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.

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.

Potential of gamma/delta T cells for solid tumor immunotherapy.

Gamma/delta T (γδ T)cells possess a unique mechanism for killing tumors, making them highly promising and distinguished among various cell therapies for tumor treatment. This review focuses on the major histocompatibility complex (MHC)-independent recognition of antigens and the interaction between γδ T cells and solid tumor cells. A comprehensive review is provided regarding the classification of human gamma-delta T cell subtypes, the characteristics and mechanisms underlying their functions, as well as their r545egulatory effects on tumor cells. The involvement of γδ T cells in tumorigenesis and migration was also investigated, encompassing potential therapeutic targets such as apoptosis-related molecules, the TNF receptor superfamily member 6(FAS)/FAS Ligand (FASL) pathways, butyrophilin 3A-butyrophilin 2A1 (BTN3A-BTN2A1) complexes, and interactions with CD4, CD8, and natural killer (NK) cells. Additionally, immune checkpoint inhibitors such as programmed cell death protein 1/Programmed cell death 1 ligand 1 (PD-1/PD-L1) have the potential to augment the cytotoxicity of γδ T cells. Moreover, a review on gamma-delta T cell therapy products and their corresponding clinical trials reveals that chimeric antigen receptor (CAR) gamma-delta T therapy holds promise as an approach with encouraging preclinical outcomes. However, practical issues pertaining to manufacturing and clinical aspects need resolution, and further research is required to investigate the long-term clinical side effects of CAR T cells. In conclusion, more comprehensive studies are necessary to establish standardized treatment protocols aimed at enhancing the quality of life and survival rates among tumor patients utilizing γδ T cell immunotherapy.

[The impact of immune cells selection on the therapeutic efficacy of CAR-T cell therapy].

Here we summarized novel Chimeric antigen receptor T-cell immunotherapy (CAR-T) based on the immune material aspect. Young healthy donor T cells, stem cell-like memory T cells, human induced pluripotent stem cells and umbilical cord blood T cells are all potential candidates to enhance CAR-T cell therapy depending on their anti-tumor efficacy. Besides, due to less restricted major histocompatibility complex (MHC) mismatch effect, viral specific T cells, γδT cells, invariant natural killer T cells and macrophages also become idealized T cell sources in terms of Universal CAR-T (UCAR-T) cell therapeutics. In addition, studies demonstrated that more balanced CD4(+)/CD8(+) T cell ratio and eliminating monocytes during leukapheresis have a positive influence on CAR-T cell functioning, whereas T cells with higher exhaustion markers expression hampers anti-tumor ability of CAR-T cells after infusion. To avoid application of such T cells or mitigate the impact using immune checkpoint inhibitors is of great importance.

Development of an antigen-based approach to noninvasively image CAR T cells in real time and as a predictive tool.

CAR T cell therapy has revolutionized the treatment of a spectrum of blood-related malignancies. However, treatment responses vary among cancer types and patients. Accurate monitoring of CAR T cell dynamics is crucial for understanding and evaluating treatment efficacy. Positron emission tomography (PET) offers a comprehensive view of CAR T cell homing, especially in critical organs such as lymphoid structures and bone marrow. This information will help assess treatment response and predict relapse risk. Current PET imaging methods for CAR T require genetic modifications, limiting clinical use. To overcome this, we developed an antigen-based imaging approach enabling whole-body CAR T cell imaging. The probe detects CAR T cells in vivo without affecting their function. In an immunocompetent B cell leukemia model, CAR-PET signal in the spleen predicted early mortality risk. The antigen-based CAR-PET approach allows assessment of CAR T therapy responses without altering established clinical protocols. It seamlessly integrates with FDA-approved and future CAR T cell generations, facilitating broader clinical application.

Off-the-shelf CAR-T cells could prove paradigm shifting for autoimmune diseases.

Early reports suggest that chimeric antigen receptor (CAR)-T therapy has remarkable potential for treating autoimmune disease. Current approaches rely on autologous CAR-T cells, creating a bottleneck to the broad deployment of this therapy. In this issue of Cell, Wang et al.1 report the first use of allogeneic CAR-T cells in three patients with systemic autoimmune disease.

Cost-per-responder analysis of patients with lenalidomide-refractory multiple myeloma receiving ciltacabtagene autoleucel in CARTITUDE-4.

