Induction of a central memory and stem cell memory phenotype in functionally active CD4+ and CD8+ CAR T cells produced in an automated good manufacturing practice system for the treatment of CD19+ acute lymphoblastic leukemia

Immunotherapeutic Potential of T Memory Stem Cells

Memory T cells include T memory stem cells (T_SCM) and central memory T cells (T_CM). Compared with effector memory T cells (T_EM) and effector T cells (T_EFF), they have better durability and anti-tumor immunity. Recent studies have shown that although T_SCM has excellent self-renewal ability and versatility, if it is often exposed to antigens and inflammatory signals, T_SCM will behave as a variety of inhibitory receptors such as PD-1, TIM-3 and LAG-3 expression, and metabolic changes from oxidative phosphorylation to glycolysis. These changes can lead to the exhaustion of T cells. Cumulative evidence in animal experiments shows that it is the least differentiated cell in the memory T lymphocyte system and is a central participant in many physiological and pathological processes in humans. It has a good clinical application prospect, so it is more and more important to study the factors affecting the formation of T_SCM. This article summarizes and prospects the phenotypic and functional characteristics of T_SCM, the regulation mechanism of formation, and its application in treatment of clinical diseases.

Production and Application of CAR T Cells: Current and Future Role of Europe

Rapid developments in the field of CAR T cells offer important new opportunities while at the same time increasing numbers of patients pose major challenges. This review is summarizing on the one hand the state of the art in CAR T cell trials with a unique perspective on the role that Europe is playing. On the other hand, an overview of reproducible processing techniques is presented, from manual or semi-automated up to fully automated manufacturing of clinical-grade CAR T cells. Besides regulatory requirements, an outlook is given in the direction of digitally controlled automated manufacturing in order to lower cost and complexity and to address CAR T cell products for a greater number of patients and a variety of malignant diseases.

Paving the Way for Immunotherapy in Pediatric Acute Myeloid Leukemia: Current Knowledge and the Way Forward

Simple Summary

Immunotherapy may be an attractive treatment option to increase survival, and to reduce treatment-related side effects, for children with acute myeloid leukemia (AML). While immunotherapies have shown successes in many cancer types, the development and subsequent clinical implementation have proven difficult in pediatric AML. To expedite the development of immunotherapy, it will be crucial to understand which pediatric AML patients are likely to respond to immunotherapies. Emerging research in solid malignancies has shown that the number and phenotype of immune cells in the tumor microenvironment is predictive of response to several types of immunotherapies. Such a predictive model may also be applicable for AML and, thus, knowledge on the immune cells infiltrating the bone marrow environment is needed. Here, we discuss the current state of knowledge on these infiltrating immune cells in pediatric AML, as well as ongoing immunotherapy trials, and provide suggestions concerning the way forward.

Abstract

Immunotherapeutic agents may be an attractive option to further improve outcomes and to reduce treatment-related toxicity for pediatric AML. While improvements in outcome have been observed with immunotherapy in many cancer types, immunotherapy development and implementation into patient care for both adult and pediatric AML has been hampered by an incomplete understanding of the bone marrow environment and a paucity of tumor-specific antigens. Since only a minority of patients respond in most immunotherapy trials across different cancer types, it will be crucial to understand which children with AML are likely to respond to or may benefit from immunotherapies. Immune cell profiling efforts hold promise to answer this question, as illustrated by the development of predictive scores in solid cancers. Such information on the number and phenotype of immune cells during current treatment regimens will be pivotal to generate hypotheses on how and when to intervene with immunotherapy in pediatric AML. In this review, we discuss the current understanding of the number and phenotype of immune cells in the bone marrow in pediatric AML, ongoing immunotherapy trials and how comprehensive immune profiling efforts may pave the way for successful clinical trials (and, ultimately, implementation into patient care).

Stem cell-like memory T cells: The generation and application

Stem cell-like memory T cells (Tscm), are a newly defined memory T cell subset with characteristics of long life span, consistent self-renewing, rapid differentiation into effector T cells, and apoptosis resistance. These features indicate that Tscm have great therapeutic or preventive purposes, including being applied in chimeric Ag receptor-engineered T cells, TCR gene-modified T cells, and vaccines. However, the little knowledge about Tscm development restrains their applications. Strength and duration of TCR signaling, cytokines and metabolism in the T cells during activation all influence the Tscm development via regulating transcriptional factors and cell signaling pathways. Here, we summarize the molecular and cellular pathways involving Tscm differentiation, and its clinical application for cancer immunotherapy and prevention.

Early-phenotype CAR-T cells for the treatment of pediatric cancers

Chimeric antigen receptor (CAR) T cell therapy is a promising approach for the treatment of childhood cancers, particularly high-risk tumors that fail to respond to standard therapies. CAR-T cells have been highly successful in treating some types of hematological malignancies. However, CAR-T cells targeting solid cancers have had limited success so far for multiple reasons, including their poor long-term persistence and proliferation. Evidence is emerging to show that maintaining CAR-T cells in an early, less differentiated state in vitro results in superior persistence, proliferation, and anti-tumor effects in vivo. Children are ideal candidates for receiving less-differentiated CAR-T cells, because their peripheral T cell pool primarily comprises naïve cells that could readily be harvested in large numbers to generate early-phenotype CAR-T cells. Although several studies have reported different approaches to successfully generate early CAR-T cells, there are only a few clinical trials testing these in adult patients. No trials are currently testing early CAR-T cells in children. Here, we summarize the different strategies used to maintain CAR-T cells in an early phenotypic stage, and present evidence suggesting that this approach may be particularly relevant to treating childhood cancers.

Lentiviral Vectors for T Cell Engineering: Clinical Applications, Bioprocessing and Future Perspectives

Lentiviral vectors have played a critical role in the emergence of gene-modified cell therapies, specifically T cell therapies. Tisagenlecleucel (Kymriah), axicabtagene ciloleucel (Yescarta) and most recently brexucabtagene autoleucel (Tecartus) are examples of T cell therapies which are now commercially available for distribution after successfully obtaining EMA and FDA approval for the treatment of blood cancers. All three therapies rely on retroviral vectors to transduce the therapeutic chimeric antigen receptor (CAR) into T lymphocytes. Although these innovations represent promising new therapeutic avenues, major obstacles remain in making them readily available tools for medical care. This article reviews the biological principles as well as the bioprocessing of lentiviral (LV) vectors and adoptive T cell therapy. Clinical and engineering successes, shortcomings and future opportunities are also discussed. The development of Good Manufacturing Practice (GMP)-compliant instruments, technologies and protocols will play an essential role in the development of LV-engineered T cell therapies.

Engineered T Cell Therapy for Gynecologic Malignancies: Challenges and Opportunities

Gynecologic malignancies, mainly including ovarian cancer, cervical cancer and endometrial cancer, are leading causes of death among women worldwide with high incidence and mortality rate. Recently, adoptive T cell therapy (ACT) using engineered T cells redirected by genes which encode for tumor-specific T cell receptors (TCRs) or chimeric antigen receptors (CARs) has demonstrated a delightful potency in B cell lymphoma treatment. Researches impelling ACT to be applied in treating solid tumors like gynecologic tumors are ongoing. This review summarizes the preclinical research and clinical application of engineered T cells therapy for gynecologic cancer in order to arouse new thoughts for remedies of this disease.

