A BAFF ligand-based CAR-T cell targeting three receptors and multiple B cell cancers

CAR-T cell targeting three receptors on autoreactive B cells for systemic lupus erythematosus therapy

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by dysregulated B cell activation, autoantibody production, and nephritis. B cell activating factor (BAFF) overexpression enhances autoreactive B-cell survival, driving autoimmunity. BAFF specific belimumab and CD20 specific rituximab antibodies are used for SLE therapy but are not curative, highlighting the need for alternative B cell depletion therapies. Here, we use BAFF ligand based chimeric antigen receptor T (CAR-T) cells targeting BAFFr, BCMA and TACI expressed on mature B cells and plasma cells. BAFF CAR-T cells efficiently killed B cells after co-culture with peripheral blood mononuclear cells (PBMCs) from SLE patients and in a patient derived SLE xenograft humanized mouse model developed by injecting patient PBMCs into immunocompromised mice. We also generated murine CD8+ T cells expressing human BAFF CAR to test their therapeutic efficacy in spontaneous (MRL/lpr) and pristane induced mouse models of SLE. In both models, BAFF CAR-T cells mediated persistent elimination of mature B cells, resulting in a decrease in the production of autoantibodies (IgM, IgG, Anti-ANA, and Anti-dsDNA IgG) and proteinuria along with prolonged survival. Adoptive transfer of B cells from control MRL/lpr lupus mice to previously BAFF CAR-T treated MRL/lpr lupus mice showed continued depletion of B cells and prolonged survival. Potential advantages of BAFF CAR-T therapy include avoiding B cell aplasia as BAFF receptors are not expressed by early B cells and preventing the escape of long-lived plasma cells post BAFF CAR-T therapy as they express receptors of BAFF. These data demonstrate the potential for a cellular immunotherapy based approach to induce remission of SLE pathogenesis using BAFF-CAR-T therapy.

Mechanisms for resistance to BCMA-targeted immunotherapies in multiple myeloma

Multiple myeloma (MM) remains incurable and patients eventually face the relapse/refractory dilemma. B cell maturation antigen (BCMA)-targeted immunotherapeutic approaches have shown great effectiveness in patients with relapsed/refractory MM, mainly including chimeric antigen receptor T cells (CAR-T), bispecific T cell engagers (TCEs), and antibody-drug conjugates (ADCs). However, their impact on long-term survival remains to be determined. Nonetheless, resistance to these novel therapies is still inevitable, raising a challenge that we have never met in both laboratory research and clinical practice. In this scenario, the investigation aiming to enhance and prolong the anti-MM activity of BCMA-targeted therapies has been expanding rapidly. Despite considerable uncertainty in our understanding of the mechanisms for their resistance, they have mainly been attributed to antigen-dependency, T cell-driven factors, and (immune) tumor microenvironment. In this review, we summarize the current understanding of the mechanisms for resistance to BCMA-targeted immunotherapies and discuss potential strategies for overcoming it.

CAR T-cell therapy for systemic lupus erythematosus: current status and future perspectives

Systemic lupus erythematosus (SLE) and lupus nephritis (LN) are debilitating autoimmune disorders characterized by pathological autoantibodies production and immune dysfunction, causing chronic inflammation and multi-organ damage. Despite current treatments with antimalarial drugs, glucocorticoids, immunosuppressants, and monoclonal antibodies, a definitive cure remains elusive, highlighting an urgent need for novel therapeutic strategies. Recent studies indicate that chimeric antigen receptor T-cell (CAR-T) therapy has shown promising results in treating B-cell malignancies and may offer a significant breakthrough for non-malignant conditions like SLE. In this paper, we aim to provide an in-depth analysis of the advancements in CAR-T therapy for SLE, focusing on its potential to revolutionize treatment for this complex disease. We explore the fundamental mechanisms of CAR-T cell action, the rationale for its application in SLE, and the immunological underpinnings of the disease. We also summarize clinical data on the safety and efficacy of anti-CD19 and anti-B cell maturation antigen (BCMA) CAR-T cells in targeting B-cells in SLE. We discuss the clinical implications of these findings and the potential for CAR-T therapy to improve outcomes in severe or refractory SLE cases. The integration of CAR-T therapy into the SLE treatment paradigm presents a new horizon in autoimmunity research and clinical practice. This review underscores the need for continued exploration and optimization of CAR-T strategies to address the unmet needs of SLE patients.

VSIG4 induces the immunosuppressive microenvironment by promoting the infiltration of M2 macrophage and Tregs in clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal cell carcinoma and has a poor prognosis. Despite the impressive advancements in treating ccRCC using immune checkpoint (IC) blockade, such as PD-1/PD-L1 inhibitors, a considerable number of ccRCC patients experience adaptive resistance. Therefore, exploring new targetable ICs will provide additional treatment options for ccRCC patients. We comprehensively analyzed multi-omics data and performed functional experiments, such as pathologic review, bulk transcriptome data, single-cell sequencing data, Western blotting, immunohistochemistry and in vitro/in vivo experiments, to explore novel immunotherapeutic targets in ccRCC. It was found that immune-related genes VSIG4, SAA1, CD7, FOXP3, IL21, TNFSF13B, BATF, CD72, MZB1, LTB, CCL25 and KLRK1 were significantly upregulated in ccRCC (Student's t test and p-value < 0.05; 36 normal and 267 ccRCC tissues in raining cohort; 36 normal and 266 ccRCC tissues in validation cohort) and correlated with the poor prognosis of ccRCC patients (Wald test and p-value < 0.05 in univariate cox analysis; log-rank test and p-value < 0.05 in Kaplan-Meier method; 267 patients in training cohort and 266 in validation cohort). In particular, we found the novel IC target VSIG4 was specifically expressed in inhibitory immune cells M2-biased tumor-associated macrophages (TAMs), conventional dendritic cell 2 (cDC2) cells, and cycling myeloid cells in ccRCC microenvironment. Moreover, VSIG4 showed a closely relation with resistance of Ipilimumab/Nivolumab immunotherapy in ccRCC. Furthermore, VSIG4 promoted the infiltration of M2 macrophages, Tregs, and cDC2 in ccRCC tissues. VSIG4+ TAMs and VSIG4+ cDC2s may be a kind of immune cell subtypes related to immunosuppression. VSIG4 may play similar roles with other IC ligands, as it is highly expressed on the surface of antigen-presenting cells and ccRCC cells to inhibit T cells activity and facilitate immune escape. Targeting IC gene VSIG4 may provide a novel immunotherapeutic strategy to ccRCC patients with resistance to existing targeted therapy options.

