CAR T cells with dual targeting of CD19 and CD22 in adult patients with recurrent or refractory B cell malignancies: a phase 1 trial

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

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

Dual targeting of CD19 and CD22 with bicistronic CAR-T cells in patients with relapsed/refractory large B-cell lymphoma

Relapse after CD19-directed chimeric antigen receptor T-cell (CAR-T) therapy for large B-cell lymphoma (LBCL) is commonly ascribed to antigen loss or CAR-T exhaustion. Multiantigen targeting and programmed cell death protein-1 blockade are rational approaches to prevent relapse. Here, we test CD19/22 dual-targeting CAR-T (AUTO3) plus pembrolizumab in relapsed/refractory LBCL (NCT03289455). End points include toxicity (primary) and response rates (secondary). Fifty-two patients received AUTO3 and 48/52 received pembrolizumab. Median age was 59 years (range, 27-83), 46/52 had stage III/ IV disease and median follow-up was 21.6 months. AUTO3 was safe; grade 1-2 and grade 3 cytokine release syndrome affected 18/52 (34.6%) and 1/52 (1.9%) patients, neurotoxicity arose in 4 patients (2/4, grade 3-4), and hemophagocytic lymphohistiocytosis affected 2 patients. Outpatient administration was tested in 20 patients, saving a median of 14 hospital days per patient. Overall response rates were 66% (48.9%, complete response [CR]; 17%, partial response). Median duration of remission (DOR) for CR patients was not reached and for all responding patients was 8.3 months (95% confidence interval [CI]: 3.0-not evaluable). 54.4% (CI: 32.8-71.7) of CR patients and 42.6% of all responding patients were projected to remain progression-free at ≥12 months. AUTO3 ± pembrolizumab for relapsed/refractory LBCL was safe and delivered durable remissions in 54.4% of complete responders, associated with robust CAR-T expansion. Neither dual-targeting CAR-T nor pembrolizumab prevented relapse in a significant proportion of patients, and future developments include next-generation-AUTO3, engineered for superior expansion in vivo, and selection of CAR binders active at low antigen densities.

An Fc Binding Peptide-Based Facile and Versatile Build Platform for Multispecific Antibodies

Multispecific antibodies (MsAbs) maintain the specificity of versatile antibodies while simultaneously addressing different epitopes for a cumulative, collaborative effect. They could be an alternative treatment to chimeric antigen receptor-T cell therapy by helping to redirect T cells to tumors in vivo. However, one major limitation of their development is their relatively complex production process, which involves performance of a massive screen with low yield, inconsistent quality, and nonnegligible impurities. Here, a poly(l-glutamic acid)-conjugated multiple Fc binding peptide-based synthesis nanoplatform was proposed, in which MsAbs were constructed by mixing the desired monoclonal antibodies (mAbs) with polymeric Fc binding peptides in aqueous solution without purification. To determine its efficacy, a dual immune checkpoint-based PD1/OX40 bispecific antibody and PDL1/CD3e/4-1BB trispecific antibody-based T cell engager were generated to trigger antitumor CD8⁺ T responses in mice, showing superior tumor suppression over free mixed mAbs. In this study, a facile, versatile build platform for MsAbs was established.

Activation priming and cytokine polyfunctionality modulate the enhanced functionality of low-affinity CD19 CAR T cells

We recently described a low-affinity second-generation CD19 chimeric antigen receptor (CAR) CAT that showed enhanced expansion, cytotoxicity, and antitumor efficacy compared with the high-affinity (FMC63-based) CAR used in tisagenlecleucel, in preclinical models. Furthermore, CAT demonstrated an excellent toxicity profile, enhanced in vivo expansion, and long-term persistence in a phase 1 clinical study. To understand the molecular mechanisms behind these properties of CAT CAR T cells, we performed a systematic in vitro characterization of the transcriptomic (RNA sequencing) and protein (cytometry by time of flight) changes occurring in T cells expressing low-affinity vs high-affinity CD19 CARs following stimulation with CD19-expressing cells. Our results show that CAT CAR T cells exhibit enhanced activation to CD19 stimulation and a distinct transcriptomic and protein profile, with increased activation and cytokine polyfunctionality compared with FMC63 CAR T cells. We demonstrate that the enhanced functionality of low-affinity CAT CAR T cells is a consequence of an antigen-dependent priming induced by residual CD19-expressing B cells present in the manufacture.

Advancements in CAR-NK therapy: lessons to be learned from CAR-T therapy

Advancements in chimeric antigen receptor engineered T-cell (CAR-T) therapy have revolutionized treatment for several cancer types over the past decade. Despite this success, obstacles including the high price tag, manufacturing complexity, and treatment-associated toxicities have limited the broad application of this therapy. Chimeric antigen receptor engineered natural killer cell (CAR-NK) therapy offers a potential opportunity for a simpler and more affordable "off-the-shelf" treatment, likely with fewer toxicities. Unlike CAR-T, CAR-NK therapies are still in early development, with few clinical trials yet reported. Given the challenges experienced through the development of CAR-T therapies, this review explores what lessons we can apply to build better CAR-NK therapies. In particular, we explore the importance of optimizing the immunochemical properties of the CAR construct, understanding factors leading to cell product persistence, enhancing trafficking of transferred cells to the tumor, ensuring the metabolic fitness of the transferred product, and strategies to avoid tumor escape through antigen loss. We also review trogocytosis, an important emerging challenge that likely equally applies to CAR-T and CAR-NK cells. Finally, we discuss how these limitations are already being addressed in CAR-NK therapies, and what future directions may be possible.

Bispecific antibodies redirect synthetic agonistic receptor modified T cells against melanoma

BACKGROUND

Melanoma is an immune sensitive disease, as demonstrated by the activity of immune check point blockade (ICB), but many patients will either not respond or relapse. More recently, tumor infiltrating lymphocyte (TIL) therapy has shown promising efficacy in melanoma treatment after ICB failure, indicating the potential of cellular therapies. However, TIL treatment comes with manufacturing limitations, product heterogeneity, as well as toxicity problems, due to the transfer of a large number of phenotypically diverse T cells. To overcome said limitations, we propose a controlled adoptive cell therapy approach, where T cells are armed with synthetic agonistic receptors (SAR) that are selectively activated by bispecific antibodies (BiAb) targeting SAR and melanoma-associated antigens.

