Phase 1 TRANSCEND CLL 004 study of lisocabtagene maraleucel in patients with relapsed/refractory CLL or SLL

A bibliometric and knowledge-map study on the treatment of hematological malignancies with CAR-T cells from 2012 to 2023

Recently, CAR-T cell therapy in hematological malignancies has received extensive attention. The objective of this study is to gain a comprehensive understanding of the current research status, development trends, research hotspots, and emerging topics pertaining to CAR-T cells in the treatment of hematological malignancies. Articles pertaining to CAR-T cell therapy for hematological malignancies from the years 2012 to 2023 were obtained and assessed from the Web of Science Core Collection (WoSCC). A bibliometric approach was employed to conduct a scientific, comprehensive, and objective quantitative analysis, as well as a visual analysis, of this particular research domain. A comprehensive analysis was conducted on a corpus of 3643 articles, which were collaboratively authored by 72 countries and various research institutions. CAR-T cell research in treating hematological malignancies shows an increasing trend each year. Notably, the study identified the countries and institutions displaying the highest level of activity, the journals with the most citations and output, as well as the authors who garnered the highest frequency of citations and co-citations. Furthermore, the analysis successfully identified the research hotspots and highlighted six emerging topics within this domain. This study conducted a comprehensive exploration and analysis of the research status, development trends, research hotspots, and emerging topics about CAR-T cells in the treatment of hematological malignancies from 2012 to 2023. The findings of this study will serve as a valuable reference and guide for researchers seeking to delve deeper into this field and determine the future direction of their research.

Suppressive immune microenvironment and CART therapy for glioblastoma: future prospects and challenges

Glioblastoma, a highly malignant intracranial tumor, has acquired slow progress in treatment. Previous clinical trials involving targeted therapy and immune checkpoint inhibitors have shown no significant benefits in treating glioblastoma. This ineffectiveness is largely due to the complex immunosuppressive environment of glioblastoma. Glioblastoma cells exhibit low immunogenicity and strong heterogeneity and the immune microenvironment is replete with inhibitory cytokines, numerous immunosuppressive cells, and insufficient effective T cells. Fortunately, recent Phase I clinical trials of CART therapy for glioblastoma have confirmed its safety, with a small subset of patients achieving survival benefits. However, CART therapy continues to face challenges, including blood-brain barrier obstruction, antigen loss, and an immunosuppressive tumor microenvironment (TME). This article provides a detailed examination of glioblastoma's immune microenvironment, both from intrinsic and extrinsic tumor cell factors, reviews current clinical and basic research on multi-targets CART treatment, and concludes by outlining the key challenges in using CART cells for glioblastoma therapy.

CD38/NAD+ glycohydrolase and associated antigens in chronic lymphocytic leukaemia: From interconnected signalling pathways to therapeutic strategies

Chronic lymphocytic leukaemia (CLL) is a heterogenous disease characterized by the accumulation of neoplastic CD5+/CD19+ B lymphocytes. The spreading of the leukaemia relies on the CLL cell's ability to survive in the blood and migrate to and proliferate within the bone marrow and lymphoid tissues. Some patients with CLL are either refractory to the currently available therapies or relapse after treatment; this emphasizes the need for novel therapeutic strategies that improving clinical responses and overcome drug resistance. CD38 is a marker of a poor prognosis and governs a set of survival, proliferation and migration signals that contribute to the pathophysiology of CLL. The literature data evidence a spatiotemporal association between the cell surface expression of CD38 and that of other CLL antigens, such as the B-cell receptor (BCR), CD19, CD26, CD44, the integrin very late antigen 4 (VLA4), the chemokine receptor CXCR4, the vascular endothelial growth factor receptor-2 (VEGF-R2), and the neutrophil gelatinase-associated lipocalin receptor (NGAL-R). Most of these proteins contribute to CLL cell survival, proliferation and trafficking, and cooperate with CD38 in multilayered signal transduction processes. In general, these antigens have already been validated as therapeutic targets in cancer, and a broad repertoire of specific monoclonal antibodies and derivatives are available. Here, we review the state of the art in this field and examine the therapeutic opportunities for cotargeting CD38 and its partners in CLL, e.g. by designing novel bi-/trispecific antibodies.

Subsequent Malignancies After CD19-Targeted Chimeric Antigen Receptor T Cells in Patients With Lymphoma

Chimeric antigen receptor (CAR) T cells are an established treatment for B cell non-Hodgkin lymphomas (B-NHL). With the remarkable success in improving survival, understanding the late effects of CAR T cell therapy is becoming more relevant. The aim of this study is to determine the incidence of subsequent malignancies in adult patients with B-NHL. We retrospectively studied 355 patients from 2 different medical centers treated with four different CAR T cell products from 2016 to 2022. The overall cumulative incidence for subsequent malignancies at 36 months was 14% (95% CI: 9.2%, 19%). Subsequent malignancies were grouped into 3 primary categories: solid tumor, hematologic malignancy, and dermatologic malignancy with cumulative incidences at 36 months of 6.1% (95% CI: 3.1%-10%), 4.5% (95% CI: 2.1%-8.1%) and 4.2% (95% CI: 2.1%-7.5%) respectively. Notably, no cases of T cell malignancies were observed. In univariable analysis, increasing age was associated with higher risk for subsequent malignancy. While the overall benefits of CAR T products continue to outweigh their potential risks, more studies and longer follow ups are needed to further demonstrate the risks, patterns, and molecular pathways that lead to the development of subsequent malignancies.

Calibrated CAR Signaling Enables Low-Dose Therapy in Large B-Cell Lymphoma

We designed a CD19-targeted CAR comprising a calibrated signaling module, termed 1XX, that differs from that of conventional CD28/CD3z and 4-1BB/CD3z CARs. Here we report the first-in-human, phase 1 clinical trial of 19(T2)28z-1XX CAR T cells in relapsed/refractory large B-cell lymphoma. We hypothesized that 1XX CAR T cells may be effective at low doses and investigated 4 doubling dose levels starting from 25×106 CAR T cells. The overall response rate (ORR) was 82% and complete response (CR) rate 71% in the entire cohort (n=28) and 88% ORR and 75% CR in 16 patients treated at 25×106. With the median follow-up of 24 months, the 1-year EFS was 61% (95% CI: 45-82%). Overall, grade ≥3 CRS and ICANS rates were low at 4% and 7%. The calibrated potency of the 1XX CAR affords excellent efficacy at low cell doses and may benefit the treatment of other hematological malignancies, solid tumors and autoimmunity.

Current understanding and management of CAR T cell-associated toxicities

Chimeric antigen receptor (CAR) T cell therapy has revolutionized the treatment of several haematological malignancies and is being investigated in patients with various solid tumours. Characteristic CAR T cell-associated toxicities such as cytokine-release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are now well-recognized, and improved supportive care and management with immunosuppressive agents has made CAR T cell therapy safer and more feasible than it was when the first regulatory approvals of such treatments were granted in 2017. The increasing clinical experience with these therapies has also improved recognition of previously less well-defined toxicities, including movement disorders, immune effector cell-associated haematotoxicity (ICAHT) and immune effector cell-associated haemophagocytic lymphohistiocytosis-like syndrome (IEC-HS), as well as the substantial risk of infection in patients with persistent CAR T cell-induced B cell aplasia and hypogammaglobulinaemia. A more diverse selection of immunosuppressive and supportive-care pharmacotherapies is now being utilized for toxicity management, yet no universal algorithm for their application exists. As CAR T cell products targeting new antigens are developed, additional toxicities involving damage to non-malignant tissues expressing the target antigen are a potential hurdle. Continued prospective evaluation of toxicity management strategies and the design of less-toxic CAR T cell products are both crucial for ongoing success in this field. In this Review, we discuss the evolving understanding and clinical management of CAR T cell-associated toxicities.

The prognostic significance of genomic complexity in patients with CLL

Chromosomal aberrations are a common feature of cancer and can fuel cancer progression and treatment resistance. In chronic lymphocytic leukemia (CLL), the presence of multiple chromosomal aberrations is commonly referred to as "genomic complexity" or "complex karyotype"- (CKT). In the context of chemo- and chemoimmunotherapy, genomic complexity is associated with poor response to treatment and short survival, while some targeted therapies are able to mitigate its adverse prognostic impact. This article reviews currently available data and literature on the role of genomic complexity in CLL. The currently established tools to measure genomic complexity in patients with CLL are summarized and their strengths and weaknesses for routine diagnostics are evaluated. Moreover, possible definitions of CKT as an indicator for genomic complexity are discussed. Finally, data on the impact of CKT on clinical outcomes of patients with CLL are reviewed and the implications for patient stratification are presented.

