Lymphodepletion - an essential but undervalued part of the chimeric antigen receptor T-cell therapy cycle

Enhancing mesothelin CAR T cell therapy for pancreatic cancer with an oncolytic herpes virus boosting CAR target antigen expression

Mesothelin (MSLN) is a prominent target antigen for CAR T cell therapy due to its extensive expression in various solid tumors, including pancreatic cancer. However, the therapeutic efficacy of MSLN-targeted CAR T cell therapy has been limited in clinical trials for pancreatic cancer, often resulting in temporary stable disease as the best response. The heterogeneous expression of MSLN and its loss over time, along with the immunosuppressive tumor microenvironment (TME), are key factors restricting effectiveness. Oncolytic viruses are emerging cancer therapies that replicate in tumor cells and remodel the TME into an immunogenic state. Here, we engineered an oncolytic herpes simplex virus type 1 expressing human MSLN (HSV-MSLN) and evaluated its combination with MSLN-CAR T cells in a murine pancreatic ductal adenocarcinoma model. In vitro, HSV-MSLN effectively induced MSLN expression on murine pancreatic cancer cells, with subsequent cell lysis. In co-culture, HSV-MSLN-infected cancer cells activated MSLN-CAR T cells, which effectively eliminated the infected cells. In vivo, HSV-MSLN delivered MSLN on the tumor cell surface and reprogrammed the TME toward an immunogenic state. The combination therapy significantly enhanced antitumor efficacy, inducing activated, proliferative CD8+ CAR T cells and reducing PD-1+TIM-3+ exhausted endogenous CD8+ T cells and regulatory T cells in tumors. Furthermore, the combination therapy increased migratory XCR1+CD103+ dendritic cells (DCs) in tumors and tumor-draining lymph nodes (TDLNs) while expanding CD44+CD8+ T cells with central and effector memory phenotypes. Taken together, these results demonstrate that HSV-MSLN reprograms immune cells in the TME and TDLNs and synergizes with MSLN-CAR T cells to enhance antitumor responses, leading to a more robust therapeutic effect.

Health and Economic Impact of Vein-to-Vein Time in CAR T-Cell Therapy in the Second-Line Treatment of Relapsed/Refractory Large B-cell Lymphoma: A US Cost-Effectiveness Analysis

BACKGROUND

Chimeric antigen receptor T-cell (CAR T) therapies are approved in the United States (US) for the treatment of relapsed/refractory (R/R) large B-cell lymphoma (LBCL). In the CAR T treatment process, a short vein-to-vein time (V2VT) is critical to minimize the likelihood of deterioration from aggressive disease while waiting for infusion.

OBJECTIVE

This study evaluated the impact of V2VT on survival and economic outcomes for R/R second-line (2L) axicabtagene ciloleucel (axi-cel) versus lisocabtagene maraleucel (liso-cel) treatment of patients with LBCL in the US.

STUDY DESIGN

An economic model was developed to evaluate the cost-effectiveness of 2L axi-cel versus liso-cel in patients with R/R LBCL over a 50-year time horizon from a US third-party payer perspective. The model was comprised of: (i) a decision tree to account for V2VT, and (ii) a 3-state partitioned survival model that captured health state transitions. Transition between health states were based on progression-free survival (PFS) and overall survival (OS) data stratified based on long (≥36 days) versus short (<36 days) V2VT. The proportion of axi-cel patients with short and long V2VT was 94% and 6%, respectively, while that for liso-cel was 50% each. Survival data were sourced from the pivotal ZUMA-7 trial and varied for short and long V2VT, where V2VT-specific OS and PFS data were based on reported hazard ratios (HRs). Inputs for healthcare resource utilization, adverse events (AEs), costs, and utilities were sourced from published data or based on assumptions. The model estimated quality-adjusted life years (QALYs), total costs (in 2023 US dollars, $), the incremental cost-effectiveness ratio (ICER), and the net monetary benefit (NMB) at a willingness-to-pay threshold (WTP) of $150,000. Sensitivity and scenario analyses were conducted.

RESULTS

Treatment with 2L axi-cel resulted in improved health outcomes compared with 2L liso-cel (incremental QALYs of 0.56) as well as reduced total costs (cost savings of $13,156). Under base case assumptions, 2L axi-cel dominated liso-cel (more effective and less costly) with an NMB of $96,407 for a WTP of $150,000. Key model drivers from one-way sensitivity analyses included OS HRs for short versus long V2VT, axi-cel acquisition costs, and the proportion of patients receiving third-line (3L) treatment. 2L axi-cel was always cost-effective compared with 2L liso-cel in probabilistic sensitivity analyses at a willingness-to-pay threshold of $50,000 per QALY, and 2L axi-cel is cost-saving compared with 2L liso-cel in 88% of the probabilistic sensitivity analysis runs. Results from scenario analyses where AE rates were varied, AEs were individually costed, and where 3L bispecific antibodies were excluded were consistent with base case results.

CONCLUSIONS

2L treatment with axi-cel was more effective and less costly compared with liso-cel in patients with LBCL in the US. These findings suggest that reduced V2VT was associated with improved clinical and economic outcomes, and highlight the importance of short V2VT in R/R 2L LBCL CAR T treatments.

Emerging trends in clinical allogeneic CAR cell therapy

There has been significant progress in the clinical development of allogeneic off-the-shelf chimeric antigen receptor (CAR)-engineered cell therapies for the treatment of cancer and autoimmune diseases. Unlike autologous CAR cell therapies, allogeneic approaches overcome challenges such as high costs, labor-intensive manufacturing, and stringent patient selection. This makes allogeneic therapies a more universally applicable option for a diverse patient population. In this review, we examine recent clinical advancements in allogeneic CAR cell therapies, including CAR-T cell therapy derived from healthy donor peripheral blood mononuclear cells, as well as CAR-NK cell therapy from cord blood or induced pluripotent stem cells. We provide an overview of their genetic engineering strategies, clinical designs, and outcomes, highlighting their promising efficacy and safety. Additionally, we summarize key preclinical developments, address key challenges, and explore future directions to provide insights into emerging trends in the field.

Treatment strategies for advanced synovial sarcoma: from chemotherapy to TCR-engineered T-cell therapy

Synovial sarcoma (SS) is the most common soft tissue sarcoma in children and adolescents. Despite the availability of new agents such as pazopanib and trabectedin, the prognosis after recurrence remains poor. Adoptive cell therapy is an emerging therapeutic strategy based on the modulation, manipulation, and selection of autologous T-cells in vitro to overcome immune system tolerance to tumor cells. Cancer-testis antigens are particularly attractive targets for immune therapy because male germ cells lack human leukocyte antigen class I molecules, limiting T-cell responses triggered by antigen presentation. T-cell receptor (TCR) engineered T-cell therapy targeting NY-ESO-1 and MAGE-A4 holds significant promise because of the high positive expression of these antigens in tumors. This approach facilitates the reprogramming of T lymphocytes by a transgenic TCR through gene transfer of TCR α and β chains specific to tumor antigens, offering potential therapeutic advances for patients with advanced SS. Clinical trials of TCR-engineered T-cell therapy targeting NY-ESO-1 and MAGE-A4 have been conducted, with an objective response rate reported to be 40-60% across several trials. This promising efficacy suggests that TCR-engineered T-cell therapy could become an attractive novel therapeutic option for advanced SS, which has limited treatment options in later stages. However, if TCR-engineered T-cell therapy is to be used in clinical practice, the standard approach following the failure of doxorubicin-based chemotherapy in patients with advanced SS must be defined. Future studies will be critical for establishing treatment strategies in this field.

Lymphodepletion chemotherapy in chimeric antigen receptor-engineered T (CAR-T) cell therapy in lymphoma

The development of chimeric antigen receptor (CAR) T-cells, engineered from peripheral T-lymphocytes of a patient with lymphoma, in order to specifically target tumor cells, has been a revolution in adoptive cell therapy (ACT). As outlined in this review, ACT was initiated by hematopoietic cell transplantation (HSCT) and re-injection of interleukin-boosted tumor-infiltrating lymphocytes (TIL). The innovative venture of genetically modifying autologous peripheral T-cells to target them to cell-surface tumoral antigens through an antibody-derived structure (i.e. independent of major histocompatibility antigen presentation, physiologically necessary for T-cell activation), and intracytoplasmic T-cell costimulatory peptides, via a novel membrane CAR, has been an outstanding breakthrough. Here, focusing on B-cell hematological malignancies and mostly non-Hodgkin lymphoma, attention is brought to the importance of providing an optimal microenvironment for such therapeutic cells to proliferate and positively develop anti-tumoral cytotoxicity. This, perhaps paradoxically, implies a pre-infusion step of deep lymphopenia and deregulation of immunosuppressive mechanisms enhanced by tumoral cells. Fludarabine and cyclophosphamide appear to be the most efficient lymphodepletive drugs in this context, dosage being of importance, as will be illustrated by a thorough literature review.