Introduction: Ciltacabtagene autoleucel (cilta-cel) is a chimeric antigen receptor T-cell therapy approved for patients with relapsed/refractory multiple myeloma (RRMM). In the phase 3 trial, CARTITUDE-4 (NCT04181827), cilta-cel demonstrated improved efficacy vs. standard of care (SOC; daratumumab plus pomalidomide and dexamethasone [DPd] or pomalidomide plus bortezomib and dexamethasone [PVd]) with a ≥ complete response (≥CR) rate of 73.1% vs. 21.8%. Methods: A cost-per-responder model was developed to assess the value of cilta-cel and SOC (87% DPd and 13% PVd) based on the CARTITUDE-4 trial data from a US mixed payer perspective (76.7% commercial, 23.3% Medicare). The model was developed using progression-free survival (PFS), overall survival (OS), and ≥CR endpoints from CARTITUDE-4 over a period of 25.4 months. Inpatient stays, outpatient visits, drug acquisition, administration, and monitoring costs were included. The base-case model assumed an inpatient setting for each cilta-cel infusion; another scenario included 30% outpatient and 70% inpatient infusions. Costs of managing grade 3-4 adverse events (AEs) and grade 1-4 cytokine release syndrome and neurotoxicity were included. Subsequent therapy costs were incurred after disease progression; terminal care costs were considered upon death events. Outcomes included total cost per treated patient, total cost per complete responder, and cost per month in PFS between cilta-cel and SOC. Costs were adjusted to 2024 US dollars. Results: Total cost per treated patient, total cost per complete responder, and total cost per month in PFS were estimated at $704,641, $963,941, and $30,978 for cilta-cel, respectively, and $840,730, $3,856,559, and $42,520 for SOC over the 25.4-month period. Cost drivers included treatment acquisition costs before progression and subsequent treatment costs ($451,318 and $111,637 for cilta-cel; $529,795 and $265,167 for SOC). A scenario analysis in which 30% of patients received an outpatient infusion (assuming the same payer mix) showed a lower cost per complete responder for cilta-cel ($956,523) than those with an infusion in the inpatient setting exclusively. Discussion: This analysis estimated that cost per treated patient, cost per complete responder, and cost per month in PFS for cilta-cel were remarkably lower than for DPd or PVd, highlighting the substantial clinical and economic benefit of cilta-cel for patients with RRMM.

Current progress in CAR-based therapy for kidney disease.

Despite significant breakthroughs in the understanding of immunological and pathophysiological features for immune-mediated kidney diseases, a proportion of patients exhibit poor responses to current therapies or have been categorized as refractory renal disease. Engineered T cells have emerged as a focal point of interest as a potential treatment strategy for kidney diseases. By genetically modifying T cells and arming them with chimeric antigen receptors (CARs), effectively targeting autoreactive immune cells, such as B cells or antibody-secreting plasma cells, has become feasible. The emergence of CAR T-cell therapy has shown promising potential in directing effector and regulatory T cells (Tregs) to the site of autoimmunity, paving the way for effective migration, proliferation, and execution of suppressive functions. Genetically modified T-cells equipped with artificial receptors have become a novel approach for alleviating autoimmune manifestations and reducing autoinflammatory events in the context of kidney diseases. Here, we review the latest developments in basic, translational, and clinical studies of CAR-based therapies for immune-mediated kidney diseases, highlighting their potential as promising avenues for therapeutic intervention.

Endothelial Activation and Stress Index Score as a Prognostic Factor of Cytokine Release Syndrome in CAR-T Patients - A Retrospective Analysis of Multiple Myeloma and Large B-Cell Lymphoma Cohorts.

Endothelial Activation and Stress Index (EASIX) has been proposed as a prognostic factor of adverse events or survival in hematological malignancies. Endothelial dysfunction has been associated with complications following stem cell transplantation and chimeric antigen receptor (CAR)-T therapy. This retrospective cohort study evaluated the utility of the EASIX score as a prognostic factor of cytokine release syndrome (CRS) in multiple myeloma/light-chain amyloidosis (MM/AL amyloidosis; N = 69) and large B-cell lymphoma (LBCL) cohorts (N = 65). Occurrence of CRS grade ≥3 was the primary endpoint. For both cohorts, the EASIX and simplified EASIX (s-EASIX) scores were calculated at four different time points before CAR-T infusion to assess its prognostic value. In the MM/AL amyloidosis cohort, neither EASIX nor s-EASIX scores calculated at any time point were associated with the occurrence of CRS grade ≥3. In the LBCL cohort, EASIX and s-EASIX scores measured before lymphodepletion (EASIX-pre and s-EASIX-pre) showed a significant relationship with CRS grade ≥3 (odds ratio [OR] = 1.06 and OR = 1.05, respectively). The cutoff value of 1.835 for EASIX-pre was associated with 4.59-fold increased OR of CRS grade ≥3 (95% confidence interval [CI]: 1.13-21.84), whereas s-EASIX-pre cutoff equaled 2.134 and was associated with 4.13-fold increased OR of CRS grade ≥3 (95% CI: 1.01-17.93). However, after internal validation with bootstrapping, the significance was lost both for the EASIX-pre and s-EASIX-pre cutoff. The presented findings indicate that the EASIX scores fail to predict CRS in MM/amyloidosis CAR-T patients, whereas they can be implemented as CRS grade ≥3 predictors in LBCL CAR-T patients.

