell activity in monotypic and organotypic tumor spheroids, prevented CAR T-cell dysfunction, and enhanced CAR T-cell proliferation. Inhibition or deletion of TBK1 also enhanced the sensitivity of cancer cells to immune-mediated killing. Taken together, our results demonstrate the feasibility and utility of ex vivo profiling of CAR T cells using PDOTS and suggest that targeting TBK1 could be used to enhance CAR T-cell efficacy by overcoming tumor-intrinsic and -extrinsic resistance mechanisms.

The Society for Immunotherapy of Cancer Perspective on Tissue-Based Technologies for Immuno-Oncology Biomarker Discovery and Application

With immuno-oncology becoming the standard of care for a variety of cancers, identifying biomarkers that reliably classify patient response, resistance, or toxicity becomes the next critical barrier toward improving care. Multiparametric, multi-omics, and computational platforms generating an unprecedented depth of data are poised to usher in the discovery of increasingly robust biomarkers for enhanced patient selection and personalized treatment approaches. Deciding which developing technologies to implement in clinical settings ultimately, applied either alone or in combination, relies on weighing pros and cons, from minimizing patient sampling to maximizing data outputs, and assessing the reproducibility and representativeness of findings, while lessening data fragmentation toward harmonization. These factors are all assessed while taking into consideration the shortest turnaround time. The Society for Immunotherapy of Cancer Biomarkers Committee convened to identify important advances in biomarker technologies and to address advances in biomarker discovery using multiplexed IHC and immunofluorescence, their coupling to single-cell transcriptomics, along with mass spectrometry-based quantitative and spatially resolved proteomics imaging technologies. We summarize key metrics obtained, ease of interpretation, limitations and dependencies, technical improvements, and outward comparisons of these technologies. By highlighting the most interesting recent data contributed by these technologies and by providing ways to improve their outputs, we hope to guide correlative research directions and assist in their evolution toward becoming clinically useful in immuno-oncology.

Adoptive cell therapy in acute myeloid leukemia: the current landscape and emerging strategies

Efforts to produce adoptive cell therapies in AML have been largely unfruitful, despite the success seen in lymphoid malignancies. Identifying targetable antigens on leukemic cells that are absent on normal progenitor cells remains a major obstacle, as is the hostile tumor microenvironment created by AML blasts. In this review, we summarize the challenges in the development of adoptive cell therapies such as CAR-T, CAR-NK, and TCR-T cells in AML, discussing both autologous and allogeneic therapies. We also discuss methods to address myelotoxicity associated with these therapies, including rapidly switchable CAR platforms and CRISPR-Cas9 genetic engineering of hematopoietic stem cells. Finally, we present the current clinical landscape in these areas, along with future directions in the field.

A multi-kinase inhibitor screen identifies inhibitors preserving stem-cell-like chimeric antigen receptor T cells

Chimeric antigen receptor T cells (CAR T cells) with T stem (TSCM) cell-like phenotypic characteristics promote sustained antitumor effects. We performed an unbiased and automated high-throughput screen of a kinase-focused compound set to identify kinase inhibitors (KIs) that preserve human TSCM cell-like CAR T cells. We identified three KIs, UNC10225387B, UNC10225263A and UNC10112761A, that combined in vitro increased the frequency of CD45RA+CCR7+TCF1hi TSCM cell-like CAR T cells from both healthy donors and patients with cancer. KI-treated CAR T cells showed enhanced antitumor effects both in vitro and in vivo in mouse tumor models. The KI cocktail maintains TSCM cell-like phenotype preferentially in CAR T cells originating from naive T cells and causes transcriptomic changes without arresting T cell activation or modulating the chromatin organization. Specific kinases, ITK, ADCK3, MAP3K4 and CDK13, targeted by the KI cocktail in a dose-dependent manner are directly associated with the preservation of TSCM cell-like CAR T cells. Knockdown of these kinases individually or in combination enriches for TSCM cell-like CAR T cells, but only CAR T cells generated in the presence of the KI cocktail show robust expansion and differentiation on stimulation with tumor cells. Overall, transient pharmacological inhibition of strategically targeted kinases maintains stem-like features in CAR T cells and improves their antitumor activity.