Advancements in the design and function of bispecific CAR-T cells targeting B Cell-Associated tumor antigens

Single-targeted CAR-T has exhibited notable success in treating B-cell tumors, effectively improving patient outcomes. However, the recurrence rate among patients remains above fifty percent, primarily attributed to antigen escape and the diminished immune persistence of CAR-T cells. Over recent years, there has been a surge of interest in bispecific CAR-T cell therapies, marked by an increasing number of research articles and clinical applications annually. This paper undertakes a comprehensive review of influential studies on the design of bispecific CAR-T in recent years, examining their impact on bispecific CAR-T efficacy concerning disease classification, targeted antigens, and CAR design. Notable distinctions in antigen targeting within B-ALL, NHL, and MM are explored, along with an analysis of how CAR scFv, transmembrane region, hinge region, and co-stimulatory region design influence Bi-CAR-T efficacy across different tumors. The summary provided aims to serve as a reference for designing novel and improved CAR-Ts, facilitating more efficient treatment for B-cell malignant tumors.

Cellular Therapies for Multiple Myeloma: Engineering Hope

Multiple myeloma (MM) treatment remains challenging due to its relapsed/refractory disease course as well as intra- and inter-patient heterogeneity. Cellular immunotherapies, especially chimeric antigen receptor (CAR)-T cells targeting B cell maturation antigen (BCMA), mark a major breakthrough, achieving long-lasting remissions and instilling hope for a potential cure. While ongoing clinical trials are increasingly driving approved cellular products towards earlier lines of therapy, novel targets as well as advanced approaches employing natural killer (NK) cells or dendritic cell (DC) vaccines are currently under investigation. Treatment resistance, driven by tumor-intrinsic factors such as antigen escape and the intricate dynamics of the tumor microenvironment (TME), along with emerging side effects such as movement and neurocognitive treatment-emergent adverse events (MNTs), are the major limitations of approved cellular therapies. To improve efficacy and overcome resistance, cutting-edge research is exploring strategies to target the microenvironment as well as synergistic combinatorial approaches. Recent advances in CAR-T cell production involve shortened manufacturing protocols and "off-the-shelf" CAR-T cells, aiming at decreasing socioeconomic barriers and thereby increasing patient access to this potential lifesaving therapy. In this review, we provide an extensive overview of the evolving field of cellular therapies for MM, underlining the potential to achieve long-lasting responses.

Split-design approach enhances the therapeutic efficacy of ligand-based CAR-T cells against multiple B-cell malignancies

To address immune escape, multi-specific CAR-T-cell strategies use natural ligands that specifically bind multiple receptors on malignant cells. In this context, we propose a split CAR design comprising a universal receptor expressed on T cells and ligand-based switch molecules, which preserves the natural trimeric structure of ligands like APRIL and BAFF. Following optimization of the hinges and switch labeling sites, the split-design CAR-T cells ensure the native conformation of ligands, facilitating the optimal formation of immune synapses between target cancer cells and CAR-T cells. Our CAR-T-cell strategy demonstrates antitumor activities against various B-cell malignancy models in female mice, potentially preventing immune escape following conventional CAR-T-cell therapies in the case of antigen loss or switching. This ligand-based split CAR design introduces an idea for optimizing CAR recognition, enhancing efficacy and potentially improving safety in clinical translation, and may be broadly applicable to cellular therapies based on natural receptors or ligands.

Current status of BAFF targeting immunotherapy in B-cell neoplasm

B-cell activating factor belonging to the TNF family (BAFF), also known as B-lymphocyte stimulator (BLyS), plays a crucial role in B-cell development. It has multiple receptors, including BCMA, TACI, and BAFF-R, with diverse roles in different cell types. BAFF induces B-cell proliferation and immunoglobulin secretion, and acts as a survival factor for immature, naive, and activated B cells. Consequently, BAFF-deficient mice often show suppressed humoral responses, while BAFF-overexpressing mice show the higher number of mature B cells and may develop autoimmune-like manifestations and B-cell lymphoproliferative diseases. Elevated BAFF levels are also associated with various hematological malignancies, and its expression correlates with disease progression in some cases. Therefore, BAFF-targeted therapies, such as belimumab, atacicept, and tabalumab, are being explored in clinical trials for conditions like chronic lymphocytic leukemia (CLL) and multiple myeloma. Belimumab, an anti-BAFF monoclonal antibody, is being investigated in combination with rituximab/venetoclax for CLL. Atacicept, a decoy receptor for BAFF and APRIL, showed tolerability in a phase 1b trial for CLL. Tabalumab, another monoclonal antibody targeting BAFF, did not demonstrate significant efficacy in a phase 2 study for relapsed/refractory multiple myeloma. BAFF ligand-based CAR-T cells are designed to target BAFF receptors and show promise in preclinical studies, particularly for B-cell malignancies. The review emphasizes the importance of understanding the roles of BAFF and its receptors in the microenvironment of hematologic malignancies. Targeting BAFF and its receptors presents potential therapeutic avenues, and ongoing clinical trials provide valuable insights.

BAFF overexpression in triple-negative breast cancer promotes tumor growth by inducing IL-10-secreting regulatory B cells that suppress anti-tumor T cell responses

PURPOSE

Despite BAFF's (B cell activating factor, BAFF) known influence on B cell survival and proliferation, its specific effects within the tumor microenvironment remain unclear. We aimed to elucidate how BAFF overexpression in breast cancer cells impacts tumor growth and the functions of T and B cells in the tumor microenvironment.

METHODS

BAFF was overexpressed in the 4T1 mouse triple-negative breast cancer cell line, and tumor growth, immune cell infiltration, and activity were assessed in vitro and in vivo using flow cytometry, co-culture assays, and mouse tumor models with B cell depletion.

RESULTS

BAFF overexpression in 4T1 cells promoted tumor growth in vivo, suppressed CD8+ T cell activity, and increased IL-10-secreting CD5+ regulatory B cells in tumors. 4T1/BAFF cells directly enhanced IL-10 production in CD5+ B cells via BAFF/BAFF-receptor interactions, and IL-10 from CD5+ B cells inhibited IFN-γ secretion by T cells. B cell depletion partially reversed the tumor-promoting effects of BAFF overexpression. Our study reveals a novel mechanism by which BAFF can foster tumor progression, with the induction of IL-10-secreting regulatory B cells that suppress anti-tumor T cell responses appearing to be a key component of BAFF's tumor-promoting activity.

CONCLUSION

These findings underscore the complex immunomodulatory effects that BAFF exerts in the tumor microenvironment and point to BAFF-induced regulatory B cells as a potential new therapeutic target in breast cancer that warrants further investigation.