Proteasome inhibition enhances the anti-leukemic efficacy of chimeric antigen receptor (CAR) expressing NK cells against acute myeloid leukemia.

BACKGROUND: Relapsed and refractory acute myeloid leukemia (AML) carries a dismal prognosis. CAR T cells have shown limited efficacy in AML, partially due to dysfunctional autologous T cells and the extended time for generation of patient specific CAR T cells. Allogeneic NK cell therapy is a promising alternative, but strategies to enhance efficacy and persistence may be necessary. Proteasome inhibitors (PI) induce changes in the surface proteome which may render malignant cells more vulnerable to NK mediated cytotoxicity. Here, we investigated the potential benefit of combining PIs with CAR-expressing allogeneic NK cells against AML. METHODS: We established the IC50 concentrations for Bortezomib and Carfilzomib against several AML cell lines. Surface expression of class-I HLA molecules and stress-associated proteins upon treatment with proteasome inhibitors was determined by multiparameter flow cytometry. Using functional in vitro assays, we explored the therapeutic synergy between pre-treatment with PIs and the anti-leukemic efficacy of NK cells with or without expression of AML-specific CAR constructs against AML cell lines and primary patient samples. Also, we investigated the tolerability and efficacy of a single PI application strategy followed by (CAR-) NK cell infusion in two different murine xenograft models of AML. RESULTS: AML cell lines and primary AML patient samples were susceptible to Bortezomib and Carfilzomib mediated cytotoxicity. Conditioned resistance to Azacitidine/Venetoclax did not confer primary resistance to PIs. Treating AML cells with PIs reduced the surface expression of class-I HLA molecules on AML cells in a time-and-dose dependent manner. Stress-associated proteins were upregulated on the transcriptional level and on the cell surface. NK cell mediated killing of AML cells was enhanced in a synergistic manner. PI pre-treatment increased effector-target cell conjugate formation and Interferon-γ secretion, resulting in enhanced NK cell activity against AML cell lines and primary samples in vitro. Expression of CD33- and CD70-specific CARs further improved the antileukemic efficacy. In vivo, Bortezomib pre-treatment followed by CAR-NK cell infusion reduced AML growth, leading to prolonged overall survival. CONCLUSIONS: PIs enhance the anti-leukemic efficacy of CAR-expressing allogeneic NK cells against AML in vitro and in vivo, warranting further exploration of this combinatorial treatment within early phase clinical trials.

Engineering potent chimeric antigen receptor T cells by programming signaling during T-cell activation.

Programming cell signaling during T-cell activation represents a simple strategy for improving the potency of therapeutic T-cell products. Stim-R technology (Lyell Immunopharma) is a customizable, degradable synthetic cell biomimetic that emulates physiologic, cell-like presentation of signal molecules to control T-cell activation. A breadth of Stim-R formulations with different anti-CD3/anti-CD28 (αCD3/αCD28) antibody densities and stoichiometries were screened for their effects on multiple metrics of T-cell function. We identified an optimized formulation that produced receptor tyrosine kinase-like orphan receptor 1 (ROR1)-targeted chimeric antigen receptor (CAR) T cells with enhanced persistence and polyfunctionality in vitro, as assessed in repeat-stimulation assays, compared with a benchmark product generated using a conventional T-cell-activating reagent. In transcriptomic analyses, CAR T cells activated with Stim-R technology showed downregulation of exhaustion-associated gene sets and retained a unique subset of stem-like cells with effector-associated gene signatures following repeated exposure to tumor cells. Compared with the benchmark product, CAR T cells activated using the optimized Stim-R technology formulation exhibited higher peak expansion, prolonged persistence, and improved tumor control in a solid tumor xenograft model. Enhancing T-cell products with Stim-R technology during T-cell activation may help improve therapeutic efficacy against solid tumors.

Metabolic tumor volume and the survival of patients with Non-Hodgkin lymphoma treated with chimeric antigen receptor T cell therapy: a meta-analysis.