A cell atlas foundation model for scalable search of similar human cells

Single-cell RNA sequencing has profiled hundreds of millions of human cells across organs, diseases, development and perturbations to date. Mining these growing atlases could reveal cell-disease associations, identify cell states in unexpected tissue contexts and relate in vivo biology to in vitro models. These require a common measure of cell similarity across the body and an efficient way to search. Here we develop SCimilarity, a metric-learning framework to learn a unified and interpretable representation that enables rapid queries of tens of millions of cell profiles from diverse studies for cells that are transcriptionally similar to an input cell profile or state. We use SCimilarity to query a 23.4-million-cell atlas of 412 single-cell RNA-sequencing studies for macrophage and fibroblast profiles from interstitial lung disease1 and reveal similar cell profiles across other fibrotic diseases and tissues. The top scoring in vitro hit for the macrophage query was a 3D hydrogel system2, which we experimentally demonstrated reproduces this cell state. SCimilarity serves as a foundation model for single-cell profiles that enables researchers to query for similar cellular states across the human body, providing a powerful tool for generating biological insights from the Human Cell Atlas.

ETV7 limits the antiviral and antitumor efficacy of CD8+ T cells by diverting their fate toward exhaustion

Terminal exhaustion is a critical barrier to antitumor immunity. By integrating and analyzing single-cell RNA-sequencing and single-cell assay for transposase-accessible chromatin with sequencing data, we found that ETS variant 7 (ETV7) is indispensable for determining CD8+ T cell fate in tumors. ETV7 introduction drives T cell differentiation from memory to terminal exhaustion, limiting antiviral and antitumor efficacy in male mice. Mechanistically, ETV7 acts as a central transcriptional node by binding to specific memory genes and exhaustion genes and functionally skewing these transcriptional programs toward exhaustion. Clinically, ETV7 expression is negatively correlated with progression and responsiveness to immune checkpoint blockade in various human cancers. ETV7 depletion strongly enhances the antitumor efficacy of CD8+ T cells and engineered chimeric antigen receptor T cells in solid tumors. Thus, these findings demonstrate a decisive role for ETV7 in driving CD8+ T cell terminal exhaustion and reveal that ETV7 may be a promising target and biomarker for improving the efficacy of cancer immunotherapy.

Next-generation BCMA-targeted chimeric antigen receptor CARTemis-1: the impact of manufacturing procedure on CAR T-cell features

PURPOSE

CAR therapy targeting BCMA is under investigation as treatment for multiple myeloma. However, given the lack of plateau in most studies, pursuing more effective alternatives is imperative. We present the preclinical and clinical validation of a new optimized anti-BCMA CAR (CARTemis-1). In addition, we explored how the manufacturing process could impact CAR-T cell product quality and fitness.

METHODS

CARTemis-1 optimizations were evaluated at the preclinical level both, in vitro and in vivo. CARTemis-1 generation was validated under GMP conditions, studying the dynamics of the immunophenotype from leukapheresis to final product. Here, we studied the impact of the manufacturing process on CAR-T cells to define optimal cell culture protocol and expansion time to increase product fitness.

RESULTS

Two different versions of CARTemis-1 with different spacers were compared. The longer version showed increased cytotoxicity. The incorporation of the safety-gene EGFRt into the CARTemis-1 structure can be used as a monitoring marker. CARTemis-1 showed no inhibition by soluble BCMA and presents potent antitumor effects both in vitro and in vivo. Expansion with IL-2 or IL-7/IL-15 was compared, revealing greater proliferation, less differentiation, and less exhaustion with IL-7/IL-15. Three consecutive batches of CARTemis-1 were produced under GMP guidelines meeting all the required specifications. CARTemis-1 cells manufactured under GMP conditions showed increased memory subpopulations, reduced exhaustion markers and selective antitumor efficacy against MM cell lines and primary myeloma cells. The optimal release time points for obtaining the best fit product were > 6 and < 10 days (days 8-10).