METHODS

Human as well as murine SAR constructs were generated and transduced into primary T cells. The approach was validated in murine, human and patient-derived cancer models expressing the melanoma-associated target antigens tyrosinase-related protein 1 (TYRP1) and melanoma-associated chondroitin sulfate proteoglycan (MCSP) (CSPG4). SAR T cells were functionally characterized by assessing their specific stimulation and proliferation, as well as their tumor-directed cytotoxicity, in vitro and in vivo.

RESULTS

MCSP and TYRP1 expression was conserved in samples of patients with treated as well as untreated melanoma, supporting their use as melanoma-target antigens. The presence of target cells and anti-TYRP1 × anti-SAR or anti-MCSP × anti-SAR BiAb induced conditional antigen-dependent activation, proliferation of SAR T cells and targeted tumor cell lysis in all tested models. In vivo, antitumoral activity and long-term survival was mediated by the co-administration of SAR T cells and BiAb in a syngeneic tumor model and was further validated in several xenograft models, including a patient-derived xenograft model.

CONCLUSION

The SAR T cell-BiAb approach delivers specific and conditional T cell activation as well as targeted tumor cell lysis in melanoma models. Modularity is a key feature for targeting melanoma and is fundamental towards personalized immunotherapies encompassing cancer heterogeneity. Because antigen expression may vary in primary melanoma tissues, we propose that a dual approach targeting two tumor-associated antigens, either simultaneously or sequentially, could avoid issues of antigen heterogeneity and deliver therapeutic benefit to patients.

Which one is better for refractory/relapsed acute B-cell lymphoblastic leukemia: Single-target (CD19) or dual-target (tandem or sequential CD19/CD22) CAR T-cell therapy?

CD19 chimeric antigen receptor (CAR) T-cell therapy has shown great success against B-cell acute lymphoblastic leukemia (B-ALL). Tandem and sequential CD19/CD22 dual-target CAR T-cell therapies have been developed to reduce the possibility of CD19-negative relapse; however, the superior strategy is still uncertain. This study screened 219 patients with relapsed/refractory B-ALL who were enrolled in clinical trials of either CD19 (NCT03919240) or CD19/CD22 CAR T-cell therapy (NCT03614858). The complete remission (CR) rates in the single CD19, tandem CD19/CD22, and sequential CD19/CD22 groups were 83.0% (122/147), 98.0% (50/51), and 95.2% (20/21), respectively (single CD19 vs. tandem CD19/CD22, P = 0.006). Patients with high-risk factors achieved a higher rate of CR in the tandem CD19/CD22 group than in the single CD19 group (100.0% vs. 82.4%, P = 0.017). Tandem CD19/CD22 CAR T-cell therapy was one of the significant favorable factors in the multivariate analysis of the CR rate. The incidence of adverse events was similar among the three groups. Multivariable analysis in CR patients showed that a low frequency of relapse, a low tumor burden, minimal residual disease-negative CR and bridging to transplantation were independently associated with better leukemia-free survival. Our findings suggested that tandem CD19/CD22 CAR T-cell therapy obtains a better response than CD19 CAR T-cell therapy and a similar response to sequential CD19/CD22 CAR T-cell therapy.

Single-Cell Discovery and Multiomic Characterization of Therapeutic Targets in Multiple Myeloma

Multiple myeloma (MM) is a highly refractory hematologic cancer. Targeted immunotherapy has shown promise in MM but remains hindered by the challenge of identifying specific yet broadly representative tumor markers. We analyzed 53 bone marrow (BM) aspirates from 41 MM patients using an unbiased, high-throughput pipeline for therapeutic target discovery via single-cell transcriptomic profiling, yielding 38 MM marker genes encoding cell-surface proteins and 15 encoding intracellular proteins. Of these, 20 candidate genes were highlighted that are not yet under clinical study, 11 of which were previously uncharacterized as therapeutic targets. The findings were cross-validated using bulk RNA sequencing, flow cytometry, and proteomic mass spectrometry of MM cell lines and patient BM, demonstrating high overall concordance across data types. Independent discovery using bulk RNA sequencing reiterated top candidates, further affirming the ability of single-cell transcriptomics to accurately capture marker expression despite limitations in sample size or sequencing depth. Target dynamics and heterogeneity were further examined using both transcriptomic and immuno-imaging methods. In summary, this study presents a robust and broadly applicable strategy for identifying tumor markers to better inform the development of targeted cancer therapy.

SIGNIFICANCE

Single-cell transcriptomic profiling and multiomic cross-validation to uncover therapeutic targets identifies 38 myeloma marker genes, including 11 transcribing surface proteins with previously uncharacterized potential for targeted antitumor therapy.

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.

Challenges of detecting measurable/minimal disease in acute leukemia

Measurable/minimal residual disease (MRD) tracking has emerged as a powerful tool for assessing treatment response and predicting outcomes in acute leukemia. However, the clinical and technological challenges associated with MRD tracking must be addressed to improve its utility in routine patient care. This review article aims to provide a summary of the different MRD methodologies used in acute leukemia. It highlights the strengths, diagnostic pitfalls, and clinical utility associated with MRD tracking in this rapidly evolving field.

Siglec receptors as new immune checkpoints in cancer

Cancer immunotherapy in the form of immune checkpoint inhibitors and cellular therapies has improved the treatment and prognosis of many patients. Nevertheless, most cancers are still resistant to currently approved cancer immunotherapies. New approaches and rational combinations are needed to overcome these resistances. There is emerging evidence that Siglec receptors could be regarded as new immune checkpoints and targets for cancer immunotherapy. In this review, we summarize the experimental evidence supporting Siglec receptors as new immune checkpoints in cancer and discuss their mechanisms of action, as well as current efforts to target Siglec receptors and their interactions with sialoglycan Siglec-ligands.