Updates on CAR T cell therapy in multiple myeloma

Multiple myeloma (MM) is a hematological cancer characterized by the abnormal proliferation of plasma cells. Initial treatments often include immunomodulatory drugs (IMiDs), proteasome inhibitors (PIs), and monoclonal antibodies (mAbs). Despite salient progress in diagnosis and treatment, most MM patients typically have a median life expectancy of only four to five years after starting treatment. In recent developments, the success of chimeric antigen receptor (CAR) T-cells in treating B-cell malignancies exemplifies a new paradigm shift in advanced immunotherapy techniques with promising therapeutic outcomes. Ide-cel and cilta-cel stand as the only two FDA-approved BCMA-targeted CAR T-cells for MM patients, a recognition achieved despite extensive preclinical and clinical research efforts in this domain. Challenges remain regarding certain aspects of CAR T-cell manufacturing and administration processes, including the lack of accessibility and durability due to T-cell characteristics, along with expensive and time-consuming processes limiting health plan coverage. Moreover, MM features, such as tumor antigen heterogeneity, antigen presentation alterations, complex tumor microenvironments, and challenges in CAR-T trafficking, contribute to CAR T-cell exhaustion and subsequent therapy relapse or refractory status. Additionally, the occurrence of adverse events such as cytokine release syndrome, neurotoxicity, and on-target, off-tumor toxicities present obstacles to CAR T-cell therapies. Consequently, ongoing CAR T-cell trials are diligently addressing these challenges and barriers. In this review, we provide an overview of the effectiveness of currently available CAR T-cell treatments for MM, explore the primary resistance mechanisms to these treatments, suggest strategies for improving long-lasting remissions, and investigate the potential for combination therapies involving CAR T-cells.

T cell-redirecting therapies in hematological malignancies: Current developments and novel strategies for improved targeting

T cell-redirecting therapies (TCRTs), such as chimeric antigen receptor (CAR) or T cell receptor (TCR) T cells and T cell engagers, have emerged as a highly effective treatment modality, particularly in the B and plasma cell-malignancy setting. However, many patients fail to achieve deep and durable responses; while the lack of truly unique tumor antigens, and concurrent on-target/off-tumor toxicities, have hindered the development of TCRTs for many other cancers. In this review, we discuss the recent developments in TCRT targets for hematological malignancies, as well as novel targeting strategies that aim to address these, and other, challenges.

Recent updates on allogeneic CAR-T cells in hematological malignancies

CAR-T cell therapy is known as an effective therapy in patients with hematological malignancies. Since 2017, several autologous CAR-T cell (auto-CAR-T) drugs have been approved by the US Food and Drug Administration (FDA) for the treatment of some kinds of relapsed/refractory hematological malignancies. However, some patients fail to respond to these drugs due to high manufacturing time, batch-to-batch variation, poor quality and insufficient quantity of primary T cells, and their insufficient expansion and function. CAR-T cells prepared from allogeneic sources (allo-CAR-Ts) can be an alternative option to overcome these obstacles. Recently, several allo-CAR-Ts have entered into the early clinical trials. Despite their promising preclinical and clinical results, there are two main barriers, including graft-versus-host disease (GvHD) and allo-rejection that may decline the safety and efficacy of allo-CAR-Ts in the clinic. The successful development of these products depends on the starter cell source, the gene editing method, and the ability to escape immune rejection and prevent GvHD. Here, we summarize the gene editing technologies and the potential of various cell sources for developing allo-CAR-Ts and highlight their advantages for the treatment of hematological malignancies. We also describe preclinical and clinical data focusing on allo-CAR-T therapy in blood malignancies and discuss challenges and future perspectives of allo-CAR-Ts for therapeutic applications.

Antigen escape in CAR-T cell therapy: Mechanisms and overcoming strategies

Chimeric antigen receptor T (CAR-T) cell therapy has shown promise in treating hematological malignancies and certain solid tumors. However, its efficacy is often hindered by negative relapses resulting from antigen escape. This review firstly elucidates the mechanisms underlying antigen escape during CAR-T cell therapy, including the enrichment of pre-existing target-negative tumor clones, antigen gene mutations or alternative splicing, deficits in antigen processing, antigen redistribution, lineage switch, epitope masking, and trogocytosis-mediated antigen loss. Furthermore, we summarize various strategies to overcome antigen escape, evaluate their advantages and limitations, and propose future research directions. Thus, we aim to provide valuable insights to enhance the effectiveness of CAR-T cell therapy.

Update on the pathophysiology and treatment of primary Sjögren syndrome

Sjögren syndrome or Sjögren disease is a chronic form of autoimmune epithelitis characterized by lymphocytic infiltration of the exocrine glands, particularly the salivary and lacrimal glands, leading to progressive glandular dysfunction and subsequent xerostomia and xerophthalmia. Other common manifestations include pain and fatigue, various systemic manifestations and non-Hodgkin's lymphoma. Sjögren syndrome is therefore a complex and disabling disease associated with a reduced quality of life and with considerable long-term damage. Most of the available treatments are merely symptomatic with limited efficacy in both preventing glandular damage and suppressing systemic disease activity. In the past 10 years, great progress has been made in understanding the pathophysiology of Sjögren syndrome, opening new avenues towards a more targeted and individualized therapeutic approach to the disease. Indeed, several randomized controlled trials have just been completed or are poised to commence evaluating the effectiveness of novel drugs targeting both innate and adaptive immune pathways, including pro-inflammatory cytokines, the type I interferon system, B cell activation, B cell and T cell co-stimulation pathway, and ectopic germinal centre formation. Novel clinical trials are also ongoing exploring various targeted approaches (that is, IgG recycling inhibition, nuclease therapy and CAR-T cell therapy) for Sjögren syndrome.

Anti-B-Cell-Activating Factor (BAFF) Therapy: A Novel Addition to Autoimmune Disease Management and Potential for Immunomodulatory Therapy in Warm Autoimmune Hemolytic Anemia

Although rituximab is not specifically approved for the treatment of warm autoimmune hemolytic anemia (WAIHA), the First International Consensus Group recommends considering its use as part of the initial therapy for patients with severe disease and as a second-line therapy for primary WAIHA. Some patients do not respond to rituximab, and relapses are common. These relapses are associated with elevated B-cell-activating factor (BAFF) levels and the presence of quiescent long-lived plasma cells (LLPCs) in the spleen. A new group of immunomodulatory drugs, B-cell-activating factor inhibitors (BAFF-i), demonstrated efficacy in multiple autoimmune diseases and have the potential to improve WAIHA treatment outcomes by targeting B-cells and LLPCs. This article reviews the role of BAFF in autoimmune disorders and the currently available literature on the use of BAFF-directed therapies in various immunologic disorders, including WAIHA. Collectively, the clinical data thus far shows robust potential for targeting BAFF in WAIHA therapy.