CONCLUSIONS

CARTemis-1 has been rationally designed to increase antitumor efficacy, overcome sBCMA inhibition, and incorporate the expression of a safety-gene. The generation of CARTemis-1 was successfully validated under GMP standards. A phase I/II clinical trial for patients with multiple myeloma will be conducted (EuCT number 2022-503063-15-00).

Subcutaneous biodegradable scaffolds for restimulating the antitumour activity of pre-administered CAR-T cells

The efficacy of adoptive T-cell therapies based on chimaeric antigen receptors (CARs) is limited by the poor proliferation and persistence of the engineered T cells. Here we show that a subcutaneously injected biodegradable scaffold that facilitates the infiltration and egress of specific T-cell subpopulations, which forms a microenvironment mimicking features of physiological T-cell activation, enhances the antitumour activity of pre-administered CAR-T cells. CAR-T-cell expansion, differentiation and cytotoxicity were driven by the scaffold's incorporation of co-stimulatory bound ligands and soluble molecules, and depended on the types of co-stimulatory molecules and the context in which they were presented. In mice with aggressive lymphoma, a single, local injection of the scaffold following non-curative CAR-T-cell dosing led to more persistent memory-like T cells and extended animal survival. Injectable biomaterials with optimized ligand presentation may boost the therapeutic performance of CAR-T-cell therapies.

Immune checkpoints in B-cell Lymphoma: Still an Unmet challenge from Basic research to clinical practice

In the last decade, advancements in immunotherapy knowledge have highlighted CTLA-4, PD-1, LAG-3, TIM-3, and TIGIT, decisive immune checkpoints exhibiting within the tumor microenvironment (TME), as fundamental objects for cancer immunotherapy. The widespread clinical use of immune checkpoint inhibitors (ICls), employing PD-1/PD-L1 or CTLA-4 antibodies to obstruct crucial checkpoint regulators, is noted in treating B-cell lymphoma patients. Nevertheless, the prolonged advantages of the currently employed treatments against CTLA-4, PD-1, and PD-L1 are uncommon among patients. Thus, recent focus has been progressively moved to additional immune checkpoints on T cells, like LAG-3, TIM-3, and TIGIT, which are now seen as reassuring targets for treatment and broadly acknowledged. There are several types of immunecheckpoint molecules expressed by T cells, and inhibitors targeting immune checkpoints can revive and amplify the immune response of T lymphocytes against tumors, a crucial aspect in lymphoma therapy. However, there is little knowledge about their regulation. Herein, we discuss the anti-tumor effects and functions of ICIs in controlling T-cell activity, as well as the progress in combined application with other immunotherapies.

The future of immunotherapy for diffuse large B-cell lymphoma

With the introduction of anti-CD19 chimeric antigen receptor (CAR) T-cell (CAR T) therapies, bispecific CD3/CD20 antibodies and anti-CD19 antibodies, immunotherapy continues to transform the treatment of diffuse large B-cell lymphoma (DLBCL). A number of novel immunotherapeutic strategies are under investigation to build upon current clinical benefit and offer further options to those patients who cannot tolerate conventional intensive therapies due to their age and/or state of health. Alongside immunotherapies that leverage the adaptive immune response, natural killer (NK) cell and myeloid cell-engaging therapies can utilize the innate immune system. Monoclonal antibodies engineered for greater recognition by the patient's immune system can enhance antitumor cytotoxic mechanisms mediated by NK cells and macrophages. In addition, CAR technology is extending into NK cells and macrophages and investigational immune checkpoint inhibitors targeting macrophage/myeloid cell checkpoints via the CD47/SIRPα axis are in development. Regimens that engage both innate and adaptive immune responses may help to overcome resistance to current immunotherapies. Furthermore, combinations of immunotherapy and oncogenic pathway inhibitors to reprogram the immunosuppressive tumor microenvironment of DLBCL may also potentiate antitumor responses. As immunotherapy treatment options continue to expand, both in the first-line setting and further lines of therapy, understanding how to harness these immunotherapies and the potential for combination approaches will be important for the development of future DLBCL treatment approaches.

