Survival advantage of native and engineered T cells is acquired by mitochondrial transfer from mesenchymal stem cells.

BACKGROUND: Apoptosis, a form of programmed cell death, is critical for the development and homeostasis of the immune system. Chimeric antigen receptor T (CAR-T) cell therapy, approved for hematologic cancers, retains several limitations and challenges associated with ex vivo manipulation, including CAR T-cell susceptibility to apoptosis. Therefore, strategies to improve T-cell survival and persistence are required. Mesenchymal stem/stromal cells (MSCs) exhibit immunoregulatory and tissue-restoring potential. We have previously shown that the transfer of umbilical cord MSC (UC-MSC)-derived mitochondrial (MitoT) prompts the genetic reprogramming of CD3+ T cells towards a Treg cell lineage. The potency of T cells plays an important role in effective immunotherapy, underscoring the need for improving their metabolic fitness. In the present work, we evaluate the effect of MitoT on apoptotis of native T lymphocytes and engineered CAR-T cells. METHODS: We used a cell-free approach using artificial MitoT (Mitoception) of UC-MSC derived MT to peripheral blood mononuclear cells (PBMCs) followed by RNA-seq analysis of CD3+ MitoTpos and MitoTneg sorted cells. Target cell apoptosis was induced with Staurosporine (STS), and cell viability was evaluated with Annexin V/7AAD and TUNEL assays. Changes in apoptotic regulators were assessed by flow cytometry, western blot, and qRT-PCR. The effect of MitoT on 19BBz CAR T-cell apoptosis in response to electroporation with a non-viral transposon-based vector was assessed with Annexin V/7AAD. RESULTS: Gene expression related to apoptosis, cell death and/or responses to different stimuli was modified in CD3+ T cells after Mitoception. CD3+MitoTpos cells were resistant to STS-induced apoptosis compared to MitoTneg cells, showing a decreased percentage in apoptotic T cells as well as in TUNEL+ cells. Additionally, MitoT prevented the STS-induced collapse of the mitochondrial membrane potential (MMP) levels, decreased caspase-3 cleavage, increased BCL2 transcript levels and BCL-2-related BARD1 expression in FACS-sorted CD3+ T cells. Furthermore, UC-MSC-derived MitoT reduced both early and late apoptosis in CAR-T cells following electroporation, and exhibited an increasing trend in cytotoxic activity levels. CONCLUSIONS: Artificial MitoT prevents STS-induced apoptosis of human CD3+ T cells by interfering with the caspase pathway. Furthermore, we observed that MitoT confers protection to apoptosis induced by electroporation in MitoTpos CAR T-engineered cells, potentially improving their metabolic fitness and resistance to environmental stress. These results widen the physiological perspective of organelle-based therapies in immune conditions while offering potential avenues to enhance CAR-T treatment outcomes where their viability is compromised.

Obstacles to global implementation of CAR T cell therapy in myeloma and lymphoma.

Chimeric Antigen Receptor T-cell (CAR-T) therapies are transforming the treatment of B-cell lymphoproliferative disorders and multiple myeloma, yet global access challenges and barriers for their implementation persist. Global access disparities persist, particularly for persons living in low and middle-income countries and for underserved populations in high income countries. In this review we address patient-related factors including age, comorbidities, fitness, race and ethnicity, and geographic location for CAR-T access. Also, we review disease-related and health system barriers like disease biology, potential for short and long-term toxicity, insurance access, referrals, supply and manufacturing, regulation, costs and treatment center capacity. Lastly, alternatives for overcoming these barriers exemplified by research efforts worldwide are discussed, emphasizing the need for a multifaceted approach from all stakeholders to improve global accessibility and ensure equitable access and improved outcomes for patients worldwide.

The cardiotoxic effects of CAR-T cell therapy: An updated systematic review and meta-analysis.

