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While CD19-directed chimeric antigen receptor (CAR) T cells can induce remission in patients with B cell acute lymphoblastic leukemia (ALL), a large subset relapse with CD19.sup.- disease. Like CD19, CD22 is broadly expressed by B-lineage cells and thus serves as an alternative immunotherapy target in ALL. Here we present the composite outcomes of two pilot clinical trials (NCT02588456 and NCT02650414) of T cells bearing a 4-1BB-based, CD22-targeting CAR in patients with relapsed or refractory ALL. The primary end point of these studies was to assess safety, and the secondary end point was antileukemic efficacy. We observed unexpectedly low response rates, prompting us to perform detailed interrogation of the responsible CAR biology. We found that shortening of the amino acid linker connecting the variable heavy and light chains of the CAR antigen-binding domain drove receptor homodimerization and antigen-independent signaling. In contrast to CD28-based CARs, autonomously signaling 4-1BB-based CARs demonstrated enhanced immune synapse formation, activation of pro-inflammatory genes and superior effector function. We validated this association between autonomous signaling and enhanced function in several CAR constructs and, on the basis of these observations, designed a new short-linker CD22 single-chain variable fragment for clinical evaluation. Our findings both suggest that tonic 4-1BB-based signaling is beneficial to CAR function and demonstrate the utility of bedside-to-bench-to-bedside translation in the design and implementation of CAR T cell therapies. A bedside-to-bench analysis identifies single-chain variable fragment linker length as an important component of chimeric antigen receptor (CAR) structure and suggests that, in contrast to CD28-based CAR T cells, tonic signaling can be beneficial for 4-1BB-based CAR T cell function., Author(s): Nathan Singh [sup.1] [sup.2] [sup.15] , Noelle V. Frey [sup.1] , Boris Engels [sup.3] , David M. Barrett [sup.4] [sup.5] , Olga Shestova [sup.2] , Pranali Ravikumar [sup.2] , [...]

Both higher- and lower-affinity self-reactive CD4+ T cells are expanded in autoimmunity; however, their individual contribution to disease remains unclear. We addressed this question using peptide-MHCII chimeric antigen receptor (pMHCII-CAR) T cells to specifically deplete peptide-reactive T cells in mice. Integration of improvements in CAR engineering with TCR repertoire analysis was critical for interrogating in vivo the role of TCR affinity in autoimmunity. Our original MOG35–55 pMHCII-CAR, which targeted only higher-affinity TCRs, could prevent the induction of experimental autoimmune encephalomyelitis (EAE). However, pMHCII-CAR enhancements to pMHCII stability, as well as increased survivability via overexpression of a dominant-negative Fas, were required to target lower-affinity MOG-specific T cells and reverse ongoing clinical EAE. Thus, these data suggest a model in which higher-affinity autoreactive T cells are required to provide the "activation energy" for initiating neuroinflammatory injury, but lower-affinity cells are sufficient to maintain ongoing disease. Engineering CAR T cells to target autoimmunity: Autoimmune diseases including multiple sclerosis (MS) are driven by pathogenic CD4+ T cells that recognize self-antigens. Yi et al. engineered chimeric antigen receptor (CAR) T cells to recognize and kill self-reactive T cells by introducing a peptide-MHCII (pMHCII) domain. Their original pMHCII-CAR design efficiently deleted T cells bearing a higher-affinity T cell receptor, whereas further modifications to enhance pMHCII stability and in vivo survival enabled simultaneous targeting of lower-affinity T cells. In a mouse experimental autoimmune encephalomyelitis model of MS-like disease, deletion of higher-affinity T cells was sufficient to prevent disease onset, whereas targeting lower-affinity T cells was necessary to reverse ongoing disease. These findings highlight strategies for designing CAR T cells to target distinct stages of autoimmune disease. [ABSTRACT FROM AUTHOR]