CAR-T therapy toxicities: the importance of macrophages in their development and possible targets for their management

CAR-T cell therapies have risen to prominence over the last decade, and their indications are increasing with several products approved as early as second line in Large B Cell non-Hodgkin Lymphomas. Their major toxicities are the cytokine release syndrome (CRS) and the Immune-effector Cell Associated Neurotoxicity Syndrome (ICANS). These entities involve a hyperinflammatory cascade which is amplified through the mononuclear phagocytic system (MPS). Herein, we review the immune mediated adverse events related to CAR therapy, including their pathophysiologies, and current therapies. In particular, we discuss the emerging role of the MPS in both the toxicity and efficacy of CAR-T therapy, and possible avenues for the modulation of the MPS to optimize efficacy while minimizing toxicity.

Enabling next-generation engineered TCR-T therapies based on high-throughput TCR discovery from diagnostic tumor biopsies

Adoptive cell therapy with tumor-infiltrating lymphocytes (TIL) can mediate tumor regression, including complete and durable responses, in a range of solid cancers, most notably in melanoma. However, its wider application and efficacy has been restricted by the limited accessibility, proliferative capacity and effector function of tumor-specific TIL. Here, we develop a platform for the efficient identification of tumor-specific TCR genes from diagnostic tumor biopsies, including core-needle biopsies frozen in a non-viable format, to enable engineered T cell therapy. Using a genetic screening approach that detects antigen-reactive TCRs with high sensitivity and specificity based on T cell activation, we show that high complexity TCR libraries can be efficiently screened against multiplexed antigen libraries to identify both HLA class I and II restricted TCRs. Through the identification of neoantigen-specific TCRs directly from melanoma as well as low tumor mutational burden microsatellite-stable colorectal carcinoma samples, we demonstrate the pan-cancer potential of this platform.

EZH2 inhibition enhances T cell immunotherapies by inducing lymphoma immunogenicity and improving T cell function

T cell-based immunotherapies have demonstrated effectiveness in treating diffuse large B cell lymphoma (DLBCL) and follicular lymphoma (FL) but predicting response and understanding resistance remains a challenge. To address this, we developed syngeneic models reflecting the genetics, epigenetics, and immunology of human FL and DLBCL. We show that EZH2 inhibitors reprogram these models to re-express T cell engagement genes and render them highly immunogenic. EZH2 inhibitors do not harm tumor-controlling T cells or CAR-T cells. Instead, they reduce regulatory T cells, promote memory chimeric antigen receptor (CAR) CD8 phenotypes, and reduce exhaustion, resulting in a decreased tumor burden. Intravital 2-photon imaging shows increased CAR-T recruitment and interaction within the tumor microenvironment, improving lymphoma cell killing. Therefore, EZH2 inhibition enhances CAR-T cell efficacy through direct effects on CAR-T cells, in addition to rendering lymphoma B cells immunogenic. This approach is currently being evaluated in two clinical trials, NCT05934838 and NCT05994235, to improve immunotherapy outcomes in B cell lymphoma patients.

Enriching central memory T cells using novel bioreactor design for T cell manufacturing

BACKGROUND

The manufacturing of T cell therapies aims to achieve high yields of product with potent phenotypes. We have developed a novel bioreactor, bioreactor with expandable culture area-dual chamber (BECA-D), which has previously demonstrated functionality for scaled T cell manufacturing.

METHODS AND RESULTS

Methods and Results: In this study, incorporation of a stirring mechanism into the double-chamber bioreactor design was tested to homogenize the media components between the two chambers. In addition to the improved media homogenization, the stirring culture was observed to have higher yield and enrichment of central memory T cells, a T cell subpopulation that has been associated with improved therapeutic efficacy compared with a static control. BECA-D with a stirring mechanism was evaluated for its performance in culturing T cells in comparison with a static control, BECA-D, and an industry benchmark, G-Rex10 (Wilson Wolf Manufacturing). BECA-D with a stirring mechanism was able to preferentially promote the enrichment of central memory T cells compared with the static cultures, indicative of the effect of the stirring mechanism.