Advancing CAR T-cell therapy for chronic lymphocytic leukemia: exploring resistance mechanisms and the innovative strategies to overcome them

Chimeric antigen receptor (CAR) T-cell therapy has ushered in substantial advancements in the management of various B-cell malignancies. However, its integration into chronic lymphocytic leukemia (CLL) treatment has been challenging, attributed largely to the development of very effective chemo-free alternatives. Additionally, CAR T-cell responses in CLL have not been as high as in other B-cell lymphomas or leukemias. However, a critical void exists in therapeutic options for patients with high-risk diseases who are resistant to the current CLL therapies, underscoring the urgency for adoptive immunotherapies in these patients. The diminished CAR T-cell efficacy within CLL can be traced to factors such as compromised T-cell fitness due to persistent antigenic stimulation inherent to CLL. Resistance mechanisms encompass tumor-related factors like antigen escape, CAR T-cell-intrinsic factors like T-cell exhaustion, and a suppressive tumor microenvironment (TME). New strategies to combat CAR T-cell resistance include the concurrent administration of therapies that augment CAR T-cell endurance and function, as well as the engineering of novel CAR T-cells targeting different antigens. Moreover, the concept of "armored" CAR T-cells, armed with transgenic modulators to modify both CAR T-cell function and the tumor milieu, is gaining traction. Beyond this, the development of readily available, allogeneic CAR T-cells and natural killer (NK) cells presents a promising countermeasure to innate T-cell defects in CLL patients. In this review, we explore the role of CAR T-cell therapy in CLL, the intricate tapestry of resistance mechanisms, and the pioneering methods studied to overcome resistance.

CAR-T Cells in Chronic Lymphocytic Leukemia

The treatment outcomes of patients with chronic lymphocytic leukemia (CLL) have considerably improved with the introduction of targeted therapies based on Bruton kinase inhibitors (BTKIs), venetoclax, and anti-CD20 monoclonal antibodies. However, despite these consistent improvements, patients who become resistant to these agents have poor outcomes and need new and more efficacious therapeutic strategies. Among these new treatments, a potentially curative approach consists of the use of chimeric antigen receptor T (CAR-T) cell therapy, which achieved remarkable success in various B-cell malignancies, including B-cell Non-Hodgkin Lymphomas (NHLs) and B-acute lymphoblastic Leukemia (ALL). However, although CAR-T cells were initially used for the treatment of CLL, their efficacy in CLL patients was lower than in other B-cell malignancies. This review analyses possible mechanisms of these failures, highlighting some recent developments that could offer the perspective of the incorporation of CAR-T cells in treatment protocols for relapsed/refractory CLL patients.

Oxidative stress is two-sided in the treatment of acute myeloid leukemia

INTRODUCTION

Oxidative stress caused by elevated ROS, as a novel therapeutic mechanism, has been implicated in various tumors including AML. AML cells are chronically under oxidative stress, yet overreliance on ROS production makes tumor cells increasingly vulnerable to further damage. Reducing the cytotoxic effect of ROS on normal cells while killing leukemia stem cell (LSC) with high levels of reactive oxygen species is a new challenge for oxidative stress therapy in leukemia.

METHODS

By searching literature databases, we summarized recent relevant studies. The relationship of ROS on AML genes, signaling pathways, and transcription factors, and the correlation of ROS with AML bone marrow microenvironment and autophagy were summarized. In addition, we summarize the current status of research on ROS and AML therapeutics. Finally, we discuss the research progress on redox resistance in AML.

RESULTS

This review discusses the evidence showing the link between redox reactions and the progression of AML and compiles the latest research findings that will facilitate future biological studies of redox effects associated with AML treatment.

CONCLUSION

We believe that exploiting this unique oxidative stress property of AML cells may provide a new way to prevent relapse and drug resistance.

Functional CRISPR screens in T cells reveal new opportunities for cancer immunotherapies

T cells are fundamental components in tumour immunity and cancer immunotherapies, which have made immense strides and revolutionized cancer treatment paradigm. However, recent studies delineate the predicament of T cell dysregulation in tumour microenvironment and the compromised efficacy of cancer immunotherapies. CRISPR screens enable unbiased interrogation of gene function in T cells and have revealed functional determinators, genetic regulatory networks, and intercellular interactions in T cell life cycle, thereby providing opportunities to revamp cancer immunotherapies. In this review, we briefly described the central roles of T cells in successful cancer immunotherapies, comprehensively summarised the studies of CRISPR screens in T cells, elaborated resultant master genes that control T cell activation, proliferation, fate determination, effector function, and exhaustion, and highlighted genes (BATF, PRDM1, and TOX) and signalling cascades (JAK-STAT and NF-κB pathways) that extensively engage in multiple branches of T cell responses. In conclusion, this review bridged the gap between discovering element genes to a specific process of T cell activities and apprehending these genes in the global T cell life cycle, deepened the understanding of T cell biology in tumour immunity, and outlined CRISPR screens resources that might facilitate the development and implementation of cancer immunotherapies in the clinic.

Transforming CLL management with immunotherapy: Investigating the potential of CAR T-cells and bispecific antibodies

Immunotherapies, such as chimeric antigen receptor (CAR) T-cell therapy and bispecific antibodies or T-cell engagers, have revolutionized the treatment landscape for various B-cell malignancies, including B-acute lymphoblastic leukemia and many non-Hodgkin lymphomas. Despite their significant impact on these malignancies, their application in chronic lymphocytic leukemia (CLL) management is still largely under investigation. Although the initial success of CD19-directed CAR T-cell therapy was observed in 3 multiply relapsed CLL patients, with 2 of them surviving over 10 years without relapse, recent CAR T-cell therapy trials in CLL have shown reduced response rates compared to their efficacy in other B-cell malignancies. One of the challenges with using immunotherapy in CLL is the compromised T-cell fitness from persistent CLL-related antigenic stimulation, and an immunosuppressive tumor microenvironment (TME). These challenges underscore a critical gap in therapeutic options for CLL patients intolerant or resistant to current therapies, emphasizing the imperative role of effective immunotherapy. Encouragingly, innovative strategies are emerging to overcome these challenges. These include integrating synergistic agents like ibrutinib to enhance CAR T-cell function and persistence and engineering newer CAR T-cell constructs targeting diverse antigens or employing dual-targeting approaches. Bispecific antibodies are an exciting "off-the-shelf" prospect for these patients, with their investigation in CLL currently entering the realm of clinical trials. Additionally, the development of allogeneic CAR T-cells and natural killer (NK) cells from healthy donors presents a promising solution to address the diminished T-cell fitness observed in CLL patients. This comprehensive review delves into the latest insights regarding the role of immunotherapy in CLL, the complex landscape of resistance mechanisms, and a spectrum of innovative approaches to surmount therapeutic challenges.

Lisocabtagene Maraleucel in Relapsed/Refractory Mantle Cell Lymphoma: Primary Analysis of the Mantle Cell Lymphoma Cohort From TRANSCEND NHL 001, a Phase I Multicenter Seamless Design Study

PURPOSE

To report the primary analysis results from the mantle cell lymphoma (MCL) cohort of the phase I seamless design TRANSCEND NHL 001 (ClinicalTrials.gov identifier: NCT02631044) study.

METHODS

Patients with relapsed/refractory (R/R) MCL after ≥two lines of previous therapy, including a Bruton tyrosine kinase inhibitor (BTKi), an alkylating agent, and a CD20-targeted agent, received lisocabtagene maraleucel (liso-cel) at a target dose level (DL) of 50 × 106 (DL1) or 100 × 106 (DL2) chimeric antigen receptor-positive T cells. Primary end points were adverse events (AEs), dose-limiting toxicities, and objective response rate (ORR) by independent review committee per Lugano criteria.