Chimeric antigen receptor (CAR)-engineered T cells have demonstrated remarkable success in the treatment of B cell malignancies. FDA approval of these therapies represents a watershed moment in the development of therapies for cancer. Despite the successes of the last decade, many patients will unfortunately not experience durable responses to CAR therapy. Emerging research has shed light on the biology responsible for these failures, and further highlighted the hurdles to broader success. Here, we review the recent research identifying how interactions between cancer cells and engineered immune cells result in resistance to CAR therapies. [ABSTRACT FROM AUTHOR]

The article presents a study that determines the role of T cell expansion potential and memory phenotype during chemotherapy in pediatric patients with acute lymphoblastic leukemia (ALL) and non-Hodgkin lymphoma (NHL). It offers details of the study, which also demonstrates that patients with T cell population for early lineage cells has expanded better in vitro. It also explains the result which indicates that early lineage cells are essential to T cell fitness for expansion and enrichment.

Improved outcomes for patients with cancer hinge on the development of new targeted therapies with acceptable short-term and long-term toxicity. Progress in basic, preclinical, and clinical arenas spanning cellular immunology, synthetic biology, and cell-processing technologies has paved the way for clinical applications of chimeric antigen receptor-based therapies. This new form of targeted immunotherapy merges the exquisite targeting specificity of monoclonal antibodies with the potent cytotoxicity and long-term persistence provided by cytotoxic T cells. Although this field is still in its infancy, clinical trials have already shown clinically significant antitumor activity in neuroblastoma, chronic lymphocytic leukemia, and B cell lymphoma, and trials targeting a variety of other adult and pediatric malignancies are under way. Ongoing work is focused on identifying optimal tumor targets and on elucidating and manipulating both cell- and host-associated factors to support expansion and persistence of the genetically engineered cells in vivo. The potential to target essentially any tumor-associated cell-surface antigen for which a monoclonal antibody can be made opens up an entirely new arena for targeted therapy of cancer. [ABSTRACT FROM AUTHOR]

Abstract: In the past decade we have witnessed important advances in the treatment of gynecological cancers and have recognized their potential immunogenicity. This has opened the door to explore immune therapy not only in HPV-induced cancers but also in ovarian and endometrial cancers. Here we will review the off-target immune effects of select chemotherapy drugs commonly used to treat gynecologic cancers and novel tools that can stimulate both the adaptive and innate immune mechanisms such as novel pleiotropic cytokines, Toll-like receptors, and powerful antibodies that can target inhibitory checkpoints, thereby activating effector cellular immune mechanisms and neutralizing suppressor cells. We will also review how existing drugs can be used for combinatorial tumor therapy. [Copyright &y& Elsevier]

The article discusses the use of engineered T cells in the treatment of cancer and a study by Ma et al. which discusses a vaccine-boosting strategy to improve the efficacy of Chimeric antigen receptor (CAR)-T cells to target solid tumors.

The cancer-testis antigen NY-ESO-1 is expressed by many solid tumors and has limited expression by mature somatic tissues, making it a highly attractive target for tumor immunotherapy. Targeting NY-ESO-1 using engineered T cells has demonstrated clinical efficacy in the treatment of some adult tumors. Neuroblastoma is a significant cause of cancer mortality in children, and is a tumor type shown to be responsive to immunotherapies. We evaluated a large panel of primarily resected neuroblastoma samples and demonstrated that 23% express NY-ESO-1. After confirming antigen-specific activity of T cells genetically engineered to express an NY-ESO-1 directed high-affinity transgenic T cell receptorin vitro, we performed xenograft mouse studies assessing the efficacy of NY-ESO-1-targeted T cells in both localized and disseminated models of neuroblastoma. Disease responses were monitored by tumor volume measurement andin vivobioluminescence. After delivery of NY-ESO-1 transgenic TCR T cells, we observed significant delay of tumor progression in mice bearing localized and disseminated neuroblastoma, as well as enhanced animal survival. These data demonstrate that NY-ESO-1 is an antigen target in neuroblastoma and that targeted T cells represent a potential therapeutic option for patients with neuroblastoma. [ABSTRACT FROM PUBLISHER]

