CRISPR Takes the Front Seat in CART-Cell Development

Antigen loss following CAR-T cell therapy: Mechanisms, implications, and potential solutions

Chimeric Antigen Receptor T-cell (CAR-T cell) therapy has emerged as a groundbreaking immunotherapeutic approach for treating various hematological malignancies. CAR-T cells are engineered to express synthetic receptors that target specific antigens on cancer cells, leading to their eradication. While the therapy has shown remarkable efficacy, a significant challenge that has been observed in 30%-70% of patients showing recurrent disease is antigen loss or downregulation. We searched PubMed/MEDLINE, EMBASE, and Google scholar for articles on antigen loss/escape following Chimeric antigen receptor T-cell therapy in malignancies. Antigen loss refers to the loss or reduction in the expression of the target antigen on cancer cells, rendering CAR-T cells ineffective. This phenomenon poses a significant clinical concern, as it can lead to disease relapse and limited treatment options. This review explores the mechanisms underlying antigen loss following CAR-T cell therapy, its implications on treatment outcomes, and potential strategies to overcome the problem.

CRISPR-Cas9: A Potent Gene-editing Tool for the Treatment of Cancer

The prokaryotic adaptive immune system has clustered regularly interspaced short palindromic repeat. CRISPR-associated protein (CRISPR-Cas) genome editing systems have been harnessed. A robust programmed technique for efficient and accurate genome editing and gene targeting has been developed. Engineered cell therapy, in vivo gene therapy, animal modeling, and cancer diagnosis and treatment are all possible applications of this ground-breaking approach. Multiple genetic and epigenetic changes in cancer cells induce malignant cell growth and provide chemoresistance. The capacity to repair or ablate such mutations has enormous potential in the fight against cancer. The CRISPR-Cas9 genome editing method has recently become popular in cancer treatment research due to its excellent efficiency and accuracy. The preceding study has shown therapeutic potential in expanding our anticancer treatments by using CRISPR-Cas9 to directly target cancer cell genomic DNA in cellular and animal cancer models. In addition, CRISPR-Cas9 can combat oncogenic infections and test anticancer medicines. It may design immune cells and oncolytic viruses for cancer immunotherapeutic applications. In this review, these preclinical CRISPRCas9- based cancer therapeutic techniques are summarised, along with the hurdles and advancements in converting therapeutic CRISPR-Cas9 into clinical use. It will increase their applicability in cancer research.

Clinical Pharmacology and Translational Considerations in the Development of CRISPR-Based Therapies

Genome editing holds the potential for curative treatments of human disease, however, clinical realization has proven to be a challenging journey with incremental progress made up until recently. Over the last decade, advances in clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) systems have provided the necessary breakthrough for genome editing in the clinic. The progress of investigational CRISPR therapies from bench to bedside reflects the culmination of multiple advances occurring in parallel, several of which intersect with clinical pharmacology and translation. Directing the CRISPR therapy to the intended site of action has necessitated novel delivery platforms, and this has resulted in special considerations for the complete characterization of distribution, metabolism, and excretion, as well as immunogenicity. Once at the site of action, CRISPR therapies aim to make permanent alterations to the genome and achieve therapeutically relevant effects with a single dose. This fundamental aspect of the mechanism of action for CRISPR therapies results in new considerations for clinical translation and dose selection. Early advances in model-informed development of CRISPR therapies have incorporated key facets of the mechanism of action and have captured hallmark features of clinical pharmacokinetics and pharmacodynamics from phase I investigations. Given the recent emergence of CRISPR therapies in clinical development, the landscape continues to evolve rapidly with ample opportunity for continued innovation. Here, we provide a snapshot of selected topics in clinical pharmacology and translation that has supported the advance of systemically administered in vivo and ex vivo CRISPR-based investigational therapies in the clinic.

CAR T cell therapy and the tumor microenvironment: Current challenges and opportunities

Chimeric antigen receptor (CAR) T cell therapy has demonstrated remarkable outcomes in individuals with hematological malignancies, but its success has been hindered by barriers intrinsic to the tumor microenvironment (TME), particularly for solid tumors, where it has yet to make its mark. In this article, we provide an updated review and future perspectives on features of the TME that represent barriers to CART cell therapy efficacy, including competition for metabolic fuels, physical barriers to infiltration, and immunosuppressive factors. We then discuss novel and promising strategies to overcome these obstacles that are in preclinical development or under clinical investigation.

GM-CSF disruption in CART cells modulates T cell activation and enhances CART cell anti-tumor activity

Inhibitory myeloid cells and their cytokines play critical roles in limiting chimeric antigen receptor T (CART) cell therapy by contributing to the development of toxicities and resistance following infusion. We have previously shown that neutralization of granulocyte-macrophage colony-stimulating factor (GM-CSF) prevents these toxicities and enhances CART cell functions by inhibiting myeloid cell activation. In this report, we study the direct impact of GM-CSF disruption during the production of CD19-directed CART cells on their effector functions, independent of GM-CSF modulation of myeloid cells. In this study, we show that antigen-specific activation of GM-CSF^KO CART19 cells consistently displayed reduced early activation, enhanced proliferation, and improved anti-tumor activity in a xenograft model for relapsed B cell malignancies. Activated CART19 cells significantly upregulate GM-CSF receptors. However, the interaction between GM-CSF and its upregulated receptors on CART cells was not the predominant mechanism of this activation phenotype. GM-CSF^KO CART19 cell had reduced BH3 interacting-domain death agonist (Bid), suggesting an interaction between GM-CSF and intrinsic apoptosis pathways. In conclusion, our study demonstrates that CRISPR/Cas9-mediated GM-CSF knockout in CART cells directly ameliorates CART cell early activation and enhances anti-tumor activity in preclinical models.