IL-18-secreting multiantigen targeting CAR T cells eliminate antigen-low myeloma in an immunocompetent mouse model

ABSTRACT

Multiple myeloma is a plasma cell malignancy that is currently incurable with conventional therapies. Following the success of CD19-targeted chimeric antigen receptor (CAR) T cells in leukemia and lymphoma, CAR T cells targeting B-cell maturation antigen (BCMA) more recently demonstrated impressive activity in relapsed and refractory myeloma patients. However, BCMA-directed therapy can fail due to weak expression of BCMA on myeloma cells, suggesting that novel approaches to better address this antigen-low disease may improve patient outcomes. We hypothesized that engineered secretion of the proinflammatory cytokine interleukin-18 (IL-18) and multiantigen targeting could improve CAR T-cell activity against BCMA-low myeloma. In a syngeneic murine model of myeloma, CAR T cells targeting the myeloma-associated antigens BCMA and B-cell activating factor receptor (BAFF-R) failed to eliminate myeloma when these antigens were weakly expressed, whereas IL-18-secreting CAR T cells targeting these antigens promoted myeloma clearance. IL-18-secreting CAR T cells developed an effector-like T-cell phenotype, promoted interferon-gamma production, reprogrammed the myeloma bone marrow microenvironment through type-I/II interferon signaling, and activated macrophages to mediate antimyeloma activity. Simultaneous targeting of weakly-expressed BCMA and BAFF-R with dual-CAR T cells enhanced T-cell:target-cell avidity, increased overall CAR signal strength, and stimulated antimyeloma activity. Dual-antigen targeting augmented CAR T-cell secretion of engineered IL-18 and facilitated elimination of larger myeloma burdens in vivo. Our results demonstrate that combination of engineered IL-18 secretion and multiantigen targeting can eliminate myeloma with weak antigen expression through distinct mechanisms.

Evolution of the clinical-stage hyperactive TcBuster transposase as a platform for robust non-viral production of adoptive cellular therapies

Cellular therapies for the treatment of human diseases, such as chimeric antigen receptor (CAR) T and natural killer (NK) cells have shown remarkable clinical efficacy in treating hematological malignancies; however, current methods mainly utilize viral vectors that are limited by their cargo size capacities, high cost, and long timelines for production of clinical reagent. Delivery of genetic cargo via DNA transposon engineering is a more timely and cost-effective approach, yet has been held back by less efficient integration rates. Here, we report the development of a novel hyperactive TcBuster (TcB-M) transposase engineered through structure-guided and in vitro evolution approaches that achieves high-efficiency integration of large, multicistronic CAR-expression cassettes in primary human cells. Our proof-of-principle TcB-M engineering of CAR-NK and CAR-T cells shows low integrated vector copy number, a safe insertion site profile, robust in vitro function, and improves survival in a Burkitt lymphoma xenograft model in vivo. Overall, TcB-M is a versatile, safe, efficient and open-source option for the rapid manufacture and preclinical testing of primary human immune cell therapies through delivery of multicistronic large cargo via transposition.

CAR T therapies in multiple myeloma: unleashing the future

In recent years, the field of cancer treatment has witnessed remarkable breakthroughs that have revolutionized the landscape of care for cancer patients. While traditional pillars such as surgery, chemotherapy, and radiation therapy have long been available, a cutting-edge therapeutic approach called CAR T-cell therapy has emerged as a game-changer in treating multiple myeloma (MM). This novel treatment method complements options like autologous stem cell transplants and immunomodulatory medications, such as proteasome inhibitors, by utilizing protein complexes or anti-CD38 antibodies with potent complement-dependent cytotoxic effects. Despite the challenges and obstacles associated with these treatments, the recent approval of the second FDA multiple myeloma CAR T-cell therapy has sparked immense promise in the field. Thus far, the results indicate its potential as a highly effective therapeutic solution. Moreover, ongoing preclinical and clinical trials are exploring the capabilities of CAR T-cells in targeting specific antigens on myeloma cells, offering hope for patients with relapsed/refractory MM (RRMM). These advancements have shown the potential for CAR T cell-based medicines or combination therapies to elicit greater treatment responses and minimize side effects. In this context, it is crucial to delve into the history and functions of CAR T-cells while acknowledging their limitations. We can strategize and develop innovative approaches to overcome these barriers by understanding their challenges. This article aims to provide insights into the application of CAR T-cells in treating MM, shedding light on their potential, limitations, and strategies employed to enhance their efficacy.

Novel and multiple targets for chimeric antigen receptor-based therapies in lymphoma

Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 in B-cell non-Hodgkin lymphoma (NHL) validates the utility of CAR-based therapy for lymphomatous malignancies. Despite the success, treatment failure due to CD19 antigen loss, mutation, or down-regulation remains the main obstacle to cure. On-target, off-tumor effect of CD19-CAR T leads to side effects such as prolonged B-cell aplasia, limiting the application of therapy in indolent diseases such as chronic lymphocytic leukemia (CLL). Alternative CAR targets and multi-specific CAR are potential solutions to improving cellular therapy outcomes in B-NHL. For Hodgkin lymphoma and T-cell lymphoma, several cell surface antigens have been studied as CAR targets, some of which already showed promising results in clinical trials. Some antigens are expressed by different lymphomas and could be used for designing tumor-agnostic CAR. Here, we reviewed the antigens that have been studied for novel CAR-based therapies, as well as CARs designed to target two or more antigens in the treatment of lymphoma.

Interaction of immune cells with renal cancer development: Mendelian randomization (MR) study

BACKGROUND

Renal cell carcinoma (RCC) is a prevalent and extensively immune-infiltrated malignancy of the urinary system. Immune cells play a crucial role in both the progression and therapeutic interventions targeting RCC. Nevertheless, the interplay between RCC and immune cells remains understudied, lacking substantial evidence supporting their causal relationship.

METHODS

For the purpose of investigating the causal connection between RCC and immune cell characteristics, a two-way two-sample Mendelian randomization (MR) analysis was carried out in this study. The aim was to determine whether specific immune cell traits have a causal impact on the risk of RCC. In order to achieve this, publicly accessible genetic data was utilized to examine and establish the potential relationship between 731 immune cell characteristics and the likelihood of developing RCC. Additionally, various techniques were applied to verify the reliability, variability, and presence of horizontal pleiotropy in the outcomes.

RESULTS

We found a bidirectional causal relationship between RCC and immune cells according to the MR analysis results. It should be noted that CD4-CD8-T cells (OR = 1.61, 95%CI = 1.02-2.55, P = 4.07 × 10-2) pose a risk for RCC, whereas BAFF-R (OR = 0.69, 95%CI = 0.53-0.89, P = 5.74 × 10-3) and CD19 (OR = 0.59, 95%CI = 1.02-2.55, P = 4.07 × 10-2) on B cells act as protective factors. Furthermore, the presence of RCC reduces the levels of B cells (OR = 1.05, 95%CI = 1.01-1.09, P = 1.19 × 10-2) and CD8 + T cells (OR = 1.04, 95%CI = 1.00-1.08, P = 2.83 × 10-2).