CONCLUSION

By achieving high T cell yields with a favorable subpopulation profile, the mechanical method of incorporating stirring into a double-chamber bioreactor such as BECA-D carries great potential as a useful research and manufacturing tool to support advanced T-cell therapy manufacturing.

Interleukin-15-armoured GPC3 CAR T cells for patients with solid cancers

Interleukin-15 (IL-15) promotes the survival of T lymphocytes and enhances the antitumour properties of chimeric antigen receptor (CAR) T cells in preclinical models of solid neoplasms in which CAR T cells have limited efficacy1-4. Glypican-3 (GPC3) is expressed in a group of solid cancers5-10, and here we report the evaluation in humans of the effects of IL-15 co-expression on GPC3-expressing CAR T cells (hereafter GPC3 CAR T cells). Cohort 1 patients ( NCT02905188 and NCT02932956 ) received GPC3 CAR T cells, which were safe but produced no objective antitumour responses and reached peak expansion at 2 weeks. Cohort 2 patients ( NCT05103631 and NCT04377932 ) received GPC3 CAR T cells that co-expressed IL-15 (15.CAR), which mediated significantly increased cell expansion and induced a disease control rate of 66% and antitumour response rate of 33%. Infusion of 15.CAR T cells was associated with increased incidence of cytokine release syndrome, which was controlled with IL-1/IL-6 blockade or rapidly ameliorated by activation of the inducible caspase 9 safety switch. Compared with non-responders, tumour-infiltrating 15.CAR T cells from responders showed repression of SWI/SNF epigenetic regulators and upregulation of FOS and JUN family members, as well as of genes related to type I interferon signalling. Collectively, these results demonstrate that IL-15 increases the expansion, intratumoural survival and antitumour activity of GPC3 CAR T cells in patients.

Antigen experience history directs distinct functional states of CD8+ CAR T cells during the antileukemia response

Although chimeric antigen receptor (CAR) T cells are effective against B-lineage malignancies, post-CAR relapse is common, and efficacy in other tumors is limited. These challenges may be addressed through rational manipulations to control CAR T cell function. Here we examine the impact of cognate T cell antigen experience on subsequent CD8+ CAR T cell activity. Prior antigen encounter resulted in superior effector function against leukemia expressing low target antigen density at the expense of reduced proliferative capacity and susceptibility to dysfunction at limiting CAR doses. Distinctive temporal transcriptomic and epigenetic profiles in naive-derived and memory-derived CAR T cells identified RUNX family transcription factors as potential targets to augment the function of naive-derived CD8+ CAR T cells. RUNX2 overexpression enhanced antitumor efficacy of mouse CAR T cells, dependent on prior cell state, and heightened human CAR T cell functions. Our data demonstrate that prior antigen experience of CAR T cells determines functional attributes and amenability to transcription factor-mediated functional enhancement.

Should CAR-T cell therapy be considered a standard of care for patients with refractory diffuse large B-cell lymphoma in second line treatment?

INTRODUCTION

CAR-T therapy has transformed the treatment landscape for relapsed/refractory diffuse large B-cell lymphomas (DLBCL).

AREAS COVERED

This article reviews the existing evidence for using CAR-T therapy as a second-line treatment. Two major phase 3 trials, ZUMA-7 and TRANSFORM, have shown that axi-cel and liso-cel, respectively, offer superior outcomes compared to historical standard chemoimmunotherapy and consolidation with autologous hematopoietic stem cell transplantation (auto-HCT). Additionally, two promising phase 2 trials, PILOT and ALYCANTE, demonstrated the efficacy of CAR-T therapy in patients who are ineligible for auto-HCT. We also reviewed the potential biological factors behind these results.

EXPERT OPINION

Several factors support the use of CAR-T therapy in earlier treatment lines: better T-cell fitness in the infused product, reduced systemic inflammation in patients, and a more favorable tumor microenvironment. Although real-world data for second-line CAR-T therapy is still early, it is expected that CAR-T will be used more widely. Additional focus highlights the need for defining suitable patient populations and the efforts to enhance accessibility and cost-effectiveness of this groundbreaking treatment approach.