BACKGROUND: Chimeric antigen receptor T-cell (CAR-T) therapy has shown promise in treating hematologic malignancies, yet its potential cardiotoxic effects require thorough investigation. OBJECTIVES: We aim to conduct a systematic review and meta-analysis to examine the cardiotoxic effects of CAR-T therapy in adults with hematologic malignancies. METHODS: We searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials for studies reporting cardiovascular outcomes, such as arrhythmias, heart failure, and reduced left ventricle ejection fraction (LVEF). RESULTS: Our analysis of 20 studies involving 4789 patients revealed a 19.68% incidence rate of cardiovascular events, with arrhythmias (7.70%), heart failure (5.73%), and reduced LVEF (3.86%) being the most prevalent. Troponin elevation was observed in 23.61% of patients, while NT-Pro-BNP elevation was observed in 9.4. Subgroup analysis showed higher risks in patients with pre-existing conditions, such as atrial arrhythmia (OR 3.12; p < .001), hypertension (OR 1.85; p = .002), previous heart failure (OR 3.38; p = .003), and coronary artery disease (OR 2.80; p = .003). CONCLUSION: Vigilant cardiovascular monitoring is crucial for patients undergoing CAR-T therapy to enhance safety and treatment efficacy.Novelty Statements.

CD19 CAR T cells for B cell malignancies: a systematic review and meta-analysis focused on clinical impacts of CAR structural domains, manufacturing conditions, cellular product, doses, patient's age, and tumor types.

CD19-targeted chimeric antigen receptors (CAR) T cells are one of the most remarkable cellular therapies for managing B cell malignancies. However, long-term disease-free survival is still a challenge to overcome. Here, we evaluated the influence of different hinge, transmembrane (TM), and costimulatory CAR domains, as well as manufacturing conditions, cellular product type, doses, patient's age, and tumor types on the clinical outcomes of patients with B cell cancers treated with CD19 CAR T cells. The primary outcome was defined as the best complete response (BCR), and the secondary outcomes were the best objective response (BOR) and 12-month overall survival (OS). The covariates considered were the type of hinge, TM, and costimulatory domains in the CAR, CAR T cell manufacturing conditions, cell population transduced with the CAR, the number of CAR T cell infusions, amount of CAR T cells injected/Kg, CD19 CAR type (name), tumor type, and age. Fifty-six studies (3493 patients) were included in the systematic review and 46 (3421 patients) in the meta-analysis. The overall BCR rate was 56%, with 60% OS and 75% BOR. Younger patients displayed remarkably higher BCR prevalence without differences in OS. The presence of CD28 in the CAR's hinge, TM, and costimulatory domains improved all outcomes evaluated. Doses from one to 4.9 million cells/kg resulted in better clinical outcomes. Our data also suggest that regardless of whether patients have had high objective responses, they might have survival benefits from CD19 CAR T therapy. This meta-analysis is a critical hypothesis-generating instrument, capturing effects in the CD19 CAR T cells literature lacking randomized clinical trials and large observational studies.

Sicca syndrome/Sjögren's disease associated with cancer immunotherapy: a narrative review on clinical presentation, biomarkers, and management.

INTRODUCTION: Almost one-quarter of immune checkpoint inhibitor (ICI) recipients experience sicca syndrome, while Sjögren's disease (SjD) is estimated at 0.3-2.5%, possibly underreported. AREAS COVERED: This narrative review (Medline/Embase until January/31/2024) addresses the pathophysiology, incidence, demographic/clinical features, biomarkers, labial salivary gland biopsy (LSGB), fulfillment of the idiopathic SjD (iSjD) classificatory criteria, differential diagnosis, and management of sicca syndrome/SjD associated with ICIs. EXPERT OPINION: SjD associated with ICIs is underdiagnosed, since studies that performed the mandatory SjD investigation identified that 40-60% of patients with sicca syndrome associated with ICIs meet the iSjD classificatory criteria. LSGB played a fundamental role in recognizing these cases, as most of them had negative anti-Ro/SS-A antibody. Despite the finding of focal lymphocytic sialoadenitis in LSGB samples mimicking iSjD, immunohistochemical analysis provided novel evidence of a distinct pattern for sicca syndrome/SjD associated with ICIs compared to iSjD. The former has scarcity of B lymphocytes, which are a hallmark of iSjD. Additionally, patients with sicca syndrome/SjD associated with ICIs have demographical/clinical/serological and treatment response dissimilarities compared to iSjD. Dryness symptoms are more acute in the former than in iSjD, with predominance of xerostomia over xerophthalmia, and partial/complete response to glucocorticoids. Dryness symptoms in ICI-treated patients warrant prompt SjD investigation.

In silico and in vivo analysis reveal impact of c-Myc tag in FMC63 scFv-CD19 protein interface and CAR-T cell efficacy.