Short-Chain Fatty Acids Modulate Anti-ROR1 CAR T-Cell Function and Exhaustion in an Intestinal Adenocarcinoma-on-Chip Model

Chimeric antigen receptor (CAR) T-cell therapy represents a promising approach for cancer treatment, with receptor tyrosine kinase-like orphan receptor 1 (ROR1) emerging as a novel target in malignancies. This study investigates how short-chain fatty acids (SCFAs), key microbiota-derived metabolites, modulate anti-ROR1 CAR T-cell efficacy using a physiologically relevant intestinal adenocarcinoma-on-chip model that replicates the human intestinal microenvironment. The findings demonstrate that propionate and butyrate inhibit anti-ROR1 CAR T-cell function by reducing infiltration, cytotoxicity, and cytokine release while preserving junctional integrity within the tumor model. Mechanistically, these SCFAs inhibit histone deacetylase activity and promote a phenotype switch toward regulatory T-cells, as indicated by increased expression of FoxP3 and RORγt. Additionally, propionate and butyrate upregulate PD-1 and TIM-3, markers of T-cell exhaustion and immune tolerance, and induce a dose- and time-dependent reduction in proinflammatory cytokines. In contrast, acetate and pentanoate promote a proinflammatory T helper 17 phenotype. These results highlight the immunomodulatory effects of SCFAs on CAR T-cell function, emphasizing the need to consider microbiota-derived metabolites in CAR T-cell therapies.

Safety and clinical efficacy of Relmacabtagene autoleucel (relma-cel) for systemic lupus erythematosus: a phase 1 open-label clinical trial

Background

Systemic lupus erythematosus (SLE) is a classic systemic autoimmune disease mediated by autoantibodies. Chimeric antigen receptor T (CAR-T) cell therapy, known for its success in cancer, has shown promise in achieving durable B cell depletion and long-term remission in SLE. Relmacabtagene autoleucel (relma-cel) is the second anti-CD19 CAR-T product approved for marketing by the National Medical Products Administration (NMPA) in China and demonstrates its long-term efficacy in relapsed/refractory (r/r) large B cell lymphoma (LBCL). We report the results from a phase I open-label clinical trial of relma-cel in treating patients with moderately to severely active SLE.

Methods

Eligible patients were aged 18-70 years, a ≥6-month history of SLE, and the disease had to remain active after at least 2 months of stable SLE standard treatment prior to screening. We evaluated four dose levels (DL) of relma-cel in a dose-escalation scheme: total dose of 25 × 106, 50 × 106, 75 × 106, and 100 × 106 anti-CD19 CAR-T cells. All patients received lymphodepletion chemotherapy with fludarabine and cyclophosphamide. The primary endpoints were the incidence of dose-limiting toxicities (DLTs) and adverse events (AEs). Secondary endpoints included the evaluation of standard cellular pharmacokinetic parameters, the SLE Responder Index (SRI) response rate, and changes from baseline in the Safety of Estrogens in Lupus Erythematosus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI), British Isles Lupus Assessment Group 2004 (BILAG-2004) and Physician's Global Assessment (PGA) scores post-treatment. This trial is registered with ClinicalTrials.gov, NCT05765006.

Findings

Between March 28, 2023 and April 8, 2024, a total of 12 patients were screened for study inclusion, of whom 8 patients were enrolled and assigned to different dose levels: 25 × 106 cells (n = 3), 50 × 106 cells (n = 2), 75 × 106 cells (n = 2), and 100 × 106 cells (n = 1). No DLT was observed. The most common AEs included cytopenia (n = 8, 100%), cytokine release syndrome (CRS) (n = 7, 88%) and hypogammaglobulinemia (n = 5, 63%). No Grade 3 or higher immune effector cell-associated hematotoxicity (ICAHT) occurred. No cases of immune effector cell-associated neurotoxicity syndrome (ICANS) were reported. CRS was predominantly grade 1, characterized mainly by mild fever and muscle soreness. A rare severe adverse event, immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS), was observed in one patient. The median time to reach maximum CAR-T cell expansion (Cmax) was 9.5 days (range: 8-22 days). The median Cmax was 18.74 CD3+CAR+ cells/μL (range: 7.94-228.36) by flow cytometry and 81766.5 copies/μg DNA (range: 50,979-1,140,893) by quantitative real-time PCR (qPCR). In all patients treated with relma-cel, CD19+ B cells in peripheral blood were almost completely depleted within 11-15 days and gradually recovered within 2-6 months. All patients achieved SRI response. Four patients achieved Definition of Remission in SLE (DORIS) remission criteria and seven patients reached the Lupus Low Disease Activity State (LLDAS) criteria within 1-4 months following relma-cel infusion.

Interpretation

This study preliminarily demonstrated that relma-cel is an effective and safe CAR-T product for the treatment of patients with moderately to severely active SLE, providing valuable clinical insights into the management of rare complications. Further studies with larger sample sizes are warranted.

Funding

National Natural Science Foundation of China.

European survey on CAR T-Cell analytical methods from apheresis to post-infusion immunomonitoring

Background

Chimeric Antigen Receptor (CAR) T-cell therapy has emerged as a revolutionary approach to cancer treatment. Given the rapid expansion of new indications addressed by newly developed CAR T-cell products, it is essential to standardize analytical methods for the characterization/monitoring of apheresis materials, drug products, and post-infusion patient samples.

Methods

The T2Evolve Consortium, part of the European Union's Innovative Medicines Initiative (IMI), conducted an extensive anonymous online survey between February and June 2022. Comprising 36 questions, the survey targeted a wide range of stakeholders involved in engineered T-cell therapies, including researchers, manufacturers, and clinicians. Its goal was to address the current variability within the CAR T-cell field, focusing on analytical assays for quality control of apheresis materials, drug products, and post-infusion immunomonitoring. Another objective was to identify gaps and needs in the field.

Results

A total of 53 respondents from 13 european countries completed the survey, providing insights into the most commonly used assays for apheresis material and drug product characterization, alongside safety and efficacy tests required by the Pharmacopeia. Notably, a minority of respondents conducted phenotypical characterization of T-cell subsets in the drug product and assessed activation/exhaustion T cell profiles.

Conclusion

The survey underscored the necessity to standardize CAR T-cell functional potency assays and identify predictive biomarkers for response, relapse, and toxicity. Additionally, responses indicated significant variability in CAR T-cell monitoring during short-term patient follow-up across clinical centers. This European survey represents the first initiative to report current approaches in different stages of CAR T-cell therapies via a survey, from drug product quality controls to post-infusion immunomonitoring. Based on these findings, and with input from T2EVOLVE experts, the next step will be to address harmonization in the identified areas. These efforts are anticipated to significantly enhance cancer patients' access to engineered T cell therapy safely and effectively throughout Europe.

State of the art in CAR-based therapy: In vivo CAR production as a revolution in cell-based cancer treatment

Chimeric antigen receptor (CAR) therapy has successfully treated relapsed/refractory hematological cancers. This strategy can effectively target tumor cells. However, despite positive outcomes in clinical applications, challenges remain to overcome. These hurdles pertain to the production of the drugs, solid tumor resistance, and side effects related to the treatment. Some cases have been missed during the drug preparation due to manufacturing issues, prolonged production times, and high costs. These challenges mainly arise from the in vitro manufacturing process, so reevaluating this process could minimize the number of missed patients. The immune cells are traditionally collected and sent to the laboratory; after several steps, the cells are modified to express the CAR gene before being injected back into the patient's body. During the in vivo method, the CAR gene is introduced to the immune cells inside the body. This allows for treatment to begin sooner, avoiding potential failures in drug preparation and the associated high costs. In this review, we will elaborate on the production and treatment process using in vivo CAR, examine the benefits and challenges of this approach, and ultimately present the available solutions for incorporating this treatment into clinical practice.