While CAR therapy has begun to demonstrate efficacy, cell-engineering techniques that result in permanent genomic modification carry several safety concerns. CAR expression driven by RNA creates a platform for delivery of highly-active cell therapy while avoiding long-term CAR-driven toxicity. Using models of pediatric neuroblastoma, we have found that RNA CAR T cell activity is limited by ineffective tumor infiltration. [ABSTRACT FROM PUBLISHER]

Chimeric antigen receptor (CAR) T cell therapy has achieved remarkable success in hematological malignancies but remains ineffective in solid tumors, due in part to CAR T cell exhaustion in the solid tumor microenvironment. To study dysfunction of mesothelin-redirected CAR T cells in pancreatic cancer, we establish a robust model of continuous antigen exposure that recapitulates hallmark features of T cell exhaustion and discover, both in vitro and in CAR T cell patients, that CAR dysregulation is associated with a CD8+ T-to-NK-like T cell transition. Furthermore, we identify a gene signature defining CAR and TCR dysregulation and transcription factors, including SOX4 and ID3 as key regulators of CAR T cell exhaustion. Our findings shed light on the plasticity of human CAR T cells and demonstrate that genetic downmodulation of ID3 and SOX4 expression can improve the efficacy of CAR T cell therapy in solid tumors by preventing or delaying CAR T cell dysfunction. [Display omitted] • CAR T cells under chronic antigen stimulation show hallmarks of T cell exhaustion • CAR dysregulation is associated with a CD8+ T-to-NK-like T cell transition • CAR T cells with NK-like transition were identified in patients after treatment • Unlike WT CAR T cells, ID3 and SOX4 knockout CAR T cells retain anti-tumor immunity Continuous antigen exposure drives CAR T cell exhaustion and promotes CD8+ T-to-NK-like T cell transition. Transcription factors ID3 and SOX4 are upregulated during CAR dysfunction and regulate genes associated with exhaustion, including NK receptors. Knocking out ID3 and SOX4 in CAR T cells slows dysfunction and improves anti-tumor immunity. [ABSTRACT FROM AUTHOR]

Chimeric antigen receptor (CAR)-based therapies have pioneered synthetic cellular immunity but remain limited in their long-term efficacy. Emerging data suggest that dysregulated CAR-driven T-cell activation causes T-cell dysfunction and therapeutic failure. To re-engage the precision of the endogenous T-cell response, we designed MHC-independent T-cell receptors (miTCR) by linking antibody variable domains to T-cell receptor constant chains. Using predictive modeling, we observed that this standard "cut and paste" approach to synthetic protein design resulted in myriad biochemical conflicts at the hybrid variable-constant domain interface. Through iterative modeling and sequence modifications, we developed structure-enhanced miTCRs which significantly improved receptor-driven T-cell function across multiple tumor models. We found that 41BB costimulation specifically prolonged miTCR T-cell persistence and enabled improved leukemic control in vivo compared with classic CAR T cells. Collectively, we have identified core features of hybrid receptor structure responsible for regulating function. Significance: Improving the durability of engineered T-cell immunotherapies is critical to enhancing efficacy. We used a structure-informed design to evolve improved miTCR function across several models. This work underscores the central role of synthetic receptor structure in T-cell function and provides a framework for improved receptor engineering., (©2024 American Association for Cancer Research.)

Genome editing technologies have seen remarkable progress in recent years, enabling precise regulation of exogenous and endogenous genes. These advances have been extensively applied to the engineering of human T lymphocytes, leading to the development of practice changing therapies for patients with cancer and the promise of synthetic immune cell therapies for a variety of nonmalignant diseases. Many distinct conceptual and technical approaches have been used to edit T-cell genomes, however targeted assessments of which techniques are most effective for manufacturing, gene editing, and transgene expression are rarely reported. Through extensive comparative evaluation, we identified methods that most effectively enhance engineering of research-scale and preclinical T-cell products at critical stages of manufacturing., (©2024 American Association for Cancer Research.)