CONCLUSIONS

Our research illustrates the intricate correlation between immune cells and RCC, presenting novel insights for the prospective safeguarding against RCC risk and the exploration of fresh therapeutic targets.

Mechanical force determines chimeric antigen receptor microclustering and signaling

Chimeric antigen receptor (CAR) T cells are activated to trigger the lytic machinery after antigen engagement, and this has been successfully applied clinically as therapy. The mechanism by which antigen binding leads to the initiation of CAR signaling remains poorly understood. Here, we used a set of short double-stranded DNA (dsDNA) tethers with mechanical forces ranging from ∼12 to ∼51 pN to manipulate the mechanical force of antigen tether and decouple the microclustering and signaling events. Our results revealed that antigen-binding-induced CAR microclustering and signaling are mechanical force dependent. Additionally, the mechanical force delivered to the antigen tether by the CAR for microclustering is generated by autonomous cell contractility. Mechanistically, the mechanical-force-induced strong adhesion and CAR diffusion confinement led to CAR microclustering. Moreover, cytotoxicity may have a lower mechanical force threshold than cytokine generation. Collectively, these results support a model of mechanical-force-induced CAR microclustering for signaling.

Chimeric Antigen Receptor T Cells in the Treatment of Multiple Myeloma

Chimeric antigen receptor T cells (CARTs) represent another powerful way to leverage the immune system to fight malignancy. Indeed, in multiple myeloma, the high response rate and duration of response to B cell maturation antigen-targeted therapies in later lines of disease has led to 2 Food and Drug Administration (FDA) drug approvals and opened the door to the development of this drug class. This review aims to provide an update on the 2 FDA-approved products, summarize the data for the most promising next-generation multiple myeloma CARTs, and outline current challenges in the field and potential solutions.

Precision Enhancement of CAR-NK Cells through Non-Viral Engineering and Highly Multiplexed Base Editing

Natural killer (NK) cells' unique ability to kill transformed cells expressing stress ligands or lacking major histocompatibility complexes (MHC) has prompted their development for immunotherapy. However, NK cells have demonstrated only moderate responses against cancer in clinical trials and likely require advanced genome engineering to reach their full potential as a cancer therapeutic. Multiplex genome editing with CRISPR/Cas9 base editors (BE) has been used to enhance T cell function and has already entered clinical trials but has not been reported in human NK cells. Here, we report the first application of BE in primary NK cells to achieve both loss-of-function and gain-of-function mutations. We observed highly efficient single and multiplex base editing, resulting in significantly enhanced NK cell function. Next, we combined multiplex BE with non-viral TcBuster transposon-based integration to generate IL-15 armored CD19 CAR-NK cells with significantly improved functionality in a highly suppressive model of Burkitt's lymphoma both in vitro and in vivo. The use of concomitant non-viral transposon engineering with multiplex base editing thus represents a highly versatile and efficient platform to generate CAR-NK products for cell-based immunotherapy and affords the flexibility to tailor multiple gene edits to maximize the effectiveness of the therapy for the cancer type being treated.

Poliovirus receptor-based chimeric antigen receptor T cells combined with NK-92 cells exert potent activity against glioblastoma

BACKGROUND

Poliovirus receptor interacts with 3 receptors: T-cell immunoglobulin immunoreceptor tyrosine-based inhibitory motif, CD96, and DNAX accessory molecule 1, which are predominantly expressed on T cells and natural killer (NK) cells. Many solid tumors, including IDH wild-type glioblastoma, have been reported to overexpress poliovirus receptor, and this overexpression is associated with poor prognosis. However, there are no preclinical or clinical trials investigating the use of cell-based immunotherapies targeting poliovirus receptor in IDH wild-type glioblastoma.

METHODS

We analyzed poliovirus receptor expression in transcriptome sequencing databases and specimens from IDH wild-type glioblastoma patients. We developed poliovirus receptor targeting chimeric antigen receptor T cells using lentivirus. The antitumor activity of chimeric antigen receptor T cells was demonstrated in patient-derived glioma stem cells, intracranial and subcutaneous mouse xenograft models.

RESULTS

We verified poliovirus receptor expression in primary glioma stem cells, surgical specimens from IDH wild-type glioblastoma patients, and organoids. Accordingly, we developed poliovirus receptor-based second-generation chimeric antigen receptor T cells. The antitumor activity of chimeric antigen receptor T cells was demonstrated in glioma stem cells and xenograft models. Tumor recurrence occurred in intracranial xenograft models because of antigen loss. The combinational therapy of tyrosine-based inhibitory motif extracellular domain-based chimeric antigen receptor T cells and NK-92 cells markedly suppressed tumor recurrence and prolonged survival.

CONCLUSIONS

Poliovirus receptor-based chimeric antigen receptor T cells were capable of killing glioma stem cells and suppressing tumor recurrence when combined with NK-92 cells.

IL6Myc mouse is an immunocompetent model for the development of aggressive multiple myeloma

Multiple Myeloma (MM) is a plasma cell neoplasm originating in the bone marrow and is the second most common blood cancer in the United States. One challenge in understanding the pathogenesis of MM and improving treatment is a lack of immunocompetent mouse models. We previously developed the IL6Myc mouse that generates plasmacytomas at 100% penetrance that phenotypically resemble aggressive MM. Using comprehensive genomic analysis, we found that the IL6Myc tumors resemble aggressive MM by RNA and protein expression. We also found that IL6Myc tumors accumulated fusions and missense mutations in genes that overlap significantly with human myeloma, indicating that the mouse is good model for studying disease etiology. Lastly, we derived cell lines from IL6Myc tumors that express cell surface markers typical of MM and readily engraft into mice, home to the bone marrow, and induce osteolytic disease. The cell lines may be useful in developing immunotherapies directed against BAFF-R and TACI, though not BCMA, and may also be a good model for studying dexamethasone resistance. These data indicate that the IL6Myc model is useful for studying development of aggressive MM and for developing new treatments against such forms of the disease.

CRISPR-based precision medicine for hematologic disorders: Advancements, challenges, and prospects

The development of programmable nucleases to introduce defined alterations in genomic sequences has been a powerful tool for precision medicine. While several nucleases such as zinc-finger nucleases (ZFN), transcriptor activator-like effector nucleases (TALEN), and meganucleases have been explored, the advent of CRISPR/Cas9 technology has revolutionized the field of genome engineering. In addition to disease modeling, the CRISPR/Cas9 technology has contributed to safer and more effective treatment strategies for hematologic diseases and personalized T-cell-based therapies. Here we discuss the applications of the CRISPR technology in the treatment of hematologic diseases, their efficacy, and ongoing clinical trials. We examine the obstacles to their successful use and the approaches investigated to overcome these challenges. Finally, we provide our perspectives to improve this genome editing tool for targeted therapies.