CLEC12A and CD33 coexpression as a preferential target for pediatric AML combinatorial immunotherapy

Emerging immunotherapies such as chimeric antigen receptor T cells have advanced the treatment of acute lymphoblastic leukemia. In contrast, long-term control of acute myeloid leukemia (AML) cannot be achieved by single lineage-specific targeting while sparing benign hematopoiesis. In addition, heterogeneity of AML warrants combinatorial targeting, and several suitable immunotargets (HAVCR2/CD33 and HAVCR2/CLEC12A) have been identified in adult AML. However, clinical and biologic characteristics of AML differ between children and the elderly. Here, we analyzed 36 bone marrow (BM) samples of pediatric AML patients and 13 age-matched healthy donors using whole RNA sequencing of sorted CD45dim and CD34+CD38-CD45dim BM populations and flow cytometry for surface expression of putative target antigens. Pediatric AML clusters apart from healthy myeloid BM precursors in principal-component analysis. Known immunotargets of adult AML, such as IL3RA, were not overexpressed in pediatric AML compared with healthy precursors by RNA sequencing. CD33 and CLEC12A were the most upregulated immunotargets on the RNA level and showed the highest surface expression on AML detected by flow cytometry. KMT2A-mutated infant AML clusters separately by RNA sequencing and overexpresses FLT3, and hence, CD33/FLT3 cotargeting is an additional specific option for this subgroup. CLEC12A and CD33/CLEC12Adouble-positive expression was absent in CD34+CD38-CD45RA-CD90+ hematopoietic stem cells (HSCs) and nonhematopoietic tissue, while CD33 and FLT3 are expressed on HSCs. In summary, we show that expression of immunotargets in pediatric AML differs from known expression profiles in adult AML. We identify CLEC12A and CD33 as preferential generic combinatorial immunotargets in pediatric AML and CD33 and FLT3 as immunotargets specific for KMT2A-mutated infant AML.

Locoregional infusion of HER2-specific CAR T cells in children and young adults with recurrent or refractory CNS tumors: an interim analysis

Locoregional delivery of chimeric antigen receptor (CAR) T cells has resulted in objective responses in adults with glioblastoma, but the feasibility and tolerability of this approach is yet to be evaluated for pediatric central nervous system (CNS) tumors. Here we show that engineering of a medium-length CAR spacer enhances the therapeutic efficacy of human erb-b2 receptor tyrosine kinase 2 (HER2)-specific CAR T cells in an orthotopic xenograft medulloblastoma model. We translated these findings into BrainChild-01 ( NCT03500991 ), an ongoing phase 1 clinical trial at Seattle Children's evaluating repetitive locoregional dosing of these HER2-specific CAR T cells to children and young adults with recurrent/refractory CNS tumors, including diffuse midline glioma. Primary objectives are assessing feasibility, safety and tolerability; secondary objectives include assessing CAR T cell distribution and disease response. In the outpatient setting, patients receive infusions via CNS catheter into either the tumor cavity or the ventricular system. The initial three patients experienced no dose-limiting toxicity and exhibited clinical, as well as correlative laboratory, evidence of local CNS immune activation, including high concentrations of CXCL10 and CCL2 in the cerebrospinal fluid. This interim report supports the feasibility of generating HER2-specific CAR T cells for repeated dosing regimens and suggests that their repeated intra-CNS delivery might be well tolerated and activate a localized immune response in pediatric and young adult patients.

CART-Cell Therapy: Recent Advances and New Evidence in Multiple Myeloma

Despite the improvement in survival outcomes, multiple myeloma (MM) remains an incurable disease. Chimeric antigen receptor (CAR) T-cell therapy targeting B-cell maturation antigen (BCMA) represents a new strategy for the treatment of relapsed/refractory MM (R/R). In this paper, we describe several recent advances in the field of anti-BCMA CAR T-cell therapy and MM. Currently, available data on anti-BCMA CART-cell therapy has demonstrated efficacy and manageable toxicity in heavily pretreated R/R MM patients. Despite this, the main issues remain to be addressed. First of all, a significant proportion of patients eventually relapse. The potential strategy to prevent relapse includes sequential or combined infusion with CAR T-cells against targets other than BCMA, CAR T-cells with novel dual-targeting vector design, and BCMA expression upregulation. Another dark side of CART therapy is safety. Cytokine release syndrome (CRS) andneurologic toxicity are well-described adverse effects. In the MM trials, most CRS events tended to be grade 1 or 2, with fewer patients experiencing grade 3 or higher. Another critical point is the extended timeline of the manufacturing process. Allo-CARs offers the potential for scalable manufacturing for on-demand treatment with shorter waiting days. Another issue is undoubtedly going to be access to this therapy. Currently, only a few academic centers can perform these procedures. Recognizing these issues, the excellent response with BCMA-targeted CAR T-cell therapy makes it a treatment strategy of great promise.

PiggyBac-Generated CAR19-T Cells Plus Lenalidomide Cause Durable Complete Remission of Triple-Hit Refractory/Relapsed DLBCL: A Case Report

MYC/BCL2/BCL6 triple-hit lymphoma (THL) is an uncommon subset of high-grade B-cell lymphoma with aggressive clinical behavior and poor prognosis. TP53 mutation is an independently poor progonistic indicator in patients with THL, hence novel therapeutic strategies are needed for these patients. CD19-directed chimeric antigen receptor(CAR19)-T cell therapy has shown promising efficacy for relapsed/refractory diffuse large B cell lymphoma (RR DLBCL), but the majority of CAR19-T cell products to date have been manufactured using viral vectors. PiggyBac transposon system, with an inclination to memory T cells, offers a more convenient and economical alternative for transgene delivery. We herein report the first case of triple-hit RR DLBCL with TP53 mutation who was treated with piggyBac-generated CAR19-T cells and accompanied by grade 2 cytokine release syndrome. The patient obtained a complete remission (CR) in the 2nd month post-infusion and demanded maintenance therapy. Whether maintenance therapy is favorable and how to administrate it after CAR-T cell infusion remain controversial. Preclinical studies demonstrated that lenalidomide could enhance antitumor activity of CAR19-T cells. Therefore, we pioneered oral lenalidomide after CAR19-T therapy in the patient from the 4th month, and he discontinued after one cycle due to side effects. The patient has still kept sustained CR for over 24 months. Our case have firstly demonstrated the feasibility, preliminary safety and efficacy of piggyBac-produced CAR19-T cell therapy in triple-hit lymphoma. The innovative combination with lenalidomide warrants further investigation. Our findings shed new light on the possible solutions to improve short-term relapse after CAR19-T cell therapy in RR DLBCL. ChiCTR, number ChiCTR1800018111.

Are chimeric antigen receptor T cells (CAR-T cells) the future in immunotherapy for autoimmune diseases?

OBJECTIVE

CAR-T cell therapy has revolutionized the treatment of oncological diseases, and potential uses in autoimmune diseases have recently been described. The review aims to integrate the available data on treatment with CAR-T cells, emphasizing autoimmune diseases, to determine therapeutic advances and their possible future clinical applicability in autoimmunity.

MATERIALS AND METHODS

A search was performed in PubMed with the keywords "Chimeric Antigen Receptor" and "CART cell". The documents of interest were selected, and a critical review of the information was carried out.

RESULTS

In the treatment of autoimmune diseases, in preclinical models, three different cellular strategies have been used, which include Chimeric antigen receptor T cells, Chimeric autoantibody receptor T cells, and Chimeric antigen receptor in regulatory T lymphocytes. All three types of therapy have been effective. The potential adverse effects within them, cytokine release syndrome, cellular toxicity and neurotoxicity must always be kept in mind.

CONCLUSIONS

Although information in humans is not yet available, preclinical models of CAR-T cells in the treatment of autoimmune diseases show promising results, so that in the future, they may become a useful and effective therapy in the treatment of these pathologies.