RESULTS

Of 104 leukapheresed patients, liso-cel was infused into 88. Median (range) number of previous lines of therapy was three (1-11) with 30% receiving ≥five previous lines of therapy, 73% of patients were age 65 years and older, 69% had refractory disease, 53% had BTKi refractory disease, 23% had TP53 mutation, and 8% had secondary CNS lymphoma. Median (range) on-study follow-up was 16.1 months (0.4-60.5). In the efficacy set (n = 83; DL1 + DL2), ORR was 83.1% (95% CI, 73.3 to 90.5) and complete response (CR) rate was 72.3% (95% CI, 61.4 to 81.6). Median duration of response was 15.7 months (95% CI, 6.2 to 24.0) and progression-free survival was 15.3 months (95% CI, 6.6 to 24.9). Most common grade ≥3 treatment-emergent AEs were neutropenia (56%), anemia (37.5%), and thrombocytopenia (25%). Cytokine release syndrome (CRS) was reported in 61% of patients (grade 3/4, 1%; grade 5, 0), neurologic events (NEs) in 31% (grade 3/4, 9%; grade 5, 0), grade ≥3 infections in 15%, and prolonged cytopenia in 40%.

CONCLUSION

Liso-cel demonstrated high CR rate and deep, durable responses with low incidence of grade ≥3 CRS, NE, and infections in patients with heavily pretreated R/R MCL, including those with high-risk, aggressive disease.

Safety, efficacy and determinants of response of allogeneic CD19-specific CAR-NK cells in CD19+ B cell tumors: a phase 1/2 trial

There is a pressing need for allogeneic chimeric antigen receptor (CAR)-immune cell therapies that are safe, effective and affordable. We conducted a phase 1/2 trial of cord blood-derived natural killer (NK) cells expressing anti-CD19 chimeric antigen receptor and interleukin-15 (CAR19/IL-15) in 37 patients with CD19+ B cell malignancies. The primary objectives were safety and efficacy, defined as day 30 overall response (OR). Secondary objectives included day 100 response, progression-free survival, overall survival and CAR19/IL-15 NK cell persistence. No notable toxicities such as cytokine release syndrome, neurotoxicity or graft-versus-host disease were observed. The day 30 and day 100 OR rates were 48.6% for both. The 1-year overall survival and progression-free survival were 68% and 32%, respectively. Patients who achieved OR had higher levels and longer persistence of CAR-NK cells. Receiving CAR-NK cells from a cord blood unit (CBU) with nucleated red blood cells ≤ 8 × 107 and a collection-to-cryopreservation time ≤ 24 h was the most significant predictor for superior outcome. NK cells from these optimal CBUs were highly functional and enriched in effector-related genes. In contrast, NK cells from suboptimal CBUs had upregulation of inflammation, hypoxia and cellular stress programs. Finally, using multiple mouse models, we confirmed the superior antitumor activity of CAR/IL-15 NK cells from optimal CBUs in vivo. These findings uncover new features of CAR-NK cell biology and underscore the importance of donor selection for allogeneic cell therapies. ClinicalTrials.gov identifier: NCT03056339 .

CAR‑T cell therapy: A breakthrough in traditional cancer treatment strategies (Review)

Chimeric antigen receptor (CAR)‑T cell therapy is an innovative approach to immune cell therapy that works by modifying the T cells of a patient to express the CAR protein on their surface, and thus induce their recognition and destruction of cancer cells. CAR‑T cell therapy has shown some success in treating hematological tumors, but it still faces a number of challenges in the treatment of solid tumors, such as antigen selection, tolerability and safety. In response to these issues, studies continue to improve the design of CAR‑T cells in pursuit of improved therapeutic efficacy and safety. In the future, CAR‑T cell therapy is expected to become an important cancer treatment, and may provide new ideas and strategies for individualized immunotherapy. The present review provides a comprehensive overview of the principles, clinical applications, therapeutic efficacy and challenges of CAR‑T cell therapy.

Mutation-specific CAR T cells as precision therapy for IGLV3-21R110 expressing high-risk chronic lymphocytic leukemia

The concept of precision cell therapy targeting tumor-specific mutations is appealing but requires surface-exposed neoepitopes, which is a rarity in cancer. B cell receptors (BCR) of mature lymphoid malignancies are exceptional in that they harbor tumor-specific-stereotyped sequences in the form of point mutations that drive self-engagement of the BCR and autologous signaling. Here, we use a BCR light chain neoepitope defined by a characteristic point mutation (IGLV3-21R110) for selective targeting of a poor-risk subset of chronic lymphocytic leukemia (CLL) with chimeric antigen receptor (CAR) T cells. We develop murine and humanized CAR constructs expressed in T cells from healthy donors and CLL patients that eradicate IGLV3-21R110 expressing cell lines and primary CLL cells, but neither cells expressing the non-pathogenic IGLV3-21G110 light chain nor polyclonal healthy B cells. In vivo experiments confirm epitope-selective cytolysis in xenograft models in female mice using engrafted IGLV3-21R110 expressing cell lines or primary CLL cells. We further demonstrate in two humanized mouse models lack of cytotoxicity towards human B cells. These data provide the basis for advanced approaches of resistance-preventive and biomarker-guided cellular targeting of functionally relevant lymphoma driver mutations sparing normal B cells.

Treatment of Double-Refractory Chronic Lymphocytic Leukemia-An Unmet Clinical Need

Recent years have seen significant improvement in chronic lymphocytic leukemia (CLL) management. Targeting B-cell lymphoma (BCL-2) and Bruton's kinase (BTK) have become the main strategies to restrain CLL activity. These agents are generally well tolerated, but the discontinuation of these therapies happens due to resistance, adverse effects, and Richter's transformation. A growing population of patients who have previously used both BTK inhibitors and BCL2 suffer from the constriction of the following regimens. This review explores the resistance mechanisms for both ibrutinib and venetoclax. Moreover, we present innovative approaches evaluated for treating double-refractory CLL.

Targeting TP53 disruption in chronic lymphocytic leukemia: Current strategies and future directions

In the modern era of Chronic Lymphocytic Leukemia (CLL) targeted therapy, the loss of p53 function due to genetic abnormalities remains a significant challenge. This is because even targeted agents, which are currently the mainstay of treatment for CLL, do not directly target p53 or restore its disrupted pathway. Consequently, resistance to therapy and unfavorable clinical outcomes often accompany these p53-related abnormalities. An essential goal of future clinical research should be to address the ostensibly "undruggable" p53 pathway. Currently, multiple therapeutic approaches are being explored to tackle TP53 dysfunction and improve outcomes in high-risk CLL. These approaches include the use of oncoprotein murine double minute 2 inhibitors, small-molecule p53 reactivators, exportin 1 (XPO1) inhibitors, and ataxia-telangiectasia mutated and Rad3-related (ATR) inhibitors. Combinations of these p53-targeting strategies, along with established novel therapies such as B-cell receptor or B-cell lymphoma-2 (BCL-2) inhibitors, may shape the future of therapeutic trials in this challenging-to-treat disease.

Lymphodepletion - an essential but undervalued part of the chimeric antigen receptor T-cell therapy cycle

Lymphodepletion (LD) or conditioning is an essential step in the application of currently used autologous and allogeneic chimeric antigen receptor T-cell (CAR-T) therapies as it maximizes engraftment, efficacy and long-term survival of CAR-T. Its main modes of action are the depletion and modulation of endogenous lymphocytes, conditioning of the microenvironment for improved CAR-T expansion and persistence, and reduction of tumor load. However, most LD regimens provide a broad and fairly unspecific suppression of T-cells as well as other hematopoietic cells, which can also lead to severe side effects, particularly infections. We reviewed 1271 published studies (2011-2023) with regard to current LD strategies for approved anti-CD19 CAR-T products for large B cell lymphoma (LBCL). Fludarabine (Flu) and cyclophosphamide (Cy) (alone or in combination) were the most commonly used agents. A large number of different schemes and combinations have been reported. In the respective schemes, doses of Flu and Cy (range 75-120mg/m2 and 750-1.500mg/m2) and wash out times (range 2-5 days) differed substantially. Furthermore, combinations with other agents such as bendamustine (benda), busulfan or alemtuzumab (for allogeneic CAR-T) were described. This diversity creates a challenge but also an opportunity to investigate the impact of LD on cellular kinetics and clinical outcomes of CAR-T. Only 21 studies explicitly investigated in more detail the influence of LD on safety and efficacy. As Flu and Cy can potentially impact both the in vivo activity and toxicity of CAR-T, a more detailed analysis of LD outcomes will be needed before we are able to fully assess its impact on different T-cell subsets within the CAR-T product. The T2EVOLVE consortium propagates a strategic investigation of LD protocols for the development of optimized conditioning regimens.