Chemoimmunotherapy synergism: mechanisms and clinical applications

Chemoimmunotherapy, combining chemotherapy and immunotherapy, has emerged as a promising strategy for treating various cancers. This approach leverages the complementary mechanisms of both modalities to enhance tumor eradication. Recent advances have shed new light on the synergistic interactions between chemotherapy and immunotherapy, revealing complex mechanisms that contribute to improved clinical outcomes. Chemotherapy induces immunogenic cell death, releasing tumor antigens and damage-associated molecular patterns (DAMPs) that stimulate immune responses. It also modulates the tumor microenvironment, enhancing immune cell infiltration and reducing immunosuppressive elements. Concurrently, immunotherapy, particularly immune checkpoint inhibitors, activates the immune system to more effectively target and destroy cancer cells. Clinical evidence demonstrates significant benefits of chemoimmunotherapy in various cancers, including non-small-cell lung cancer, triple-negative breast cancer, and melanoma. Recent trials, such as KEYNOTE- 189 and IMpassion130, have shown improved overall survival and progression-free survival compared to chemotherapy alone. Emerging biomarkers, including tumor mutational burden, Programmed Death Ligand- 1 (PD-L1) expression, and immune cell infiltration patterns, are refining patient selection and response prediction. Novel strategies, such as nanoparticle-based drug delivery systems and personalized medicine approaches, are being explored to optimize chemoimmunotherapy combinations. However, challenges remain, including managing treatment-related toxicities, determining optimal dosing and sequencing, and addressing potential resistance mechanisms. Ongoing research focuses on elucidating the complex interplay between chemotherapy-induced immunomodulation and immune checkpoint inhibition to further improve treatment efficacy and patient outcomes. This review provides a comprehensive update on the mechanisms, clinical applications, and future directions of chemoimmunotherapy, highlighting its potential to revolutionize cancer treatment strategies. Clinical trial number: not applicable.

Chimeric autoantibody receptor T cells specifically eliminate Graves' Disease autoreactive B cells

Introduction

Chimeric antigen receptor (CAR) T cells have recently become an important treatment for hematological cancers by efficiently eliminating B cells. B cell depleting CAR T cells are also in clinical trials for their use in treating severe autoimmune diseases and have shown promise in patients who have exhausted other treatment options; however, they do result in immunosuppression due to B cell depletion. Specifically eliminating the disease-causing B cells while leaving the healthy B cells untouched could address this limitation.

Methods

A chimeric autoantibody receptor (CAAR) has an autoantigen as the binding domain of the CAR T cell and could allow for specific targeting of autoreactive B cell populations. In Graves' Disease (GD), pathogenesis is centered around autoreactive B cells which are specific for thyroid stimulating hormone receptor (TSHR). By engineering epitopes of TSHR as the binding domain, our CAAR was able to bind to anti-TSHR antibodies and B cell receptors.

Results

These TSHR CAAR T cells specifically eliminated anti-TSHR B cells, without exhibiting cytotoxicity against healthy B cells. We hypothesized that soluble autoantibodies and thyroid stimulating hormone (TSH) could bind to the CAAR, potentially causing overactivation or inhibition. When evaluated, we found that one construct was significantly impacted by soluble autoantibodies, while the other construct was uninhibited. Soluble TSH did not significantly affect either construct. The TSHR CAAR T cells were also effective at eliminating anti-TSHR B cells in the presence of plasma from various GD patients.

Discussion

Thus, TSHR CAAR T cells show promise in eliminating the disease-causing autoreactive B cells in GD without eliminating healthy cells. This treatment mechanism also has the potential to be used in other B cell-mediated autoimmune diseases.

Progress and challenges in developing allogeneic cell therapies

The new era of cell therapeutics has started with autologous products to avoid immune rejection. However, therapeutics derived from allogeneic cells could be scaled and made available for a much larger patient population if immune rejection could reliably be overcome. In this review, we outline gene engineering concepts aimed at generating immune-evasive cells. First, we summarize the current state of allogeneic immune cell therapies, and second, we compile the still limited data for allogeneic cell replacement therapies. We emphasize the advances in this fast-developing field and provide an optimistic outlook for future allogeneic cell therapies.

Diverse potential of chimeric antigen receptor-engineered cell therapy: Beyond cancer

BACKGROUND

Chimeric antigen receptor (CAR)-engineered cell therapies have made significant progress in haematological cancer treatment. This success has motivated researchers to investigate its potential applications in non-cancerous diseases, with substantial strides already made in this field.

MAIN BODY

This review summarises the latest research on CAR-engineered cell therapies, with a particular focus on CAR-T cell therapy for non-cancerous diseases, including but not limited to infectious diseases, autoimmune diseases, cardiac diseases and immune-mediated disorders in transplantation. Additionally, the review discusses the current obstacles that need to be addressed for broader clinical applications.

CONCLUSION

With ongoing research and continuous improvements, CAR-engineered cell therapy holds promise as a potent tool for treating various diseases in the future.

KEY POINTS

CAR-engineered cell therapy has expanded beyond cancer to treat autoimmune diseases, infections, cardiac diseases, and transplant-related rejection. The CAR platform is diverse, with various cell types such as CAR-T, CAR-NK, and CAR-M potentially suited for different disease contexts. The safety, efficacy, and practicality of CAR cell therapy in non-cancer diseases remain challenging, requiring further technological optimization and clinical translation.

The clinical landscape of CAR NK cells

Chimeric antigen receptor (CAR) NK cell therapy has emerged as a promising alternative to CAR T cell therapy, offering significant advantages in terms of safety and versatility. Here we explore the current clinical landscape of CAR NK cells, and their application in hematologic malignancies and solid cancers, as well as their potential for treating autoimmune disorders. Our analysis draws from data collected from 120 clinical trials focused on CAR NK cells, and presents insights into the demographics and characteristics of these studies. We further outline the specific targets and diseases under investigation, along with the major cell sources, genetic modifications, combination strategies, preconditioning- and dosing regimens, and manufacturing strategies being utilized. Initial results from 16 of these clinical trials demonstrate promising efficacy of CAR NK cells, particularly in B cell malignancies, where response rates are comparable to those seen with CAR T cells but with lower rates of severe adverse effects, such as cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and graft-versus-host disease (GvHD). However, challenges remain in solid tumor applications, where only modest efficacy has been observed to date. Our analysis reveals that research is increasingly focused on enhancing CAR NK cell persistence, broadening their therapeutic targets, and refining manufacturing processes to improve accessibility and scalability. With recent advancements in NK cell engineering and their increased clinical applications, CAR NK cells are predicted to become an integral component of next-generation immunotherapies, not only for cancer but potentially for immune-mediated diseases as well.

Mitigation and Management of Common Toxicities Associated with the Administration of CAR-T Therapies in Oncology Patients

Chimeric antigen receptor T-cell (CAR-T) therapies are one of the main approaches among targeted cellular therapies. Despite the potential benefit and durable responses observed in some patients receiving CAR-T therapies, serious and potentially fatal toxicities remain a major challenge. The most common CAR-T-associated toxicities include cytokine release syndrome (CRS), neurotoxicity, cytopenias, and infections. While CRS and neurotoxicity are generally managed with tocilizumab and corticosteroids, respectively, high-grade toxicities can be life-threatening. Close postinfusion monitoring and assessment of clinical laboratory parameters, patient-related and clinical risk factors (e.g., age, tumor burden, comorbidities, baseline laboratory parameters, and underlying abnormalities), and therapy-related risk factors (e.g., CAR-T type, dose, and CAR-T-induced toxicity) are effective strategies to mitigate the toxicities. Clinical laboratory parameters, including various cytokines, have been identified for CRS (interleukin [IL]-1, IL-2, IL-5, IL-6, IL-8, IL-10, C-reactive protein [CRP], interferon [IFN]-γ, ferritin, granulocyte-macrophage colony-stimulating factor [GM-CSF], and monocyte chemoattractant protein-1), neurotoxicity (IL-1, IL-2, IL-6, IL-15, tumor necrosis factor [TNF]-α, GM-CSF, and IFN-γ), cytopenias (IL-2, IL-4, IL-6, IL-10, IFN-γ, ferritin, and CRP), and infections (IL-8, IL-1β, CRP, IFN-γ, and procalcitonin). CAR-T-associated toxicities can be monitored and treated to mitigate the risk to patients. Assessment of alterations in clinical laboratory parameter values that are correlated with CAR-T-associated toxicities may predict development and/or severity of a given toxicity, which can improve patient management strategies and ultimately enable the patients to better tolerate these therapies.