Obstacles and Coping Strategies of CAR-T Cell Immunotherapy in Solid Tumors

Chimeric antigen receptor (CAR) T-cell immunotherapy refers to an adoptive immunotherapy that has rapidly developed in recent years. It is a novel type of treatment that enables T cells to express specific CARs on their surface, then returns these T cells to tumor patients to kill the corresponding tumor cells. Significant strides in CAR-T cell immunotherapy against hematologic malignancies have elicited research interest among scholars in the treatment of solid tumors. Nonetheless, in contrast with the efficacy of CAR-T cell immunotherapy in the treatment of hematologic malignancies, its general efficacy against solid tumors is insignificant. This has been attributed to the complex biological characteristics of solid tumors. CAR-T cells play a better role in solid tumors, for instance by addressing obstacles including the lack of specific targets, inhibition of tumor microenvironment (TME), homing barriers of CAR-T cells, differentiation and depletion of CAR-T cells, inhibition of immune checkpoints, trogocytosis of CAR-T cells, tumor antigen heterogeneity, etc. This paper reviews the obstacles influencing the efficacy of CAR-T cell immunotherapy in solid tumors, their mechanism, and coping strategies, as well as economic restriction of CAR-T cell immunotherapy and its solutions. It aims to provide some references for researchers to better overcome the obstacles that affect the efficacy of CAR-T cells in solid tumors.

Single-cell multiomics dissection of basal and antigen-specific activation states of CD19-targeted CAR T cells

Background

Autologous T cells engineered to express a chimeric antigen receptor (CAR) specific for CD19 molecule have transformed the therapeutic landscape in patients with highly refractory leukemia and lymphoma, and the use of donor-generated allogeneic CAR T is paving the way for further breakthroughs in the treatment of cancer. However, it remains unknown how the intrinsic heterogeneities of these engineered cells mediate therapeutic efficacy and whether allogeneic products match the effectiveness of autologous therapies.

Methods

Using single-cell mRNA sequencing in conjunction with CITE-seq, we performed multiomics characterization of CAR T cells generated from healthy donor and patients with acute lymphoblastic leukemia. CAR T cells used in this study were manufactured at the University of Pennsylvania through lentiviral transduction with a CD19-4-1BB-CD3ζ construct. Besides the baseline condition, we engineered NIH-3T3 cells with human CD19 or mesothelin expression to conduct ex vivo antigen-specific or non-antigen stimulation of CAR T cells through 6-hour coculture at a 1:1 ratio.

Results

We delineated the global cellular and molecular CAR T landscape and identified that transcriptional CAR tonic signaling was regulated by a mixture of early activation, exhaustion signatures, and cytotoxic activities. On CD19 stimulation, we illuminated the disparities of CAR T cells derived from different origins and found that donor CAR T had more pronounced activation level in correlation with the upregulation of major histocompatibility complex class II genes compared with patient CAR T cells. This finding was independently validated in additional datasets from literature. Furthermore, GM-CSF(CSF2) expression was found to be associated with functional gene productions, but it induced little impact on the CAR T activation.

Conclusions

Through integrated multiomics profiling and unbiased canonical pathway analyses, our results unveil heterogeneities in the transcriptional, phenotypic, functional, and metabolic profiles of donor and patient CAR T cells, providing mechanistic basis for ameliorating clinical outcomes and developing next-generation ‘off- the-shelf’ allogeneic products.

CDK4/6 inhibition promotes anti-tumor immunity through the induction of T cell memory

Pharmacological inhibitors of cyclin dependent kinases 4 and 6 (CDK4/6) are an approved treatment for hormone receptor-positive breast cancer and are currently under evaluation across hundreds of clinical trials for other cancer types. The clinical success of these inhibitors is largely attributed to well-defined tumor-intrinsic cytostatic mechanisms, while their emerging role as immunomodulatory agents is less understood. Using integrated epigenomic, transcriptomic and proteomic analyses, we demonstrated a novel action of CDK4/6 inhibitors in promoting the phenotypic and functional acquisition of immunological T cell memory. Short-term priming with a CDK4/6 inhibitor promoted long-term endogenous anti-tumor T cell immunity in mice, enhanced the persistence and therapeutic efficacy of chimeric antigen receptor (CAR)-T cells, and induced an RB-dependent T cell phenotype supportive of favorable responses to immune checkpoint blockade in melanoma patients. Together, these mechanistic insights significantly broaden the prospective utility of CDK4/6 inhibitors as clinical tools to boost anti-tumor T cell immunity.

The S enantiomer of 2-hydroxyglutarate increases central memory CD8 populations and improves CAR-T therapy outcome

Cancer immunotherapy is advancing rapidly and gene-modified T cells expressing chimeric antigen receptors (CARs) show particular promise. A challenge of CAR-T cell therapy is that the ex vivo-generated CAR-T cells become exhausted during expansion in culture, and do not persist when transferred back to patients. It has become clear that naive and memory CD8 T cells perform better than the total CD8 T-cell populations in CAR-T immunotherapy because of better expansion, antitumor activity, and persistence, which are necessary features for therapeutic success and prevention of disease relapse. However, memory CAR-T cells are rarely used in the clinic due to generation challenges. We previously reported that mouse CD8 T cells cultured with the S enantiomer of the immunometabolite 2-hydroxyglutarate (S-2HG) exhibit enhanced antitumor activity. Here, we show that clinical-grade human donor CAR-T cells can be generated from naive precursors after culture with S-2HG. S-2HG-treated CAR-T cells establish long-term memory cells in vivo and show superior antitumor responses when compared with CAR-T cells generated with standard clinical protocols. This study provides the basis for a phase 1 clinical trial evaluating the activity of S-2HG-treated CD19-CAR-T cells in patients with B-cell malignancies.

CD22-directed CAR T-cell therapy induces complete remissions in CD19-directed CAR-refractory large B-cell lymphoma

The prognosis of patients with large B-cell lymphoma (LBCL) that progresses after treatment with chimeric antigen receptor (CAR) T-cell therapy targeting CD19 (CAR19) is poor. We report on the first 3 consecutive patients with autologous CAR19-refractory LBCL who were treated with a single infusion of autologous 1 × 106 CAR+ T cells per kilogram targeting CD22 (CAR22) as part of a phase 1 dose-escalation study. CAR22 therapy was relatively well tolerated, without any observed nonhematologic adverse events higher than grade 2. After infusion, all 3 patients achieved complete remission, with all responses continuing at the time of last follow-up (mean, 7.8 months; range, 6-9.3). Circulating CAR22 cells demonstrated robust expansion (peak range, 85.4-350 cells per microliter), and persisted beyond 3 months in all patients with continued radiographic responses and corresponding decreases in circulating tumor DNA beyond 6 months after infusion. Further accrual at a higher dose level in this phase 1 dose-escalation study is ongoing and will explore the role of this therapy in patients in whom prior CAR T-cell therapies have failed. This trial is registered on clinicaltrials.gov as #NCT04088890.

TRIM68, PIKFYVE, and DYNLL2: The Possible Novel Autophagy- and Immunity-Associated Gene Biomarkers for Osteosarcoma Prognosis

Introduction

Osteosarcoma is among the most common orthopedic neoplasms, and currently, there are no adequate biomarkers to predict its prognosis. Therefore, the present study was aimed to identify the prognostic biomarkers for autophagy-and immune-related osteosarcoma using bioinformatics tools for guiding the clinical diagnosis and treatment of this disease.

Materials and Methods

The gene expression and clinical information data were downloaded from the Public database. The genes associated with autophagy were extracted, followed by the development of a logistic regression model for predicting the prognosis of osteosarcoma using univariate and multivariate COX regression analysis and LASSO regression analysis. The accuracy of the constructed model was verified through the ROC curves, calibration plots, and Nomogram plots. Next, immune cell typing was performed using CIBERSORT to analyze the expression of the immune cells in each sample. For the results obtained from the analysis, we used qRT-PCR validation in two strains of human osteosarcoma cells.