Chimeric Antigen Receptor T-Cells in Indolent Lymphoma, Mantle Cell Lymphoma, Chronic Lymphocytic Leukemia

The advent of chimeric antigen receptor (CAR)-T cell therapy has revolutionized the treatment of several hematological malignancies. Although the initial benefit was mainly observed in aggressive leukemias and lymphomas, recent data have resulted in the approval of multiple CAR-T therapies in indolent lymphomas, with ongoing research showing great promise for further improvements and therapeutic optimizations. In this article, we review the published data and approved therapies for CAR-T cell therapy for indolent lymphomas focusing on mantle cell lymphoma and follicular lymphoma while describing the work in chronic lymphocytic leukemia and future strategies.

Chimeric Antigen Receptor T-Cell Therapy in Aggressive B-Cell Lymphoma

Chimeric antigen receptor (CAR) T-cell therapy is a revolutionary therapy increasingly used in the treatment of non-Hodgkin B-cell lymphoma. This review focuses on the use of CAR T-cell therapy in aggressive B-cell lymphoma including clinical indications, known short- and long-term toxicity, mechanisms of CAR T-cell efficacy and tumor resistance, and future directions in the treatment of aggressive lymphoma with CAR T-cell therapy.

Mechanisms of resistance to chimeric antigen receptor-T cells in haematological malignancies

Chimeric antigen receptor (CAR)-T cells have recently emerged as a powerful therapeutic approach for the treatment of patients with chemotherapy-refractory or relapsed blood cancers, including acute lymphoblastic leukaemia, diffuse large B cell lymphoma, follicular lymphoma, mantle cell lymphoma and multiple myeloma. Nevertheless, resistance to CAR-T cell therapies occurs in most patients. In this Review, we summarize the resistance mechanisms to CAR-T cell immunotherapy by analysing CAR-T cell dysfunction, intrinsic tumour resistance and the immunosuppressive tumour microenvironment. We discuss current research strategies to overcome multiple resistance mechanisms, including optimization of the CAR design, improvement of in vivo T cell function and persistence, modulation of the immunosuppressive tumour microenvironment and synergistic combination strategies.

CAR-modified Cellular Therapies in Chronic Lymphocytic Leukemia: Is the Uphill Road Getting Less Steep?

The clinical development of chimeric antigen receptor (CAR) T-cell therapy has been more challenging for chronic lymphocytic leukemia (CLL) compared to other settings. One of the main reasons is the CLL-associated state of immune dysfunction that specifically involves patient-derived T cells. Here, we provide an overview of the clinical results obtained with CAR T-cell therapy in CLL, describing the identified immunologic reasons for the inferior efficacy. Novel CAR T-cell formulations, such as lisocabtagene maraleucel, administered alone or in combination with the Bruton tyrosine kinase inhibitor ibrutinib, are currently under investigation. These approaches are based on the rationale that improving the quality of the T-cell source and of the CAR T-cell product may deliver a more functional therapeutic weapon. Further strategies to boost the efficacy of CAR T cells should rely not only on the production of CAR T cells with an improved cellular composition but also on additional changes. Such alterations could include (1) the coadministration of immunomodulatory agents capable of counteracting CLL-related immunological alterations, (2) the design of improved CAR constructs (such as third- and fourth-generation CARs), (3) the incorporation into the manufacturing process of immunomodulatory compounds overcoming the T-cell defects, and (4) the use of allogeneic CAR T cells or alternative CAR-modified cellular vectors. These strategies may allow to develop more effective CAR-modified cellular therapies capable of counteracting the more aggressive and still incurable forms of CLL.

Chimeric Antigen Receptor T-cell Therapy for Chronic Lymphocytic Leukemia: What is the supporting evidence so far?

While acknowledging that newer therapies have improved survival rates in chronic lymphocytic leukemia (CLL), patients with high-risk disease features are at an increased risk of treatment failure. Allogeneic hematopoietic cell transplantation (allo-HCT) was traditionally offered as front-line consolidation in high-risk CLL; however, with the emergence of targeted therapies like Bruton tyrosine kinase (BTK) and B-cell lymphoma 2 (BCL-2) inhibitors, the role of allo-HCT has been relegated to later stages of the disease. Patients with relapsed/refractory (R/R) CLL who have failed both BTK and BCL-2 inhibitors represent a therapeutic challenge owing to a poor prognosis. Chimeric antigen receptor T-cell (CAR T) therapies targeting CD19 have improved response rates and overall survival in various types of R/R B-cell non-Hodgkin lymphomas. For CLL, no approved CAR T-cell therapies are yet available. Emerging data appear to show a therapeutic benefit of CAR T-cell therapy in patients with R/R CLL, even after failing an allo-HCT.

Factors associated with long-term outcomes of CD19 CAR T-cell therapy for relapsed/refractory CLL

High response rates have been reported after CD19-targeted chimeric antigen receptor-modified (CD19 CAR) T-cell therapy for relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL), yet the factors associated with duration of response in this setting are poorly characterized. We analyzed long-term outcomes in 47 patients with R/R CLL and/or Richter transformation treated on our phase 1/2 clinical trial of CD19 CAR T-cell therapy with an updated median follow-up of 79.6 months. Median progression-free survival (PFS) was 8.9 months, and the 6-year PFS was 17.8%. Maximum standardized uptake value (hazard ratio [HR], 1.15; 95% confidence interval [CI], 1.07-1.23; P < .001) and bulky disease (≥5 cm; HR, 2.12; 95% CI, 1.06-4.26; P = .034) before lymphodepletion were associated with shorter PFS. Day +28 complete response by positron emission tomography-computed tomography (HR, 0.13; 95% CI, 0.04-0.40; P < .001), day +28 measurable residual disease (MRD) negativity by multiparameter flow cytometry (HR, 0.08; 95% CI, 0.03-0.22; P < .001), day +28 MRD negativity by next-generation sequencing (HR, 0.21; 95% CI, 0.08-0.51; P < .001), higher peak CD8+ CAR T-cell expansion (HR, 0.49; 95% CI; 0.36-0.68; P < .001), higher peak CD4+ CAR T-cell expansion (HR, 0.47; 95% CI; 0.33-0.69; P < .001), and longer CAR T-cell persistence (HR, 0.56; 95% CI, 0.44-0.72; P < .001) were associated with longer PFS. The 6-year duration of response and overall survival were 26.4% and 31.2%, respectively. CD19 CAR T-cell therapy achieved durable responses with curative potential in a subset of patients with R/R CLL. This trial was registered at www.clinicaltrials.gov as #NCT01865617.

CAR-T Cell Therapy in the Treatment of Pediatric Non-Hodgkin Lymphoma

Non-Hodgkin lymphomas (NHL) are a group of cancers that originate in the lymphatic system, especially from progenitor or mature B-cells, T-cells, or natural killer (NK) cells. NHL is the most common hematological malignancy worldwide and also the fourth most frequent type of cancer among pediatric patients. This cancer can occur in children of any age, but it is quite rare under the age of 5 years. In recent decades, available medicines and therapies have significantly improved the prognosis of patients with this cancer. However, some cases of NHL are treatment resistant. For this reason, immunotherapy, as a more targeted and personalized treatment strategy, is becoming increasingly important in the treatment of NHL in pediatric patients. The objective of the following review is to gather the latest available research results, conducted among pediatric and/or adult patients with NHL, regarding one immunotherapy method, i.e., chimeric antigen receptor (CAR) T cell therapy. We focus on assessing the effectiveness of CAR-T cell therapy, which mainly targets B cell markers, CD19, CD20, and CD22, their connections with one another, sequential treatment, or connections with co-stimulatory molecules. In addition, we also evaluate the safety, aftermath (especially neurotoxicities) and limitations of CAR-T cell therapy.