Anti-CD19 CAR-T cell therapy represents a breakthrough in the treatment of B-cell malignancies, and it is expected that this therapy modality will soon cover a range of solid tumors as well. Therefore, a universal cheap and sensitive method to detect CAR expression is of foremost importance. One possibility is the use of epitope tags such as c-Myc, HA or FLAG tags attached to the CAR extracellular domain, however, it is important to determine whether these tags can influence binding of the CAR with its target molecule. Here, we conducted in-silico structural modelling of an FMC63-based anti-CD19 single-chain variable fragment (scFv) with and without a c-Myc peptide tag added to the N-terminus portion and performed molecular dynamics simulation of the scFv with the CD19 target. We show that the c-Myc tag presence in the N-terminus portion does not affect the scFv's structural equilibrium and grants more stability to the scFv. However, intermolecular interaction potential (IIP) analysis reveals that the tag can approximate the complementarity-determining regions (CDRs) present in the scFv and cause steric impediment, potentially disturbing interaction with the CD19 protein. We then tested this possibility with CAR-T cells generated from human donors in a Nalm-6 leukemia model, showing that CAR-T cells with the c-Myc tag have overall worse antitumor activity, which was also observed when the tag was added to the C-terminus position. Ultimately, our results suggest that tag addition is an important aspect of CAR design and can influence CAR-T cell function, therefore its use should be carefully considered.

CAR T-cell therapy and the onco-nephrologist.

Cell therapy, specifically the revolutionary chimeric antigen receptor (CAR) T-cell therapy, has transformed the landscape of oncology, making substantial strides in practical treatment approaches. Today, established guidelines for diseases such as lymphomas, myelomas, and leukemias actively advocate the utilization of these once-unconventional therapies. The practical impact of these therapies is underscored by their unparalleled efficacy, reshaping the way we approach and implement treatments in the realm of oncology. However, CAR T-cell therapy, with its performance in anti-tumor aggression through cellular action and inflammatory response, also comes with various adverse events, one of which is kidney injury. Therefore, the management of these side effects is extremely important. The integration of knowledge between oncologists and specialized nephrologists has led to the emergence of a new sub-area of expertise for onco-nephrologists specializing in managing kidney complications from immune effector therapies.

CAR-T therapy for gastrointestinal cancers: current status, challenges, and future directions

Chimeric antigen receptor (CAR) T-cell therapy is a revolutionary immunotherapeutic strategy that has shown efficacy in hematological malignancies. However, its application in solid tumors, particularly gastrointestinal cancers, faces significant challenges. These include the selection of target antigens, the complexity of the tumor microenvironment, and safety and toxicity concerns. This review provides a current overview of CAR-T therapy in various gastrointestinal cancers, such as esophageal, gastric, colorectal, pancreatic, and liver cancers. It discusses the limitations and future directions of CAR-T therapy in this context. This review highlights innovative strategies, including novel target antigens, multispecific CAR-T cells, armored CAR-T cells, and the development of universal CAR-T cells. These insights aim to inform ongoing research and foster advancements in CAR-T therapy for gastrointestinal cancers.

CAR-T cell therapy: a game-changer in cancer treatment and beyond.

In recent years, cancer has become one of the primary causes of mortality, approximately 10 million deaths worldwide each year. The most advanced, chimeric antigen receptor (CAR) T cell immunotherapy has turned out as a promising treatment for cancer. CAR-T cell therapy involves the genetic modification of T cells obtained from the patient's blood, and infusion back to the patients. CAR-T cell immunotherapy has led to a significant improvement in the remission rates of hematological cancers. CAR-T cell therapy presently limited to hematological cancers, there are ongoing efforts to develop additional CAR constructs such as bispecific CAR, tandem CAR, inhibitory CAR, combined antigens, CRISPR gene-editing, and nanoparticle delivery. With these advancements, CAR-T cell therapy holds promise concerning potential to improve upon traditional cancer treatments such as chemotherapy and radiation while reducing associated toxicities. This review covers recent advances and advantages of CAR-T cell immunotherapy.

CAR-T Cell Therapy: From the Shop to Cancer Therapy.