Results

The screening process identified a total of three genes that fulfilled all the screening criteria. The survival curves of the constructed prognostic model revealed that patients with the high risk presented significantly lower survival than the patients with low risk. Finally, the immune cell component analysis revealed that all three genes were significantly associated with the immune cells. The expressions of TRIM68, PIKFYVE, and DYNLL2 were higher in the osteosarcoma cells compared to the control cells. Finally, we used human pathological tissue sections to validate the expression of the genes modeled in osteosarcoma and paracancerous tissue.

Conclusion

The TRIM68, PIKFYVE, and DYNLL2 genes can be used as biomarkers for predicting the prognosis of osteosarcoma.

CAR-T cells and BiTEs in solid tumors: challenges and perspectives

Chimeric antigen receptor (CAR)-modified T cells and BiTEs are both immunotherapies which redirect T cell specificity against a tumor-specific antigen through the use of antibody fragments. They demonstrated remarkable efficacy in B cell hematologic malignancies, thus paving the way for their development in solid tumors. Nonetheless, the use of such new drugs to treat solid tumors is not straightforward. So far, the results from early phase clinical trials are not as impressive as expected but many improvements are under way. In this review we present an overview of the clinical development of CAR-T cells and BiTEs targeting the main antigens expressed by solid tumors. We emphasize the most frequent hurdles encountered by either CAR-T cells or BiTEs, or both, and summarize the strategies that have been proposed to overcome these obstacles.

Lymphocyte expansion in bioreactors: upgrading adoptive cell therapy

Bioreactors are essential tools for the development of efficient and high-quality cell therapy products. However, their application is far from full potential, holding several challenges when reconciling the complex biology of the cells to be expanded with the need for a manufacturing process that is able to control cell growth and functionality towards therapy affordability and opportunity. In this review, we discuss and compare current bioreactor technologies by performing a systematic analysis of the published data on automated lymphocyte expansion for adoptive cell therapy. We propose a set of requirements for bioreactor design and identify trends on the applicability of these technologies, highlighting the specific challenges and major advancements for each one of the current approaches of expansion along with the opportunities that lie in process intensification. We conclude on the necessity to develop targeted solutions specially tailored for the specific stimulation, supplementation and micro-environmental needs of lymphocytes’ cultures, and the benefit of applying knowledge-based tools for process control and predictability.

Endogenous TCR promotes in vivo persistence of CD19-CAR-T cells compared to a CRISPR/Cas9-mediated TCR knockout CAR

Anti-CD19 chimeric antigen receptor (CAR) T cells showed significant antileukemic activity in B-precursor acute lymphoblastic leukemia (ALL). Allogeneic, HLA-mismatched off-the-shelf third-party donors may offer ideal fitness of the effector cells, but carry the risk of graft-versus-host disease. Knockout (KO) of the endogenous T-cell receptor (TCR) in CD19-CAR-T cells may be a promising solution. Here, we induced a CRISPR/Cas9-mediated KO of the TCRβ chain in combination with a second-generation retroviral CAR transduction including a 4-1BB costimulatory domain in primary T cells. This tandem engineering led to a highly functional population of TCR-KO-CAR-T cells with strong activation (CD25, interferon γ), proliferation, and specific killing upon CD19 target recognition. TCR-KO-CAR-T cells had a balanced phenotype of central memory and effector memory T cells. KO of the endogenous TCR in T cells strongly ablated alloreactivity in comparison with TCR-expressing T cells. In a patient-derived xenograft model of childhood ALL, TCR-KO-CAR-T cells clearly controlled CD19+ leukemia burden and improved survival in vivo. However, coexpression of endogenous TCR plus CAR led to superior persistence of T cells and significantly prolonged leukemia control in vivo, confirmed by a second in vivo model using the leukemia cell line NALM6. These results point toward an essential role of the endogenous TCR for longevity of the response at the price of alloreactivity. In conclusion, anti-CD19 CAR T cells with a CRISPR/Cas9-mediated TCR-KO are promising candidates for nonmatched third-party adoptive T-cell transfer with high antileukemic functionality in the absence of alloreactivity, but long-term persistence in vivo is better in the presence of the endogenous TCR.

The BCMA-Targeted Fourth-Generation CAR-T Cells Secreting IL-7 and CCL19 for Therapy of Refractory/Recurrent Multiple Myeloma

Chimeric antigen receptor (CAR) technology has revolutionized cancer treatment, particularly in malignant hematological tumors. Currently, the BCMA-targeted second-generation CAR-T cells have showed impressive efficacy in the treatment of refractory/relapsed multiple myeloma (R/R MM), but up to 50% relapse remains to be addressed urgently. Here we constructed the BCMA-targeted fourth-generation CAR-T cells expressing IL-7 and CCL19 (i.e., BCMA-7 × 19 CAR-T cells), and demonstrated that BCMA-7 × 19 CAR-T cells exhibited superior expansion, differentiation, migration and cytotoxicity. Furthermore, we have been carrying out the first-in-human clinical trial for therapy of R/R MM by use of BCMA-7 × 19 CAR-T cells (ClinicalTrials.gov Identifier: NCT03778346), which preliminarily showed promising safety and efficacy in first two enrolled patients. The two patients achieved a CR and VGPR with Grade 1 cytokine release syndrome only 1 month after one dose of CAR-T cell infusion, and the responses lasted more than 12-month. Taken together, BCMA-7 × 19 CAR-T cells were safe and effective against refractory/relapsed multiple myeloma and thus warranted further clinical study.

CAR T cells with dual targeting of CD19 and CD22 in adult patients with recurrent or refractory B cell malignancies: a phase 1 trial

Despite impressive progress, more than 50% of patients treated with CD19-targeting chimeric antigen receptor T cells (CAR19) experience progressive disease. Ten of 16 patients with large B cell lymphoma (LBCL) with progressive disease after CAR19 treatment had absent or low CD19. Lower surface CD19 density pretreatment was associated with progressive disease. To prevent relapse with CD19^- or CD19^lo disease, we tested a bispecific CAR targeting CD19 and/or CD22 (CD19-22.BB.z-CAR) in a phase I clinical trial ( NCT03233854 ) of adults with relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) and LBCL. The primary end points were manufacturing feasibility and safety with a secondary efficacy end point. Primary end points were met; 97% of products met protocol-specified dose and no dose-limiting toxicities occurred during dose escalation. In B-ALL (n = 17), 100% of patients responded with 88% minimal residual disease-negative complete remission (CR); in LBCL (n = 21), 62% of patients responded with 29% CR. Relapses were CD19^-/lo in 50% (5 out of 10) of patients with B-ALL and 29% (4 out of 14) of patients with LBCL but were not associated with CD22^-/lo disease. CD19/22-CAR products demonstrated reduced cytokine production when stimulated with CD22 versus CD19. Our results further implicate antigen loss as a major cause of CAR T cell resistance, highlight the challenge of engineering multi-specific CAR T cells with equivalent potency across targets and identify cytokine production as an important quality indicator for CAR T cell potency.

Chimeric Antigen Receptor Based Therapy as a Potential Approach in Autoimmune Diseases: How Close Are We to the Treatment?

Despite significant breakthroughs in understanding of immunological and physiological features of autoimmune diseases, there is currently no specific therapeutic option with prolonged remission. Cell-based therapy using engineered-T cells has attracted tremendous attention as a practical treatment for autoimmune diseases. Genetically modified-T cells armed with chimeric antigen receptors (CARs) attack autoreactive immune cells such as B cells or antibody-secreting plasma cells. CARs can further guide the effector and regulatory T cells (Tregs) to the autoimmune milieu to traffic, proliferate, and exert suppressive functions. The genetically modified-T cells with artificial receptors are a promising option to suppress autoimmune manifestation and autoinflammatory events. Interestingly, CAR-T cells are modified to a new chimeric auto-antibody receptor T (CAAR-T) cell. This cell, with its specific-antigen, recognizes and binds to the target autoantibodies expressing autoreactive cells and, subsequently, destroy them. Preclinical studies of CAR-T cells demonstrated satisfactory outcomes against autoimmune diseases. However, the lack of target autoantigens remains one of the pivotal problems in the field of CAR-T cells. CAR-based therapy has to pass several hurdles, including stability, durability, trafficking, safety, effectiveness, manufacturing, and persistence, to enter clinical use. The primary goal of this review was to shed light on CAR-T immunotherapy, CAAR-T cell therapy, and CAR-Treg cell therapy in patients with immune system diseases.