Insights gained from single-cell analysis of chimeric antigen receptor T-cell immunotherapy in cancer

Advances in chimeric antigen receptor (CAR)-T cell therapy have significantly improved clinical outcomes of patients with relapsed or refractory hematologic malignancies. However, progress is still hindered as clinical benefit is only available for a fraction of patients. A lack of understanding of CAR-T cell behaviors in vivo at the single-cell level impedes their more extensive application in clinical practice. Mounting evidence suggests that single-cell sequencing techniques can help perfect the receptor design, guide gene-based T cell modification, and optimize the CAR-T manufacturing conditions, and all of them are essential for long-term immunosurveillance and more favorable clinical outcomes. The information generated by employing these methods also potentially informs our understanding of the numerous complex factors that dictate therapeutic efficacy and toxicities. In this review, we discuss the reasons why CAR-T immunotherapy fails in clinical practice and what this field has learned since the milestone of single-cell sequencing technologies. We further outline recent advances in the application of single-cell analyses in CAR-T immunotherapy. Specifically, we provide an overview of single-cell studies focusing on target antigens, CAR-transgene integration, and preclinical research and clinical applications, and then discuss how it will affect the future of CAR-T cell therapy.

Deletion of the inhibitory co-receptor CTLA-4 enhances and invigorates chimeric antigen receptor T cells

Chimeric antigen receptor (CAR) T cell therapy targeting CD19 has achieved tremendous success treating B cell malignancies; however, some patients fail to respond due to poor autologous T cell fitness. To improve response rates, we investigated whether disruption of the co-inhibitory receptors CTLA4 or PD-1 could restore CART function. CRISPR-Cas9-mediated deletion of CTLA4 in preclinical models of leukemia and myeloma improved CAR T cell proliferation and anti-tumor efficacy. Importantly, this effect was specific to CTLA4 and not seen upon deletion of CTLA4 and/or PDCD1 in CAR T cells. Mechanistically, CTLA4 deficiency permitted unopposed CD28 signaling and maintenance of CAR expression on the T cell surface under conditions of high antigen load. In clinical studies, deletion of CTLA4 rescued the function of T cells from patients with leukemia that previously failed CAR T cell treatment. Thus, selective deletion of CTLA4 reinvigorates dysfunctional chronic lymphocytic leukemia (CLL) patient T cells, providing a strategy for increasing patient responses to CAR T cell therapy.

Cellular Therapy in Chronic Lymphocytic Leukemia: Have We Advanced in the Last Decade?

BACKGROUND

Chronic lymphocytic leukemia (CLL) is a heterogeneous B-cell malignancy, affecting mainly older adults. Despite the recent introduction of multiple targeted agents, CLL remains an incurable disease. Cellular therapy is a promptly evolving area that has developed over the last decades from such standard of care as hematopoietic cell transplantation (HCT) to the novel treatment modalities employing genetically engineered immune cells.

SUMMARY

Tailoring the proper treatment for each patient is warranted and should take into account the disease biology, patient characteristics, and the available treatment modalities. Nowadays, the most broadly applied cellular therapies for CLL management are HCT and chimeric antigen receptor-T (CAR-T) cells. However, CAR-T cell therapy is currently not yet approved in CLL, and the appropriate sequencing for the administration of these agents remains to be clarified.

KEY MESSAGES

The current review will discuss various available cellular treatment options, their advances and limitations, as well as the optimal timing for the employment of such therapies in CLL patients.

Clinical development of chimeric antigen receptor-T cell therapy for hematological malignancies

ABSTRACT

Cellular therapies have revolutionized the treatment of hematological malignancies since their conception and rapid development. Chimeric antigen receptor (CAR)-T cell therapy is the most widely applied cellular therapy. Since the Food and Drug Administration approved two CD19-CAR-T products for clinical treatment of relapsed/refractory acute lymphoblastic leukemia and diffuse large B cell lymphoma in 2017, five more CAR-T cell products were subsequently approved for treating multiple myeloma or B cell malignancies. Moreover, clinical trials of CAR-T cell therapy for treating other hematological malignancies are ongoing. Both China and the United States have contributed significantly to the development of clinical trials. However, CAR-T cell therapy has many limitations such as a high relapse rate, adverse side effects, and restricted availability. Various methods are being implemented in clinical trials to address these issues, some of which have demonstrated promising breakthroughs. This review summarizes developments in CAR-T cell trials and advances in CAR-T cell therapy.

Relapsed/Refractory Chronic Lymphocytic Leukemia (CLL)

PURPOSE OF REVIEW

There have been significant advances in the treatment of relapsed/refractory chronic lymphocytic leukemia (CLL) over the past two decades. However, the intention of treatment remains control of the disease and delay of progression rather than a cure which remains largely elusive. Considering that CLL is mostly seen in older patients, there are multiple factors that play a role in the selection of CLL beyond the frontline treatment. Here, we review the concept of relapsed CLL, factors that predispose to relapse, and therapeutic options available to this patient population. We also review investigational therapies and provide a framework for selection of therapies in this setting.

RECENT FINDINGS

Targeted therapies with continuous BTK inhibitors (BTKi) or fixed duration venetoclax plus anti-CD20 monoclonal antibody therapy have established superiority over chemoimmunotherapy in relapsed CLL and have become the preferred standard of care treatment. The second-generation more selective BTK inhibitors (acalabrutinib and zanubrutinib) have shown improved safety profile compared to ibrutinib. However, resistance to the covalent BTK inhibitors may emerge and is commonly associated with mutations in BTK or other downstream enzymes. The novel non-covalent BTK inhibitors such as pirtobrutinib (Loxo-305) and nemtabrutinib (ARQ 531) are showing promising activities for relapsed CLL refractory to prior covalent BTKi. Other novel therapies such as chimeric antigen receptor (CAR) T cell therapy have also shown significant activities for relapsed and refractory CLL. Measurable residual disease (MRD) assessment has a growing importance in venetoclax-based limited-duration therapy and there is mounting evidence that MRD negativity improves outcomes. However, it remains to be seen if this will become an established clinically significant endpoint. Further, the optimal sequence of various treatment options remains to be determined. Patients with relapsed CLL now have more options for the treatment of the disease. The choice of therapy is best individualized especially in the absence of direct comparisons of targeted therapies, and the coming years will bring more data on the best sequence of use of the therapeutic agents.

Updated Indications for Immune Effector Cell Therapy: 2023 Guidelines from the American Society for Transplantation and Cellular Therapy

The American Society for Transplantation and Cellular Therapy (ASTCT) published its guidelines on indications for autologous and allogeneic hematopoietic cell transplantation (HCT) and immune effector cell therapy (IECT) in 2020. Since then, we have witnessed rapid advancements in the field of IECT, resulting in several new chimeric antigen receptor T cell (CAR-T) products and disease indications being approved by the US Food and Drug Administration (FDA). To keep abreast of these practice changes, the ASTCT Committee on Practice Guidelines commissioned a focused update covering CAR-T therapy indications. Here we present updated ASTCT recommendations on indications for CAR-T therapy. Only FDA-approved indications for CAR-T were recommended and categorized as "standard of care," where the indication is well defined and supported by evidence. The ASTCT will continue to periodically review these guidelines and update them as new evidence becomes available.

Final analysis of the CLL2-GIVe trial: obinutuzumab, ibrutinib, and venetoclax for untreated CLL with del(17p)/TP53mut

The final analysis of the open-label, multicenter phase 2 CLL2-GIVe trial shows response and tolerability of the triple combination of obinutuzumab, ibrutinib, and venetoclax (GIVe regimen) in 41 previously untreated patients with high-risk chronic lymphocytic leukemia (CLL) with del(17p) and/or TP53 mutation. Induction consisted of 6 cycles of GIVe; venetoclax and ibrutinib were continued up to cycle 12 as consolidation. Ibrutinib was given until cycle 15 or up to cycle 36 in patients not achieving a complete response and with detectable minimal residual disease. The primary end point was the complete remission rate at cycle 15, which was achieved at 58.5% (95% CI, 42.1-73.7; P < .001). The last patient reached the end of the study in January 2022. After a median observation time of 38.4 months (range, 3.7-44.9), the 36-month progression-free survival was 79.9%, and the 36-month overall survival was 92.6%. Only 6 patients continued ibrutinib maintenance. Adverse events of concern were neutropenia (48.8%, grade ≥3) and infections (19.5%, grade ≥3). Cardiovascular toxicity grade 3 occurred as atrial fibrillation at a rate of 2.4% between cycles 1 and 12, as well as hypertension (4.9%) between cycles 1 and 6. The incidence of adverse events of any grade and grade ≥3 was highest during induction and decreased over time. Progressive disease was observed in 7 patients between cycles 27 and 42. In conclusion, the CLL2-GIVe regimen is a promising fixed-duration, first-line treatment for patients with high-risk CLL with a manageable safety profile.