Advancing CAR T cell therapy through the use of multidimensional omics data

Despite the notable success of chimeric antigen receptor (CAR) T cell therapies in the treatment of certain haematological malignancies, challenges remain in optimizing CAR designs and cell products, improving response rates, extending the durability of remissions, reducing toxicity and broadening the utility of this therapeutic modality to other cancer types. Data from multidimensional omics analyses, including genomics, epigenomics, transcriptomics, T cell receptor-repertoire profiling, proteomics, metabolomics and/or microbiomics, provide unique opportunities to dissect the complex and dynamic multifactorial phenotypes, processes and responses of CAR T cells as well as to discover novel tumour targets and pathways of resistance. In this Review, we summarize the multidimensional cellular and molecular profiling technologies that have been used to advance our mechanistic understanding of CAR T cell therapies. In addition, we discuss current applications and potential strategies leveraging multi-omics data to identify optimal target antigens and other molecular features that could be exploited to enhance the antitumour activity and minimize the toxicity of CAR T cell therapy. Indeed, fully utilizing multi-omics data will provide new insights into the biology of CAR T cell therapy, further accelerate the development of products with improved efficacy and safety profiles, and enable clinicians to better predict and monitor patient responses.

Translational advances in the treatment of childhood acute lymphoblastic leukemia: narrative review of current and emerging molecular and immunotherapies

Background and Objective

Acute lymphoblastic leukemia (ALL) is the most common hematologic malignancy of lymphoid origin in children. The prognosis for newly diagnosed ALL in the pediatric population is generally favorable, with a 5-year overall survival rate of more than 90%. Though conventional therapy has led to meaningful improvements in cure rates for new-onset pediatric ALL, one-third of patients still experience a relapse or refractory disease, contributing to a significant cause of pediatric cancer-related mortality.

Methods

An extensive literature review was undertaken via various databases of medical literature, focusing on both results of larger clinical trials, but also with evaluation of recent abstract publications at large hematologic conferences.

Key Content and Findings

Remission is achievable in most of these patients by re-induction with currently available therapies, but the long-term overall survival rate is deemed suboptimal and remains a therapeutic challenge. As part of never-ceasing efforts to improve pediatric ALL outcomes, newer modalities, including targeted molecular therapies as well as immunotherapy, and chimeric antigen receptor (CAR) T-cell therapy, are currently being employed to increase treatment effectiveness as well as lessen the side effects from conventional chemotherapy. These approaches explore the use of early genome-based disease characterization and medications developed against actionable molecular targets.

Conclusions

Additional clinical research is nonetheless required to learn more about the potentially harmful effects of targeted therapies and investigate the possibility of these agents replacing or decreasing the use of conventional chemotherapy in treating pediatric ALL.

Recent advances in microfluidics for single-cell functional proteomics

Single-cell proteomics (SCP) reveals phenotypic heterogeneity by profiling individual cells, their biological states and functional outcomes upon signaling activation that can hardly be probed via other omics characterizations. This has become appealing to researchers as it enables an overall more holistic view of biological details underlying cellular processes, disease onset and progression, as well as facilitates unique biomarker identification from individual cells. Microfluidic-based strategies have become methods of choice for single-cell analysis because they allow facile assay integrations, such as cell sorting, manipulation, and content analysis. Notably, they have been serving as an enabling technology to improve the sensitivity, robustness, and reproducibility of recently developed SCP methods. Critical roles of microfluidics technologies are expected to further expand rapidly in advancing the next phase of SCP analysis to reveal more biological and clinical insights. In this review, we will capture the excitement of the recent achievements of microfluidics methods for both targeted and global SCP, including efforts to enhance the proteomic coverage, minimize sample loss, and increase multiplexity and throughput. Furthermore, we will discuss the advantages, challenges, applications, and future prospects of SCP.

Coadministration of CD19- and CD22-Directed Chimeric Antigen Receptor T-Cell Therapy in Childhood B-Cell Acute Lymphoblastic Leukemia: A Single-Arm, Multicenter, Phase II Trial

PURPOSE

We determined the safety and efficacy of coadministration of CD19- and CD22-chimeric antigen receptor (CAR) T cells in patients with refractory disease or high-risk hematologic or isolated extramedullary relapse of B-acute lymphoblastic leukemia.

PATIENTS AND METHODS

This phase II trial enrolled 225 evaluable patients age ≤ 20 years between September 17, 2019, and December 31, 2021. We first conducted a safety run-in stage to determine the recommended dose. After interim analysis of the first 30 patients treated (27 at the recommended dose) showing that the treatment was safe and effective, the study enrolled additional patients according to the study design.

RESULTS

Complete remission was achieved in 99.0% of the 194 patients with refractory leukemia or hematologic relapse, all negative for minimal residual disease. Their overall 12-month event-free survival (EFS) was 73.5% (95% CI, 67.3 to 80.3). Relapse occurred in 43 patients (24 with CD19+/CD22+ relapse, 16 CD19-/CD22+, one CD19-/CD22-, and two unknown). Consolidative transplantation and persistent B-cell aplasia at 6 months were associated with favorable outcomes. The 12-month EFS was 85.0% (95% CI, 77.2 to 93.6) for the 78 patients treated with transplantation and 69.2% (95% CI, 60.8 to 78.8) for the 116 nontransplanted patients (P = .03, time-dependent covariate Cox model). All 25 patients with persistent B-cell aplasia at 6 months remained in remission at 12 months. The 12-month EFS for the 20 patients with isolated testicular relapse was 95.0% (95% CI, 85.9 to 100), and for the 10 patients with isolated CNS relapse, it was 68.6% (95% CI, 44.5 to 100). Cytokine release syndrome developed in 198 (88.0%) patients, and CAR T-cell neurotoxicity in 47 (20.9%), resulting in three deaths.

CONCLUSION

CD19-/CD22-CAR T-cell therapy achieved relatively durable remission in children with relapsed or refractory B-acute lymphoblastic leukemia, including those with isolated or combined extramedullary relapse.

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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.