The Role of the Tumor Microenvironment (TME) in Advancing Cancer Therapies: Immune System Interactions, Tumor-Infiltrating Lymphocytes (TILs), and the Role of Exosomes and Inflammasomes

Understanding how different contributors within the tumor microenvironment (TME) function and communicate is essential for effective cancer detection and treatment. The TME encompasses all the surroundings of a tumor such as blood vessels, fibroblasts, immune cells, signaling molecules, exosomes, and the extracellular matrix (ECM). Subsequently, effective cancer therapy relies on addressing TME alterations, known drivers of tumor progression, immune evasion, and metastasis. Immune cells and other cell types act differently under cancerous conditions, either driving or hindering cancer progression. For instance, tumor-infiltrating lymphocytes (TILs) include lymphocytes of B and T cell types that can invade malignancies, bringing in and enhancing the ability of immune system to recognize and destroy cancer cells. Therefore, TILs display a promising approach to tackling the TME alterations and have the capability to significantly hinder cancer progression. Similarly, exosomes and inflammasomes exhibit a dual effect, resulting in either tumor progression or inhibition depending on the origin of exosomes, type of inflammasome and tumor. This review will explore how cells function in the presence of a tumor, the communication between cancer cells and immune cells, and the role of TILs, exosomes and inflammasomes within the TME. The efforts in this review are aimed at garnering interest in safer and durable therapies for cancer, in addition to providing a promising avenue for advancing cancer therapy and consequently improving survival rates.

T lymphocyte-based immune response and therapy in hepatocellular carcinoma: focus on TILs and CAR-T cells

Hepatocellular carcinoma (HCC) is among the leading causes of cancer-related death worldwide. The primary therapies for HCC are liver transplantation, hepatic tumor excision, radiofrequency ablation, and molecular-targeted medicines. An unfavorable prognosis marks HCC and has limited pharmacological response in therapeutic studies. The tumor immune microenvironment (TME) imposes significant selection pressure on HCC, resulting in its evolution and recurrence after various treatments. As the principal cellular constituents of tumor-infiltrating lymphocytes (TILs), T cells have shown both anti-tumor and protumor actions in HCC. T cell-mediated immune responses are pivotal in cancer monitoring and elimination. TILs are recognized for their critical involvement in the progression, prognosis, and immunotherapeutic management of HCC. Foxp3 + , CD8 + , CD3 + , and CD4 + T cells are the extensively researched subtypes of TILs. This article examines the functions and processes of several subtypes of TILs in HCC. Emerging T cell-based therapies, including TILs and chimeric antigen receptor (CAR)-T cell therapy, have shown tumor regression in several clinical and preclinical studies. Herein, it also delves into the existing T cell-based immunotherapies in HCC, with emphasis on TILs and CAR-T cells.

Implementation of chimeric antigen receptor (CAR) T-cell therapy in the NHS: prospects, promises and pitfalls

The approval, introduction, and provision of chimeric antigen receptor (CAR) T-cell therapy in the UK NHS presents a innovative and revolutionary approach in cancer treatment and management. CAR T-cell therapy is a highly specialised and personalised type of immunotherapy that involves reprogramming a patient's immune system by synthetically modifying their T-cells to specifically target and eliminate cancer cells. This therapy offers the potential to cure malignancies that were previously deemed incurable or refractory to conventional chemotherapy. CAR T-cell therapy, however, is associated with significant risks and life-threatening complications, and it entails substantial financial cost. The implementation of CAR T-cell therapy in the NHS marks a new era of personalised medicine, offering a promising approach not only for improving cancer outcomes, but for enhancing survivorship and quality of life among patients with advanced and relapsing haematologic malignancies.

Dynamics of Immune Reconstitution and Impact on Outcomes across CAR-T Cell Products in Large B-cell Lymphoma

SIGNIFICANCE

This study reveals differences in IR patterns after CAR-T therapy in patients with large B-cell lymphoma, with early NK cell recovery emerging as a key predictor of survival. These findings provide potential future avenues of research for improving patient outcomes and tailoring post-therapy management strategies to mitigate relapse risk.

Bispecific antibody and chimeric antigen receptor (CAR) modified T-cell in the treatment of multiple myeloma: Where do we stand today?

Although the prognosis of patients with multiple myeloma (MM) has been significantly improved by the introduction of proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies, MM is still considered an incurable disease in the vast majority of the patients. In recent years, T-cell based immunotherapy represents a novel treatment strategy for relapsed/refractory (RR) MM. So far, chimeric antigen receptor (CAR) modified T-cells and bispecific T-cell engaging antibodies (bsAb) have shown promising anti-MM efficacy and manageable safety profile within clinical trials, and B-cell maturation antigen (BCMA) is the most commonly used immune target for T-cell based immunotherapies in MM. To date, several CAR T-cell and bsAb products have already been approved for the treatment of RRMM, leading to a paradigm shift in the MM therapy and providing a potential curative option. In this review, we provide a summary of mechanisms of action, immune targets, selected clinical data, resistance mechanisms and therapy sequencing of CAR T-cell and bsAb in MM.

Barriers to CAR T-cell therapy in rheumatology

Chimeric antigen receptor (CAR) T cells have recently shown remarkable promise in treating rheumatic diseases, including systemic lupus erythematosus (SLE), idiopathic inflammatory myopathies, and systemic sclerosis. Currently, there are 37 clinical trials registered for CAR T-cell therapy in rheumatic diseases and many more are being planned. Much of this enthusiasm is justifiable, but widespread adoption of CAR T-cell therapy in rheumatology faces several barriers. The trajectory of autoimmune diseases differs from malignancies and a surprisingly narrow population could be eligible for CAR T-cell therapy. Current CAR T-cell approaches rely on B-cell depletion, which has a mixed record of success for many diseases. The high cost of CAR T-cell therapy and potential safety concerns, such as cytokine release syndrome and long-term infection risks, also pose substantial challenges. Moving forward, more targeted CAR T-cell approaches, such as antigen-specific chimeric autoantibody receptors or chimeric autoantigen T-cell receptors, could offer greater efficacy and safety in treating rheumatic diseases.

Tumor-Infiltrating Lymphocyte Therapy for Melanoma and Other Solid Tumors: Looking Back, Yet Moving Forward

Lifileucel, the first solid tumor adoptive tumor infiltrating lymphocyte (TIL) therapy product to receive regulatory approval in advanced melanoma, represents a critical achievement in the pursuit of improving outcomes using cellular therapies in patients with solid tumors. This review traces the development of adoptive TIL therapy from the initial human studies in melanoma, through recent advances in studies of other solid tumors, and previews ongoing and future areas for preclinical and clinical advances to improve upon this novel therapeutic strategy.

Mechanistic Evaluation of Anti-CD19 CAR-T Cell Therapy Repurposed in Systemic Lupus Erythematosus Using a Quantitative Systems Pharmacology Model

CAR-T cell therapy, renowned for its success in oncology, is now venturing into the realm of B cell-mediated autoimmune diseases. Recent observations have revealed significant pharmacological effects of CD19 CAR-T cells in patients with systemic lupus erythematosus (SLE), suggesting promising applications in other autoimmune conditions. Consequently, as of December 2024, there are 116 different clinical trials evaluating CAR-T cells against autoimmune conditions. While the field is starting to understand the overall pharmacological actions of CAR-T cells in autoimmune diseases, the dose-exposure-response relationship remains inadequately characterized due to limited clinical data. To address these uncertainties, we have developed a Quantitative Systems Pharmacology (QSP) model using short-term limited clinical data of anti-CD19 CAR-Ts in autoimmune disease patients (n = 5), followed by a model qualification step utilizing an external dataset (n = 13). The developed QSP model integrated and effectively characterized the (1) cellular kinetics of different immunophenotypic population of CAR-T cells, (2) impact of lymphodepletion chemotherapy on host immune cells, (3) CAR-mediated elimination of CD19+ B-cells and (4) dynamic changes in disease surrogate biomarkers and its relationship with clinical score. The key pharmacological biomarkers which were incorporated within the QSP model included anti double stranded DNA (anti-dsDNA) antibodies, proteinuria, C3 protein and IFN-alpha. Later, a linear regression analysis-based relationship was developed between continuous disease biomarkers and the categorical SLE disease activity index (SLE-DAI) determined by the investigators offering a predictive framework for disease progression in SLE patients. This proposed QSP model holds potential to elucidate quantitative pharmacology and expedite clinical advancement of autologous and allogeneic cell therapies in autoimmune diseases.