Cancer is a worldwide health problem. Nevertheless, new technologies in the immunotherapy field have emerged. Chimeric antigen receptor (CAR) technology is a novel biological form to treat cancer; CAR-T cell genetic engineering has positively revolutionized cancer immunotherapy. In this paper, we review the latest developments in CAR-T in cancer treatment. We present the structure of the different generations and variants of CAR-T cells including TRUCK (T cells redirected for universal cytokine killing. We explain the approaches of the CAR-T cells manufactured ex vivo and in vivo. Moreover, we describe the limitations and areas of opportunity for this immunotherapy and the current challenges of treating hematological and solid cancer using CAR-T technology as well as its constraints and engineering approaches. We summarize other immune cells that have been using CAR technology, such as natural killer (NK), macrophages (M), and dendritic cells (DC). We conclude that CAR-T cells have the potential to treat not only cancer but other chronic diseases.

Delivery of Plasmid DNA by Ionizable Lipid Nanoparticles to Induce CAR Expression in T Cells.

Introduction: Chimeric antigen receptor (CAR) cell therapy represents a hallmark in cancer immunotherapy, with significant clinical results in the treatment of hematological tumors. However, current approved methods to engineer T cells to express CAR use viral vectors, which are integrative and have been associated with severe adverse effects due to constitutive expression of CAR. In this context, non-viral vectors such as ionizable lipid nanoparticles (LNPs) arise as an alternative to engineer CAR T cells with transient expression of CAR. Methods: Here, we formulated a mini-library of LNPs to deliver pDNA to T cells by varying the molar ratios of excipient lipids in each formulation. LNPs were characterized and screened in vitro using a T cell line (Jurkat). The optimized formulation was used ex vivo to engineer T cells derived from human peripheral blood mononuclear cells (PBMCs) for the expression of an anti-CD19 CAR (CAR-CD19BBz). The effectiveness of these CAR T cells was assessed in vitro against Raji (CD19+) cells. Results: LNPs formulated with different molar ratios of excipient lipids efficiently delivered pDNA to Jurkat cells with low cytotoxicity compared to conventional transfection methods, such as electroporation and lipofectamine. We show that CAR-CD19BBz expression in T cells was transient after transfection with LNPs. Jurkat cells transfected with our top-performing LNPs underwent activation when exposed to CD19+ target cells. Using our top-performing LNP-9-CAR, we were able to engineer human primary T cells to express CAR-CD19BBz, which elicited significant specific killing of CD19+ target cells in vitro. Conclusion: Collectively, our results show that LNP-mediated delivery of pDNA is a suitable method to engineer human T cells to express CAR, which holds promise for improving the production methods and broader application of this therapy in the future.

Autologous, allogeneic hematopoietic cell transplantation and CAR-T/NK therapy: what is their real importance in PTCL?

Peripheral T cell lymphoma (PTCL) is a rare and aggressive type of non-Hodgkin's lymphoma that affects mature T cells. This type of cancer is characterized by the abnormal growth of T cells, which can accumulate in the lymph nodes, spleen, bone marrow, and other organs, leading to a variety of symptoms. PTCLs are often difficult to diagnose and treat, and they have a poorer prognosis than other types of lymphoma. However, recent advancements in treatment options, such as targeted therapies have shown promise in improving outcomes for patients with PTCL. Here, we discuss the use of autologous and allogeneic hematopoietic cell transplantation (HCT) as a treatment strategy for patients with PTCL, as well as the recent treatment approaches based on advanced cellular therapy. The current evidence for the use of HCT in PTCL is mainly derived from registry data, retrospective studies, and expert opinion, as randomized trials are limited due to the low incidence and histological heterogeneity of PTCL subtypes.

Genome Editing for Engineering the Next Generation of Advanced Immune Cell Therapies.

Our current genetic engineering capacity through synthetic biology and genome editing is the foundation of a revolution in biomedical science: the use of genetically programmed cells as therapeutics. The prime example of this paradigm is the adoptive transfer of genetically engineered T cells to express tumor-specific receptors, such as chimeric antigen receptors (CARs) or engineered T-cell receptors (TCR). This approach has led to unprecedented complete remission rates in patients with otherwise incurable hematological malignancies. However, this approach is still largely ineffective against solid tumors, which comprise the vast majority of neoplasms. Also, limitations associated with the autologous nature of this therapy and shared markers between cancer cells and T cells further restrict the access to these therapies. Here, we described how cutting-edge genome editing approaches have been applied to unlock the full potential of these revolutionary therapies, thereby increasing therapeutic efficacy and patient accessibility.