The evolution of acute lymphoblastic leukemia research and therapy at MD Anderson over four decades

Progress in the research and therapy of adult acute lymphoblastic leukemia (ALL) is accelerating. This analysis summarizes the data derived from the clinical trials conducted at MD Anderson between 1985 and 2022 across ALL subtypes. In Philadelphia chromosome-positive ALL, the addition of BCR::ABL1 tyrosine kinase inhibitors (TKIs) to intensive chemotherapy since 2000, improved outcomes. More recently, a chemotherapy-free regimen with blinatumomab and ponatinib resulted in a complete molecular remission rate of 85% and an estimated 3-year survival rate of 90%, potentially reducing the role of, and need for allogeneic stem cell transplantation (SCT) in remission. In younger patients with pre-B Philadelphia chromosome-negative ALL, the integration of blinatumomab and inotuzumab into the frontline therapy has improved the estimated 3-year survival rate to 85% across all risk categories. Our future strategy is to evaluate the early integration of both immunotherapy agents, inotuzumab and blinatumomab, with low-dose chemotherapy (dose-dense mini-Hyper-CVD-inotuzumab-blinatumomab) into the frontline setting followed by CAR T cells consolidation in high-risk patients, without any further maintenance therapy. In older patients, using less intensive chemotherapy (mini-Hyper-CVD) in combination with inotuzumab and blinatumomab has improved the 5-year survival rate to 50%. Among patients ≥ 65-70 years, the mortality in complete remission (CR) is still high and is multifactorial (old age, death in CR with infections, development of myelodysplastic syndrome or acute myeloid leukemia). A chemotherapy-free regimen with inotuzumab and blinatumomab is being investigated. The assessment of measurable residual disease (MRD) by next-generation sequencing (NGS) is superior to conventional assays, with early MRD negativity by NGS being associated with the best survival. We anticipate that the future therapy in B-ALL will involve less intensive and shorter chemotherapy regimens in combination with agents targeting CD19 (blinatumomab), CD20, and CD22 (inotuzumab). The optimal timing and use of CAR T cells therapy may be in the setting of minimal disease, and future trials will assess the role of CAR T cells as a consolidation among high-risk patients to replace allogeneic SCT. In summary, the management of ALL has witnessed significant progress during the past four decades. Novel combination regimens including newer-generation BCR::ABL1 TKIs and novel antibodies are questioning the need and duration of intensive chemotherapy and allogeneic SCT.

Efficacy and Safety of Dual-Targeting Chimeric Antigen Receptor-T Therapy for Relapsed or Refractory B Cell Lymphoid Malignancies: A Systematic Review and Meta-Analysis

Dual-targeting chimeric antigen receptor (CAR)-T cell therapy has been proposed as a potential solution for overcoming antigen escape during anti-CD19 CAR-T treatment. We performed this systematic review and meta-analysis to investigate the efficacy and safety of this novel treatment in patients with B cell non-Hodgkin lymphoma (B-NHL) and B cell acute lymphoblastic leukemia (B-ALL). We systematically searched relevant literature based on databases (PubMed, Web of Science, Embase and Cochrane) and conference abstracts. The primary outcomes measured were the best objective response rate (ORR) or complete response (CR), 12-month overall survival (OS) and progression-free survival (PFS), cytokine release syndrome (CRS), and neurotoxicity. Fifteen registered prospective open-label clinical trials were included. Among the 260 patients with B-NHL, the pooled best ORR and CR were 77% (95% confidence interval [CI]: 0.71-0.82) and 52% (95% CI: 0.40-0.63), respectively, and the pooled 12-month PFS and OS were 54.0% (95% CI: 0.47-0.61) and 66.0% (95% CI: 0.56-0.77), respectively. In the 159 patients with B-ALL, the combined best CR was observed to be 92% (95% CI: 0.82-0.99) and the pooled 12-month PFS and OS were 65.0% (95% CI: 0.51-0.77) and 73.0% (95% CI: 0.56-0.92), respectively. Moreover, in B-NHL patients, grade ≥3 CRS was observed in 14.0% (95% CI: 0.04-0.29) of these patients, and 5.0% (95% CI: 0.02-0.08) showed grade ≥3 neurotoxicity; in the case of B-ALL patients, grade ≥3 CRS and neurotoxicity occurred in 11.0% (95% CI: 0.04-0.19) and 2.0% (95% CI: 0.00-0.06), respectively. This study demonstrates the safety and clinical efficacy of dual-targeting CAR-T cell therapies in B cell malignancies. Further, well-designed randomized controlled trials are required to establish the role of dual-targeting CAR-T cell therapy in patients with B cell malignancies.

A phase 2 study of axicabtagene ciloleucel in relapsed or refractory large B-cell lymphoma in Japan: 1-year follow-up and biomarker analysis

Axicabtagene ciloleucel (axi-cel) is an autologous, CD19-targeting chimeric antigen receptor T‑cell therapy. We recently reported the 3-month follow-up results of a phase 2, multicenter, open‑label, single-arm study of axi-cel in Japanese patients with relapsed or refractory (R/R) large B-cell lymphoma (LBCL) (JapicCTI-183914). Here, we present 1-year efficacy and safety data and biomarker analysis data regarding mechanisms of resistance to axi-cel. Primary and secondary endpoints included investigator-assessed objective response rate (ORR), serious adverse events, and treatment-emergent adverse events. Axi-cel pharmacokinetics were also examined. Biomarker analysis was performed by cytokine measurement, immunohistochemistry, RNA sequencing, and whole-exome sequencing. At a median follow-up of 13.4 months, ORR was 86.7% (13/15 patients), and the complete response (CR) rate improved to 53.3% (8/15 patients) due to response conversion. Seven patients experienced disease progression, and one achieved CR after re-treatment with axi-cel. No new safety concerns were detected. Plausible resistance mechanisms to axi-cel varied among patients but included CD19 downregulation, programmed death-ligand 1 upregulation, and increased macrophage and angiogenesis signatures. The 1-year efficacy and safety of axi-cel were confirmed in Japanese patients with R/R LBCL. Resistance to treatment may involve multiple factors, including target antigen loss and an unfavorable tumor environment.Clinical trial registration: Japan Clinical Trials Information; JapicCTI-183914.

Cancer stem cells: Recent insights and therapies

Tumors are intricate ecosystems containing malignant components that generate adaptive and evolutionarily driven abnormal tissues. Through self-renewal and differentiation, cancers are reconstructed by a dynamic subset of stem-like cells that enforce tumor heterogeneity and remodel the tumor microenvironment (TME). Through recent technology advances, we are now better equipped to investigate the fundamental role of cancer stem cells (CSCs) in cancer biology. In this review, we discuss the latest insights into characteristics, markers and mechanism of CSCs and describe the crosstalk between CSCs and other cells in TME. Additionally, we explore the performance of single-cell sequencing and spatial transcriptome analysis in CSCs studies and summarize the therapeutic strategies to eliminate CSCs, which could broaden the understanding of CSCs and exploit for therapeutic benefit.