Advances in cellular therapies for children and young adults with solid tumors

PURPOSE OF REVIEW

Adoptive immunotherapy brings hope to children and young adults diagnosed with high-risk solid tumors. Cellular (cell) therapies such as chimeric antigen receptor (CAR) T cell, CAR natural killer (NK) cell, and T cell receptor (TCR) T cell therapy are potential avenues of targeted therapy with limited long-term toxicities. However, development of cell therapies for solid tumors is in its nascent stages. Here, we will review the current clinical experience, barriers to efficacy, and strategies to improve clinical response and patient access.

RECENT FINDINGS

Cell therapies are shown to be generally safe and well tolerated. Strategies to optimize antitumor activity have now moved into early-phase trials. The immunosuppressive tumor microenvironment remains a major barrier to efficacy, and efforts are underway to gain better understanding. This will inform future treatment strategies to enhance the antitumor activity of cell therapies.

SUMMARY

Clinical experiences to date provide important insights on how to leverage cell therapies against solid tumors. Key factors in advancing the field include a better understanding of immune cell biology, tumor cell behavior, and the tumor microenvironment. Lastly, improving access to novel cell therapies remains an important consideration in the conduct of clinical trials and for future implementation into standard practice.

Basic Concepts and Indications of CAR T Cells

Chimeric antigen receptor (CAR) T cell therapy has revolutionized cancer immunotherapy, particularly for hematological malignancies. This personalized approach is based on genetically engineering T cells derived from the patient to target antigens expressed-among others-on malignant cells. Nowadays they offer new hope where conventional therapies, such as chemotherapy and radiation, have often failed. Since the first FDA approval in 2017, CAR T cell therapy has rapidly expanded, proving highly effective against previously refractory diseases with otherwise a dismal outcome. Despite its promise, CAR T cell therapy continues to face significant challenges, including complex manufacturing, the management of toxicities, resistance mechanisms that impact long-term efficacy, and limited access as well as high costs, which continue to shape ongoing research and clinical applications. This review aims to provide an overview of CAR T cell therapy, including its fundamental concepts, clinical applications, current challenges, and future directions in hematological malignancies.

Rapamycin-resistant polyclonal Th1/Tc1 cell therapy (RAPA-201) safely induces disease remissions in relapsed, refractory multiple myeloma

BACKGROUND

Polyclonal autologous T cells that are epigenetically reprogrammed through mTOR inhibition and IFN-α polarization (RAPA-201) represent a novel approach to the adoptive T cell therapy of cancer. Ex vivo inhibition of mTOR results causes a shift towards T central memory (TCM) whereas ex vivo IFN-α promotes type I cytokines, with each of these functions known to enhance the adoptive T cell therapy of cancer. Rapamycin-resistant T cells polarized for a type II cytokine phenotype were previously evaluated in the allogeneic transplantation context.

METHODS

The clinical trial (NCT04176380) evaluated RAPA-201 therapy in combination with fludarabine-sparing low-dose host conditioning for the treatment of patients with relapsed, refractory multiple myeloma (RRMM).

RESULTS

From December 2020 to December 2022, 14 patients with RRMM received a median of three RAPA-201 infusions (median dose, 80×106 cells). RAPA-201 drug products (DPs) were: polyclonal; enriched for TCM cells; reduced for immune checkpoint expression, including PD1, CD73, and LAIR1; and preferentially secreted Th1 cytokines. The median chemotherapy dose administered per cycle was 1,817 mg total for cyclophosphamide (range, 1,100-2,200) and 2.35 mg/M2 for pentostatin (range, 0-16). Nine of 14 patients (64%) achieved disease remission, with eight partial responses and one stringent complete response. Median progression-free survival was 6.0 months (range, 2.1 to>16.8 months). There were no toxicities of any grade attributable to RAPA-201, including no cytokine release syndrome and no immune effector cell-associated neurotoxicity syndrome. Only 4 of 14 patients (29%) had a serious adverse event (≥ grade 3) of any attribution.

CONCLUSIONS

Consistent with our hypothesis, ex vivo manufacturing using mTOR inhibition and IFN-α polarization consistently yielded a novel RAPA-201 DP that possessed a desirable phenotype relative to cytokine phenotype, memory status, and checkpoint expression. RAPA-201 recipients had preservation of T cell counts and Th1 cytokine secretion yet had increased T cell receptor clonality that associates with antitumor responses in the setting of monoclonal antibody checkpoint therapy. RAPA-201 therapy overcomes previous barriers to effective autologous polyclonal T-cell therapy, as it is feasible to manufacture, exquisitely safe to administer, and mediates remission in patients with RRMM.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT04176380.

CD19-directed chimeric antigen receptor T-cell therapy: what can we learn from the haematologist?

CD19-directed chimeric antigen receptor (CAR) T-cell therapy, originally developed for haematological malignancies, has recently emerged as a promising therapy for patients with autoimmune diseases. By selectively depleting CD19-positive B-cells, this therapy brings a new approach in resetting immune dysregulation and potentially providing long-term remission for patients with a refractory disease. Recent reports have highlighted its effectiveness in conditions such as SLE, systemic sclerosis and myositis. However, while these early results are encouraging, questions remain regarding strategies for optimal patient selection and minimising toxicity on the short and long term. The experiences with CD19 CAR T-cell therapy in haematology may offer valuable insights for immunologists and rheumatologists. This article reviews the key principles learnt in haematology, the results and the mechanisms behind its efficacy, toxicities, and the challenges that need to be addressed for its broader application in clinical practice.

Prognostic significance of immune reconstitution following CD19 CAR T-cell therapy for relapsed/refractory B-cell lymphoma

Immune deficits after CD19 chimeric antigen receptor (CAR) T-cell therapy can be long-lasting, predisposing patients to infections and non-relapse mortality. In B-cell non-Hodgkin lymphoma (B-NHL), the prognostic impact of immune reconstitution (IR) remains ill-defined, and detailed cross-product comparisons have not been performed to date. In this retrospective observational study, we longitudinally characterized lymphocyte subsets and immunoglobulin levels in 105 B-NHL patients to assess patterns of immune recovery arising after CD19 CAR-T. Three key IR criteria were defined as CD4+ T helper (TH) cells > 200/µL, any detectable B cells, and serum immunoglobulin G (IgG) levels >4 g/L. After a median follow-up of 24.6 months, 38% of patients displayed TH cells, 11% showed any B cells, and 41% had IgG recovery. Notable product-specific differences emerged, including deeper TH cell aplasia with CD28z- versus longer B-cell aplasia with 41BBz-based products. Patients with any IR recovery experienced extended progression-free survival (PFS) (median 20.8 vs. 1.7 months, p < 0.0001) and overall survival (OS) (34.9 vs. 4.0 months, p < 0.0001). While landmark analysis at 90 days confirmed improved PFS in patients with any recovery (34.9 vs. 8.6 months, p = 0.005), no significant OS difference was noted. Notably, 72% of patients with refractory disease never displayed recovery of any IR criteria. Early progressors showed diminished IR at the time of progression/relapse compared to patients with late progression/recurrence (after Day 90). Our results highlight the profound immune deficits observed after CD19 CAR-T and shed light on the intersection of IR and efficacy in B-NHL. Importantly, IR was impaired considerably postprogression, carrying significant implications for subsequent T-cell-engaging therapies and treatment sequencing.

Innovative cell therapies for systemic sclerosis: available evidence and new perspectives

INTRODUCTION

Systemic sclerosis (SSc) is the rheumatic disease with the highest individual mortality rate with a detrimental impact on quality of life. Cell-based therapies may offer new perspectives for this disease as recent phase I trials support the safety of IV infusion of allogeneic mesenchymal stromal cells in SSc and case reports highlight the potential use of Chimeric Antigen Receptor (CAR)-T cells targeting CD19 in active SSc patients who have not responded to conventional immunosuppressive therapies.

