Chimeric Antigen Receptor T-Cell Therapies for Aggressive B-Cell Lymphomas: Current and Future State of the Art

CAR-T lymphocyte-based cell therapies; mechanistic substantiation, applications and biosafety enhancement with suicide genes: new opportunities to melt side effects

Immunotherapy has made significant strides in cancer treatment with strategies like checkpoint blockade antibodies and adoptive T cell transfer. Chimeric antigen receptor T cells (CAR-T) have emerged as a promising approach to combine these strategies and overcome their limitations. This review explores CAR-T cells as a living drug for cancer treatment. CAR-T cells are genetically engineered immune cells designed to target and eliminate tumor cells by recognizing specific antigens. The study involves a comprehensive literature review on CAR-T cell technology, covering structure optimization, generations, manufacturing processes, and gene therapy strategies. It examines CAR-T therapy in haematologic cancers and solid tumors, highlighting challenges and proposing a suicide gene-based mechanism to enhance safety. The results show significant advancements in CAR-T technology, particularly in structure optimization and generation. The manufacturing process has improved for broader clinical application. However, a series of inherent challenges and side effects still need to be addressed. In conclusion, CAR-T cells hold great promise for cancer treatment, but ongoing research is crucial to improve efficacy and safety for oncology patients. The proposed suicide gene-based mechanism offers a potential solution to mitigate side effects including cytokine release syndrome (the most common toxic side effect of CAR-T therapy) and the associated neurotoxicity.

How to manage poor mobilisers

Autologous hematopoietic progenitor cell transplantation (ASCT) has been used for more than five decades to treat malignant and non-malignant diseases. Successful engraftment after high-dose chemotherapy relies on the ability to collect sufficient CD34 + hematopoietic progenitor cells (HPCs), typically from peripheral blood after mobilization. Commonly, either granulocyte colony-stimulating factor (G-CSF) alone as a single agent (i.e. steady-state mobilization) or G-CSF after chemotherapy is administered to collect adequate numbers of HPCs (minimum ≥2 × 106 CD34 + cells/kg for one ASCT; optimal up to 5 × 106 CD34 + cells/kg). However, a significant proportion of patients fail successful HPC mobilization, which is commonly defined as a CD34+ cell count below 10-15/µL after at least 4 days of 10 µg/kg b.w. G-CSF alone, or after chemo-mobilization in combination with 5-10 µg/kg b.w. G-CSF. In these situations plerixafor, a chemokine receptor inhibitor (CXCR4) can be used to enhance HPC collection in patients with multiple myeloma and malignant lymphoma whose cells mobilize poorly. Risk factors for poor mobilization have been evaluated and several strategies (e.g. plerixafor to rescue the mobilization approach or pre-emptive use) have been suggested to optimize mobilization, especially in patients at risk. This manuscript discusses the risk factors of poor CD34+ mobilization and summarizes the current strategies to optimize mobilization and HPC collection.

Thinking "outside the germinal center": Re-educating T cells to combat follicular lymphoma

There have been significant advancements in the management of follicular lymphoma (FL), the most common indolent lymphoma. These include immunomodulatory agents such as lenalidomide, epigenetic modifiers (tazemetostat), and phosphoinotiside-3 kinase inhibitors (copanlisib). The focus of this review is T cell-engager therapies, namely chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies, have recently transformed the treatment landscape of FL. Two CAR T cell products, axicabtagene ciloleucel (axi-cel) and tisagenlecleucel (tisa-cel), and one bispecific antibody, mosunetuzumab, recently received FDA approvals in FL. Several other new immune effector drugs are being evaluated and will expand the treatment armamentarium. This review focuses on CAR T-cell and bispecific antibody therapies, details their safety and efficacy and considers their evolving role in the current treatment landscape of FL.

Immune-based Therapies-What the Emergency Physician Needs to Know

Immunotherapy is a treatment modality that has a broad and rapidly growing range of applications to treat both chronic and acute diseases, including rheumatoid arthritis, Crohn disease, cancer, and COVID-19. Emergency physicians must be aware of the breadth of applications and be able to consider the effects of immunotherapies when patients on these treatments present to the hospital. This article provides a review of the mechanisms of action, indications for use, and potential complications of immunotherapy treatments that are relevant in the emergency care setting.

Recent findings on chimeric antigen receptor (CAR)-engineered immune cell therapy in solid tumors and hematological malignancies

Advancements in adoptive cell therapy over the last four decades have revealed various new therapeutic strategies, such as chimeric antigen receptors (CARs), which are dedicated immune cells that are engineered and administered to eliminate cancer cells. In this context, CAR T-cells have shown significant promise in the treatment of hematological malignancies. However, many obstacles limit the efficacy of CAR T-cell therapy in both solid tumors and hematological malignancies. Consequently, CAR-NK and CAR-M cell therapies have recently emerged as novel therapeutic options for addressing the challenges associated with CAR T-cell therapies. Currently, many CAR immune cell trials are underway in various human malignancies around the world to improve antitumor activity and reduce the toxicity of CAR immune cell therapy. This review will describe the comprehensive literature of recent findings on CAR immune cell therapy in a wide range of human malignancies, as well as the challenges that have emerged in recent years.