Preclinical evaluation of CD70-specific CAR T cells targeting acute myeloid leukemia

Backgrounds

Chimeric antigen receptor (CAR)-T cell therapy has achieved unprecedented success in treating hematopoietic malignancies. However, this cell therapy is hampered in treating acute myeloid leukemia (AML) due to lack of ideal cell surface targets that only express on AML blasts and leukemia stem cells (LSCs) but not on normal hematopoietic stem cells (HSCs).

Methods

We detected the CD70 expression on the surfaces of AML cell lines, primary AML cells, HSC, and peripheral blood cells and generated a second-generation CD70-specific CAR-T cells using a construct containing a humanized 41D12-based scFv and a 41BB-CD3ζ intracellular signaling domain. Cytotoxicity, cytokine release, and proliferation in antigen stimulation, CD107a assay, and CFSE assays were used to demonstrate the potent anti-leukemia activity in vitro. A Molm-13 xenograft mouse model was established to evaluate the anti-leukemic activity of CD70 CAR-T in vivo. CFU assay was explored to assess the safety of CD70 CAR-T on HSC.

Results

CD70 heterogeneously expressed on AML primary cells, including leukemia blasts, leukemic progenitor, and stem cells, but not expressed on normal HSCs and majority of blood cells. Anti-CD70 CAR-T cells exhibited potent cytotoxicity, cytokines production, and proliferation when incubated with CD70⁺ AML cell lines. It also displayed robust anti-leukemia activity and prolonged survival in Molm-13 xenograft mouse model. However, such CAR-T cell therapy did not completely eliminate leukemia in vivo.

Discussion

Our study reveals that anti-CD70 CAR-T cells are a new potential treatment for AML. However, such CAR-T cell therapy did not completely eliminate leukemia in vivo, suggesting that future studies aiming to generate innovative combinatorial CAR constructs or to increase CD70 expression density on leukemia cell surface to prolong the life-span of CAR-T cells in the circulation will be needed in order to optimize CAR-T cell responses for AML.

Challenges and optimal strategies of CAR T therapy for hematological malignancies

ABSTRACT

Remarkable improvement relative to traditional approaches in the treatment of hematological malignancies by chimeric antigen receptor (CAR) T-cell therapy has promoted sequential approvals of eight commercial CAR T products within last 5 years. Although CAR T cells' productization is now rapidly boosting their extensive clinical application in real-world patients, the limitation of their clinical efficacy and related toxicities inspire further optimization of CAR structure and substantial development of innovative trials in various scenarios. Herein, we first summarized the current status and major progress in CAR T therapy for hematological malignancies, then described crucial factors which possibly compromise the clinical efficacies of CAR T cells, such as CAR T cell exhaustion and loss of antigen, and finally, we discussed the potential optimization strategies to tackle the challenges in the field of CAR T therapy.

CAR immune cells: design principles, resistance and the next generation

The remarkable clinical activity of chimeric antigen receptor (CAR) therapies in B cell and plasma cell malignancies has validated the use of this therapeutic class for liquid cancers, but resistance and limited access remain as barriers to broader application. Here we review the immunobiology and design principles of current prototype CARs and present emerging platforms that are anticipated to drive future clinical advances. The field is witnessing a rapid expansion of next-generation CAR immune cell technologies designed to enhance efficacy, safety and access. Substantial progress has been made in augmenting immune cell fitness, activating endogenous immunity, arming cells to resist suppression via the tumour microenvironment and developing approaches to modulate antigen density thresholds. Increasingly sophisticated multispecific, logic-gated and regulatable CARs display the potential to overcome resistance and increase safety. Early signs of progress with stealth, virus-free and in vivo gene delivery platforms provide potential paths for reduced costs and increased access of cell therapies in the future. The continuing clinical success of CAR T cells in liquid cancers is driving the development of increasingly sophisticated immune cell therapies that are poised to translate to treatments for solid cancers and non-malignant diseases in the coming years.

Potent preclinical activity of FLT3-directed chimeric antigen receptor T-cell immunotherapy against FLT3- mutant acute myeloid leukemia and KMT2A-rearranged acute lymphoblastic leukemia

Chimeric antigen receptor (CAR) T-cell immunotherapies targeting CD19 or CD22 induce remissions in the majority of patients with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL), although relapse due to target antigen loss or downregulation has emerged as a major clinical dilemma. Accordingly, great interest exists in developing CAR T cells directed against alternative leukemia cell surface antigens that may help to overcome immunotherapeutic resistance. The fms-like tyrosine kinase 3 receptor (FLT3) is constitutively activated via FLT3 mutation in acute myeloid leukemia (AML) or wild-type FLT3 overexpression in KMT2A (lysine-specific methyltransferase 2A)-rearranged ALL, which are associated with poor clinical outcomes in children and adults. We developed monovalent FLT3-targeted CAR T cells (FLT3CART) and bispecific CD19xFLT3CART and assessed their anti-leukemia activity in preclinical models of FLT3-mutant AML and KMT2A-rearranged infant ALL. We report robust in vitro FLT3CART-induced cytokine production and cytotoxicity against AML and ALL cell lines with minimal cross-reactivity against normal hematopoietic and non-hematopoietic tissues. We also observed potent in vivo inhibition of leukemia proliferation in xenograft models of both FLT3-mutant AML and KMT2A-rearranged ALL, including a post-tisagenlecleucel ALL-to-AML lineage switch patient-derived xenograft model pairing. We further demonstrate significant in vitro and in vivo activity of bispecific CD19xFLT3CART against KMT2Arearranged ALL and posit that this additional approach might also diminish potential antigen escape in these high-risk leukemias. Our preclinical data credential FLT3CART as a highly effective immunotherapeutic strategy for both FLT3- mutant AML and KMT2A-rearranged ALL which is poised for further investigation and clinical translation.