AREAS COVERED

This narrative review highlights the most recent evidence supporting the use of cellular therapies in SSc as well as their potential mechanisms of action and discusses future perspectives for cell-based therapies in SSc. Medline/PubMed was used to identify the articles of interest, using the keywords 'Cellular therapies,' 'Mesenchymal stromal cells,' 'Chimeric Antigen Receptor' AND 'systemic sclerosis.' Milestones articles reported by the authors were also used.

EXPERT OPINION

Cellular therapies may represent an opportunity for long-term remission/cure in patients with different autoimmune diseases, including SSc who have not responded to conventional therapies. Multiple ongoing phase I/II trials will provide greater insights into the efficacy and toxicity of cellular therapies.

Therapeutic advantage of combinatorial chimeric antigen receptor T cell and chemotherapies

Chimeric antigen receptor (CAR) T cell therapies have transformed outcomes for many patients with hematological malignancies. However, some patients do not respond to CAR T cell treatment, and adapting CAR T cells for treatment of solid and brain tumors has been met with many challenges, including a hostile tumor microenvironment and poor CAR T cell persistence. Thus, it is unlikely that CAR T cell therapy alone will be sufficient for consistent, complete tumor clearance across patients with cancer. Combinatorial therapies of CAR T cells and chemotherapeutics are a promising approach for overcoming this because chemotherapeutics could augment CAR T cells for improved antitumor activity or work in tandem with CAR T cells to clear tumors. Herein, we review efforts toward achieving successful CAR T cell and chemical drug combination therapies. We focus on combination therapies with approved chemotherapeutics because these will be more easily translated to the clinic but also review nonapproved chemotherapeutics and drug screens designed to reveal promising new CAR T cell and chemical drug combinations. Overall, this review highlights the promise of CAR T cell and chemotherapy combinations with a specific focus on how combinatorial therapy overcomes challenges faced by either monotherapy and supports the potential of this therapeutic strategy to improve outcomes for patients with cancer. SIGNIFICANCE STATEMENT: Improving currently available CAR T cell products via combinatorial therapy with chemotherapeutics has the potential to drastically expand the types of cancers and number of patients that could benefit from these therapies when neither alone has been sufficient to achieve tumor clearance. Herein, we provide a thorough review of the current efforts toward studying CAR T and chemotherapy combinatorial therapies and offer perspectives on optimal ways to identify new and effective combinations moving forward.

CARs for lymphoma

Chimeric Antigen Receptor (CAR)-T cell therapy has revolutionized treatment options for B-cell Non-Hodgkin Lymphoma (NHL). CD19-targeting CAR-T cell therapy is approved for treatment in Diffuse Large B Cell Lymphoma, Follicular Lymphoma, Mantle Cell Lymphoma, and Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma. CAR-T cells demonstrate robust and durable responses even in heavily pretreated patients. Clinicians should monitor for Cytokine Release Syndrome (CRS) and Immune Effector Cell Neurotoxicity Syndrome (ICANS), as well as cytopenias, infection, and secondary malignancies. Ongoing questions remain in improving manufacturing efficacy, sequencing CAR-T cells amongst other therapies including bi-specific antibodies (BiTEs), and predicting optimal responders. In addition, novel CARs are being developed with alternative targets or that secrete activating cytokines (i.e. "armored CARs"). CAR-T cells represent an effective lymphoma therapy and should be considered for eligible patients.

Better, Faster, Stronger: Accelerating mRNA-Based Immunotherapies With Nanocarriers

Messenger ribonucleic acid (mRNA) therapeutics are attracting attention as promising tools in cancer immunotherapy due to their ability to leverage the in vivo expression of all known protein sequences. Even small amounts of mRNA can have a powerful effect on cancer vaccines by promoting the synthesis of tumor-specific antigens (TSA) or tumor-associated antigens (TAA) by antigen-presenting cells (APC). These antigens are then presented to T cells, eliciting strong antitumor immune stimulation. The potential of mRNA can be further enhanced by expressing immunomodulatory agents, such as cytokines, antibodies, and chimeric antigen receptors (CAR), enhancing tumor immunity. Recent research also explores mRNA-encoded tumor death inducers or tumor microenvironment (TME) modulators. Despite its promise, the clinical translation of mRNA-based anticancer strategies faces challenges, including inefficient targeted delivery in vivo, failure of endosomal escape, and inadequate intracellular mRNA release, resulting in poor transfection efficiencies. Inspired by the approval of lipid nanoparticle-loaded mRNA vaccines against coronavirus disease 2019 (COVID-19) and the encouraging outcomes of mRNA-based cancer therapies in trials, innovative nonviral nanotechnology delivery systems have been engineered. These aim to advance mRNA-based cancer immunotherapies from research to clinical application. This review summarizes recent preclinical and clinical progress in lipid and polymeric nanomedicines for delivering mRNA-encoded antitumor therapeutics, including cytokines and antibody-based immunotherapies, cancer vaccines, and CAR therapies. It also addresses advanced delivery systems for direct oncolysis or TME reprogramming and highlights key challenges in translating these therapies to clinical use, exploring future perspectives, including the role of artificial intelligence and machine learning in their development.

Advancing CAR T-cell therapies: Preclinical insights and clinical translation for hematological malignancies

Chimeric antigen receptor (CAR) T-cell therapy has achieved significant success in achieving durable and potentially curative responses in patients with hematological malignancies. CARs are tailored fusion proteins that direct T cells to a specific antigen on tumor cells thereby eliciting a targeted immune response. The approval of several CD19-targeted CAR T-cell therapies has resulted in a notable surge in clinical trials involving CAR T cell therapies for hematological malignancies. Despite advancements in understanding response mechanisms, resistance patterns, and adverse events associated with CAR T-cell therapy, the translation of these insights into robust clinical efficacy has shown modest outcomes in both clinical trials and real-world scenarios. Therefore, the assessment of CAR T-cell functionality through rigorous preclinical studies plays a pivotal role in refining therapeutic strategies for clinical applications. This review provides an overview of the various in vitro and animal models used to assess the functionality of CAR T-cells. We discuss the findings from preclinical research involving approved CAR T-cell products, along with the implications derived from recent preclinical studies aiming to optimize the functionality of CAR T-cells. The review underscores the importance of robust preclinical evaluations and the need for models that accurately replicate human disease to bridge the gap between preclinical success and clinical efficacy.

Enhanced anti-tumor efficacy of electroporation (EP)-mediated DNA vaccine boosted by allogeneic lymphocytes in pre-established tumor models

BACKGROUND

Tumor-reactive T cells play a crucial role in anti-tumor responses, but T cells induced by DNA vaccination are time-consuming processes and exhibit limited anti-tumor efficacy. Therefore, we evaluated the anti-tumor effectiveness of reactive T cells elicited by electroporation (EP)-mediated DNA vaccine targeting epidermal growth factor receptor variant III (pEGFRvIII plasmid), in conjunction with adoptive cell therapy (ACT), involving the transfer of lymphocytes from a pEGFRvIII EP-vaccinated healthy donor.

METHODS

The validation of the established pEGFRvIII plasmid and EGFRvIII-positive cell model was confirmed through immunofluorescence and western blot analysis. Flow cytometry and cytotoxicity assays were performed to evaluate the functionality of antigen-specific reactive T cells induced by EP-mediated pEGFRvIII vaccines, ACT, or their combination. The anti-tumor effectiveness of EP-mediated pEGFRvIII vaccines alone or combined with ACT was evaluated in the B16F10-EGFRvIII tumor model.

RESULTS

EP-mediated pEGFRvIII vaccines elicited serum antibodies and a robust cellular immune response in both healthy and tumor-bearing mice. However, this response only marginally inhibited early-stage tumor growth in established tumor models. EP-mediated pEGFRvIII vaccination followed by adoptive transfer of lymphocytes from vaccinated healthy donors led to notable anti-tumor efficacy, attributed to the synergistic action of antigen-specific CD4+ Th1 cells supplemented by ACT and antigen-specific CD8+ T cells elicited by the EP-mediated DNA vaccination.

CONCLUSIONS

Our preclinical studies results demonstrate an enhanced anti-tumor efficacy of EP-mediated DNA vaccination boosted with adoptively transferred, vaccinated healthy donor-derived allogeneic lymphocytes.