Background: Chimeric antigen receptor T cell (CAR-T) is a promising treatment for aggressive Non-Hodgkin lymphoma (NHL). The aim of the meta-analysis was to determine the association between metabolic tumor volumes (MTV) derived on positron emission tomography before CAR-T infusion and the survival of patients with NHL. Methods: Relevant observational studies pertaining to the purpose of the meta-analysis were obtained through a search of PubMed, Web of Science, and Embase from inception of the databases to April 1, 2024. The data was combined using a random-effects model that accounted for the potential influence of between-study heterogeneity. Results: Fifteen observational studies were included. Pooled results showed that compared to those with a lower MTV, the NHL patients with a higher MTV before CAR-T infusion were associated with a poor progression-free survival (hazard ratio [HR]: 1.73, 95% confidence interval [CI]: 1.48 to 2.02, p < 0.001; I2 = 20%) and overall survival (HR: 2.11, 95% CI: 1.54 to 2.89, p < 0.001; I2 = 58%). Subgroup analysis showed that the association between MTV and survival of NHL patients after CAR-T was not significantly impacted by study design, methods for determination of MTV cutoff, or analytic models (univariate or multivariate, p for each subgroup all < 0.05). Subgroup analysis suggested a stronger association between MTV and poor survival outcomes in patients with median of lines of previous treatment of 2 or 3 as compared to those of 4 (p for subgroup difference < 0.05). Further meta-regression analyses suggested that the association between MTV and survival was not significantly affected by sample size, age, proportion of men, cutoff value of MTV, follow-up duration, or study quality scores (p all > 0.05). Conclusion: A high MTV at baseline is associated with a poor survival of NHL patients after CAR-T. Systematic Review Registration: https://inplasy.com/, identifier INPLASY (INPLASY202450069).

In vivo CAR T cell therapy against angioimmunoblastic T cell lymphoma.

BACKGROUND: For angioimmunoblastic T cell lymphoma (AITL), a rare cancer, no specific treatments are available and survival outcome is poor. We previously developed a murine model for AITL that mimics closely human disease and allows to evaluate new treatments. As in human AITL, the murine CD4+ follicular helper T (Tfh) cells are drivers of the malignancy. Therefore, chimeric antigen receptor (CAR) T cell therapy might represent a new therapeutic option. METHODS: To prevent fratricide among CAR T cells when delivering an CD4-specific CAR, we used a lentiviral vector (LV) encoding an anti-CD4 CAR, allowing exclusive entry into CD8 T cells. RESULTS: These anti-CD4CAR CD8-targeted LVs achieved in murine AITL biopsies high CAR-expression levels in CD8 T cells. Malignant CD4 Tfh cells were eliminated from the mAITL lymphoma, while the CAR + CD8 T cells expanded upon encounter with the CD4 receptor and were shaped into functional cytotoxic cells. Finally, in vivo injection of the CAR + CD8-LVs into our preclinical AITL mouse model carrying lymphomas, significantly prolonged mice survival. Moreover, the in vivo generated functional CAR + CD8 T cells efficiently reduced neoplastic T cell numbers in the mAITL tumors. CONCLUSION: This is the first description of in vivo generated CAR T cells for therapy of a T cell lymphoma. The strategy described offers a new therapeutic concept for patients suffering from CD4-driven T cell lymphomas.

The Current Landscape of Secondary Malignancies after CAR T-Cell Therapies: How Could Malignancies Be Prevented?

Chimeric antigen receptor (CAR) T-cell therapies have revolutionised the field of haematological malignancies by achieving impressive remission rates in patients with highly refractory haematological malignancies, improving overall survival. To date, six commercial anti-CD19 and anti-BCMA CAR T-cell products have been approved by the Food and Drug Administration (FDA) for the treatment of relapsed/refractory B-cell haematological malignancies and multiple myeloma. The indications for CAR T-cell therapies are gradually expanding, with these therapies being investigated in a variety of diseases, including non-malignant ones. Despite the great success, there are several challenges surrounding CAR T-cell therapies, such as non-durable responses and high-grade toxicities. In addition, a new safety concern was added by the FDA on 28 November 2023 following reports of T-cell malignancies in patients previously treated with either anti-CD19 or anti-BCMA autologous CAR T-cell therapies both in clinical trials and in the real-world setting. Since then, several reports have been published presenting the incidence and analysing the risks of other secondary malignancies after CAR T-cell therapies. In this opinion article, the current landscape of secondary malignancies after CAR T-cell therapies is presented, along with a proposed strategy for future research aiming at potentially diminishing or abrogating the risk of developing secondary malignancies after CAR T-cell therapies.