Sequential Single-Cell Transcriptional and Protein Marker Profiling Reveals TIGIT as a Marker of CD19 CAR-T Cell Dysfunction in Patients with Non-Hodgkin Lymphoma

Chimeric antigen receptor T-cell (CAR-T cell) therapy directed at CD19 produces durable remissions in the treatment of relapsed/refractory non-Hodgkin lymphoma (NHL). Nonetheless, many patients receiving CD19 CAR-T cells fail to respond for unknown reasons. To reveal changes in 4-1BB-based CD19 CAR-T cells and identify biomarkers of response, we used single-cell RNA sequencing and protein surface marker profiling of patient CAR-T cells pre- and postinfusion into patients with NHL. At the transcriptional and protein levels, we note the evolution of CAR-T cells toward a nonproliferative, highly differentiated, and exhausted state, with an enriched exhaustion profile in CAR-T cells of patients with poor response marked by TIGIT expression. Utilizing in vitro and in vivo studies, we demonstrate that TIGIT blockade alone improves the antitumor function of CAR-T cells. Altogether, we provide evidence of CAR-T cell dysfunction marked by TIGIT expression driving a poor response in patients with NHL.

SIGNIFICANCE

This is the first study investigating the mechanisms linked to CAR-T patient responses based on the sequential analysis of manufactured and infused CAR-T cells using single-cell RNA and protein expression data. Furthermore, our findings are the first to demonstrate an improvement of CAR-T cell efficacy with TIGIT inhibition alone. This article is highlighted in the In This Issue feature, p. 1825.

An orthogonal IL-2 and IL-2Rβ system drives persistence and activation of CAR T cells and clearance of bulky lymphoma

[Figure: see text].

Relapsed disease: off-the-shelf immunotherapies vs customized engineered products

Innovations in immuno-oncology for lymphomas have outpaced therapeutic developments in any other cancer histology. In the 1990s, rituximab, a CD20 monoclonal antibody, drastically changed treatment paradigms for B-cell non-Hodgkin lymphomas (B-NHLs). In parallel, the concept that T cells could be genetically reprogrammed and regulated to address tumor cell evasion was developed. Twenty years later, this concept has materialized-3 customized engineered CD19 chimeric antigen receptor T-cell (CART) constructs have been embraced as third-line therapies and beyond for aggressive B-NHL. Responses with CARTs are durable in 30% to 40% of patients, with consistent results in older patients, primary refractory disease, high-grade B-cell lymphoma, and patients with concurrent secondary central nervous system disease, all features historically associated with poorer outcomes. Challenges associated with the administration of CARTs include cumbersome and time-consuming manufacturing processes, toxicities, and cost, not to mention a substantial risk of relapse. Fortunately, as our understanding of how to manipulate the immune system to achieve full antitumor potential has grown, so has the rapid development of off-the-shelf immunotherapies, with CD20/CD3 bispecific antibodies standing out above all others. These agents have shown promising activity in aggressive B-NHL and have the potential to circumvent some of the challenges encountered with customized engineered products. However, toxicities remain substantial, dosing schedules intensive, and experience limited with these agents. Novel customized and off-the-shelf therapeutics as well as rational combinations of these agents are underway. Ultimately, growing experience with both customized engineered and off-the-shelf immunotherapies will provide guidance on optimal methods of delivery and sequencing.

Immune-based Therapies-What the Emergency Physician Needs to Know

Immunotherapy is a treatment modality that has a broad and rapidly growing range of applications to treat both chronic and acute diseases, including rheumatoid arthritis, Crohn disease, cancer, and COVID-19. Emergency physicians must be aware of the breadth of applications and be able to consider the effects of immunotherapies when patients on these treatments present to the hospital. This article provides a review of the mechanisms of action, indications for use, and potential complications of immunotherapy treatments that are relevant in the emergency care setting.

Perspectives on outpatient administration of CAR-T cell therapy in aggressive B-cell lymphoma and acute lymphoblastic leukemia

Chimeric antigen receptor (CAR) T-cell therapies that specifically target the CD19 antigen have emerged as a highly effective treatment option in patients with refractory B-cell hematological malignancies. Safety and efficacy outcomes from the pivotal prospective clinical trials of axicabtagene ciloleucel, tisagenlecleucel and lisocabtagene maraleucel and the retrospective, postmarketing, real-world analyses have confirmed high response rates and durable remissions in patients who had failed multiple lines of therapy and had no meaningful treatment options. Although initially administered in the inpatient setting, there has been a growing interest in delivering CAR-T cell therapy in the outpatient setting; however, this has not been adopted as standard clinical practice for multiple reasons, including logistic and reimbursement issues. CAR-T cell therapy requires a multidisciplinary approach and coordination, particularly if given in an outpatient setting. The ability to monitor patients closely is necessary and proper protocols must be established to respond to clinical changes to ensure efficient, effective and rapid evaluation either in the clinic or emergency department for management decisions regarding fever, sepsis, cytokine release syndrome and neurological events, specifically immune effector cell-associated neurotoxicity syndrome. This review presents the authors' institutional experience with the preparation and delivery of outpatient CD19-directed CAR-T cell therapy.