Methods to engineer the genomes of human cells for therapeutic intervention continue to advance at a remarkable pace. Chimeric antigen receptor-engineered T lymphocytes have pioneered the way for these therapies, initially beginning with insertions of chimeric antigen receptor transgenes into T-cell genomes using classical gene therapy vectors. The broad use of clustered regularly interspaced short palindromic repeats (CRISPR)-based technologies to edit endogenous genes has now opened the door to a new era of precision medicine. To add complexity, many engineered cellular therapies under development integrate gene therapy with genome editing to introduce novel biological functions and enhance therapeutic efficacy. Here, we review the current state of scientific, translational, and regulatory oversight of gene-edited cell products., (©2024 American Association for Cancer Research.)

Both higher- and lower-affinity self-reactive CD4 + T cells are expanded in autoimmunity; however, their individual contribution to disease remains unclear. We addressed this question using peptide-MHCII chimeric antigen receptor (pMHCII-CAR) T cells to specifically deplete peptide-reactive T cells in mice. Integration of improvements in CAR engineering with TCR repertoire analysis was critical for interrogating in vivo the role of TCR affinity in autoimmunity. Our original MOG 35-55 pMHCII-CAR, which targeted only higher-affinity TCRs, could prevent the induction of experimental autoimmune encephalomyelitis (EAE). However, pMHCII-CAR enhancements to pMHCII stability, as well as increased survivability via overexpression of a dominant-negative Fas, were required to target lower-affinity MOG-specific T cells and reverse ongoing clinical EAE. Thus, these data suggest a model in which higher-affinity autoreactive T cells are required to provide the "activation energy" for initiating neuroinflammatory injury, but lower-affinity cells are sufficient to maintain ongoing disease.

Immunotherapy is now a well-established modality in the treatment of cancer. Although several platforms to redirect the immune response exist, the use of genetically modified T cells has garnered particular attention in recent years. This is due, in large part, to their success in the treatment of B-cell malignancies. Adoptively transferred T cells have also demonstrated efficacy in the treatment of systemic viral infections that occur following hematopoietic cell transplantation prior to immune reconstitution. Here we discuss the techniques that enable redirection of T lymphocytes to treat cancer or infection and the current indications for these therapies., (Copyright © 2021 by The American Society of Hematology.)

Primary resistance to CD19-directed chimeric antigen receptor T-cell therapy (CART19) occurs in 10% to 20% of patients with acute lymphoblastic leukemia (ALL); however, the mechanisms of this resistance remain elusive. Using a genome-wide loss-of-function screen, we identified that impaired death receptor signaling in ALL led to rapidly progressive disease despite CART19 treatment. This was mediated by an inherent resistance to T-cell cytotoxicity that permitted antigen persistence and was subsequently magnified by the induction of CAR T-cell functional impairment. These findings were validated using samples from two CAR T-cell clinical trials in ALL, where we found that reduced expression of death receptor genes was associated with worse overall survival and reduced T-cell fitness. Our findings suggest that inherent dysregulation of death receptor signaling in ALL directly leads to CAR T-cell failure by impairing T-cell cytotoxicity and promoting progressive CAR T-cell dysfunction. SIGNIFICANCE: Resistance to CART19 is a significant barrier to efficacy in the treatment of B-cell malignancies. This work demonstrates that impaired death receptor signaling in tumor cells causes failed CART19 cytotoxicity and drives CART19 dysfunction, identifying a novel mechanism of antigen-independent resistance to CAR therapy. See related commentary by Green and Neelapu, p. 492 ., (©2020 American Association for Cancer Research.)

Chimeric antigen receptor (CAR) T cell therapy relies on the ex vivo manipulation of patient T cells to create potent, cancer-targeting therapies, shown to be capable of inducing remission in patients with acute lymphoblastic leukemia and large B cell lymphoma. However, current CAR T cell engineering methods use viral delivery vectors, which induce permanent CAR expression and could lead to severe adverse effects. Messenger RNA (mRNA) has been explored as a promising strategy for inducing transient CAR expression in T cells to mitigate the adverse effects associated with viral vectors, but it most commonly requires electroporation for T cell mRNA delivery, which can be cytotoxic. Here, ionizable lipid nanoparticles (LNPs) were designed for ex vivo mRNA delivery to human T cells. A library of 24 ionizable lipids was synthesized, formulated into LNPs, and screened for luciferase mRNA delivery to Jurkat cells, revealing seven formulations capable of enhanced mRNA delivery over lipofectamine. The top-performing LNP formulation, C14-4, was selected for CAR mRNA delivery to primary human T cells. This platform induced CAR expression at levels equivalent to electroporation, with substantially reduced cytotoxicity. CAR T cells engineered via C14-4 LNP treatment were then compared to electroporated CAR T cells in a coculture assay with Nalm-6 acute lymphoblastic leukemia cells, and both CAR T cell engineering methods elicited potent cancer-killing activity. These results demonstrate the ability of LNPs to deliver mRNA to primary human T cells to induce functional protein expression, and indicate the potential of LNPs to enhance mRNA-based CAR T cell engineering methods.