Lymphodepletion in Chimeric Antigen Receptor T-Cell Therapy for Solid Tumors: A Focus on Brain Tumors

Chimeric antigen receptor (CAR)-T cell therapy, which has demonstrated remarkable efficacy in hematologic malignancies, is being extended to the treatment of refractory solid tumors, including brain tumors. Lymphodepletion (LD) is an essential preconditioning process that enhances CAR-T efficacy by promoting CAR-T cell expansion and persistence in the body, and has become a standard regimen for hematologic cancers. Recent clinical results of CAR-T therapy for solid tumors, including brain tumors, have shown that cyclophosphamide/fludarabine-based preconditioning has potential benefits and is gradually becoming adopted in solid tumor CAR-T trials. Furthermore, some CAR-T trials for solid tumors are attempting to develop LD regimens optimized specifically for solid tumors, distinct from the standard LD regimens used in hematologic cancers. In contrast, CAR-T therapy targeting brain tumors frequently employs locoregionally repeated administration in tumors or cerebrospinal fluid, resulting in less frequent use of LD compared to other solid tumors. Nevertheless, several clinical studies suggest that LD may still provide potential benefits for CAR-T expansion and improvement in clinical responses in systemic CAR-T administration. The studies presented in this review suggest that while LD can be beneficial for enhancing CAR-T efficacy, considerations must be made regarding its compatibility with the CAR-T administration route, potential excessive activation based on CAR-T structural characteristics, and target expression in normal organs. Additionally, given the unique characteristics of brain tumors, optimized selection of LD agents, as well as dosing and regimens, may be required, highlighting the need for further research.

The complexity of immune evasion mechanisms throughout the metastatic cascade

Metastasis, the spread of cancer from a primary site to distant organs, is an important challenge in oncology. This Review explores the complexities of immune escape mechanisms used throughout the metastatic cascade to promote tumor cell dissemination and affect organotropism. Specifically, we focus on adaptive plasticity of disseminated epithelial tumor cells to understand how they undergo phenotypic transitions to survive microenvironmental conditions encountered during metastasis. The interaction of tumor cells and their microenvironment is analyzed, highlighting the local and systemic effects that innate and adaptive immune systems have in shaping an immunosuppressive milieu to foster aggressive metastatic tumors. Effectively managing metastatic disease demands a multipronged approach to target the parallel and sequential mechanisms that suppress anti-tumor immunity. This management necessitates a deep understanding of the complex interplay between tumor cells, their microenvironment and immune responses that we provide with this Review.

ReCARving the future: bridging CAR T-cell therapy gaps with synthetic biology, engineering, and economic insights

Chimeric antigen receptor (CAR) T-cell therapy has revolutionized the treatment of hematologic malignancies, offering remarkable remission rates in otherwise refractory conditions. However, its expansion into broader oncological applications faces significant hurdles, including limited efficacy in solid tumors, safety concerns related to toxicity, and logistical challenges in manufacturing and scalability. This review critically examines the latest advancements aimed at overcoming these obstacles, highlighting innovations in CAR T-cell engineering, novel antigen targeting strategies, and improvements in delivery and persistence within the tumor microenvironment. We also discuss the development of allogeneic CAR T cells as off-the-shelf therapies, strategies to mitigate adverse effects, and the integration of CAR T cells with other therapeutic modalities. This comprehensive analysis underscores the synergistic potential of these strategies to enhance the safety, efficacy, and accessibility of CAR T-cell therapies, providing a forward-looking perspective on their evolutionary trajectory in cancer treatment.

The Role of Chimeric Antigen Receptor T-Cell Therapy in Immune-Mediated Neurological Diseases

Despite the use of 'high efficacy' disease-modifying therapies, disease activity and clinical progression of different immune-mediated neurological diseases continue for some patients, resulting in accumulating disability, deteriorating social and mental health, and high economic cost to patients and society. Although autologous hematopoietic stem cell transplant is an effective treatment modality, it is an intensive chemotherapy-based therapy with a range of short- and long-term side-effects. Chimeric antigen receptor T-cell therapy (CAR-T) has revolutionized the treatment of B-cell and other hematological malignancies, conferring long-term remission for otherwise refractory diseases. However, the toxicity of this treatment, particularly cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, and the complexity of production necessitate the need for a high level of specialization at treating centers. Early-phase trials of CAR-T therapies in immune-mediated B cell driven conditions, such as systemic lupus erythematosus, neuromyelitis optica spectrum disorder and myasthenia gravis, have shown dramatic clinical response with few adverse events. Based on the common physiopathology, CAR-T therapy in other immune-mediated neurological disease, including multiple sclerosis, chronic inflammatory polyradiculopathy, autoimmune encephalitis, and stiff person syndrome, might be an effective option for patients, avoiding the need for long-term immunosuppressant medications. It may prove to be a more selective immunoablative approach than autologous hematopoietic stem cell transplant, with potentially increased efficacy and lower adverse events. In this review, we present the state of the art and future directions of the use of CAR-T in such conditions. ANN NEUROL 2024;96:441-452.

Allogeneic "Off-the-Shelf" CAR T cells: Challenges and advances

Chimeric antigen receptor (CAR) T cell therapy has shown impressive clinical efficacy in B cell malignancies and multiple myeloma, leading to the approval of six CAR T cell products by the U.S. Food and Drug Administration (FDA) to date. However, broad application of these autologous (patient-derived) CAR T cells is limited by several factors, including high production costs, inconsistent product quality, contamination of the cell product with malignant cells, manufacturing failure especially in heavily pre-treated patients, and lengthy manufacturing times resulting in subsequent treatment delay. A potential solution to these barriers lies in the use of allogeneic "off-the-shelf" CAR T cells produced from healthy donors. Many efforts are underway to make allogeneic CAR T cells a safe and efficacious therapeutic option. In this review, we will discuss the major challenges that have to be addressed to successfully develop allogeneic CAR T cell therapies, specifically graft-versus-host disease (GVHD) and host-mediated immune rejection of the donor cells. Furthermore, we will summarize approaches that have been utilized to overcome these limitations, focusing on the use of gene editing technologies and strategies employing alternative cell populations as the source for allogeneic CAR T cell production.

Advancements and challenges in CAR T cell therapy in autoimmune diseases

Chimeric antigen receptor (CAR) T cells are highly effective at targeting and eliminating cells of the B cell lineage. CAR T cell therapy has become a standard-of-care treatment for patients with relapsed or refractory B cell malignancies. In addition, the administration of genetically modified T cells with the capacity to deplete B cells and/or plasma cells has tremendous therapeutic potential in autoimmune diseases. In the past few years, CD19-based and B cell maturation antigen (BCMA)-based CAR T cell therapies have been applied to various B cell-mediated autoimmune diseases including systemic lupus erythematosus, idiopathic inflammatory myopathy, systemic sclerosis, neuromyelitis optica spectrum disorder, myasthenia gravis and multiple sclerosis. The scientific rationale behind this approach is that deep depletion of B cells, including autoreactive B cell clones, could restore normal immune function, referred to as an immune reset. In this Review, we discuss important aspects of CAR T cell therapy in autoimmune disease, including considerations relating to patient selection, safety, efficacy and medical management. These considerations are based on the early experiences of CAR T cell therapy in autoimmune diseases, and as the field of CAR T cell therapy in autoimmune diseases continues to rapidly evolve, these issues will remain subject to ongoing refinement and adaptation.

CAR-T Therapy can be a Useful Treatment Modality for more than Just Hematologic Malignancies

Chimeric antigen receptor-T-cell (CAR-T) therapy for hematologic malignancies has made significant advancements over the years, and it is now incorporated as a treatment algorithm. Early phase clinical trials are underway for various solid tumors, and the effectiveness of CAR-T cell therapy has been demonstrated for specific types of glioma and several solid tumors. However, its efficacy does not match that observed in hematological malignancies. Recently, a case series reported CAR-T therapy targeting CD19 for autoimmune diseases such as systemic lupus erythematosus, leading to a dramatic improvement in the clinical symptoms and the possibility of discontinuing immunosuppressive agents. Furthermore, CAR-T cell therapy is expected to be effective against various viruses and Aspergillus spp. Finally, attempts have been made to introduce CAR constructs into regulatory T cells to target their immunosuppressive effects. This article introduces the current progress in CAR-T cell therapy beyond the treatment of only hematologic malignancies and discusses future directions, considering the current medical situation in Japan.