Recent advances in CAR T-cell therapy for lymphoma in China.

Lymphoma is a hematologic malignancy which mainly consists of Hodgkin lymphoma (HL) and non-Hodgkin lymphoma (NHL). Although systemic chemotherapy, radiotherapy, and other advanced therapeutics, including rituximab or immune checkpoint inhibitors, have improved the prognosis in recent decades, there are still a number of patients with relapsed or refractory (R/R) lymphoma with a poor prognosis. Chimeric antigen receptor (CAR) T-cell therapy has provided a curative option for patients with relapsed or refractory lymphoma. Numerous clinical trials have been conducted worldwide and presented inspiring results that give insight into this breakthrough therapy. The development of cancer cell therapy in China has been rapid in the past years and dominates the field with the USA. This review aims to summarize the published results of CAR T-cell therapy alone or in combination with other therapies in mainland China, both in R/R NHL and R/R HL.

DC vaccine enhances CAR-T cell antitumor activity by overcoming T cell exhaustion and promoting T cell infiltration in solid tumors.

OBJECTIVE: Great success has been achieved in CAR-T cell immunotherapy in the treatment of hematological tumors. However, it is particularly difficult in solid tumors, because CAR-T is difficult to enter interior and exert long-term stable immune effects. Dendritic cells (DCs) can not only present tumor antigens but also promote the infiltration of T cells. Therefore, CAR-T cells with the help of DC vaccines are a reliable approach to treat solid tumors. METHODS: To test whether DC vaccine could promote CAR-T cell therapy in solid tumors, DC vaccine was co-cultured with MSLN CAR-T cells. The in vitro effects of DC vaccine on CAR-T were assessed by measuring cell proliferation, cell differentiation, and cytokine secretion. Effects of DC vaccine on CAR-T were evaluated using mice with subcutaneous tumors in vivo. The infiltration of CAR-T was analyzed using immunofluorescence. The persistence of CAR-T in mouse blood was analyzed using real-time quantitative PCR. RESULTS: The results showed that DC vaccine significantly enhanced the proliferation potential of MSLN CAR-T cells in vitro. DC vaccines not only promoted the infiltration of CAR-T cells, but also significantly improved the persistence of CAR-T in solid tumors in vivo. CONCLUSION: In conclusion, this study has demonstrated that DC vaccine can promote CAR-T therapy in solid tumors, which provides the possibility of widespread clinical application of CAR-T cells in the future.

Emerging Targeted Therapies for HER2-Positive Breast Cancer.

Breast cancer is the most common cancer in women and the leading cause of death. HER2 overexpression is found in approximately 20% of breast cancers and is associated with a poor prognosis and a shorter overall survival. Tratuzumab, a monoclonal antibody directed against the HER2 receptor, is the standard of care treatment. However, a third of the patients do not respond to therapy. Given the high rate of resistance, other HER2-targeted strategies have been developed, including monoclonal antibodies such as pertuzumab and margetuximab, trastuzumab-based antibody drug conjugates such as trastuzumab-emtansine (T-DM1) and trastuzumab-deruxtecan (T-DXd), and tyrosine kinase inhibitors like lapatinib and tucatinib, among others. Moreover, T-DXd has proven to be of use in the HER2-low subtype, which suggests that other HER2-targeted therapies could be successful in this recently defined new breast cancer subclassification. When patients progress to multiple strategies, there are several HER2-targeted therapies available; however, treatment options are limited, and the potential combination with other drugs, immune checkpoint inhibitors, CAR-T cells, CAR-NK, CAR-M, and vaccines is an interesting and appealing field that is still in development. In this review, we will discuss the highlights and pitfalls of the different HER2-targeted therapies and potential combinations to overcome metastatic disease and resistance to therapy.

Chimeric antigen receptor T cells therapy in solid tumors.