GAS6-based CAR-T cells exhibit potent antitumor activity against pancreatic cancer

BACKGROUND

The receptor tyrosine kinases TAM family (TYRO3, AXL, and MERTK) are highly expressed in multiple forms of cancer cells and tumor-associated macrophages and promote the development of cancers including pancreatic tumor. Targeting TAM receptors could be a promising therapeutic option.

METHODS

We designed a novel CAR based on the extracellular domain of growth arrest-specific protein 6 (GAS6), a natural ligand for all TAM members. The ability of CAR-T to kill pancreatic cancer cells is tested in vitro and in vivo, and the safety is evaluated in mice and nonhuman primate.

RESULTS

GAS6-CAR-T cells efficiently kill TAM-positive pancreatic cancer cell lines, gemcitabine-resistant cancer cells, and cancer stem-like cells in vitro. GAS6-CAR-T cells also significantly suppressed the growth of PANC1 xenografts and patient-derived xenografts in mice. Furthermore, these CAR-T cells did not induce obvious side effects in nonhuman primate or mice although the CAR was demonstrated to recognize mouse TAM.

CONCLUSIONS

Our findings indicate that GAS6-CAR-T-cell therapy may be effective for pancreatic cancers with low toxicity.

RIPK1 is aberrantly expressed in multiple B-cell cancers and implicated in the underlying pathogenesis

According to the latest epidemiology of the US, B-cell cancers account for > 3% of all new cancer cases and > 80% of non-Hodgkin lymphomas. However, the disease-modifying small molecular drug suitable for most B-cell cancers is still lacking. RIPK1 (receptor-interacting serine/threonine-protein kinase 1) has been observed to be dysregulated and implicated in the pathogenesis of multiple solid cancers, of which, however, the roles in blood cancers are quite unclear. In our study, to identify multi-function targets for B-cell cancer treatment, we reanalyzed a public transcriptomic dataset from the database of Gene Expression Omnibus, which includes CD19⁺ B-cell populations from 6 normal donors and patients of 5 CLL, 10 FL, and 8 DLBCL. After overlapping three groups (CLL vs. normal, FL vs. normal, and DLBCL vs. normal) of differentially expressed genes (DEGs), we obtained 69 common DEGs, of which 3 were validated by real-time quantitative PCR, including RIPK3, IGSF3, TGFBI. Interestingly, we found that the loss function of RIPK1 significantly increases the proliferation and viability of GM12878 cells (a normal human B lymphocyte cell line). Consistently, overexpression of RIPK1 in TMD8 and U2932 cells effectively inhibited cell proliferation and growth. More importantly, modifying RIPK1 kinase activity by a small molecule (such as necrostain-1, HOIPIN-1, etc.) alters the cell growth status of B-cell lymphoma, showing that RIPK1 exhibits anti-tumor activity in the context of B-cell lymphoma. Taken together, we consider that RIPK1 may be a potential target in the clinical application of B-cell lymphoma (including CLL, DLBCL, and FL) treatment.

3-O sulfation of syndecan-1 mediated by the sulfotransferase HS3ST3a1 enhances myeloma aggressiveness

Multiple myeloma is a hematological neoplasm derived from plasma cells invariably developing in the bone marrow (BM). The persisting clinical challenge in MM resides in its high ability to resist drugs as shown by the frequent relapses observed in patients regardless of the treatment applied. In a mouse model of MM, we identified a subpopulation of cells harboring increased resistance to current MM drugs. These cells bound a proliferation inducing ligand (APRIL), a key MM promoting/survival factor. APRIL binding involved the heparan sulfate (HS) chain present on syndecan-1 (SDC-1), and correlated with reactivity to the anti-HS antibody 10e4. 10e4+cells had a high proliferation activity, and were able to form colonies in 3-D cultures. 10e4+ cells were the only cells able to develop in BM after intravenous injection. They also resisted drugs in vivo, since their number increased after treatment in BM. Notably, 10e4+ cells differentiated into 10e4- cells upon in vitro and in vivo expansion. Expression of one sulfotransferase, HS3ST3a1, allowed modification of syndecan-1 to confer reactivity to 10e4 and binding to APRIL. HS3ST3a1 deletion inhibited tumorigenesis in BM. Notably, the two populations coexisted at a variable frequency in the BM of MM patients at diagnosis. In total, our results indicate that 3-O-sulfation on SDC-1 carried out by HS3ST3a1 defines aggressive MM cells, and that targeting of this enzyme could possibly be used to better control drug resistance.

Directed targeting of B-cell maturation antigen-specific CAR T cells by bioinformatic approaches: From in-silico to in-vitro

AIMS

Chimeric Antigen Receptor (CAR) T-cell is a breakthrough in cancer immunotherapy. The primary step of successful CAR T cell therapy is designing a specific single-chain fragment variable (scFv). This study aims to verify the designed anti-BCMA (B cell maturation antigen) CAR using bioinformatic techniques with the following experimental evaluations.

MAIN METHODS

Following the second generation of anti-BCMA CAR designing, the protein structure, function prediction, physicochemical complementarity at the ligand-receptor interface, and biding sites analysis of anti-BCMA CAR construct were confirmed using different modeling and docking server, including Expasy, I-TASSER, HDock, and PyMOL software. To generate CAR T-cells, isolated T cells were transduced. Then, anti-BCMA CAR mRNA and its surface expression were confirmed by real-time -PCR and flow cytometry methods, respectively. To evaluate the surface expression of anti-BCMA CAR, anti-(Fab')2 and anti-CD8 antibodies were employed. Finally, anti-BCMA CAR T cells were co-cultured with BCMA+/- cell lines to assess the expression of CD69 and CD107a as activation and cytotoxicity markers.

KEY FINDINGS

In-silico results approved the suitable protein folding, perfect orientation, and correct locating of functional domains at the receptor-ligand binding site. The in-vitro results confirmed high expression of scFv (89 ± 1.15% (and CD8α (54 ± 2.88%). The expression of CD69 (91.97 ± 1.7%) and CD107a (92.05 ± 1.29%) were significantly increased, indicating appropriate activation and cytotoxicity.

SIGNIFICANCE

In-silico studies before experimental assessments are crucial for state-of-art CAR designing. Highly activation and cytotoxicity of anti-BCMA CAR T-cell revealed that our CAR construct methodology would be applicable to define the road map of CAR T cell therapy.

