Unique CDR3 epitope targeting by CAR-T cells is a viable approach for treating T-cell malignancies

CAR T Cells in T Cell Acute Lymphoblastic Leukemia and Lymphoblastic Lymphoma

Chimeric antigen receptor (CAR T) therapy produced excellent activity in patients with relapsed/refractory B-lineage malignancies. However, extending these therapies to T cell cancers requires overcoming unique challenges. In the recent years, multiple approaches have been developed in preclinical models and some were tested in clinical trials in patients with treatment-refractory T-cell malignanices with promising early results. Here, we review main hurdles impeding the success of CAR T therapy in T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL), discuss potential solutions, and summarize recent progress in both preclinical and clinical development of CAR T therapy for these diseases.

Chimeric antigen receptor T cells march into T cell malignancies

T cell malignancies represent a diverse collection of leukemia/lymphoma conditions in humans arising from aberrant T cells. Such malignancies are often associated with poor clinical prognoses, cancer relapse, as well as progressive resistance to anti-cancer treatments. While chimeric antigen receptor (CAR) T cell immunotherapy has emerged as a revolutionary treatment strategy that is highly effective for treating B cell malignancies, its application as a treatment for T cell malignancies remains to be better explored. Furthermore, the effectiveness of CAR-T treatment in T cell malignancies is significantly influenced by the quality of contamination-free CAR-T cells during the manufacturing process, as well as by multiple characteristics of such malignancies, including the sharing of antigens across normal and malignant T cells, fratricide, and T cell aplasia. In this review, we provide a detailed account of the current developments in the clinical application of CAR-T therapy to treat T cell malignancies, offer strategies for addressing current challenges, and outline a roadmap toward its effective implementation as a broad treatment option for this condition.

CAR T-Cells in Acute Lymphoblastic Leukemia: Current Status and Future Prospects

The currently available treatment for acute lymphoblastic leukemia (ALL) is mainly dependent on the combination of chemotherapy, steroids, and allogeneic stem cell transplantation. However, refractoriness and relapse (R/R) after initial complete remission may reach up to 20% in pediatrics. This percentage may even reach 60% in adults. To overcome R/R, a new therapeutic approach was developed using what is called chimeric antigen receptor-modified (CAR) T-cell therapy. The Food and Drug Administration (FDA) in the United States has so far approved four CAR T-cells for the treatment of ALL. Using this new therapeutic strategy has shown a remarkable success in treating R/R ALL. However, the use of CAR T-cells is expensive, has many imitations, and is associated with some adverse effects. Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are two common examples of these adverse effects. Moreover, R/R to CAR T-cell therapy can take place during treatment. Continuous development of this therapeutic strategy is ongoing to overcome these limitations and adverse effects. The present article overviews the use of CAR T-cell in the treatment of ALL, summarizing the results of relevant clinical trials and discussing future prospects intended to improve the efficacy of this therapeutic strategy and overcome its limitations.

An Update on Clinical Trials and Potential Therapeutic Strategies in T-Cell Acute Lymphoblastic Leukemia

Current therapies for T-cell acute leukemia are based on risk stratification and have greatly improved the survival rate for patients, but mortality rates remain high owing to relapsed disease, therapy resistance, or treatment-related toxicities/infection. Patients with relapsed disease continue to have poor outcomes. In the past few years, newer agents have been investigated to optimize upfront therapies for higher-risk patients in the hopes of decreasing relapse rates. This review summarizes the progress of chemo/targeted therapies using Nelarabine/Bortezomib/CDK4/6 inhibitors for T-ALL in clinical trials and novel strategies to target NOTCH-induced T-ALL. We also outline immunotherapy clinical trials using monoclonal/bispecific T-cell engaging antibodies, anti-PD1/anti-PDL1 checkpoint inhibitors, and CAR-T for T-ALL therapy. Overall, pre-clinical studies and clinical trials showed that applying monoclonal antibodies or CAR-T for relapsed/refractory T-ALL therapy is promising. The combination of target therapy and immunotherapy may be a novel strategy for T-ALL treatment.

The use of non-functional clonotypes as a natural calibrator for quantitative bias correction in adaptive immune receptor repertoire profiling

High-throughput sequencing of adaptive immune receptor repertoires is a valuable tool for receiving insights in adaptive immunity studies. Several powerful TCR/BCR repertoire reconstruction and analysis methods have been developed in the past decade. However, detecting and correcting the discrepancy between real and experimentally observed lymphocyte clone frequencies are still challenging. Here, we discovered a hallmark anomaly in the ratio between read count and clone count-based frequencies of non-functional clonotypes in multiplex PCR-based immune repertoires. Calculating this anomaly, we formulated a quantitative measure of V- and J-genes frequency bias driven by multiplex PCR during library preparation called Over Amplification Rate (OAR). Based on the OAR concept, we developed an original software for multiplex PCR-specific bias evaluation and correction named iROAR: immune Repertoire Over Amplification Removal (https://github.com/smiranast/iROAR). The iROAR algorithm was successfully tested on previously published TCR repertoires obtained using both 5' RACE (Rapid Amplification of cDNA Ends)-based and multiplex PCR-based approaches and compared with a biological spike-in-based method for PCR bias evaluation. The developed approach can increase the accuracy and consistency of repertoires reconstructed by different methods making them more applicable for comparative analysis.