Promises and challenges of a decentralized CAR T-cell manufacturing model

Autologous chimeric antigen receptor-modified T-cell (CAR T) products have demonstrated un-precedent efficacy in treating many relapsed/refractory B-cell and plasma cell malignancies, leading to multiple commercial products now in routine clinical use. These positive responses to CAR T therapy have spurred biotech and big pharma companies to evaluate innovative production methods to increase patient access while maintaining adequate quality control and profitability. Autologous cellular therapies are, by definition, manufactured as single patient batches, and demand has soared for manufacturing facilities compliant with current Good Manufacturing Practice (cGMP) regulations. The use of a centralized production model is straining finite resources even in developed countries in North America and the European Union, and patient access is not feasible for most of the developing world. The idea of having a more uniform availability of these cell therapy products promoted the concept of point-of-care (POC) manufacturing or decentralized in-house production. While this strategy can potentially decrease the cost of manufacturing, the challenge comes in maintaining the same quality as currently available centrally manufactured products due to the lack of standardized manufacturing techniques amongst institutions. However, academic medical institutions and biotech companies alike have forged ahead innovating and adopting new technologies to launch clinical trials of CAR T products produced exclusively in-house. Here we discuss POC production of CAR T products.

Lisocabtagene maraleucel in chronic lymphocytic leukaemia and small lymphocytic lymphoma (TRANSCEND CLL 004): a multicentre, open-label, single-arm, phase 1-2 study

BACKGROUND

Patients with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma for whom treatment has failed with both Bruton tyrosine kinase (BTK) inhibitor and venetoclax have few treatment options and poor outcomes. We aimed to evaluate the efficacy and safety of lisocabtagene maraleucel (liso-cel) at the recommended phase 2 dose in patients with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma.

METHODS

We report the primary analysis of TRANSCEND CLL 004, an open-label, single-arm, phase 1-2 study conducted in the USA. Patients aged 18 years or older with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma and at least two previous lines of therapy, including a BTK inhibitor, received an intravenous infusion of liso-cel at one of two target dose levels: 50 × 106 (dose level 1) or 100 × 106 (dose level 2, DL2) chimeric antigen receptor-positive T cells. The primary endpoint was complete response or remission (including with incomplete marrow recovery), assessed by independent review according to the 2018 International Workshop on Chronic Lymphocytic Leukemia criteria, in efficacy-evaluable patients with previous BTK inhibitor progression and venetoclax failure (the primary efficacy analysis set) at DL2 (null hypothesis of ≤5%). This trial is registered with ClinicalTrials.gov, NCT03331198.

FINDINGS

Between Jan 2, 2018, and June 16, 2022, 137 enrolled patients underwent leukapheresis at 27 sites in the USA. 117 patients received liso-cel (median age 65 years [IQR 59-70]; 37 [32%] female and 80 [68%] male; 99 [85%] White, five [4%] Black or African American, two [2%] other races, and 11 [9%] unknown race; median of five previous lines of therapy [IQR 3-7]); all 117 participants had received and had treatment failure on a previous BTK inhibitor. A subset of patients had also experienced venetoclax failure (n=70). In the primary efficacy analysis set at DL2 (n=49), the rate of complete response or remission (including with incomplete marrow recovery) was statistically significant at 18% (n=9; 95% CI 9-32; p=0·0006). In patients treated with liso-cel, grade 3 cytokine release syndrome was reported in ten (9%) of 117 (with no grade 4 or 5 events) and grade 3 neurological events were reported in 21 (18%; one [1%] grade 4, no grade 5 events). Among 51 deaths on the study, 43 occurred after liso-cel infusion, of which five were due to treatment-emergent adverse events (within 90 days of liso-cel infusion). One death was related to liso-cel (macrophage activation syndrome-haemophagocytic lymphohistiocytosis).

INTERPRETATION

A single infusion of liso-cel was shown to induce complete response or remission (including with incomplete marrow recovery) in patients with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma, including patients who had experienced disease progression on a previous BTK inhibitor and venetoclax failure. The safety profile was manageable.

FUNDING

Juno Therapeutics, a Bristol-Myers Squibb Company.

Immunotherapy in hematologic malignancies: achievements, challenges and future prospects

The immune-cell origin of hematologic malignancies provides a unique avenue for the understanding of both the mechanisms of immune responsiveness and immune escape, which has accelerated the progress of immunotherapy. Several categories of immunotherapies have been developed and are being further evaluated in clinical trials for the treatment of blood cancers, including stem cell transplantation, immune checkpoint inhibitors, antigen-targeted antibodies, antibody-drug conjugates, tumor vaccines, and adoptive cell therapies. These immunotherapies have shown the potential to induce long-term remission in refractory or relapsed patients and have led to a paradigm shift in cancer treatment with great clinical success. Different immunotherapeutic approaches have their advantages but also shortcomings that need to be addressed. To provide clinicians with timely information on these revolutionary therapeutic approaches, the comprehensive review provides historical perspectives on the applications and clinical considerations of the immunotherapy. Here, we first outline the recent advances that have been made in the understanding of the various categories of immunotherapies in the treatment of hematologic malignancies. We further discuss the specific mechanisms of action, summarize the clinical trials and outcomes of immunotherapies in hematologic malignancies, as well as the adverse effects and toxicity management and then provide novel insights into challenges and future directions.

Non-Covalent Bruton's Tyrosine Kinase Inhibitors in the Treatment of Chronic Lymphocytic Leukemia

Covalent Bruton's tyrosine kinase inhibitors (cBTKi) have led to a paradigm shift in the treatment of chronic lymphocytic leukemia (CLL). These targeted oral therapies are administered as standard treatments in both the front-line and relapsed and/or refractory settings. Given their administration as a continuous therapy with a "treat-to-progression" strategy, limitations of their use include discontinuation due to toxicity or from progression of the disease. Non-covalent Bruton's tyrosine kinase inhibitors (ncBTKi) distinguish themselves by binding reversibly to the BTK target, which may address the limitations of toxicity and acquired resistance seen with cBTKi. Several ncBTKis have been studied preclinically and in clinical trials, including pirtobrutinib and nemtabrutinib. Pirtobrutinib, which is now FDA approved for relapsed and/or refractory mantle cell lymphoma (MCL), has shown outstanding safety and preliminary efficacy in CLL in phase 1 and 2 clinical trials, with phase 3 trials underway. This agent may fill an unmet medical need for CLL patients requiring treatment after a cBTKi. Pirtobrutinib is particularly promising for the treatment of "double exposed" CLL, defined as CLL requiring treatment after both a cBTKi and venetoclax. Some patients have now developedacquired resistance to pirtobrutinib, and resistance mechanisms (including novel acquired mutations in BTK outside of the C481 position) have been recently described. Further study regarding the mechanisms of resistance to pirtobrutinib in patients without prior cBTKi exposure, as well as the potential for cross-resistance between cBTKi and ncBTKis, may be important to help inform where ncBTKis will ultimately fit in the treatment sequencing paradigm for CLL. An emerging clinical challenge is the treatment of CLL after ncBTKi discontinuation. Novel therapeutic strategies are being investigated to address the treatment of patients following disease progression on ncBTKis. Such strategies include novel agents (BTK degraders, bispecific antibody therapy, CAR T-cell therapy, PKC-beta inhibitors) as well as combination approaches incorporating a ncBTKi (e.g., pirtobrutinib and venetoclax) that may help overcome this acquired resistance.