Novel CD37, Humanized CD37 and Bi-Specific Humanized CD37-CD19 CAR-T Cells Specifically Target Lymphoma

Simple Summary

Chimeric antigen receptor (CAR) T cell therapy represents a major advancement in cancer treatment. Recently, FDA approved CAR-T cells directed against the CD19 protein for treatment of leukemia and lymphoma. In spite of impressive clinical responses with CD19-CAR-T cells, some patients demonstrate disease relapse due to either antigen loss, cancer heterogeneity or other mechanisms. Novel CAR-T cells and targets are important for the field. This report describes novel CD37, humanized CD37 and bispecific humanized CD37-CD19-CAR-T cells targeting both CD37 and CD19. The study demonstrates that these novel CAR-T cells specifically targeted either CD37 positive or CD37 and CD19-positive cells with endogenous and exogenous protein expression and provides a basis for future clinical studies.

Abstract

CD19 and CD37 proteins are highly expressed in B-cell lymphoma and have been successfully targeted with different monotherapies, including chimeric antigen receptor (CAR)-T cell therapy. The goal of this study was to target lymphoma with novel CD37, humanized CD37, and bi-specific humanized CD37-CD19 CAR-T cells. A novel mouse monoclonal anti-human CD37 antibody (clone 2B8D12F2D4) was generated with high binding affinity for CD37 antigen (KD = 1.6 nM). The CD37 antibody specifically recognized cell surface CD37 protein in lymphoma cells and not in multiple myeloma or other types of cancer. The mouse and humanized CD37-CAR-T cells specifically killed Raji and CHO-CD37 cells and secreted IFN-gamma. In addition, we generated bi-specific humanized hCD37-CD19 CAR-T cells that specifically killed Raji cells, CHO-CD37, and Hela-CD19 cells and did not kill control CHO or Hela cells. Moreover, the hCD37-CD19 CAR-T cells secreted IFN-gamma against CD37-positive and CD19-positive target CHO-CD37, Hela-CD19 cells, respectively, but not against CD19 and CD37-negative parental cell line. The bi-specific hCD37-CD19 significantly inhibited Raji xenograft tumor growth and prolonged mouse survival in NOD scid gamma mouse (NSG) mouse model. This study demonstrates that novel humanized CD37 and humanized CD37-CD19 CAR-T cells specifically targeted either CD37 positive or CD37 and CD19-positive cells and provides a basis for future clinical studies.

Selecting the Optimal CAR-T for the Treatment of B-Cell Malignancies

PURPOSE OF REVIEW

Chimeric antigen receptor T-cell (CAR-T) therapy is a form of adoptive cellular therapy that has revolutionized the treatment landscape in hematologic malignancies, especially B-cell lymphomas. In this review, we will discuss some of the landmark data behind these therapies and then lay out our approach to utilizing this new therapy.

RECENT FINDINGS

CD19-directed CAR-Ts are the most common type currently used in treatment of relapsed B-cell lymphoid neoplasms. There are currently three FDA-approved products: axicabtagene ciluecel and tisagenlecleucel for the treatment of relapsed/refractory large B-cell lymphoma and pediatric B-cell acute lymphocytic leukemia (tisagenlecleucel only) and brexucabtagene autoleucel for the treatment of relapsed/refractory mantle cell lymphoma. These therapies are associated with distinctive acute toxicities such as cytokine release syndrome and neurotoxicity and chronic toxicities such as cytopenias and hypogammaglobulinemia. CAR-T therapy provides significant potential in the treatment of relapsed B-cell lymphomas despite current limitations. Several novel CAR cell designs are currently being studied in clinical trials which include tandem CAR-Ts, allogeneic CAR-Ts, and CAR-NK cells.

Advancing CAR T-Cell Therapy for Solid Tumors: Lessons Learned from Lymphoma Treatment

Chimeric antigen receptor (CAR) immunotherapy is one of the most promising modern approaches for the treatment of cancer. To date only two CAR T-cell products, Kymriah^® and Yescarta^®, have been approved by the Food and Drug Administration (FDA) for the treatment of lymphoblastic leukemia and B-cell lymphoma. Administration of CAR T-cells to control solid tumors has long been envisaged as one of the most difficult therapeutic tasks. The first two clinical trials conducted in sarcoma and neuroblastoma patients showed clinical benefits of CAR T-cells, yet multiple obstacles still hold us back from having accessible and efficient therapy. Why did such an effective treatment for relapsed and refractory hematological malignancies demonstrate only relatively modest efficiency in the context of solid tumors? Is it due to the lucky selection of the “magic” CD19 antigen, which might be one of a kind? Or do lymphomas lack the immunosuppressive features of solid tumors? Here we review the existing knowledge in the field of CAR T-cell therapy and address the heterogeneity of solid tumors and their diverse strategies of immunoevasion. We also provide an insight into prospective developments of CAR T-cell technologies against solid tumors.