CD8α Structural Domains Enhance GUCY2C CAR-T Cell Efficacy

Despite success in treating some hematological malignancies, CAR-T cells have not yet produced similar outcomes in solid tumors due, in part, to the tumor microenvironment, poor persistence, and a paucity of suitable target antigens. Importantly, the impact of the CAR components on these challenges remains focused on the intracellular signaling and antigen-binding domains. In contrast, the flexible hinge and transmembrane domains have been commoditized and are the least studied components of the CAR. Here, we compared the hinge and transmembrane domains derived from either the CD8ɑ or CD28 molecule in identical GUCY2C-targeted third-generation designs for colorectal cancer. While these structural domains do not contribute to differences in antigen-independent contexts, such as CAR expression and differentiation and exhaustion phenotypes, the CD8ɑ structural domain CAR has a greater affinity for GUCY2C. This results in increased production of inflammatory cytokines and granzyme B, improved cytolytic effector function with low antigen-expressing tumor cells, and robust anti-tumor efficacy in vivo compared with the CD28 structural domain CAR. This suggests that CD8α structural domains should be considered in the design of all CARs for the generation of high-affinity CARs and optimally effective CAR-T cells in solid tumor immunotherapy.

CAR-T cell therapy: Advances in digestive system malignant tumors

Malignant tumors of the digestive system have had a notoriously dismal prognosis throughout history. Immunotherapy, radiotherapy, surgery, and chemotherapy are the primary therapeutic approaches for digestive system cancers. The rate of recurrence and metastasis, nevertheless, remains elevated. As one of the immunotherapies, chimeric antigen receptor T cell (CAR-T) therapy has demonstrated a promising antitumor effect in hematologic cancer. Despite undergoing numerous clinical trials, the ineffective antitumor effect and adverse effects of CAR-T cell therapy in the treatment of digestive system cancers continue to impede its clinical translation. It is necessary to surmount the restricted options for targeting proteins, the obstacles that impede CAR-T cell infiltration into solid tumors, and the limited survival time in vivo. We examined and summarized the developments, obstacles, and countermeasures associated with CAR-T therapy in digestive system cancers. Emphasis was placed on the regulatory functions of potential antigen targets, the tumor microenvironment, and immune evasion in CAR-T therapy. Thus, our analysis has furnished an all-encompassing comprehension of CAR-T cell therapy in digestive system cancers, which will generate tremendous enthusiasm for subsequent in-depth research into CAR-T-based therapies in digestive system cancers.

A novel mitochondrial pyruvate carrier inhibitor drives stem cell-like memory CAR T cell generation and enhances antitumor efficacy

Adoptive cell transfer with chimeric antigen receptor (CAR)-expressing T cells can induce remarkable complete responses in cancer patients. Therapeutic success has been correlated with central and stem cell-like memory T cell subsets in the infusion product, which are better able to drive efficient CAR T cell in vivo expansion and long-term persistence. We previously reported that inhibition of the mitochondrial pyruvate carrier (MPC) during mouse CAR T cell culture induces a memory phenotype and enhances antitumor efficacy against melanoma. Here, we use a novel MPC inhibitor, MITO-66, which robustly induces a stem cell-like memory phenotype in CD19-CAR T cells generated from healthy donors and patients with relapsed/refractory B cell malignancies. MITO-66-conditioned CAR T cells were superior in controlling human pre-B cell acute lymphoblastic leukemia in mice. Following adoptive cell transfer, MITO-66-conditioned CAR T cells maintained a memory phenotype and protected cured mice against tumor rechallenge. Furthermore, in an in vivo B cell leukemia stress model, CD19-CAR T cells generated in the presence of MITO-66 largely outperformed clinical-stage AKT and PI-3Kδ inhibitors. Thus, we provide compelling preclinical evidence that MPC inhibition with MITO-66 during CAR T cell manufacturing dramatically enhances their antitumor efficacy, thereby paving the way to clinical translation.