Long-term outcomes following CAR T cell therapy: what we know so far

Chimeric antigen receptors (CAR) are engineered fusion proteins designed to target T cells to antigens expressed on cancer cells. CAR T cells are now an established treatment for patients with relapsed and/or refractory B cell lymphomas, B cell acute lymphoblastic leukaemia and multiple myeloma. At the time of this writing, over a decade of follow-up data are available from the initial patients who received CD19-targeted CAR T cells for B cell malignancies. Data on the outcomes of patients who received B cell maturation antigen (BCMA)-targeted CAR T cells for multiple myeloma are more limited owing to the more recent development of these constructs. In this Review, we summarize long-term follow-up data on efficacy and toxicities from patients treated with CAR T cells targeting CD19 or BCMA. Overall, the data demonstrate that CD19-targeted CAR T cells can induce prolonged remissions in patients with B cell malignancies, often with minimal long-term toxicities, and are probably curative for a subset of patients. By contrast, remissions induced by BCMA-targeted CAR T cells are typically more short-lived but also generally have only limited long-term toxicities. We discuss factors associated with long-term remissions, including the depth of initial response, malignancy characteristics predictive of response, peak circulating CAR levels and the role of lymphodepleting chemotherapy. We also discuss ongoing investigational strategies designed to improve the length of remission following CAR T cell therapy.

SOHO State of the Art Updates and Next Questions: New Targetable Pathways in Chronic Lymphocytic Leukemia

Regulatory approvals of Bruton tyrosine kinase (BTK) inhibitors and BCL2 inhibitors have transformed the therapeutic paradigm in chronic lymphocytic leukemia (CLL). However, despite significant improvement, treatment discontinuations due to an acquired resistance mutation or intolerance to these agents are common. Those who are refractory and/or intolerant to both these classes of drugs - the "double exposed/refractory" patients - pose a real challenge in clinical practice and are in dire need of novel therapeutic approaches. In this manuscript, we review the ongoing efforts addressing this unmet clinical need including the ongoing development of non-covalent BTK inhibitors, BTK degraders, novel BH3-mimetics, therapeutic antibodies targeting novel antigens and immune cell enabling therapies.

Diagnosis and Treatment of Chronic Lymphocytic Leukemia: A Review

IMPORTANCE

Chronic lymphocytic leukemia (CLL), defined by a minimum of 5 × 109/L monoclonal B cells in the blood, affects more than 200 000 people and is associated with approximately 4410 deaths in the US annually. CLL is associated with an immunocompromised state and an increased rate of complications from infections.

OBSERVATIONS

At the time of diagnosis, the median age of patients with CLL is 70 years, and an estimated 95% of patients have at least 1 medical comorbidity. Approximately 70% to 80% of patients with CLL are asymptomatic at the time of diagnosis, and one-third will never require treatment for CLL. Prognostic models have been developed to estimate the time to first treatment and the overall survival, but for patients who are asymptomatic, irrespective of disease risk category, clinical observation is the standard of care. Patients with symptomatic disease who have bulky or progressive lymphadenopathy or hepatosplenomegaly and those with a low neutrophil count, anemia, or thrombocytopenia and/or symptoms of fever, drenching night sweats, and weight loss (B symptoms) should be offered treatment. For these patients, first-line treatment consists of a regimen containing either a covalent Bruton tyrosine kinase (BTK) inhibitor (acalabrutinib, zanubrutinib, or ibrutinib) or a B-cell leukemia/lymphoma 2 (BCL2) inhibitor (venetoclax). There is no evidence that starting either class before the other improves outcomes. The covalent BTK inhibitors are typically used indefinitely. Survival rates are approximately 88% at 4 years for acalabrutinib, 94% at 2 years for zanubrutinib, and 78% at 7 years for ibrutinib. Venetoclax is prescribed in combination with obinutuzumab, a monoclonal anti-CD20 antibody, in first-line treatment for 1 year (overall survival, 82% at 5-year follow-up). A noncovalent BTK inhibitor, pitobrutinib, has shown an overall response rate of more than 70% after failure of covalent BTK inhibitors and venetoclax. Phosphoinositide 3'-kinase (PI3K) inhibitors (idelalisib and duvelisib) can be prescribed for disease that progresses with BTK inhibitors and venetoclax, but patients require close monitoring for adverse events such as autoimmune conditions and infections. In patients with multiple relapses, chimeric antigen receptor T-cell (CAR-T) therapy with lisocabtagene maraleucel was associated with a 45% complete response rate. The only potential cure for CLL is allogeneic hematopoietic cell transplant, which remains an option after use of targeted agents.

CONCLUSIONS AND RELEVANCE

More than 200 000 people in the US are living with a CLL diagnosis, and CLL causes approximately 4410 deaths each year in the US. Approximately two-thirds of patients eventually need treatment. Highly effective novel targeted agents include BTK inhibitors such as acalabrutinib, zanubrutinib, ibrutinib, and pirtobrutinib or BCL2 inhibitors such as venetoclax.

Cellular Therapies in Chronic Lymphocytic Leukemia and Richter’s Transformation: Recent Developments in Chimeric Antigen Receptor T-Cells, Natural Killer Cells, and Allogeneic Stem Cell Transplant

Cellular therapies can be viewed as both the newest and oldest techniques for treating chronic lymphocytic leukemia (CLL) and Richter’s transformation (RT). On one hand, allogeneic hematopoietic stem cell transplantation (alloHSCT) has been available for decades, though its use is diminishing with the increasing availability of effective novel targeted agents, especially in CLL. Among newer techniques, chimeric antigen receptor T-cells (CAR-T) have demonstrated astounding efficacy in several hematologic malignancies, leading to FDA approval and use in clinical practice. However, though CLL is the earliest disease type for which CAR-T were studied, development has been slower and has yet to lead to regulatory approval. Owing partially to its rarity but also due to the aggressive behavior of RT, CAR-T in RT have only been minimally explored. Here, we will focus on the applications of cellular therapies in CLL and RT, specifically reviewing more recent data related to alloHSCT in the novel-agent era and CAR-T cell development in CLL/RT, focusing on safety and efficacy successes and limitations. We will review strategies to improve upon CAR-T efficacy and discuss ongoing trials utilizing CAR-T in CLL/RT, as well as emerging technologies, such as allogeneic CAR-T and natural killer CAR (CAR NK) cells.

Emerging Therapies in CLL in the Era of Precision Medicine

Over the past decade, the treatment landscape of CLL has vastly changed from the conventional FC (fludarabine and cyclophosphamide) and FCR (FC with rituximab) chemotherapies to targeted therapies, including inhibitors of Bruton tyrosine kinase (BTK) and phosphatidylinositol 3-kinase (PI3K) as well as inhibitors of BCL2. These treatment options dramatically improved clinical outcomes; however, not all patients respond well to these therapies, especially high-risk patients. Clinical trials of immune checkpoint inhibitors (PD-1, CTLA4) and chimeric antigen receptor T (CAR T) or NK (CAR NK) cell treatment have shown some efficacy; still, long-term outcomes and safety issues have yet to be determined. CLL remains an incurable disease. Thus, there are unmet needs to discover new molecular pathways with targeted or combination therapies to cure the disease. Large-scale genome-wide whole-exome and whole-genome sequencing studies have discovered genetic alterations associated with disease progression, refined the prognostic markers in CLL, identified mutations underlying drug resistance, and pointed out critical targets to treat the disease. More recently, transcriptome and proteome landscape characterization further stratified the disease and revealed novel therapeutic targets in CLL. In this review, we briefly summarize the past and present available single or combination therapies, focusing on potential emerging therapies to address the unmet clinical needs in CLL.

Chronic lymphocytic leukemia presence impairs antigen-specific CD8+ T-cell responses through epigenetic reprogramming towards short-lived effectors

T-cell dysregulation in chronic lymphocytic leukemia (CLL) associates with low response rates to autologous T cell-based therapies. How CLL affects antigen-specific T-cell responses remains largely unknown. We investigated (epi)genetic and functional consequences of antigen-specific T-cell responses in presence of CLL in vitro and in an adoptive-transfer murine model. Already at steady-state, antigen-experienced patient-derived T cells were skewed towards short-lived effector cells (SLEC) at the expense of memory-precursor effector cells (MPEC). Stimulation of these T cells in vitro showed rapid induction of effector genes and suppression of key memory transcription factors only in presence of CLL cells, indicating epigenetic regulation. This was investigated in vivo by following antigen-specific responses of naïve OT-I CD8⁺ cells to mCMV-OVA in presence/absence of TCL1 B-cell leukemia. Presence of leukemia resulted in increased SLEC formation, with disturbed inflammatory cytokine production. Chromatin and transcriptome profiling revealed strong epigenetic modifications, leading to activation of an effector and silencing of a memory profile through presence of CLL cells. Secondary challenge in vivo confirmed dysfunctional memory responses by antigen-experienced OT-I cells generated in presence of CLL. Altogether, we show that presence of CLL induces a short-lived effector phenotype and impaired memory responses by epigenetic reprogramming during primary responses.