CAR T-Cell Immunotherapy Treating T-ALL: Challenges and Opportunities

T-cell acute lymphoblastic leukemia (T-ALL), a form of T-cell malignancy, is a typically aggressive hematological malignancy with high rates of disease relapse and a poor prognosis. Current guidelines do not recommend any specific treatments for these patients, and only allogeneic stem cell transplant, which is associated with potential risks and toxicities, is a curative therapy. Recent clinical trials showed that immunotherapies, including monoclonal antibodies, checkpoint inhibitors, and CAR T therapies, are successful in treating hematologic malignancies. CAR T cells, which specifically target the B-cell surface antigen CD19, have demonstrated remarkable efficacy in the treatment of B-cell acute leukemia, and some progress has been made in the treatment of other hematologic malignancies. However, the development of CAR T-cell immunotherapy targeting T-cell malignancies appears more challenging due to the potential risks of fratricide, T-cell aplasia, immunosuppression, and product contamination. In this review, we discuss the current status of and challenges related to CAR T-cell immunotherapy for T-ALL and review potential strategies to overcome these limitations.

Adoptive Cell Therapy for T-Cell Malignancies

T-cell malignancies are often aggressive and associated with poor prognoses. Adoptive cell therapy has recently shown promise as a new line of therapy for patients with hematological malignancies. However, there are currently challenges in applying adoptive cell therapy to T-cell malignancies. Various approaches have been examined in preclinical and clinical studies to overcome these obstacles. This review aims to provide an overview of the recent progress on adoptive cell therapy for T-cell malignancies. The benefits and drawbacks of different types of adoptive cell therapy are discussed. The potential advantages and current applications of innate immune cell-based adoptive cell therapy for T cell malignancies are emphasized.

Advances in Cellular Therapy for T-Cell Prolymphocytic Leukemia

T-cell prolymphocytic leukemia (T-PLL) is a rare, aggressive hematologic malignancy with a poor prognosis. Alemtuzumab (Campath) remains the cornerstone for treatment, with an 80% complete response (CR). Hematopoietic stem cell transplant (HSCT) is considered the standard of care as consolidative therapy in eligible patients. However, allogeneic stem cell transplant is also complicated by increased rates of infections from chemotherapy, acute graft-versus-host disease (GVHD), and chronic GVHD. This review aims to report the available literature on the efficacy and complications of consolidative HSCT. It also discusses the importance of patient selection and pre- and post-transplant complications including atypical infections and GVHD.

The methods and advances of adaptive immune receptors repertoire sequencing

The adaptive immune response is a powerful tool, capable of recognizing, binding to, and neutralizing a vast number of internal and external threats via T or B lymphatic receptors with widespread sets of antigen specificities. The emergence of high-throughput sequencing technology and bioinformatics provides opportunities for research in the fields of life sciences and medicine. The analysis and annotation for immune repertoire data can reveal biologically meaningful information, including immune prediction, target antigens, and effective evaluation. Continuous improvements of the immunological repertoire sequencing methods and analysis tools will help to minimize the experimental and calculation errors and realize the immunological information to meet the clinical requirements. That said, the clinical application of adaptive immune repertoire sequencing requires appropriate experimental methods and standard analytical tools. At the population cell level, we can acquire the overview of cell groups, but the information about a single cell is not obtained accurately. The information that is ignored may be crucial for understanding the heterogeneity of each cell, gene expression and drug response. The combination of high-throughput sequencing and single-cell technology allows us to obtain single-cell information with low-cost and high-throughput. In this review, we summarized the current methods and progress in this area.

Neutrophil Extracellular Traps (NETs): Opportunities for Targeted Therapy

Antitumor therapy, including adoptive immunotherapy, inevitably faces powerful counteraction from advanced cancer. If hematological malignancies are currently amenable to therapy with CAR-T lymphocytes (T-cells modified by the chimeric antigen receptor), solid tumors, unfortunately, show a significantly higher degree of resistance to this type of therapy. As recent studies show, the leading role in the escape of solid tumors from the cytotoxic activity of immune cells belongs to the tumor microenvironment (TME). TME consists of several types of cells, including neutrophils, the most numerous cells of the immune system. Recent studies show that the development of the tumor and its ability to metastasize directly affect the extracellular traps of neutrophils (neutrophil extracellular traps, NETs) formed as a result of the response to tumor stimuli. In addition, the nuclear DNA of neutrophils - the main component of NETs - erects a spatial barrier to the interaction of CAR-T with tumor cells. Previous studies have demonstrated the promising potential of deoxyribonuclease I (DNase I) in the destruction of NETs. In this regard, the use of eukaryotic deoxyribonuclease I (DNase I) is promising in the effort to increase the efficiency of CAR-T by reducing the NETs influence in TME. We will examine the role of NETs in TME and the various approaches in the effort to reduce the effect of NETs on a tumor.