A Hydrogel-Integrated Culture Device to Interrogate T Cell Activation with Physicochemical Cues

The recent rise of adoptive T cell therapy (ATCT) as a promising cancer immunotherapy has triggered increased interest in therapeutic T cell bioprocessing. T cell activation is a critical processing step and is known to be modulated by physical parameters, such as substrate stiffness. Nevertheless, relatively little is known about how biophysical factors regulate immune cells, such as T cells. Understanding how T cell activation is modulated by physical and biochemical cues may offer novel methods to control cell behavior for therapeutic cell processing. Inspired by T cell mechanosensitivity, we developed a multiwell, reusable, customizable, two-dimensional (2D) polyacrylamide (PA) hydrogel-integrated culture device to study the physicochemical stimulation of Jurkat T cells. Substrate stiffness and ligand density were tuned by concentrations of the hydrogel cross-linker and antibody in the coating solution, respectively. We cultured Jurkat T cells on 2D hydrogels of different stiffnesses that presented surface-immobilized stimulatory antibodies against CD3 and CD28 and demonstrated that Jurkat T cells stimulated by stiff hydrogels (50.6 ± 15.1 kPa) exhibited significantly higher interleukin-2 (IL-2) secretion, but lower proliferation, than those stimulated by softer hydrogels (7.1 ± 0.4 kPa). In addition, we found that increasing anti-CD3 concentration from 10 to 30 μg/mL led to a significant increase in IL-2 secretion from cells stimulated on 7.1 ± 0.4 and 9.3 ± 2.4 kPa gels. Simultaneous tuning of substrate stiffness and stimulatory ligand density showed that the two parameters synergize (two-way ANOVA interaction effect: p < 0.001) to enhance IL-2 secretion. Our results demonstrate the importance of physical parameters in immune cell stimulation and highlight the potential of designing future immunostimulatory biomaterials that are mechanically tailored to balance stimulatory strength and downstream proliferative capacity of therapeutic T cells.

Anti-CD19 CAR-T cells: Digging in the dark side of the golden therapy

The unprecedented technological advances in genetic engineering have resulted in the advent of the very promising chimeric antigen receptor (CAR)-T cell therapy. Based on the striking outcomes of clinical trials, the first two commercial CAR-T cell products, tisagenlecleucel and axicabtagene ciloleucel, have been approved in both the United States and Europe for the treatment of patients with highly aggressive CD19-positive hematological malignancies. Despite the initial remarkable responses many patients finally relapse, implying the presence of resistance mechanisms. In this review, we describe the limitations and resistance mechanisms to anti-CD19 CAR-T cells and address potential strategies to overcome CAR-T cell barriers.

CAR T Cell Therapy for Solid Tumors: Bright Future or Dark Reality?

Chimeric antigen receptor (CAR) T cell therapy has garnered significant excitement due to its success for hematological malignancies in clinical studies leading to the US Food and Drug Administration (FDA) approval of three CD19-targeted CAR T cell products. In contrast, the clinical experience with CAR T cell therapy for solid tumors and brain tumors has been less encouraging, with only a few patients achieving complete responses. Clinical and preclinical studies have identified multiple "roadblocks," including (1) a limited array of targetable antigens and heterogeneous antigen expression, (2) limited T cell fitness and survival before reaching tumor sites, (3) an inability of T cells to efficiently traffic to tumor sites and penetrate physical barriers, and (4) an immunosuppressive tumor microenvironment. Herein, we review these challenges and discuss strategies that investigators have taken to improve the effector function of CAR T cells for the adoptive immunotherapy of solid tumors.

Effect of Malus asiatica Nakai Leaf Flavonoids on the Prevention of Esophageal Cancer in C57BL/6J Mice by Regulating the IL-17 Signaling Pathway

Background

The aim of this study was to observe the preventive effect of flavonoids extracted from Malus asiatica Nakai leaves (FMANL) on esophageal cancer in mice, especially the ability of FMANL to regulate the interleukin 17 (IL-17) signaling pathway during this process.

Materials and Methods

The C57BL/6J mice were treated with 4-nitroquinoline N-oxide (4NQO) to induce esophageal cancer, and the visceral tissue index and the serum and esophageal tissue indexes of mice were used to verify the effect of FMANL.

Results

The experimental results showed that FMANL can effectively control the changes in visceral tissue caused by esophageal cancer. FMANL could increase the cytokine levels of interleukin 10 (IL-10), monocyte chemotactic protein 1 (MCP-1) and decrease the cytokine levels of tumor necrosis factor alpha (TNF-α), interferon-γ (IFN-γ), interleukin 6 (IL-6), and interleukin 12p70 (IL-12p70) in serum of mice with esophageal cancer. FMANL could also reduce CD3⁺, CD4⁺, and CD8⁺ and enhance CD19⁺ mouse peripheral blood lymphocytes. The results of qPCR and Western blot analysis showed that FMANL could down-regulate the mRNA and protein expression levels of IL-17, interleukin 23 (IL-23), interleukin 1 beta (IL-1β), chemokine (C-X-C) ligand 1 (CXCL1), chemokine (C-X-C) ligand 2 (CXCL2), S100 calcium-binding protein A8 (S100A8), S100 calcium-binding protein A9 (S100A9), matrix metalloprotein 9 (MMP-9), and matrix metalloprotein 13 (MMP-1) in mice with esophageal cancer. High-performance liquid chromatography (HPLC) detection showed that FMANL contained 10 chemicals, including rutin, hyperoside, isoquercitrin, dihydroquercetin, quercitrin, hesperidin, myricetin, baicalin, neohesperidin dihydrochalcone, and quercetin.

Conclusion

It could be concluded that FMANL can effectively prevent experimentally induced esophageal cancer in mice, and its effects might be obtained from 10 compounds present in FMANL.

Modulation of Determinant Factors to Improve Therapeutic Combinations with Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (ICPi) have shown their superiority over conventional therapies to treat some cancers. ICPi are effective against immunogenic tumors. However, patients with tumors poorly infiltrated with immune cells do not respond to ICPi. Combining ICPi with other anticancer therapies such as chemotherapy, radiation, or vaccines, which can stimulate the immune system and recruit antitumor T cells into the tumor bed, may be a relevant strategy to increase the proportion of responding patients. Such an approach still raises the following questions: What are the immunological features modulated by immunogenic therapies that can be critical to ensure not only immediate but also long-lasting tumor protection? How must the combined treatments be administered to the patients to harness their full potential while limiting adverse immunological events? Here, we address these points by reviewing how immunogenic anticancer therapies can provide novel therapeutic opportunities upon combination with ICPi. We discuss their ability to create a permissive tumor microenvironment through the generation of inflamed tumors and stimulation of memory T cells such as resident (T_RM) and stem-cell like (T_SCM) cells. We eventually underscore the importance of sequence, dose, and duration of the combined anticancer therapies to design optimal and successful cancer immunotherapy strategies.