Sequencing antigen-targeting antibodies and cellular therapies in adults with relapsed/refractory B-cell acute lymphoblastic leukemia

The recent approvals of four CD19-or CD22-targeted therapies for B-cell acute lymphoblastic leukemia (B-ALL) have transformed the treatment of relapsed/refractory (r/r) disease. Adults with r/r B-ALL are usually eligible for all options, but there are no studies directly comparing these agents, and the treating physician must decide which to select. Each therapy has notable activity as a single agent but has limitations in particular settings, and the optimal choice varies. These therapies can be complementary and used either sequentially or concomitantly. Here, we review the current landscape of antigen-targeted therapies for r/r B-ALL and discuss considerations for their use.

The BAFF-APRIL System in Cancer

B cell-activating factor (BAFF; also known as CD257, TNFSF13B, BLyS) and a proliferation-inducing ligand (APRIL; also known as CD256, TNFSF13) belong to the tumor necrosis factor (TNF) family. BAFF was initially discovered as a B-cell survival factor, whereas APRIL was first identified as a protein highly expressed in various cancers. These discoveries were followed by over two decades of extensive research effort, which identified overlapping signaling cascades between BAFF and APRIL, controlling immune homeostasis in health and driving pathogenesis in autoimmunity and cancer, the latter being the focus of this review. High levels of BAFF, APRIL, and their receptors have been detected in different cancers and found to be associated with disease severity and treatment response. Here, we have summarized the role of the BAFF-APRIL system in immune cell differentiation and immune tolerance and detailed its pathogenic functions in hematological and solid cancers. We also highlight the emerging therapeutics targeting the BAFF-APRIL system in different cancer types.

Past, Present, and a Glance into the Future of Multiple Myeloma Treatment

Multiple myeloma (MM) is a challenging hematological cancer which typically grows in bone marrow. MM accounts for 10% of hematological malignancies and 1.8% of cancers. The recent treatment strategies have significantly improved progression-free survival for MM patients in the last decade; however, a relapse for most MM patients is inevitable. In this review we discuss current treatment, important pathways for proliferation, survival, immune suppression, and resistance that could be targeted for future treatments.

CAR-T cell therapy in multiple myeloma: Current limitations and potential strategies

Over the last decade, the survival outcome of patients with multiple myeloma (MM) has been substantially improved with the emergence of novel therapeutic agents, such as proteasome inhibitors, immunomodulatory drugs, anti-CD38 monoclonal antibodies, selective inhibitors of nuclear export (SINEs), and T cell redirecting bispecific antibodies. However, MM remains an incurable neoplastic plasma cell disorder, and almost all MM patients inevitably relapse due to drug resistance. Encouragingly, B cell maturation antigen (BCMA)-targeted chimeric antigen receptor T (CAR-T) cell therapy has achieved impressive success in the treatment of relapsed/refractory (R/R) MM and brought new hopes for R/R MM patients in recent years. Due to antigen escape, the poor persistence of CAR-T cells, and the complicated tumor microenvironment, a significant population of MM patients still experience relapse after anti-BCMA CAR-T cell therapy. Additionally, the high manufacturing costs and time-consuming manufacturing processes caused by the personalized manufacturing procedures also limit the broad clinical application of CAR-T cell therapy. Therefore, in this review, we discuss current limitations of CAR-T cell therapy in MM, such as the resistance to CAR-T cell therapy and the limited accessibility of CAR-T cell therapy, and summarize some optimization strategies to overcome these challenges, including optimizing CAR structure, such as utilizing dual-targeted/multi-targeted CAR-T cells and armored CAR-T cells, optimizing manufacturing processes, combing CAR-T cell therapy with existing or emerging therapeutic approaches, and performing subsequent anti-myeloma therapy after CAR-T cell therapy as salvage therapy or maintenance/consolidation therapy.

Human Bone Marrow Plasma Cell Atlas: Maturation and Survival Pathways Unraveled by Single Cell Analyses

Human bone marrow (BM) plasma cells are heterogeneous, ranging from newly arrived antibody-secreting cells (ASC) to long-lived plasma cells (LLPC). We provide single cell transcriptional resolution of 17,347 BM ASC from 5 healthy adults. Fifteen clusters were identified ranging from newly minted ASC (cluster 1) expressing MKI67 and high MHC Class II that progressed to late clusters 5-8 through intermediate clusters 2-4. Additional clusters included early and late IgM-predominant ASC of likely extra-follicular origin; IFN-responsive; and high mitochondrial activity ASC. Late ASCs were distinguished by differences in G2M checkpoints, MTOR signaling, distinct metabolic pathways, CD38 expression, and utilization of TNF-receptor superfamily members. They mature through two distinct paths differentiated by the degree of TNF signaling through NFKB. This study provides the first single cell resolution atlas and molecular roadmap of LLPC maturation, thereby providing insight into differentiation trajectories and molecular regulation of these essential processes in the human BM microniche. This information enables investigation of the origin of protective and pathogenic antibodies in multiple diseases and development of new strategies targeted to the enhancement or depletion of the corresponding ASC. One Sentence Summary: The single cell transcriptomic atlas of human bone marrow plasma cell heterogeneity shows maturation of class-switched early and late subsets, specific IgM and Interferon-driven clusters, and unique heterogeneity of the late subsets which encompass the long-lived plasma cells.

A systematic review and meta-analysis of CD22 CAR T-cells alone or in combination with CD19 CAR T-cells

Chimeric antigen receptor (CAR) T-cells are an emerging therapy for the treatment of relapsed/refractory B-cell malignancies. While CD19 CAR-T cells have been FDA-approved, CAR T-cells targeting CD22, as well as dual-targeting CD19/CD22 CAR T-cells, are currently being evaluated in clinical trials. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of CD22-targeting CAR T-cell therapies. We searched MEDLINE, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials from inception to March 3rd 2022 for full-length articles and conference abstracts of clinical trials employing CD22-targeting CAR T-cells in acute lymphocytic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). The primary outcome was best complete response (bCR). A DerSimonian and Laird random-effects model with arcsine transformation was used to pool outcome proportions. From 1068 references screened, 100 were included, representing 30 early phase studies with 637 patients, investigating CD22 or CD19/CD22 CAR T-cells. CD22 CAR T-cells had a bCR of 68% [95% CI, 53-81%] in ALL (n= 116), and 64% [95% CI, 46-81%] in NHL (n= 28) with 74% and 96% of patients having received anti-CD19 CAR T-cells previously in ALL and NHL studies respectively. CD19/CD22 CAR T-cells had a bCR rate of 90% [95% CI, 84-95%] in ALL (n= 297) and 47% [95% CI, 34-61%] in NHL (n= 137). The estimated incidence of total and severe (grade ≥3) CRS were 87% [95% CI, 80-92%] and 6% [95% CI, 3-9%] respectively. ICANS and severe ICANS had an estimated incidence of 16% [95% CI, 9-25%] and 3% [95% CI, 1-5%] respectively. Early phase trials of CD22 and CD19/CD22 CAR T-cells show high remission rates in ALL and NHL. Severe CRS or ICANS were (1)rare and dual-targeting did not increase toxicity. Variability in CAR construct, dose, and patient factors amongst studies limits comparisons, with long-term outcomes yet to be reported.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42020193027.