Relapsed or refractory large B-cell lymphoma after chimeric antigen receptor T-cell therapy: Current challenges and therapeutic options

Chimeric antigen receptor (CAR) T-cell (CAR-T) therapy can provide durable remission in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL) after failure of chemoimmunotherapy. However, patients who are refractory or relapsing after CAR-T therapy have poor outcomes. Multiple mechanisms of CAR-T therapy failure have been proposed but management of these patients remains a challenge. As CAR-T therapy moves earlier in the treatment of DLBCL, we urgently need trials focused on patients with relapse after CAR-T therapy. Recent advances in novel immunotherapies such as bispecific antibodies, antibody-drug conjugates and next-generation CAR-T therapies may provide avenues for treatment. Here we review the available data on using these drugs after failure of CAR-T therapy and provide a framework for the ideal sequencing of these novel agents.

Current advances and challenges in CAR T-Cell therapy for solid tumors: tumor-associated antigens and the tumor microenvironment

The past decade has witnessed ongoing progress in immune therapy to ameliorate human health. As an emerging technique, chimeric antigen receptor (CAR) T-cell therapy has the advantages of specific killing of cancer cells, a high remission rate of cancer-induced symptoms, rapid tumor eradication, and long-lasting tumor immunity, opening a new window for tumor treatment. However, challenges remain in CAR T-cell therapy for solid tumors due to target diversity, tumor heterogeneity, and the complex microenvironment. In this review, we have outlined the development of the CAR T-cell technique, summarized the current advances in tumor-associated antigens (TAAs), and highlighted the importance of tumor-specific antigens (TSAs) or neoantigens for solid tumors. We also addressed the challenge of the TAA binding domain in CARs to overcome off-tumor toxicity. Moreover, we illustrated the dominant tumor microenvironment (TME)-induced challenges and new strategies based on TME-associated antigens (TMAs) for solid tumor CAR T-cell therapy.

Multispecific CAR T Cells Deprive Lymphomas of Escape via Antigen Loss

Chimeric antigen receptor (CAR) modified T cell therapy has transformed the management of relapsed/refractory B cell malignancies. Despite high overall response rates, relapse post CAR T treatment remains a clinical challenge. Loss of target antigen, specifically CD19, is one well-defined mechanism of disease relapse. The mechanism of CD19 loss and which patients are at higher risk of CD19 loss remain poorly understood. To overcome CD19 loss, CARs targeting multiple antigens are being tested in clinical trials. CD19/20 and CD19/22 bispecific CARs demonstrate cytotoxicity against CD19-negative cells in preclinical studies. These CARs have also shown efficacy, safety, and a relatively low rate of CD19-negative relapse in phase I trials. These small studies suggest that multispecific CAR T cells can deprive lymphomas of escape via antigen loss. However, the selection of an ideal target, the right CAR construct, and whether these multispecific CARs can induce long-term remissions are still under investigation.

CARs and Drugs: Pharmacological Ways of Boosting CAR-T-Cell Therapy

The development of chimeric antigen receptor T cells (CAR-T cells) has marked a new era in cancer immunotherapy. Based on a multitude of durable complete remissions in patients with hematological malignancies, FDA and EMA approval was issued to several CAR products targeting lymphoid leukemias and lymphomas. Nevertheless, about 50% of patients treated with these approved CAR products experience relapse or refractory disease necessitating salvage strategies. Moreover, in the vast majority of patients suffering from solid tumors, CAR-T-cell infusions could not induce durable complete remissions so far. Crucial obstacles to CAR-T-cell therapy resulting in a priori CAR-T-cell refractory disease or relapse after initially successful CAR-T-cell therapy encompass antigen shutdown and CAR-T-cell dysfunctionality. Antigen shutdown predominately rationalizes disease relapse in hematological malignancies, and CAR-T-cell dysfunctionality is characterized by insufficient CAR-T-cell proliferation and cytotoxicity frequently observed in patients with solid tumors. Thus, strategies to surmount those obstacles are being developed with high urgency. In this review, we want to highlight different approaches to combine CAR-T cells with drugs, such as small molecules and antibodies, to pharmacologically boost CAR-T-cell therapy. In particular, we discuss how certain drugs may help to counteract antigen shutdown and CAR-T-cell dysfunctionality in both hematological malignancies and solid tumors.

Flow cytometric assessment for minimal/measurable residual disease in B lymphoblastic leukemia/lymphoma in the era of immunotherapy

Minimal/measurable residual disease (MRD) is the most important independent prognostic factor for patients with B-lymphoblastic leukemia (B-LL). MRD post therapy has been incorporated into risk stratification and clinical management, resulting in substantially improved outcomes in pediatric and adult patients. Currently, MRD in B-ALL is most commonly assessed by multiparametric flow cytometry and molecular (polymerase chain reaction or high-throughput sequencing based) methods. The detection of MRD by flow cytometry in B-ALL often begins with B cell antigen-based gating strategies. Over the past several years, targeted immunotherapy directed against B cell markers has been introduced in patients with relapsed or refractory B-ALL and has demonstrated encouraging results. However, targeted therapies have significant impact on the immunophenotype of leukemic blasts, in particular, downregulation or loss of targeted antigens on blasts and normal B cell precursors, posing challenges for MRD detection using standard gating strategies. Novel flow cytometric approaches, using alternative strategies for population identification, sometimes including alternative gating reagents, have been developed and implemented to monitor MRD in the setting of post targeted therapy.

Molecular and therapeutic effect of CRISPR in treating cancer

Cancer has become one of the common causes of mortality around the globe due to mutations in the genome which allows rapid growth of cells uncontrollably without repairing DNA errors. Cancers could arise due alterations in DNA repair mechanisms (errors in mismatch repair genes), activation of oncogenes and inactivation of tumor suppressor genes. Each cancer type is different and each individual has a unique genetic change which leads them to cancer. Studying genetic and epigenetic alterations in the genome leads to understanding the underlying features. CAR T therapy over other immunotherapies such as monoclonal antibodies, immune checkpoint inhibitors, cancer vaccines and adoptive cell therapies has been widely used to treat cancer in recent days and gene editing has now become one of the promising treatments for many genetic diseases. This tool allows scientists to change the genome by adding, removing or altering genetic material of an organism. Due to advance in genetics and novel molecular techniques such as CRISPR, TALEN these genes can be edited in such a way that their original function could be replaced which in turn improved the treatment possibilities and can be used against malignancies and even cure cancer in future along with CAR T cell therapy due to the specific recognition and attacking of tumor.