Challenges and opportunities of CAR T cell therapies for CLL

Chimeric antigen receptor (CAR) T-cell therapies have transformed the treatment landscape of blood cancers. These engineered receptors which endow T cells with antibody-like target cell recognition combined with the typical T cell target cell lysis abilities. Introduced into the clinic in the 2010s, CAR T-cells have shown efficacy in chronic B lymphocytic leukemia (CLL), but a majority of patients do not achieve sustained remission. Here we discuss the current treatment landscape in CLL using small molecules and allogeneic stem cell transplantation, the niche CAR T-cells filled in this context, and what we have learned from biomarker and mechanistic studies. Several product parameters and improvements are introduced as examples of how the bedside-to-bench is translated into improved CAR T-cells for CLL. We hope to convey to our readers the crucial role translational medicine plays in transforming the treatment outcomes for patients with CLL and how this line of research is an essential component of modern medicine.

The role of allogeneic hematopoietic cell transplantation for chronic lymphocytic leukemia: A review

Although the use of allogeneic hematopoietic cell transplantation (HCT) for chronic lymphocytic leukemia (CLL) has declined with the development of novel targeted agents, it continues to play an important role for eligible patients with high-risk or heavily pretreated CLL who lack other treatment options. CLL is susceptible to a potent graft-versus-leukemia (GVL) effect which produces long-lasting remissions in 30-50% of transplanted patients. While allogeneic HCT is associated with significant risks of graft-versus-host disease (GVHD), infection, and non-relapse mortality (NRM), improvements in patient and donor selection, reduced intensity conditioning (RIC), GVHD prophylaxis, and supportive care have rendered this an increasingly safe and effective procedure in the current era. In this review, we discuss recent advances in allogeneic HCT for CLL, with a focus on the optimal evidence-based strategies to maximize benefit and minimize toxicity of this potentially curative cellular therapy.

Radiotherapy as a means to increase the efficacy of T-cell therapy in solid tumors

Chimeric antigen receptor (CAR)-T cells have demonstrated significant improvements in the treatment of refractory B-cell malignancies that previously showed limited survival. In contrast, early-phase clinical studies targeting solid tumors have been disappointing. This may be due to both a lack of specific and homogeneously expressed targets at the surface of tumor cells, as well as intrinsic properties of the solid tumor microenvironment that limit homing and activation of adoptive T cells. Faced with these antagonistic conditions, radiotherapy (RT) has the potential to change the overall tumor landscape, from depleting tumor cells to reshaping the tumor microenvironment. In this article, we describe the current landscape and discuss how RT may play a pivotal role for enhancing the efficacy of adoptive T-cell therapies in solid tumors. Indeed, by improving homing, expansion and activation of infused T cells while reducing tumor volume and heterogeneity, the use of RT could help the implementation of engineered T cells in the treatment of solid tumors.

Novel therapies and combinations in CLL refractory to BTK inhibitors and venetoclax

Patients with chronic lymphocytic leukemia (CLL) refractory to covalent BTK and BCL2 inhibitors have a new unmet clinical need. Standard treatment options are able to obtain only limited and short-lasting disease control associated with reduced overall survival, and thus these patients have become ideal candidates for enrollment in clinical trials. Favorable results have been obtained with the use of noncovalent BTK inhibitors (roughly 70% overall response rate regardless of the actual resistance or intolerance to previous covalent BTK inhibitors) and anti-CD19 chimeric antigen receptor (CAR) T-cell therapy (with complete responses in up to 45% of cases and an undetectable measurable residual disease rate of 65% in the bone marrow). These 2 approaches should be considered valid options in this setting, although not yet approved. For young fit patients achieving remissions with salvage treatments, the option of allogeneic stem cell transplantation should be discussed as the outcome appears to be unaffected by number and type of previous targeted agents. Novel treatment strategies interfering with different mechanisms of CLL cell survival and proliferation are warranted, including small molecules with novel targets (eg, CDK9, MCL1, ERK inhibitors), CAR T cells targeting different antigens, CAR natural killer cells, or bispecific antibodies.

Current Status of Novel Agents for the Treatment of B Cell Malignancies: What's Coming Next?

Resistance to death is one of the hallmarks of human B cell malignancies and often contributes to the lack of a lasting response to today's commonly used treatments. Drug discovery approaches designed to activate the death machinery have generated a large number of inhibitors of anti-apoptotic proteins from the B-cell lymphoma/leukemia 2 family and the B-cell receptor (BCR) signaling pathway. Orally administered small-molecule inhibitors of Bcl-2 protein and BCR partners (e.g., Bruton's tyrosine kinase and phosphatidylinositol-3 kinase) have already been included (as monotherapies or combination therapies) in the standard of care for selected B cell malignancies. Agonistic monoclonal antibodies and their derivatives (antibody-drug conjugates, antibody-radioisotope conjugates, bispecific T cell engagers, and chimeric antigen receptor-modified T cells) targeting tumor-associated antigens (TAAs, such as CD19, CD20, CD22, and CD38) are indicated for treatment (as monotherapies or combination therapies) of patients with B cell tumors. However, given that some patients are either refractory to current therapies or relapse after treatment, novel therapeutic strategies are needed. Here, we review current strategies for managing B cell malignancies, with a focus on the ongoing clinical development of more effective, selective drugs targeting these molecules, as well as other TAAs and signaling proteins. The observed impact of metabolic reprogramming on B cell pathophysiology highlights the promise of targeting metabolic checkpoints in the treatment of these disorders.

Cytopenias following anti-CD19 chimeric antigen receptor (CAR) T cell therapy: a systematic analysis for contributing factors

BACKGROUND

Cytopenia is one of the most common adverse events following the CAR-T cell infusion, affecting the quality of life and potentially leading to life-threatening bleeding and infection. This study aimed to systematically review the cytopenias following anti-CD19 CAR-T therapy and further analyse the contributing factors.

METHODS

Databases including PubMed, MEDLINE, Embase and Cochrane were systematically searched on 8 May 2022. A random-effect meta-analysis was used to estimate the incidence of cytopenia, and subgroup analyses were applied to explore heterogeneity.

RESULTS

A total of 68 studies involving 2950 patients were included in this study. The overall incidence of all grade anaemia, thrombocytopenia, neutropenia, leukopoenia, lymphocytopenia and febrile neutropenia was 65%, 55%, 78%, 62%, 70% and 27%, respectively, and the corresponding cytopenias of grade 3 or worse were 33%, 31%, 61%, 45%, 46%, and 21%, respectively. Subgroup analysis showed increased incidence of cytopenias in subgroups with lower median age, proportion of males (<65%) and proportion of bridging therapy (<80%) and in the subgroup with a median line of prior therapy ≥3. In terms of disease and therapeutic target, cytopenias were more frequent in ALL patients and in dual-target CAR-T therapies (targeting CD19 in combination with other targets). Furthermore, CAR-T products manufactured by lentiviral vectors and those with the costimulatory domain of CD28 were more likely to cause haematological toxicity. No significant differences were observed in cytopenia between patients treated with CAR-T products with murine and humanized scFv.

CONCLUSION

In conclusion, neutropenia is the most frequent cytopenia after CAR-T therapy, both in all grades or grade ≥3. The incidence of cytopenias following CAR-T therapy is influenced by the age, sex, disease and number of prior therapy lines of the patients, as well as the target and costimulatory domain of CAR-T cells, and viral vectors used for manufacturing.KEY MESSAGESNeutropenia is the most frequent cytopenia after CAR-T therapy.The clinical characteristics of the patients, the design of CAR-T cells and the protocol of CAR-T treatment can influence the occurrence of cytopenias following the CAR-T therapy.