Acute Myeloid Leukemia Skews Therapeutic WT1-specific CD8 TCR-T Cells Towards an NK-like Phenotype that Compromises Function and Persistence

Acute myeloid leukemia (AML) that is relapsed and/or refractory post-allogeneic hematopoietic cell transplantation (HCT) is usually fatal. In a prior study, we demonstrated that AML relapse in high-risk patients was prevented by post-HCT immunotherapy with Epstein-Barr virus (EBV)-specific donor CD8+ T cells engineered to express a high-affinity Wilms Tumor Antigen 1 (WT1)-specific T-cell receptor (TTCR-C4). However, in the present study, infusion of EBV- or Cytomegalovirus (CMV)-specific TTCR-C4 did not clearly improve outcomes in fifteen patients with active disease post-HCT. TCRC4-transduced EBV-specific T cells persisted longer post-transfer than CMV-specific T cells. Persisting TTCR-C4 skewed towards dysfunctional natural killer-like terminal differentiation, distinct from the dominant exhaustion programs reported for T-cell therapies targeting solid tumors. In one patient with active AML post-HCT, a sustained TTCR-C4 effector-memory profile correlated with long-term TTCR-C4 persistence and disease control. These findings reveal complex mechanisms underlying AML-induced T-cell dysfunction, informing future therapeutic strategies for addressing post-HCT relapse.

Baseline immune state and T-cell clonal kinetics are associated with durable response to CAR-T therapy in large B-cell lymphoma

ABSTRACT

Engineered cellular therapy with CD19-targeting chimeric antigen receptor T cells (CAR-Ts) has revolutionized outcomes for patients with relapsed/refractory large B-cell lymphoma (LBCL), but the cellular and molecular features associated with response remain largely unresolved. We analyzed serial peripheral blood samples ranging from the day of apheresis (day -28/baseline) to 28 days after CAR-T infusion from 50 patients with LBCL treated with axicabtagene ciloleucel by integrating single-cell RNA and T-cell receptor sequencing, flow cytometry, and mass cytometry to characterize features associated with response to CAR-T. Pretreatment patient characteristics associated with response included the presence of B cells and increased absolute lymphocyte count to absolute monocyte count ratio (ALC/AMC). Infusion products from responders were enriched for clonally expanded, highly activated CD8+ T cells. We expanded these observations to 99 patients from the ZUMA-1 cohort and identified a subset of patients with elevated baseline B cells, 80% of whom were complete responders. We integrated B-cell proportion ≥0.5% and ALC/AMC ≥1.2 into a 2-factor predictive model and applied this model to the ZUMA-1 cohort. Estimated progression-free survival at 1 year in patients meeting 1 or both criteria was 65% vs 31% for patients meeting neither criterion. Our results suggest that patients' immunologic state at baseline affects the likelihood of response to CAR-T through both modulation of the T-cell apheresis product composition and promoting a more favorable circulating immune compartment before therapy. These baseline immunologic features, measured readily in the clinical setting before CAR-T, can be applied to predict response to therapy.

Impact of T cell characteristics on CAR-T cell therapy in hematological malignancies

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment paradigms for hematological malignancies. However, more than half of these patients cannot achieve sustainable tumor control, partially due to the inadequate potency of CAR-T cells in eradicating tumor cells. T cells are crucial components of the anti-tumor immune response, and multiple intrinsic T-cell features significantly influence the outcomes of CAR-T cell therapy. Herein, we review progressing research on T-cell characteristics that impact the effectiveness of CAR-T cells, including T-cell exhaustion, memory subsets, senescence, regulatory T-cells, the CD4+ to CD8+ T-cell ratio, metabolism, and the T-cell receptor repertoire. With comprehensive insight into the biological processes underlying successful CAR-T cell therapy, we will further refine the applications of these novel therapeutic modalities, and enhance their efficacy and safety for patients.