Systemic toxicity of CAR-T therapy and potential monitoring indicators for toxicity prevention

Malignant tumors of the hematologic system have a high degree of malignancy and high mortality rates. Chimeric antigen receptor T cell (CAR-T) therapy has become an important option for patients with relapsed/refractory tumors, showing astonishing therapeutic effects and thus, it has brought new hope to the treatment of malignant tumors of the hematologic system. Despite the significant therapeutic effects of CAR-T, its toxic reactions, such as Cytokine Release Syndrome (CRS) and Immune Effector Cell-Associated Neurotoxicity Syndrome (ICANS), cannot be ignored since they can cause damage to multiple systems, including the cardiovascular system. We summarize biomarkers related to prediction, diagnosis, therapeutic efficacy, and prognosis, further exploring potential monitoring indicators for toxicity prevention. This review aims to summarize the effects of CAR-T therapy on the cardiovascular, hematologic, and nervous systems, as well as potential biomarkers, and to explore potential monitoring indicators for preventing toxicity, thereby providing references for clinical regulation and assessment of therapeutic effects.

Strategies for Improving CAR T Cell Persistence in Solid Tumors

CAR T cells require optimization to be effective in patients with solid tumors. There are many barriers affecting their ability to succeed. One barrier is persistence, as to achieve an optimal antitumor response, infused CAR T cells must engraft and persist. This singular variable is impacted by a multitude of factors-the CAR T cell design, lymphodepletion regimen used, expansion method to generate the T cell product, and more. Additionally, external agents can be utilized to augment CAR T cells, such as the addition of novel cytokines, pharmaceutical drugs that bolster memory formation, or other agents during either the ex vivo expansion process or after CAR T cell infusion to support them in the oppressive tumor microenvironment. This review highlights many strategies being used to optimize T cell persistence as well as future directions for improving the persistence of infused cells.

Distinct host preconditioning regimens differentially impact the antitumor potency of adoptively transferred Th17 cells

BACKGROUND

How distinct methods of host preconditioning impact the efficacy of adoptively transferred antitumor T helper cells is unknown.

METHODS

CD4+ T cells with a transgenic T-cell receptor that recognize tyrosinase-related peptide (TRP)-1 melanoma antigen were polarized to the T helper 17 (Th17) phenotype and then transferred into melanoma-bearing mice preconditioned with either total body irradiation or chemotherapy.

RESULTS

We found that preconditioning mice with a non-myeloablative dose of total body irradiation (TBI of 5 Gy) was more effective than using an equivalently dosed non-myeloablative chemotherapy (cyclophosphamide (CTX) of 200 mg/kg) at augmenting therapeutic activity of antitumor TRP-1 Th17 cells. Antitumor Th17 cells engrafted better following preconditioning with TBI and regressed large established melanoma in all animals. Conversely, only half of mice survived long-term when preconditioned with CTX and infused with anti-melanoma Th17 cells. Interleukin (IL)-17 and interferon-γ, produced by the infused Th17 cells, were detected in animals given either TBI or CTX preconditioning. Interestingly, inflammatory cytokines (granulocyte colony stimulating factor, IL-6, monocyte chemoattractant protein-1, IL-5, and keratinocyte chemoattractant) were significantly elevated in the serum of mice preconditioned with TBI versus CTX after Th17 therapy. The addition of fludarabine (FLU, 200 mg/kg) to CTX (200 mg/kg) improved the antitumor response to the same degree mediated by TBI, whereas FLU alone with Th17 therapy was ineffective.

CONCLUSIONS

Our results indicate, for the first time, that the antitumor response, persistence, and cytokine profiles resulting from Th17 therapy are impacted by the specific regimen of host preconditioning. This work is important for understanding mechanisms that promote long-lived responses by adoptive cellular therapy, particularly as CD4+ based T-cell therapies are now emerging in the clinic.

Comparing 2-day vs 3-day flu-CY lymphodepleting regimens for CD19 CAR T-cell therapy in patients with non-hodgkin's lymphoma

Introduction

Lymphodepleting chemotherapy (LDC) is critical to CAR T-cell expansion and efficacy. Despite this, there is not a consensus in the literature regarding the optimal LDC regimen, including dose and frequency.

Methods

We retrospectively reviewed consecutive patients at a single institution that received LDC prior to treatment with the CD19 directed CAR T-cell products axicabtagene ciloleucel and tisagenlecleucel. Patients treated at our center received fludarabine 30 mg/m2 and cyclophosphamide 500 mg/m2 for 3 consecutive days prior to May 2019. After this timepoint patients routinely received fludarabine 40 mg/m2 and cyclophosphamide 500 mg/m2 for 2 consecutive days. Clinical data from each cohort were obtained from the electronic medical record and compared for differences in CAR T-cell efficacy and toxicity.

Results

From June 2018 to August 2023, LDC was given to 92 patients prior to CD19 directed CAR T-cell therapy for relapsed non-Hodgkin's lymphoma. Twenty-eight patients received a 3-day regimen, and 64 patients received a 2-day regimen. In the total cohort, 75% of patients received axicabtagene ciloleucel and 25% received tisagenlecleucel. The overall response rates in both the 2-day regimen group and the 3-day regimen group were similar (69% vs 75%, p= 0.21) as were the complete response rates (50% vs 54%, p=0.82). There were no significant differences between the 2-day and 3-day regimens for grade 2-4 cytokine release syndrome (55% vs 50%, p=0.82), grade 2-4 immune effector cell associated-neurotoxicity syndrome (42% vs 29%, p=0.25), or time to resolution of neutropenia or thrombocytopenia. The rate of prolonged platelet recovery lasting greater than 60 days was higher with the 3-day regimen (9% vs 27%, p=0.026).

Discussion

As the number of patients eligible for CAR T-cell therapy continues to increase, optimizing each component of therapy is necessary. We show that a 2-day regimen of LDC with fludarabine and cyclophosphamide is feasible without significant impact on CAR T-cell efficacy or toxicity. Prospective studies are necessary to further determine the most effective LDC regimen.

Direct in vivo CAR T cell engineering

T cells modified to express intelligently designed chimeric antigen receptors (CARs) are exceptionally powerful therapeutic agents for relapsed and refractory blood cancers and have the potential to revolutionize therapy for many other diseases. To circumvent the complexity and cost associated with broad-scale implementation of ex vivo manufactured adoptive cell therapy products, alternative strategies to generate CAR T cells in vivo by direct infusion of nanoparticle-formulated nucleic acids or engineered viral vectors under development have received a great deal of attention in the past few years. Here, we outline the ex vivo manufacturing process as a motivating framework for direct in vivo strategies and discuss emerging data from preclinical models to highlight the potency of the in vivo approach, the applicability for new disease indications, and the remaining challenges associated with clinical readiness, including delivery specificity, long term efficacy, and safety.

Current advances in experimental and computational approaches to enhance CAR T cell manufacturing protocols and improve clinical efficacy

Since the FDA's approval of chimeric antigen receptor (CAR) T cells in 2017, significant improvements have been made in the design of chimeric antigen receptor constructs and in the manufacturing of CAR T cell therapies resulting in increased in vivo CAR T cell persistence and improved clinical outcome in certain hematological malignancies. Despite the remarkable clinical response seen in some patients, challenges remain in achieving durable long-term tumor-free survival, reducing therapy associated malignancies and toxicities, and expanding on the types of cancers that can be treated with this therapeutic modality. Careful analysis of the biological factors demarcating efficacious from suboptimal CAR T cell responses will be of paramount importance to address these shortcomings. With the ever-expanding toolbox of experimental approaches, single-cell technologies, and computational resources, there is renowned interest in discovering new ways to streamline the development and validation of new CAR T cell products. Better and more accurate prognostic and predictive models can be developed to help guide and inform clinical decision making by incorporating these approaches into translational and clinical workflows. In this review, we provide a brief overview of recent advancements in CAR T cell manufacturing and describe the strategies used to selectively expand specific phenotypic subsets. Additionally, we review experimental approaches to assess CAR T cell functionality and summarize current in silico methods which have the potential to improve CAR T cell manufacturing and predict clinical outcomes.