Cell composition and expansion strategy can reduce the beneficial effect of AKT-inhibition on functionality of CD8+ T cells

AKT-inhibition is a promising approach to improve T cell therapies; however, its effect on CD4⁺ T cells is insufficiently explored. Previously, we and others showed that AKT-inhibition during ex vivo CD8⁺ T cell expansion facilitates the generation of polyfunctional T cells with stem cell memory-like traits. However, most therapeutic T cell products are generated from lymphocytes, containing CD4⁺ T cells that can affect CD8⁺ T cells dependent on the Th-subset. Here, we investigated the effect of AKT-inhibition on CD4⁺ T cells, during separate as well as total T cell expansions. Interestingly, ex vivo AKT-inhibition preserved the early memory phenotype of CD4⁺ T cells based on higher CD62L, CXCR4 and CCR7 expression. However, in the presence of AKT-inhibition, Th-differentiation was skewed toward more Th2-associated at the expense of Th1-associated cells. Importantly, the favorable effect of AKT-inhibition on the functionality of CD8⁺ T cells drastically diminished in the presence of CD4⁺ T cells. Moreover, also the expansion method influenced the effect of AKT-inhibition on CD8⁺ T cells. These findings indicate that the effect of AKT-inhibition on CD8⁺ T cells is dependent on cell composition and expansion strategy, where presence of CD4⁺ T cells as well as polyclonal stimulation impede the favorable effect of AKT-inhibition.

Mechanisms underlying CD19-positive ALL relapse after anti-CD19 CAR T cell therapy and associated strategies

Chimeric antigen receptor (CAR) T cell therapy, especially anti-CD19 CAR T cell therapy, has shown remarkable anticancer activity in patients with relapsed/refractory acute lymphoblastic leukemia, demonstrating an inspiring complete remission rate. However, with extension of the follow-up period, the limitations of this therapy have gradually emerged. Patients are at a high risk of early relapse after achieving complete remission. Although there are many studies with a primary focus on the mechanisms underlying CD19^- relapse related to immune escape, early CD19⁺ relapse owing to poor in vivo persistence and impaired efficacy accounts for a larger proportion of the high relapse rate. However, the mechanisms underlying CD19⁺ relapse are still poorly understood. Herein, we discuss factors that could become obstacles to improved persistence and efficacy of CAR T cells during production, preinfusion processing, and in vivo interactions in detail. Furthermore, we propose potential strategies to overcome these barriers to achieve a reduced CD19⁺ relapse rate and produce prolonged survival in patients after CAR T cell therapy.

Chimeric antigen receptor therapy in hematological malignancies: antigenic targets and their clinical research progress

Chimeric antigen receptor (CAR)-based immunotherapy has achieved dramatic success in the treatment of B cell malignancies, based on the summary of current research data, and has shown good potential in early phase cancer clinical trials. Modified constructs are being optimized to recognize and destroy tumor cells more effectively. By targeting the proper B-lineage-specific antigens such as CD19 and CD20, adoptive immunotherapy has demonstrated promising clinical results and already plays a role in the treatment of several lymphoid malignancies, which highlights the importance of target selection for other CAR therapies. The high efficacy of CAR-T cells has resulted in the approval of anti-CD19-directed CAR-T cells for the treatment of B cell malignancies. In this review, we focus on the basic structure and current clinical application of CAR-T cells, detail the research progress of CAR-T for different antigenic targets in hematological malignancies, and further discuss the current barriers and proposed solutions, investigating the possible mechanisms of recurrence of CAR-T cell therapy. A summary of the paper is also given to overview as the prospects for this therapy.

Enhancing CAR T cell efficacy: the next step toward a clinical revolution?

Introduction: The field of immunotherapy has witnessed considerable progress over the last two decades. Beginning with the ability to conceptualize CAR T cell therapy as immunotherapeutic approach, to effortlessly genetically modifying T cells, we have now reached the stage of mass production for clinical needs, all within less than quarter of a century.Areas covered: CAR T cell therapy has been tremendously successful in acute leukemia patients, specifically even in relapsed/refractory disease states. However, similar success is yet to be realized in other malignancies. This review article covers the challenges encountered with the current CD19-targeted CARs, as well as specific obstacles faced by adoptive therapy in solid tumors. It also discusses various strategies to counteract these problems.Expert opinion: CD19-directed trials in the past decade have exposed vulnerabilities in the current CAR T cell design, particularly concerning safety aspects, antigen escape, and T cell persistence. Building on these lessons and factoring in the unique challenges associated with immunotherapy in solid tumors will help generate CARs designed for future trials. Also, research related to the production of allogeneic CAR T cell products will boost the patient reach of this unique technology and possibly reduce financial burden.

Clinical practice: chimeric antigen receptor (CAR) T cells: a major breakthrough in the battle against cancer

Chimeric antigen receptor (CAR) T cell therapy has come of age, offering a potentially curative option for patients who are refractory to standard anti-cancer treatments. The success of CAR T cell therapy in the setting of acute lymphoblastic leukemia and specific types of B cell lymphoma led to rapid regulatory approvals of CD19-directed CAR T cells, first in the United States and subsequently across the globe. Despite these major milestones in the field of immuno-oncology, growing experience with CAR T cells has also highlighted the major limitations of this strategy, namely challenges associated with manufacturing a bespoke patient-specific product, intrinsic immune cell defects leading to poor CAR T cell function as well as persistence, and/or tumor cell resistance resulting from loss or modulation of the targeted antigen. In addition, both on- and off-tumor immunotoxicities and the financial burden inherent in conventional cellular biomanufacturing often hamper the success of CAR T cell-based treatment approaches. Herein, we provide an overview of the opportunities and challenges related to the first form of gene transfer therapy to gain commercial approval in the United States. Ongoing advances in the areas of genetic engineering, precision genome editing, toxicity mitigation methods and cell manufacturing will improve the efficacy and safety of CAR T cells for hematologic malignancies and expand the use of this novel class of therapeutics to reach solid tumors.

Point-Of-Care CAR T-Cell Production (ARI-0001) Using a Closed Semi-automatic Bioreactor: Experience From an Academic Phase I Clinical Trial

Development of semi-automated devices that can reduce the hands-on time and standardize the production of clinical-grade CAR T-cells, such as CliniMACS Prodigy from Miltenyi, is key to facilitate the development of CAR T-cell therapies, especially in academic institutions. However, the feasibility of manufacturing CAR T-cell products from heavily pre-treated patients with this system has not been demonstrated yet. Here we report and characterize the production of 28 CAR T-cell products in the context of a phase I clinical trial for CD19+ B-cell malignancies (NCT03144583). The system includes CD4-CD8 cell selection, lentiviral transduction and T-cell expansion using IL-7/IL-15. Twenty-seven out of 28 CAR T-cell products manufactured met the full list of specifications and were considered valid products. Ex vivo cell expansion lasted an average of 8.5 days and had a mean transduction rate of 30.6 ± 13.44%. All products obtained presented cytotoxic activity against CD19+ cells and were proficient in the secretion of pro-inflammatory cytokines. Expansion kinetics was slower in patient's cells compared to healthy donor's cells. However, product potency was comparable. CAR T-cell subset phenotype was highly variable among patients and largely determined by the initial product. T_CM and T_EM were the predominant T-cell phenotypes obtained. 38.7% of CAR T-cells obtained presented a T_N or T_CM phenotype, in average, which are the subsets capable of establishing a long-lasting T-cell memory in patients. An in-depth analysis to identify individual factors contributing to the optimal T-cell phenotype revealed that ex vivo cell expansion leads to reduced numbers of T_N, T_SCM, and T_EFF cells, while T_CM cells increase, both due to cell expansion and CAR-expression. Overall, our results show for the first time that clinical-grade production of CAR T-cells for heavily pre-treated patients using CliniMACS Prodigy system is feasible, and that the obtained products meet the current quality standards of the field. Reduced ex vivo expansion may yield CAR T-cell products with increased persistence in vivo.