Impact of immunological aging on T cell-mediated therapies in older adults with multiple myeloma and lymphoma

The treatment landscape for lymphoma and multiple myeloma, which disproportionally affect older adults, has been transformed by the advent of T cell-mediated immunotherapies, including immune checkpoint inhibition, T cell-engaging bispecific antibodies, and chimeric antigen receptor (CAR) T cell therapy, during the last decade. These treatment modalities re-enable the patient's own immune system to combat malignant cells and offer the potential for sustained remissions and cure for various diseases.Age profoundly affects the physiological function of the immune system. The process of biological aging is largely driven by inflammatory signaling, which is reciprocally fueled by aging-related alterations of physiology and metabolism. In the T cell compartment, aging contributes to T cell senescence and exhaustion, increased abundance of terminally differentiated cells, a corresponding attrition in naïve T cell numbers, and a decrease in the breadth of the receptor repertoire. Furthermore, inflammatory signaling drives aging-related pathologies and contributes to frailty in older individuals. Thus, there is growing evidence of biological aging modulating the efficacy and toxicity of T cell-mediated immunotherapies.Here, we review the available evidence from biological and clinical studies focusing on the relationship between T cell-mediated treatment of hematologic malignancies and age. We discuss biological features potentially impacting clinical outcomes in various scenarios, and potential strategies to improve the safety and efficacy of immune checkpoint inhibitors, T cell-engaging bispecific antibodies, and CAR-T cell therapy in older patients.

Titrating chimeric antigen receptors on CAR T cells enabled by a microfluidic-based dosage-controlled intracellular mRNA delivery platform

Chimeric antigen receptor (CAR) T-cell therapy shows unprecedented efficacy for cancer treatment, particularly in treating patients with various blood cancers, most notably B-cell acute lymphoblastic leukemia. In recent years, CAR T-cell therapies have been investigated for treating other hematologic malignancies and solid tumors. Despite the remarkable success of CAR T-cell therapy, cytokine release syndrome (CRS) is an unexpected side effect that is potentially life-threatening. Our aim is to reduce pro-inflammatory cytokine release associated with CRS by controlling CAR surface density on CAR T cells. We show that CAR expression density can be titrated on the surface of primary T cells using an acoustic-electric microfluidic platform. The platform performs dosage-controlled delivery by uniformly mixing and shearing cells, delivering approximately the same amount of CAR gene coding mRNA into each T cell.

New horizons in our understanding of precursor multiple myeloma and early interception

Multiple myeloma is an incurable plasma cell malignancy that evolves over decades through the selection and malignant transformation of monoclonal plasma cells. The evolution from precursor states to symptomatic disease is characterized by an increasing complexity of genomic alterations within the plasma cells and a remodelling of the microenvironment towards an immunosuppressive state. Notably, in patients with advanced disease, similar mechanisms of tumour escape and immune dysfunction mediate resistance to modern T cell-based therapies, such as T cell-engaging bispecific antibodies and chimeric antigen receptor (CAR)-T cells. Thus, an increasing number of clinical trials are assessing the efficiency and safety of these therapies in individuals with newly diagnosed multiple myeloma and high-risk smoldering multiple myeloma. In this Review, we summarize the current knowledge about tumour intrinsic and extrinsic processes underlying progression from precursor states to symptomatic myeloma and discuss the rationale for early interception including the use of T cell-redirecting therapies.

A high-density microfluidic bioreactor for the automated manufacturing of CAR T cells

The manufacturing of autologous chimaeric antigen receptor (CAR) T cells largely relies either on fed-batch and manual processes that often lack environmental monitoring and control or on bioreactors that cannot be easily scaled out to meet patient demands. Here we show that human primary T cells can be activated, transduced and expanded to high densities in a 2 ml automated closed-system microfluidic bioreactor to produce viable anti-CD19 CAR T cells (specifically, more than 60 million CAR T cells from donor cells derived from patients with lymphoma and more than 200 million CAR T cells from healthy donors). The in vitro secretion of cytokines, the short-term cytotoxic activity and the long-term persistence and proliferation of the cell products, as well as their in vivo anti-leukaemic activity, were comparable to those of T cells produced in a gas-permeable well. The manufacturing-process intensification enabled by the miniaturized perfusable bioreactor may facilitate the analysis of the growth and metabolic states of CAR T cells during ex vivo culture, the high-throughput optimization of cell-manufacturing processes and the scale out of cell-therapy manufacturing.