Several factors that predict the outcome of large B-cell lymphoma patients who relapse/progress after chimeric antigen receptor (CAR) T-cell therapy can be identified before cell administration.

AIM: The aim of this study was to analyse the outcomes of patients with large B-cell lymphoma (LBCL) treated with chimeric antigen receptor T-cell therapy (CAR-Tx), with a focus on outcomes after CAR T-cell failure, and to define the risk factors for rapid progression and further treatment. METHODS: We analysed 107 patients with LBCL from the Czech Republic and Slovakia who were treated in ≥3rd-line with tisagenlecleucel or axicabtagene ciloleucel between 2019 and 2022. RESULTS: The overall response rate (ORR) was 60%, with a 50% complete response (CR) rate. The median progression-free survival (PFS) and overall survival (OS) were 4.3 and 26.4 months, respectively. Sixty-three patients (59%) were refractory or relapsed after CAR-Tx. Of these patients, 39 received radiotherapy or systemic therapy, with an ORR of 22% (CR 8%). The median follow-up of surviving patients in whom treatment failed was 10.6 months. Several factors predicting further treatment administration and outcomes were present even before CAR-Tx. Risk factors for not receiving further therapy after CAR-Tx failure were high lactate dehydrogenase (LDH) levels before apheresis, extranodal involvement (EN), high ferritin levels before lymphodepletion (LD) and ECOG PS >1 at R/P. The median OS-2 (from R/P after CAR-Tx) was 6.7 months (6-month 57.9%) for treated patients and 0.4 months (6-month 4.2%) for untreated patients (p < 0.001). The median PFS-2 (from R/P after CAR-Tx) was 3.2 months (6-month 28.5%) for treated patients. The risk factors for a shorter PFS-2 (n = 39) included: CRP > limit of the normal range (LNR) before LD, albumin < LNR and ECOG PS > 1 at R/P. All these factors, together with LDH > LNR before LD and EN involvement at R/P, predicted OS-2 for treated patients. CONCLUSION: Our findings allow better stratification of CAR-Tx candidates and stress the need for a proactive approach (earlier restaging, intervention after partial remission achievement).

TCR/CD3-based synthetic antigen receptors (TCC) convey superior antigen sensitivity combined with high fidelity of activation.

Low antigen sensitivity and a gradual loss of effector functions limit the clinical applicability of chimeric antigen receptor (CAR)-modified T cells and call for alternative antigen receptor designs for effective T cell-based cancer immunotherapy. Here, we applied advanced microscopy to demonstrate that TCR/CD3-based synthetic constructs (TCC) outperform second-generation CAR formats with regard to conveyed antigen sensitivities by up to a thousandfold. TCC-based antigen recognition occurred without adverse nonspecific signaling, which is typically observed in CAR-T cells, and did not depend-unlike sensitized peptide/MHC detection by conventional T cells-on CD4 or CD8 coreceptor engagement. TCC-endowed signaling properties may prove critical when targeting antigens in low abundance and aiming for a durable anticancer response.

Chick Embryo Chorioallantoic Membrane as a Platform for Assessing the In Vivo Efficacy of Chimeric Antigen Receptor T-cell Therapy in Solid Tumors.

The fertilized chicken egg chorioallantoic membrane (CAM), a highly vascularized membrane nourishing the developing embryo, also supports rapid growth of three-dimensional vascularized tumors from engrafted cells and tumor explants. Because murine xenograft models suffer limitations of time, cost, and scalability, we propose CAM tumors as a rapid, efficient screening tool for assessing anti-tumor efficacy of chimeric Ag receptor (CAR) T cells against solid tumors. We tested the efficacy of human epidermal growth factor receptor 2 (HER2)-specific CAR T cells against luminescent, HER2-expressing (FaDu, SCC-47) or HER2-negative (MDA-MB-468) CAM-engrafted tumors. Three days after tumor engraftment, HER2-specific CAR T cells were applied to tumors grown on the CAM. Four days post-CAR T cell treatment, HER2-expressing FaDu and SCC-47 tumors treated with CAR T showed reduced viable cancer cells as assessed by luciferase activity. This reduction in viable tumor cells was confirmed by histology, with lower Ki-67 staining observed in CAR T cell-treated tumors relative to T cell-treated controls. Persistence of CAR T in CAM and tumor tissue 4 days post-treatment was confirmed by CD3 staining. Altogether, our findings support further development of the chick CAM as an in vivo system for rapid, scalable screening of CAR T cell efficacy against human solid tumors.