Both APRIL and antibody-fragment-based CAR T cells for myeloma induce BCMA downmodulation by trogocytosis and internalization

BACKGROUND

Chimeric antigen receptor (CAR) T cell therapy targeting B cell maturation antigen (BCMA) on multiple myeloma (MM) produces fast but not long-lasting responses. Reasons for treatment failure are poorly understood. CARs simultaneously targeting two antigens may represent an alternative. Here, we (1) designed and characterized novel A proliferation inducing ligand (APRIL) based dual-antigen targeting CARs, and (2) investigated mechanisms of resistance to CAR T cells with three different BCMA-binding moieties (APRIL, single-chain-variable-fragment, heavy-chain-only).

METHODS

Three new APRIL-CARs were designed and characterized. Human APRIL-CAR T cells were evaluated for their cytotoxic function in vitro and in vivo, for their polyfunctionality, immune synapse formation, memory, exhaustion phenotype and tonic signaling activity. To investigate resistance mechanisms, we analyzed BCMA levels and cellular localization and quantified CAR T cell-target cell interactions by live microscopy. Impact on pathway activation and tumor cell proliferation was assessed in vitro and in vivo.

RESULTS

APRIL-CAR T cells in a trimeric ligand binding conformation conferred fast but not sustained antitumor responses in vivo in mouse xenograft models. In vitro trimer-BBζ CAR T cells were more polyfunctional and formed stronger immune synapses than monomer-BBζ CAR T cells. After CAR T cell-myeloma cell contact, BCMA was rapidly downmodulated on target cells with all evaluated binding moieties. CAR T cells acquired BCMA by trogocytosis, and BCMA on MM cells was rapidly internalized. Since BCMA can be re-expressed during progression and persisting CAR T cells may not protect patients from relapse, we investigated whether non-functional CAR T cells play a role in tumor progression. While CAR T cell-MM cell interactions activated BCMA pathway, we did not find enhanced tumor growth in vitro or in vivo.

CONCLUSION

Antitumor responses with APRIL-CAR T cells were fast but not sustained. Rapid BCMA downmodulation occurred independently of whether an APRIL or antibody-based binding moiety was used. BCMA internalization mostly contributed to this effect, but trogocytosis by CAR T cells was also observed. Our study sheds light on the mechanisms underlying CAR T cell failure in MM when targeting BCMA and can inform the development of improved treatment strategies.

Spermidine Promotes Nb CAR-T Mediated Cytotoxicity to Lymphoma Cells Through Elevating Proliferation and Memory

Purpose

Due to the natural advantages of spermidine in immunity, we investigated the effects of spermidine pretreatment on nanobody-based CAR-T cells (Nb CAR-T) mediated cytotoxicity and potential mechanism.

Patients and Methods

The optimal concentration of spermidine was determined by detecting its impact on viability and proliferation of T cells. The phenotypic characteristic of CAR-T cells, which were treated with spermidine for 4 days, was examined by flow cytometry. The expansion ability of CAR-T cells was monitored in being cocultured with tumor cells. Additionally, CAR-T cells were stimulated by lymphoma cells to test its cytotoxicity in vitro, and the supernatant in co-culture models were collected to test the cytokine production. Furthermore, xenograft models were constructed to detect the anti-tumor activity of CAR-T cells in vivo.

Results

The optimal concentration of spermidine acting on T cells was 5μM. The antigen-dependent proliferation of spermidine pretreatment CD19 CAR-T cells or Nb CAR-T cells was increased compared to control. Central memory T cells(TCM) dominated the CAR-T cell population in the presence of spermidine. When spermidine pretreatment CAR-T cells were stimulated with Daudi cells, the secretion of IL-2 and IFN-γ has been significantly enhanced. The ability of CAR-T cells to lysis Daudi cells was enhanced with the help of spermidine, even at higher tumor loads. Pre-treated Nb CAR-T cells with spermidine were able to control tumor cells in vivo, and therefore prolong mice survival.

Conclusion

Our results revealed that spermidine could promote Nb CAR-T mediated cytotoxicity to lymphomas cells through enhancing memory and proliferation, and provided a meaningful approach to strengthen the anti-tumor effect of CAR-T cells.

CAR-T cell therapy for hematological malignancies: Limitations and optimization strategies

In the past decade, the emergence of chimeric antigen receptor (CAR) T-cell therapy has led to a cellular immunotherapy revolution against various cancers. Although CAR-T cell therapies have demonstrated remarkable efficacy for patients with certain B cell driven hematological malignancies, further studies are required to broaden the use of CAR-T cell therapy against other hematological malignancies. Moreover, treatment failure still occurs for a significant proportion of patients. CAR antigen loss on cancer cells is one of the most common reasons for cancer relapse. Additionally, immune evasion can arise due to the hostile immunosuppressive tumor microenvironment and the impaired CAR-T cells in vivo persistence. Other than direct antitumor activity, the adverse effects associated with CAR-T cell therapy are another major concern during treatment. As a newly emerged treatment approach, numerous novel preclinical studies have proposed different strategies to enhance the efficacy and attenuate CAR-T cell associated toxicity in recent years. The major obstacles that impede promising outcomes for patients with hematological malignancies during CAR-T cell therapy have been reviewed herein, along with recent advancements being made to surmount them.

CAR-T Cell Therapy in Hematological Malignancies: Current Opportunities and Challenges

Chimeric antigen receptor T (CAR-T) cell therapy represents a major breakthrough in cancer treatment, and it has achieved unprecedented success in hematological malignancies, especially in relapsed/refractory (R/R) B cell malignancies. At present, CD19 and BCMA are the most common targets in CAR-T cell therapy, and numerous novel therapeutic targets are being explored. However, the adverse events related to CAR-T cell therapy might be serious or even life-threatening, such as cytokine release syndrome (CRS), CAR-T-cell-related encephalopathy syndrome (CRES), infections, cytopenia, and CRS-related coagulopathy. In addition, due to antigen escape, the limited CAR-T cell persistence, and immunosuppressive tumor microenvironment, a considerable proportion of patients relapse after CAR-T cell therapy. Thus, in this review, we focus on the progress and challenges of CAR-T cell therapy in hematological malignancies, such as attractive therapeutic targets, CAR-T related toxicities, and resistance to CAR-T cell therapy, and provide some practical recommendations.