Chimeric antigen receptor T cells therapy (CAR-T therapy) is a class of ACT therapy. Chimeric antigen receptor (CAR) is an engineered synthetic receptor of CAR-T, which give T cells the ability to recognize tumor antigens in a human leukocyte antigen-independent (HLA-independent) manner and enables them to recognize more extensive target antigens than natural T cell surface receptor (TCR), resulting in tumor destruction. CAR-T is composed of an extracellular single-chain variable fragment (scFv) of antibody, which serves as the targeting moiety, hinge region, transmembrane spacer, and intracellular signaling domain(s). CAR-T has been developing in many generations, which differ according to costimulatory domains. CAR-T therapy has several limitations that reduce its wide availability in immunotherapy which we can summarize in antigen escape that shows either partial or complete loss of target antigen expression, so multiplexing CAR-T cells are promoted to enhance targeting of tumor profiles. In addition, the large diversity in the tumor microenvironment also plays a major role in limiting this kind of treatment. Therefore, engineered CAR-T cells can evoke immunostimulatory signals that rebalance the tumor microenvironment. Using CAR-T therapy in treating the solid tumor is mainly restricted by the difficulty of CAR-T cells infiltrating the tumor site, so local administration was developed to improve the quality of treatment. The most severe toxicity after CAR-T therapy is on-target/on-tumor toxicity, such as cytokine release syndrome (CRS). Another type of toxicity is on-target/off-tumor toxicity which originates from the binding of CAR-T cells to target antigen that has shared expression on normal cells leading to damage in healthy cells and organs. Toxicity management should become a focus of implementation to permit management beyond specialized centers.

CAR-T cell therapy for multiple myeloma: a practical toolkit for treatment in Brazil.

INTRODUCTION: Chimeric antigen receptor T (CAR-T) cell therapy is an emerging treatment option for relapsed/refractory multiple myeloma (RRMM) that is a multi-step process involving various stakeholders. Appropriate education on the practical logistics is therefore paramount to ensure treatment success. METHODS: A group of key opinion leaders met to explore the key elements of setting up and running a CAR-T center in Brazil. For each step in the CAR-T cell therapy process, the experts agreed on basic requirements, gave their key recommendations from practical experience, and considered any remaining unanswered questions. RESULTS: This paper presents best-practice recommendations and advice on how to overcome common challenges for each step in the CAR-T cell therapy process, with a focus on the current situation in Brazil. Key themes throughout the process are collaboration within the multidisciplinary team and with the referring physician, along with communication and education for patients and their caregivers. CONCLUSION: We believe that the expert insights presented in this paper, in particular on optimal patient selection and timing of CAR-T cell therapy, will deepen understanding of the CAR-T process and aid implementation of this novel therapy for patients with RRMM in Brazil.

Impacto do Complexo Repressor Polycomb 2 (PRC2) na modulação in vitro de células T CD8+ humanas / Impact of Polycomb Repressive Complex 2 (PRC2) on the in vitro modulation of human CD8+ T cells

INTRODUÇÃO: Células T CD8+ citotóxicas (CTLs) têm como principal atributo a capacidade de reconhecer e eliminar células-alvo que apresentem epítopos não próprios. Na resposta anti-tumoral, a estimulação persistente ao antígeno pode levar à indução da exaustão de tais células, que passam a apresentar um aumento na expressão de marcadores inibitórios, tornando-as disfuncionais. Nesse contexto, lançamos a hipótese de que mecanismos epigenéticos podem agir como indutores de programas intracelulares envolvidos na supressão de CTLs e que a manipulação farmacológica do epigenoma pode contribuir para a potencialização da resposta citotóxica ao aumentar a capacidade antitumoral dessas células. METODOLOGIA: Foi avaliada inicialmente a atividade modulatória de inibidores de diferentes subunidades do complexo repressor polycomb 2 (PRC2) sobre a função efetora de linfócitos T CD8+ humanos isolados a partir de PBMCs de doadores saudáveis. Além disso, desenvolvemos um sistema de células CAR-T antiCD19 utilizando metodologias não-virais de inserção gênica como o sistema transposontransposase Sleeping Beauty (SB), que representa uma alternativa mais acessível comparada à abordagem tradicional e possibilita a entrega do transgene por eletroporação, agilizando o processo de geração das células CAR-T. RESULTADOS: A inibição das subunidades EED e EZH2 através das sondas epigenéticas A395 e GSK343, respectivamente, aumentou e sustentou ao longo de uma cinética temporal a expressão de marcadores de ativação (CD25 e CD69), mediadores inflamatórios (IFN-γ e TNF-α) e granzima B (GzmB), principal mediador citotóxico produzido por linfócitos T CD8+ , sem que houvesse perda de viabilidade celular. Ademais, a inibição do complexo PRC2 impactou discretamente a proliferação de células T CD8+ , enquanto diminuiu a frequência de marcadores inibitórios como PD1. Utilizando-se dados públicos de expressão gênica de células T CD8+ de camundongos estimuladas in vitro por 72h com anti-CD3/CD28, a deleção condicional de EZH2 promoveu o aumento da expressão gênica de citocinas, quimiocinas e de seus receptores, além da maquinaria de citotoxicidade, o que favoreceu o enriquecimento de vias relacionadas à citotoxicidade celular e à capacidade efetora. Para validarmos o potencial antitumoral citotóxico de linfócitos T CD8+ após a repressão do PRC2, tratamos células CAR-T anti-CD19 com os inibidores GSK343 e A395, os quais também favoreceram o aumento da expressão de mediadores antitumorais e reduziram a expressão de PD1. Além disso, células CAR-T anti-CD19 tratadas com inibidores de PRC2 eliminaram as células de linhagem tumoral de Leucemia Linfoblástica Aguda de células B (LLA-B) CD19+ Nalm-6 mais eficientemente em comparação com células CAR-T anti-CD19 tratadas com os controles negativos. CONCLUSÃO: A inibição do complexo PRC2 potencializou a produção de mediadores inflamatórios e citotóxicos pelas células T CD8 ou células CAR-T. Portanto, nossos resultados sugerem que a modulação epigenética por meio da inibição deste complexo pode ser uma abordagem terapêutica promissora no tratamento oncológico.