Outcomes After Nonresponse and Relapse Post-Tisagenlecleucel in Children, Adolescents, and Young Adults With B-Cell Acute Lymphoblastic Leukemia

PURPOSE

Nonresponse and relapse after CD19-chimeric antigen receptor (CAR) T-cell therapy continue to challenge survival outcomes. Phase II landmark data from the ELIANA trial demonstrated nonresponse and relapse rates of 14.5% and 28%, respectively, whereas use in the real-world setting showed nonresponse and relapse rates of 15% and 37%. Outcome analyses describing fate after post-CAR nonresponse and relapse remain limited. Here, we aim to establish survival outcomes after nonresponse and both CD19+ and CD19- relapses and explore treatment variables associated with inferior survival.

METHODS

We conducted a retrospective multi-institutional study of 80 children and young adults with B-cell acute lymphoblastic leukemia experiencing nonresponse (n = 23) or relapse (n = 57) after tisagenlecleucel. We analyze associations between baseline characteristics and these outcomes and establish survival rates and salvage approaches.

RESULTS

The overall survival (OS) at 12 months was 19% across nonresponders (n = 23; 95% CI, 7 to 50). Ninety-five percent of patients with nonresponse had high preinfusion disease burden. Among 156 morphologic responders, the cumulative incidence of relapse was 37% (95% CI, 30 to 47) at 12 months (CD19+; 21% [15 to 29], CD19-; 16% [11 to 24], median follow-up; 380 days). Across 57 patients experiencing relapse, the OS was 52% (95% CI, 38 to 71) at 12 months after time of relapse. Notably, CD19- relapse was associated with significantly decreased OS as compared with patients who relapsed with conserved CD19 expression (CD19- 12-month OS; 30% [14 to 66], CD19+ 12-month OS; 68% [49 to 92], P = .0068). Inotuzumab, CAR reinfusion, and chemotherapy were used as postrelapse salvage therapy with greatest frequency, yet high variability in treatment sequencing and responses limits efficacy analysis across salvage approaches.

CONCLUSION

We describe poor survival across patients experiencing nonresponse to tisagenlecleucel. In the post-tisagenlecleucel relapse setting, patients can be salvaged; however, CD19- relapse is distinctly associated with decreased survival outcomes.

Determinants of resistance to engineered T cell therapies targeting CD19 in large B cell lymphomas

Most relapsed/refractory large B cell lymphoma (r/rLBCL) patients receiving anti-CD19 chimeric antigen receptor (CAR19) T cells relapse. To characterize determinants of resistance, we profiled over 700 longitudinal specimens from two independent cohorts (n = 65 and n = 73) of r/rLBCL patients treated with axicabtagene ciloleucel. A method for simultaneous profiling of circulating tumor DNA (ctDNA), cell-free CAR19 (cfCAR19) retroviral fragments, and cell-free T cell receptor rearrangements (cfTCR) enabled integration of tumor and both engineered and non-engineered T cell effector-mediated factors for assessing treatment failure and predicting outcomes. Alterations in multiple classes of genes are associated with resistance, including B cell identity (PAX5 and IRF8), immune checkpoints (CD274), and those affecting the microenvironment (TMEM30A). Somatic tumor alterations affect CAR19 therapy at multiple levels, including CAR19 T cell expansion, persistence, and tumor microenvironment. Further, CAR19 T cells play a reciprocal role in shaping tumor genotype and phenotype. We envision these findings will facilitate improved chimeric antigen receptor (CAR) T cells and personalized therapeutic approaches.

Successful Treatment of Large B-Cell Lymphoma in a Child with Compound Heterozygous Mutation in the ATM Gene

Ataxia-telangiectasia (AT) is a multisystemic neurodegenerative inborn error of immunity (IEI) characterized by DNA repair defect, chromosomal instability, and hypersensitivity to ionizing radiation. Impaired DNA double-strand break repair determines a high risk of developing hematological malignancies, especially lymphoproliferative diseases. Poor response to treatment, excessive chemotherapy toxicities, and the need for avoiding exposure to ionizing radiation make the successful clinical management of patients with AT challenging for oncologists. We describe the favorable outcome of the LBCL with IRF4 rearrangement at stage III in a 7-year-old female patient diagnosed with AT. The patient was treated according to the B-HR arm of the INTER-B-NHL-COP 2010 protocol, including the administration of rituximab, cyclophosphamide, methotrexate, prednisone, etc. She presented excessive treatment toxicities despite individually reduced doses of methotrexate and cyclophosphamide. However, in the MRI there was no significant reduction in pathologic lymph nodes after three immunochemotherapy courses. Therefore, a lymph node biopsy was taken. Its subsequent histopathological examination revealed tuberculosis-like changes, though tuberculosis suspicion was excluded. After two following immunochemotherapy courses, PET-CT confirmed complete remission. From March 2022 onwards, the patient has remained in remission under the care of the outpatient children's oncology clinic.

Is CD19-directed chimeric antigen receptor T cell therapy a smart strategy to combat central nervous system lymphoma?

Primary central nervous system lymphoma (PCNSL) is a rare form and aggressive type of diffuse large B-cell lymphoma (DLBCL) that occurs in both immunocompetent and immunocompromised adults. While adding rituximab to chemotherapeutic regimens resulted in dramatic improvement in both progression-free survival and overall survival in patients with non-central nervous system (CNS) DLBCL, the outcomes of PCNSL are generally poor due to the immune-privileged tumor microenvironment or suboptimal delivery of systemic agents into tumor tissues. Therefore, more effective therapy for PCNSL generally requires systemic therapy with sufficient CNS penetration, including high-dose intravenous methotrexate with rituximab or high-dose chemotherapy followed by autologous stem cell transplantation. However, overall survival is usually inferior in comparison to non-CNS lymphomas, and treatment options are limited for elderly patients or patients with relapsed/refractory disease. Chimeric antigen receptor T (CAR-T) cell therapy has emerged as a cutting-edge cancer therapy, which led to recent FDA approvals for patients with B-cell malignancies and multiple myeloma. Although CAR-T cell therapy in patients with PCNSL demonstrated promising results without significant toxicities in some small cohorts, most cases of PCNSL are excluded from the pivotal CAR-T cell trials due to the concerns of neurotoxicity after CAR-T cell infusion. In this review, we will provide an overview of PCNSL and highlight current approaches, resistance mechanisms, and future perspectives of CAR-T cell therapy in patients with PCNSL.