Advances and Perspectives in the Treatment of T-PLL

PURPOSE OF REVIEW

T cell prolymphocytic leukemia (T-PLL) is a rare mature T cell tumor. Available treatment options in this aggressive disease are largely inefficient and patient outcomes are highly dissatisfactory. Current therapeutic strategies mainly employ the CD52-antibody alemtuzumab as the most active single agent. However, sustained remissions after sole alemtuzumab-based induction are exceptions. Responses after available second-line strategies are even less durable. More profound disease control or rare curative outcomes can currently only be expected after a consolidating allogeneic hematopoietic stem cell transplantation (allo-HSCT) in best first response. However, only 30-50% of patients are eligible for this procedure. Major advances in the molecular characterization of T-PLL during recent years have stimulated translational studies on potential vulnerabilities of the T-PLL cell. We summarize here the current state of "classical" treatments and critically appraise novel (pre)clinical strategies.

RECENT FINDINGS

Alemtuzumab-induced first remissions, accomplished in ≈ 90% of patients, last at median ≈ 12 months. Series on allo-HSCT in T-PLL, although of very heterogeneous character, suggest a slight improvement in outcomes among transplanted patients within the past decade. Dual-action nucleosides such as bendamustine or cladribine show moderate clinical activity as single agents in the setting of relapsed or refractory disease. Induction of apoptosis via reactivation of p53 (e.g., by inhibitors of HDAC or MDM2) and targeting of its downstream pathways (i.e., BCL2 family antagonists, CDK inhibitors) are promising new approaches. Novel strategies also focus on inhibition of the JAK/STAT pathway with the first clinical data. Implementations of immune-checkpoint blockades or CAR-T cell therapy are at the stage of pre-clinical assessments of activity and feasibility. The recommended treatment strategy in T-PLL remains a successful induction by infusional alemtuzumab followed by a consolidating allo-HSCT in eligible patients. Nevertheless, long-term survivors after this "standard" comprise only 10-20%. The increasingly revealed molecular make-up of T-PLL and the tremendous expansion of approved targeted compounds in oncology represent a "never-before" opportunity to successfully tackle the voids in T-PLL. Approaches, e.g., those reinstating deficient cell death execution, show encouraging pre-clinical and first-in-human results in T-PLL, and urgently have to be transferred to systematic clinical testing.

A Novel Approach for the Treatment of T Cell Malignancies: Targeting T Cell Receptor Vβ Families

Peripheral T cell lymphomas (PTCLs) are generally chemotherapy resistant and have a poor prognosis. The lack of targeted immunotherapeutic approaches for T cell malignancies results in part from potential risks associated with targeting broadly expressed T cell markers, namely T cell depletion and clinically significant immune compromise. The knowledge that the T cell receptor (TCR) β chain in human α/β TCRs are grouped into Vβ families that can each be targeted by a monoclonal antibody can therefore be exploited for therapeutic purposes. Here, we develop a flexible approach for targeting TCR Vβ families by engineering T cells to express a chimeric CD64 protein that acts as a high affinity immune receptor (IR). We found that CD64 IR-modified T cells can be redirected with precision to T cell targets expressing selected Vβ families by combining CD64 IR-modified T cells with a monoclonal antibody directed toward a specific TCR Vβ family in vitro and in vivo. These findings provide proof of concept that TCR Vβ-family-specific T cell lysis can be achieved using this novel combination cell–antibody platform and illuminates a path toward high precision targeting of T cell malignancies without substantial immune compromise.

Peripheral T cell lymphomas: from the bench to the clinic

Peripheral T cell lymphomas (PTCLs) are a heterogeneous group of orphan neoplasms. Despite the introduction of anthracycline-based chemotherapy protocols, with or without autologous haematopoietic transplantation and a plethora of new agents, the progression-free survival of patients with PTCLs needs to be improved. The rarity of these neoplasms, the limited knowledge of their driving defects and the lack of experimental models have impaired clinical successes. This scenario is now rapidly changing with the discovery of a spectrum of genomic defects that hijack essential signalling pathways and foster T cell transformation. This knowledge has led to new genomic-based stratifications, which are being used to establish objective diagnostic criteria, more effective risk assessment and target-based interventions. The integration of genomic and functional data has provided the basis for targeted therapies and immunological approaches that underlie individual tumour vulnerabilities. Fortunately, novel therapeutic strategies can now be rapidly tested in preclinical models and effectively translated to the clinic by means of well-designed clinical trials. We believe that by combining new targeted agents with immune regulators and chimeric antigen receptor-expressing natural killer and T cells, the overall survival of patients with PTCLs will dramatically increase.