CAR T cells for brain tumors: Lessons learned and road ahead

Malignant brain tumors, including glioblastoma, represent some of the most difficult to treat of solid tumors. Nevertheless, recent progress in immunotherapy, across a broad range of tumor types, provides hope that immunological approaches will have the potential to improve outcomes for patients with brain tumors. Chimeric antigen receptors (CAR) T cells, a promising immunotherapeutic modality, utilizes the tumor targeting specificity of any antibody or receptor ligand to redirect the cytolytic potency of T cells. The remarkable clinical response rates of CD19-targeted CAR T cells and early clinical experiences in glioblastoma demonstrating safety and evidence for disease modifying activity support the potential of further advancements ultimately providing clinical benefit for patients. The brain, however, is an immune specialized organ presenting unique and specific challenges to immune-based therapies. Remaining barriers to be overcome for achieving effective CAR T cell therapy in the central nervous system (CNS) include tumor antigenic heterogeneity, an immune-suppressive microenvironment, unique properties of the CNS that limit T cell entry, and risks of immune-based toxicities in this highly sensitive organ. This review will summarize preclinical and clinical data for CAR T cell immunotherapy in glioblastoma and other malignant brain tumors, including present obstacles to advancement.

'Off-the-shelf' allogeneic CAR T cells: development and challenges

Autologous chimeric antigen receptor (CAR) T cells have changed the therapeutic landscape in haematological malignancies. Nevertheless, the use of allogeneic CAR T cells from donors has many potential advantages over autologous approaches, such as the immediate availability of cryopreserved batches for patient treatment, possible standardization of the CAR-T cell product, time for multiple cell modifications, redosing or combination of CAR T cells directed against different targets, and decreased cost using an industrialized process. However, allogeneic CAR T cells may cause life-threatening graft-versus-host disease and may be rapidly eliminated by the host immune system. The development of next-generation allogeneic CAR T cells to address these issues is an active area of research. In this Review, we analyse the different sources of T cells for optimal allogeneic CAR-T cell therapy and describe the different technological approaches, mainly based on gene editing, to produce allogeneic CAR T cells with limited potential for graft-versus-host disease. These improved allogeneic CAR-T cell products will pave the way for further breakthroughs in the treatment of cancer.

TEG001 Insert Integrity from Vector Producer Cells until Medicinal Product

Despite extensive usage of gene therapy medicinal products (GTMPs) in clinical studies and recent approval of chimeric antigen receptor (CAR) T cell therapy, little information has been made available on the precise molecular characterization and possible variations in terms of insert integrity and vector copy numbers of different GTMPs during the complete production chain. Within this context, we characterize αβT cells engineered to express a defined γδT cell engineered to express a defined γδT receptor (TEG) currently used in a first-in-human clinical study (NTR6541). Utilizing targeted locus amplification in combination with next generation sequencing for the vector producer clone and TEG001 products, we report on five single-nucleotide variants and nine intact vector copies integrated in the producer clone. The vector copy number in TEG001 cells was on average a factor 0.72 (SD 0.11) below that of the producer cell clone. All nucleotide variants were transferred to TEG001 without having an effect on cellular proliferation during extensive in vitro culture. Based on an environmental risk assessment of the five nucleotide variants present in the non-coding viral region of the TEG001 insert, there was no altered environmental impact of TEG001 cells. We conclude that TEG001 cells do not have an increased risk for malignant transformation in vivo.

Mechanisms of Relapse After CD19 CAR T-Cell Therapy for Acute Lymphoblastic Leukemia and Its Prevention and Treatment Strategies

Chimeric antigen receptor (CAR) T-cell therapy is highly effective in the treatment of B-cell acute lymphoblastic leukemia (ALL) or B-cell lymphoma, providing alternative therapeutic options for patients who failed to respond to conventional treatment or relapse. Moreover, it can bridge other therapeutic strategies and greatly improve patient prognosis, with broad applicable prospects. Even so, 30–60% patients relapse after treatment, probably due to persistence of CAR T-cells and escape or downregulation of CD19 antigen, which is a great challenge for disease control. Therefore, understanding the mechanisms that underlie post-CAR relapse and establishing corresponding prevention and treatment strategies is important. Herein, we discuss post-CAR relapse from the aspects of CD19-positive and CD19-negative and provide some reasonable prevention and treatment strategies.

In vivo generated human CAR T cells eradicate tumor cells

Chimeric antigen receptor (CAR) T cells are in prime focus of current research in cancer immunotherapy. Facilitating CAR T cell generation is among the top goals. We have recently demonstrated direct in vivo generation of human CD19-CAR T cells by targeting CD8⁺ cells using lentiviral vectors (LVs). The anti-tumor potency of in vivo generated CAR T cells was assessed in human PBMC-transplanted NSG mice carrying i.v. injected CD19⁺ Nalm-6 tumor cells. A single injection of CD8-targeted LV delivering CD19-CAR was sufficient to completely eliminate the tumor cells from bone marrow and spleen, whereas control animals contained high levels of CD19⁺ cells. Tumor elimination was due to in vivo generated CAR⁺ cells. Notably, these were not only composed of T lymphocytes but also included CAR⁺ natural killer cells (NK and NKT). This is the first demonstration of tumor elimination by in vivo generated human CAR T cells.

Resistance Mechanisms to CAR T-Cell Therapy and Overcoming Strategy in B-Cell Hematologic Malignancies

Chimeric antigen receptor (CAR) T-cell therapy has shown promising clinical impact against hematologic malignancies. CD19 is a marker on the surface of normal B cells as well as most B-cell malignancies, and thus has a role as an effective target for CAR T-cell therapy. In numerous clinical data, successes with cell therapy have provided anticancer therapy as a potential therapeutic option for patients who are resistant to standard chemotherapies. However, recent growing evidence showed the limitations of the treatment such as antigen-positive relapse due to poor CAR T-cell persistence and antigen-negative relapses associated with CAR-driven mutations, alternative splicing, epitope masking, low antigen density, and lineage switching. The understanding of the resistance mechanisms to the cell therapy has developed novel potential treatment strategies, including dual-targeting therapy (dual and tandem CAR), and armored and universal CAR T-cell therapies. In this review, we provide an overview of resistance mechanisms to CD19 CAR T-cell therapy in B-cell malignancies and also review therapeutic strategies to overcome these resistances.

Chimeric antigen receptor modified T cell (CAR-T) co-expressed with ICOSL-41BB promote CAR-T proliferation and tumor rejection

T cells edited by chimeric antigen receptors (CAR) have shown great potential in the treatment of tumors, especially malignant blood tumors. However, there remain many obstacles in the CAR-T therapy against solid tumors, such as the expansion of CAR-T cells ex vivo and the exhaustion of CAR-T cells in vivo. In order to solve these problems, we described a novel CAR which is targeting GPC3 by expressing CD28 co-stimulation domain and CD3z ITAM (G328z), meanwhile co-expressing ICOSL extracellular and transmembrane region fused with 41BB cytoplasmic domain (G328z-ICOSL-41BB). Compared with G328z, G328z-ICOSL-41BB fusion protein significantly reinforced the expansion ability of CAR-T cells ex vivo, and prolonged the survival time of mice with hepatocellular carcinoma. We now demonstrate that the enhancement of CAR-T cell activity is dependent on the enhanced PI3K signaling pathway and up-regulated expression of Bcl2 to inhibit apoptosis and promote proliferation of CAR-T cells. Besides, the CAR with ICOSL-41BB fusion protein have been strengthened significantly in comparison with fusing ICOSL protein only, which might be caused by the fact that ICOSL-41BB not only supplies ICOS signal for other cells, but also provides 41BB signal for itself. Consequently, CARs with ICOSL-41BB fusion protein could increase the therapeutic efficacy against solid tumors in vivo compared with the G328z CAR, which might further assist the development of potent and durable T cell therapeutics.

