Strategies for Reducing Toxicity and Enhancing Efficacy of Chimeric Antigen Receptor T Cell Therapy in Hematological Malignancies

Chimeric antigen receptor T cell (CAR-T) therapy in hematologic malignancies has made great progress, but there are still some problems. First, T cells from tumor patients show an exhaustion phenotype; thus, the persistence and function of the CAR-Ts are poor, and achieving a satisfactory curative effect is difficult. Second, some patients initially respond well but quickly develop antigen-negative tumor recurrence. Thirdly, CAR-T treatment is not effective in some patients and is accompanied by severe side effects, such as cytokine release syndrome (CRS) and neurotoxicity. The solution to these problems is to reduce the toxicity and enhance the efficacy of CAR-T therapy. In this paper, we describe various strategies for reducing the toxicity and enhancing the efficacy of CAR-T therapy in hematological malignancies. In the first section, strategies for modifying CAR-Ts using gene-editing technologies or combining them with other anti-tumor drugs to enhance the efficacy of CAR-T therapy are introduced. The second section describes some methods in which the design and construction of CAR-Ts differ from the conventional process. The aim of these methods is to enhance the anti-tumor activity of CAR-Ts and prevent tumor recurrence. The third section describes modifying the CAR structure or installing safety switches to radically reduce CAR-T toxicity or regulating inflammatory cytokines to control the symptoms of CAR-T-associated toxicity. Together, the knowledge summarized herein will aid in designing better-suited and safer CAR-T treatment strategies.

Tuning the ignition of CAR: optimizing the affinity of scFv to improve CAR-T therapy

How single-chain variable fragments (scFvs) affect the functions of chimeric antigen receptors (CARs) has not been well studied. Here, the components of CAR with an emphasis on scFv were described, and then several methods to measure scFv affinity were discussed. Next, scFv optimization studies for CD19, CD38, HER2, GD2 or EGFR were overviewed, showing that tuning the affinity of scFv could alleviate the on-target/off-tumor toxicity. The affinities of scFvs for different antigens were also summarized to designate a relatively optimal working range for CAR design. Last, a synthetic biology approach utilizing a low-affinity synthetic Notch (synNotch) receptor to achieve ultrasensitivity of antigen-density discrimination and murine models to assay the on-target/off-tumor toxicity of CARs were highlighted. Thus, this review provides preliminary guidelines of choosing the right scFvs for CARs.

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.

Recent Advances in CAR-T Cell Therapy for Non-Hodgkin Lymphoma

Adoptive cellular immunotherapy with anti CD19 chimeric antigen receptor (CAR)-T cell has changed the treatment landscape in relapsed/refractory B cell lymphomas. They have emerged as effective therapy in patients with multiple relapsed/refractory disease, capable of sustaining durable remissions. Two CAR-T cell products (axicabtagene ciloleucel and tisagenlecleucel) are currently approved by the United States Food and Drug Administration. A third anti CD19 CAR-T cell, lisocabtagene ciloleucel is currently being evaluated in large clinical trials and may also be United States Food and Drug Administration-approved soon. CAR-T cell-related toxicities, including infections, cytokine release syndrome, and neurotoxicity are potential complications of therapy. With increasing use of CAR-T cells, the mechanism of toxicities and mitigation strategies needs to be developed. Additionally, reasons for CAR-T cell failure and progression following this therapy needs to be further studied. We describe the recent developments in this field, with emphasis on the complications of therapy and factors contributing to toxicities, efficacy, and resistance. We also describe the ongoing research in this field and the newer CAR-T cell constructs that are being developed to counter the challenges that have been identified in this field.

Chimeric Antigen Receptor T-Cell Therapy: Reach to Solid Tumor Experience

Chimeric antigen receptor (CAR) modified T-cell therapy, a unique platform technology highlighting precision medicine through utilization of molecular biology and cell-based therapeutics has shown unprecedented rates in patients with hematological malignancies such as acute lymphocyte leukemia, non-Hodgkin's lymphoma and multiple myeloma (MM). With the approval of CD19-targeted CAR T-cells by the Food and Drug Administration in acute lymphoblastic leukemia (ALL) and NHL, this technology is positioned for aggressive expansion to combination therapeutic opportunities and proof of principle towards utility in other malignant disorders. However, despite the impressive results seen with hematological malignancies, CAR T-cells have shown limited efficacy in solid tumors with several unsuccessful preclinical studies. Regardless, these attempts have provided us with a better understanding of the imminent challenges specific to solid tumors even if they have not so far led to expanded clinical treatment opportunities outside ALL/NHL/MM. This review summarizes our current understanding of CAR T-cell mechanism of action, while presenting the major limitations of CAR T-cell derived treatments in solid tumors. We further discuss recent findings and present new potential strategies to overcome the challenges facing solid tumor targeting by CAR T-cell platforms.

Anti-CD19 Chimeric Antigen Receptor T Cell Therapies: Harnessing the Power of the Immune System to Fight Diffuse Large B Cell Lymphoma

PURPOSE OF REVIEW

This article will review the use of anti-CD19 CAR-T therapy used in relapsed/refractory diffuse large B cell lymphoma.

RECENT FINDINGS

The clinical outcomes, safety analysis, and other relevant considerations will be discussed with an emphasis on the most recently published data regarding the ZUMA-1, JULIET, and TRANSCEND NHL-001 trials. Anti-CD19 CAR-T therapy is an exciting new therapy now approved and available to patients with relapsed/refractory diffuse large B cell lymphoma. Secondary to the increasing success and availability of these products, caregivers should expect to become familiar with the indications, toxicity, and limitations of these treatment options and when patients should be considered for referral.