Allogeneic Chimeric Antigen Receptor Therapy in Lymphoma

The therapeutic armamentarium has significantly expanded since the approval of various CD19-targeting chimeric antigen receptor T cell (CAR-T) therapies in non-Hodgkin lymphoma (NHL). These CAR-Ts are patient-specific and require a complex, resource, and time-consuming process. While this appears promising, autologous CAR-Ts are limited due to the lack of accessibility, manufacturing delays, and variable product quality. To overcome these, allogeneic (allo) CARs from healthy donors appear appealing. These can be immediately available as “off the shelf” ready-to-use products of standardized and superior quality exempt from the effects of an immunosuppressive tumor microenvironment and prior treatments, and potentially with lower healthcare utilization using industrialized scale production. Allogeneic CARs, however, are not devoid of complications and require genomic editing, especially with αβ T cells to avoid graft versus host disease (GvHD) and allo-rejection by the recipient’s immune system. Tools for genomic editing such as TALEN and CRISPR provide promise to develop truly “off the shelf” universal CARs and further advance the field of cellular immunotherapy. Several allogeneic CARs are currently in early phase clinical trials, and preliminary data is encouraging. Longer follow-up is required to truly assess the feasibility and safety of these techniques in the patients. This review focuses on the strategies for developing allogeneic CARs along with cell sources and clinical experience thus far in lymphoma.

An overview of the recent findings of cell-based therapies for the treatment and management of COVID-19

The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic taking the lives of millions. The virus itself not only invades and destroys the angiotensin-converting enzyme 2 (ACE2)-expressing cells of the lungs, kidneys, liver, etc. but also elicits a hyperinflammatory immune response, further damaging the tissue leading to acute respiratory distress syndrome (ARDS) and death. Although vaccines, as a prime example of active immunotherapy, have clearly disrupted the transmission of virus and reduced mortality, hospitalization, and burden of disease, other avenues of immunotherapy are also being explored. One such approach would be to adoptively transfer modified/unmodified immune cells to the critically ill. Here, we compiled and summarized the immunopathogenesis of SARS-CoV-2 and the recent preclinical and clinical data on the potential of cell-based therapies in the fight against COVID-19.

Deliver the promise: RNAs as a new class of molecular entities for therapy and vaccination

The concepts of developing RNAs as new molecular entities for therapies have arisen again and again since the discoveries of antisense RNAs, direct RNA-protein interactions, functional noncoding RNAs, and RNA-directed gene editing. The feasibility was demonstrated with the development and utilization of synthetic RNA agents to selectively control target gene expression, modulate protein functions or alter the genome to manage diseases. Rather, RNAs are labile to degradation and cannot cross cell membrane barriers, making it hard to develop RNA medications. With the development of viable RNA technologies, such as chemistry and pharmaceutics, eight antisense oligonucleotides (ASOs) (fomivirsen, mipomersen, eteplirsen, nusinersen, inotersen, golodirsen, viltolarsen and casimersen), one aptamer (pegaptanib), and three small interfering RNAs (siRNAs) (patisiran, givosiran and lumasiran) have been approved by the United States Food and Drug Administration (FDA) for therapies, and two mRNA vaccines (BNT162b2 and mRNA-1273) under Emergency Use Authorization for the prevention of COVID-19. Therefore, RNAs have become a great addition to small molecules, proteins/antibodies, and cell-based modalities to improve the public health. In this article, we first summarize the general characteristics of therapeutic RNA agents, including chemistry, common delivery strategies, mechanisms of actions, and safety. By overviewing individual RNA medications and vaccines approved by the FDA and some agents under development, we illustrate the unique compositions and pharmacological actions of RNA products. A new era of RNA research and development will likely lead to commercialization of more RNA agents for medical use, expanding the range of therapeutic targets and increasing the diversity of molecular modalities.

CRISPR/Cas-Dependent and Nuclease-Free In Vivo Therapeutic Gene Editing

Precise gene manipulation by gene editing approaches facilitates the potential to cure several debilitating genetic disorders. Gene modification stimulated by engineered nucleases induces a double-stranded break (DSB) in the target genomic locus, thereby activating DNA repair mechanisms. DSBs triggered by nucleases are repaired either by the nonhomologous end-joining or the homology-directed repair pathway, enabling efficient gene editing. While there are several ongoing ex vivo genome editing clinical trials, current research underscores the therapeutic potential of CRISPR/Cas-based (clustered regularly interspaced short palindrome repeats-associated Cas nuclease) in vivo gene editing. In this review, we provide an overview of the CRISPR/Cas-mediated in vivo genome therapy applications and explore their prospective clinical translatability to treat human monogenic disorders. In addition, we discuss the various challenges associated with in vivo genome editing technologies and strategies used to circumvent them. Despite the robust and precise nuclease-mediated gene editing, a promoterless, nuclease-independent gene targeting strategy has been utilized to evade the drawbacks of the nuclease-dependent system, such as off-target effects, immunogenicity, and cytotoxicity. Thus, the rapidly evolving paradigm of gene editing technologies will continue to foster the progress of gene therapy applications.