Adoptive CD8+ T cell therapy against cancer:Challenges and opportunities

Cancer immunotherapy is a new and promising option for cancer treatment. Unlike traditional chemo- and radiotherapy, immunotherapy actives host immune system to attack malignancies, and this potentially offers long-term protection from recurrence with less toxicity in comparison to conventional chemo- and radiation therapy. In adoptive CD8⁺ T cell therapy (ACT), large numbers of tumor-specific T cells are sourced from patients and expanded in vitro and infused back to patients. T cells can be expanded from naturally-induced tumor-specific CD8⁺ T cells isolated from tumor infiltrating lymphocytes (TIL) or genetically-modified autologous circulating CD8⁺ T cells. The engineered T cells expressed tumor-specific antigen receptors including chimeric antigen receptors (CARs) and T cell receptors (TCRs), prepared from cultured B and T cell clones, respectively. The most successful ACT, anti-CD19 chimeric antigen receptor T (CAR-T) cell therapy directed against B cell lymphoma, is already approved for use based on evidence of efficacy. Efficacy of solid tumors is not yet forthcoming. This review summarizes current technology developments using ACT in clinical trials. In this review, differences between various ACT approaches are discussed. Furthermore, resistance factors in the tumor microenvironment are also considered, as are immune related adverse effects, critical clinic monitoring parameters and potential mitigation approaches.

Low mutational load in pediatric medulloblastoma still translates into neoantigens as targets for specific T-cell immunotherapy

BACKGROUND

Medulloblastoma is the most common malignant brain tumor in childhood and adolescence. Although some patients present with distinct genetic alterations, such as mutated TP53 or MYC amplification, pediatric medulloblastoma is a tumor entity with minimal mutational load and low immunogenicity.

METHODS

We identified tumor-specific mutations using next-generation sequencing of medulloblastoma DNA and RNA derived from primary tumor samples from pediatric patients. Tumor-specific mutations were confirmed using deep sequencing and in silico analyses predicted high binding affinity of the neoantigen-derived peptides to the patients' human leukocyte antigen molecules. Tumor-specific peptides were synthesized and used to induce a de novo T-cell response characterized by interferon gamma and tumor necrosis factor alpha release of CD8⁺ cytotoxic T cells in vitro.

RESULTS

Despite low mutational tumor burden, at least two immunogenic tumor-specific peptides were identified in each patient. T cells showed a balanced CD4/CD8 ratio and mostly effector memory phenotype. Induction of a CD8-specific T-cell response was achieved for the neoepitopes derived from Histidine Ammonia-Lyase (HAL), Neuraminidase 2 (NEU2), Proprotein Convertase Subtilisin (PCSK9), Programmed Cell Death 10 (PDCD10), Supervillin (SVIL) and tRNA Splicing Endonuclease Subunit 54 (TSEN54) variants.

CONCLUSION

Detection of patient-specific, tumor-derived neoantigens confirms that even in tumors with low mutational load a molecular design of targets for specific T-cell immunotherapy is possible. The identified neoantigens may guide future approaches of adoptive T-cell transfer, transgenic T-cell receptor transfer or tumor vaccination.

Mechanisms of resistance to CAR T cell therapy

The successes with chimeric antigen receptor (CAR) T cell therapy in early clinical trials involving patients with pre-B cell acute lymphoblastic leukaemia (ALL) or B cell lymphomas have revolutionized anticancer therapy, providing a potentially curative option for patients who are refractory to standard treatments. These trials resulted in rapid FDA approvals of anti-CD19 CAR T cell products for both ALL and certain types of B cell lymphoma - the first approved gene therapies in the USA. However, growing experience with these agents has revealed that remissions will be brief in a substantial number of patients owing to poor CAR T cell persistence and/or cancer cell resistance resulting from antigen loss or modulation. Furthermore, the initial experience with CAR T cells has highlighted challenges associated with manufacturing a patient-specific therapy. Understanding the limitations of CAR T cell therapy will be critical to realizing the full potential of this novel treatment approach. Herein, we discuss the factors that can preclude durable remissions following CAR T cell therapy, with a primary focus on the resistance mechanisms that underlie disease relapse. We also provide an overview of potential strategies to overcome these obstacles in an effort to more effectively incorporate this unique therapeutic strategy into standard treatment paradigms.

Gene-edited stem cells enable CD33-directed immune therapy for myeloid malignancies

Acute myeloid leukemia is a disease that lacks effective therapies, especially in postremission patients. Immunotherapies directed against a lineage-specific antigen (LSA), such as CD33 has demonstrated on-target effects on AML cells but is limited by toxicities because normal myeloid cells and hematopoietic progenitors also express CD33. Here we show that genetically ablating CD33 in human stem/progenitor cells, using Cas9/guide RNA mediated strategies, enables immunotherapy against leukemias using anti-CD33 CAR-T or antibody therapy. We model a postremission human marrow with minimal residual leukemic disease in mice and show effective clearance of acute myeloid leukemia and the reconstitution of the CD33-deleted human graft, enabling future clinical studies. This study presents an approach to treat myeloid leukemias and could be extended to other cancers and other antigens.

Antigen-directed immunotherapies for acute myeloid leukemia (AML), such as chimeric antigen receptor T cells (CAR-Ts) or antibody-drug conjugates (ADCs), are associated with severe toxicities due to the lack of unique targetable antigens that can distinguish leukemic cells from normal myeloid cells or myeloid progenitors. Here, we present an approach to treat AML by targeting the lineage-specific myeloid antigen CD33. Our approach combines CD33-targeted CAR-T cells, or the ADC Gemtuzumab Ozogamicin with the transplantation of hematopoietic stem cells that have been engineered to ablate CD33 expression using genomic engineering methods. We show highly efficient genetic ablation of CD33 antigen using CRISPR/Cas9 technology in human stem/progenitor cells (HSPC) and provide evidence that the deletion of CD33 in HSPC doesn’t impair their ability to engraft and to repopulate a functional multilineage hematopoietic system in vivo. Whole-genome sequencing and RNA sequencing analysis revealed no detectable off-target mutagenesis and no loss of functional p53 pathways. Using a human AML cell line (HL-60), we modeled a postremission marrow with minimal residual disease and showed that the transplantation of CD33-ablated HSPCs with CD33-targeted immunotherapy leads to leukemia clearance, without myelosuppression, as demonstrated by the engraftment and recovery of multilineage descendants of CD33-ablated HSPCs. Our study thus contributes to the advancement of targeted immunotherapy and could be replicated in other malignancies.

Optimization of manufacturing conditions for chimeric antigen receptor T cells to favor cells with a central memory phenotype

BACKGROUND

Chimeric antigen receptor (CAR)-T cells are genetically engineered to recognize tumor-associated antigens and have potent cytolytic activity against tumors. Adoptive therapy with CAR-T cells has been highly successful in B-cell leukemia and lymphoma. However, in solid tumor settings, CAR-T cells face a particularly hostile tumor microenvironment where multiple immune suppressive factors serve to thwart the anti-cancer immune response. Clinical trials of solid tumor antigen-targeted CAR-T cells have shown limited efficacy, and issues for current CAR-T cell therapies include failures of expansion and persistence, tumor entry, deletion and functional exhaustion.

METHODS

We compared our standard protocol for CAR-T cell manufacturing, currently used to generate CAR-T cells for a phase 1 clinical trial, with two alternative approaches for T-cell activation and expansion. The resulting cultures were analyzed using multicolor flow cytometry, cytokine bead array and xCELLigence cytotoxicity assays.

RESULTS

We have found that by changing the method of activation we can promote generation of CAR-T cells with enhanced CD62L and CCR7 expression, increased interleukin (IL)-2 production and retention of cytolytic activity, albeit with slower kinetics.

DISCUSSION

We propose that these phenotypic characteristics are consistent with a central memory phenotype that will better enable CAR-T cell survival and persistence after activation in vivo, and we aim to test this in a continuation of our current phase 1 clinical trial of CAR-T cells in patients with advanced melanoma.