INTRODUCTION: Cytotoxic CD8+ T lymphocytes (CTLs) are the main cells responsible for the recognition and elimination of tumor cells. During antitumor responses, chronic antigen stimulation induces CTL exhaustion, which is characterized by the progressive accumulation of inhibitory markers and suboptimal functional properties. Here, we hypothesized that epigenetic mechanisms govern CTL functions, and that pharmacological approaches capable of modulating the CTL epigenome can improve their cytotoxic activity, leading to an improved antitumor response. METHODS: We evaluated the modulatory effect of inhibitors that target different subunits of the Polycomb Repressive Complex 2 (PRC2) on the function of human CD8+ T lymphocytes from healthy PBMCs. In addition, we have developed anti-CD19 CAR-T cells using the Sleeping Beauty (SB) transposon-transposase system, a non-viral gene insertion method. RESULTS: The inhibition of the EED and EZH2 subunits using the epigenetic probes A395 and GSK343 increased and sustained across time the CTL expression of activation markers (i.e., CD25 and CD69), inflammatory mediators (i.e., IFN-γ and TNF-α) and the main cytotoxic granule granzyme B (GzmB), without affecting the CTL viability. In addition, the PRC2 inhibition showed a subtle impact on the CTL proliferation. Furthermore, the use of the epigenetic probes seemed to mitigate the CTL exhaustion process, as seen by the lower expression of PD1 upon PRC2 inhibition when compared with untreated cells. Taking advantage of publicly available transcriptome data from murine CD8+ T cells polyclonally stimulated with anti-CD3/CD28 for 72h, we found that the conditional deletion of EZH2 upregulated the gene expression of cytokines, chemokines/receptors, and the whole cytotoxic machinery, which favored the enrichment of pathways associated with cell cytotoxicity and effector-like cells. In line with this, the PRC2 inhibition of anti-CD19 CAR-T cells also potentiated the expression of antitumor (Gzmb) and inflammatory (IFN-  and TNF-) mediators when compared to the control groups. Moreover, inhibition of the PRC2 complex also seemed to have an impact on CAR-T cell exhaustion, as PD1 was dramatically reduced after the treatment. To validate the antitumor cytotoxic potential of CD8+ T lymphocytes after PRC2 repression, we cocultured CAR-T cells with LLA-B CD19+ Nalm-6 tumor lineage cells and found that the PRC2 inhibition eliminated more efficiently the target cells compared to the control group. CONCLUSION: The PRC2 inhibition potentiated inflammatory and cytotoxic mediators of human lymphocytes and led to improved antitumor activity of CAR-T cells. Therefore, our results suggest that epigenetic modulation through the inhibition of this complex can be a promising therapeutic approach in cancer treatment.