Allogeneic hematopoietic cell transplantation offers the best chance for cure in many hematologic malignancies. Key decisions include patient selection, donor and graft source, conditioning regimen, and graft-versus-host disease (GVHD) prophylaxis. Transplant is risky; only one-third survive long term. Complications include relapse, GVHD, infection, and end-organ dysfunction. Expanding indications for transplantation, advancing upper age limits, and improvements in patient care have resulted in increasing numbers of transplant survivors. These patients may suffer substantial long-term health consequences and require intensive follow-up. Future directions include graft engineering and cellular therapy, optimizing donor selection, sensitive disease assessments and/or maintenance therapies, and improvements in care., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Immunotherapy using engineered autologous T cells has been attempted for decades, but clinical trials have only recently demonstrated efficacy. The combination of enhanced manufacturing techniques, highly efficient engineering, appropriate target selection and synthetic receptors with potent T cell activating domains has led to the development of highly-active cellular therapy products. B-cell malignancies have served as the paradigmatic diseases to initially evaluate and subsequently hone engineered T cells targeting cancer. Two engineered receptors, transgenic T cell receptors (tTCRs) and chimeric antigen receptors (CARs), have been explored clinically at several different institutions. The most profound success has been in pediatric and adult acute lymphoblastic leukemia, in which complete response rates after treatment with CD19-directed CAR T cells approach 90%. Success has been slightly less impressive in slower-growing diseases such as chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL), and experience is much more limited in the plasma cell disease multiple myeloma. A great deal of investigation is underway to understand the differences in response rates observed, and enhance the efficacy of these therapies in B cell cancers. Here, we review landmark and recent clinical trials, as well as pre-clinical work that demonstrates significant promise in propelling this field further in the coming years.

The cancer-testis antigen NY-ESO-1 is expressed by many solid tumors and has limited expression by mature somatic tissues, making it a highly attractive target for tumor immunotherapy. Targeting NY-ESO-1 using engineered T cells has demonstrated clinical efficacy in the treatment of some adult tumors. Neuroblastoma is a significant cause of cancer mortality in children, and is a tumor type shown to be responsive to immunotherapies. We evaluated a large panel of primarily resected neuroblastoma samples and demonstrated that 23% express NY-ESO-1. After confirming antigen-specific activity of T cells genetically engineered to express an NY-ESO-1 directed high-affinity transgenic T cell receptor in vitro , we performed xenograft mouse studies assessing the efficacy of NY-ESO-1-targeted T cells in both localized and disseminated models of neuroblastoma. Disease responses were monitored by tumor volume measurement and in vivo bioluminescence. After delivery of NY-ESO-1 transgenic TCR T cells, we observed significant delay of tumor progression in mice bearing localized and disseminated neuroblastoma, as well as enhanced animal survival. These data demonstrate that NY-ESO-1 is an antigen target in neuroblastoma and that targeted T cells represent a potential therapeutic option for patients with neuroblastoma.

While CAR therapy has begun to demonstrate efficacy, cell-engineering techniques that result in permanent genomic modification carry several safety concerns. CAR expression driven by RNA creates a platform for delivery of highly-active cell therapy while avoiding long-term CAR-driven toxicity. Using models of pediatric neuroblastoma, we have found that RNA CAR T cell activity is limited by ineffective tumor infiltration.