How I treat high-risk acute myeloid leukemia using preemptive adoptive cellular immunotherapy

Allogeneic hematopoietic stem cell transplantation (alloHSCT) is a potentially curative treatment for patients with high-risk acute leukemias, but unfortunately disease recurrence remains the major cause of death in these patients. Infusion of donor lymphocytes (DLI) has the potential to restore graft-versus-leukemia immunologic surveillance; however, efficacy varies across different hematologic entities. Although relapsed chronic myeloid leukemia, transplanted in chronic phase, has proven remarkably susceptible to DLI, response rates are more modest for relapsed acute myeloid leukemia and acute lymphoblastic leukemia. To prevent impending relapse, a number of groups have explored administering DLI preemptively on detection of measurable residual disease (MRD) or mixed chimerism. Evidence for the effectiveness of this strategy, although encouraging, comes from only a few, mostly single-center retrospective, nonrandomized studies. This article seeks to (1) discuss the available evidence supporting this approach while highlighting some of the inherent challenges of MRD-triggered treatment decisions post-transplant, (2) portray other forms of postremission cellular therapies, including the role of next-generation target-specific immunotherapies, and (3) provide a practical framework to support clinicians in their decision-making process when considering preemptive cellular therapy for this difficult-to-treat patient population.

Emerging frontiers in immuno- and gene therapy for cancer

BACKGROUND AIMS

The field of cell and gene therapy in oncology has moved rapidly since 2017 when the first cell and gene therapies, Kymriah followed by Yescarta, were approved by the Food and Drug Administration in the United States, followed by multiple other countries. Since those approvals, several new products have gone on to receive approval for additional indications. Meanwhile, efforts have been made to target different cancers, improve the logistics of delivery and reduce the cost associated with novel cell and gene therapies. Here, we highlight various cell and gene therapy-related technologies and advances that provide insight into how these new technologies will speed the translation of these therapies into the clinic.

CONCLUSIONS

In this review, we provide a broad overview of the current state of cell and gene therapy-based approaches for cancer treatment - discussing various effector cell types and their sources, recent advances in both CAR and non-CAR genetic modifications, and highlighting a few promising approaches for increasing in vivo efficacy and persistence of therapeutic drug products.

A Review of CAR-T Therapy in Pediatric and Young Adult B-Lineage Acute Leukemia: Clinical Perspectives in Singapore

Approximately 10-15% of pediatric B-cell acute lymphoblastic leukemia (B-ALL) are high risk at diagnosis or relapsed/ refractory. Prior to the availability of chimeric antigen receptor T-cell (CAR-T) in Singapore and the region, the treatment options for these paediatric and young adults are conventional salvage chemotherapy or chemo-immunotherapy regimens as a bridge to allogeneic total body irradiation-based hematopoietic stem cell transplantation (allo-HSCT). This results in significant acute and long-term toxicities, with suboptimal survival outcomes. Finding a curative salvage therapy with fewer long-term toxicities would translate to improved quality-adjusted life years in these children and young adults. In this review, we focus on the burden of relapsed/refractory pediatric B-ALL, the limitations of current strategies, the emerging paradigms for the role of CAR-T in r/r B-ALL, our local perspectives on the health economics and future direction of CAR-T therapies in pediatric patients.

Immune-based therapies in diffuse large B-cell lymphoma

INTRODUCTION

Diffuse large B-cell lymphoma (DLBCL) is an aggressive and clinically heterogeneous malignancy originating from B-cells with up to 40% of patients experiencing primary refractory disease or relapse after first-line treatment. However, the past 5 years have seen a flurry of new drug approvals for DLBCL anchored upon new immune therapies, including chimeric antigen receptor (CAR) T-cells and antibody-based therapies.

AREAS COVERED

This article summarizes recent advances in the treatment of DLBCL, including in the first line and relapsed and refractory setting (second-line and beyond). A literature search was conducted for publications relevant to the immunotherapeutic approach to DLBCL from 2000 through March 2023 within PubMed and articles were reviewed. The search terms were immunotherapy, monoclonal antibodies, chimeric antigen receptor modified T-cell (CAR-T), and classification of DLBCL. Relevant clinical trials and pre-clinical studies exploring the strengths and weaknesses of current immune therapies against DLBCL were chosen. We additionally explored how intrinsic differences amongst DLBCL subtype biology and endogenous host immune recruitment contribute to variable therapeutic efficacy.

EXPERT OPINION

Future treatments will minimize chemotherapy exposure and be chosen by underlying tumor biology, paving the way for the promise of chemotherapeutic free regimens and improved outcomes for poor-risk subgroups.

Current and future concepts for the generation and application of genetically engineered CAR-T and TCR-T cells

Adoptive cell therapy (ACT) has seen a steep rise of new therapeutic approaches in its immune-oncology pipeline over the last years. This is in great part due to the recent approvals of chimeric antigen receptor (CAR)-T cell therapies and their remarkable efficacy in certain soluble tumors. A big focus of ACT lies on T cells and how to genetically modify them to target and kill tumor cells. Genetically modified T cells that are currently utilized are either equipped with an engineered CAR or a T cell receptor (TCR) for this purpose. Both strategies have their advantages and limitations. While CAR-T cell therapies are already used in the clinic, these therapies face challenges when it comes to the treatment of solid tumors. New designs of next-generation CAR-T cells might be able to overcome these hurdles. Moreover, CARs are restricted to surface antigens. Genetically engineered TCR-T cells targeting intracellular antigens might provide necessary qualities for the treatment of solid tumors. In this review, we will summarize the major advancements of the CAR-T and TCR-T cell technology. Moreover, we will cover ongoing clinical trials, discuss current challenges, and provide an assessment of future directions within the field.

Analysis of RBP expression and binding sites identifies PTBP1 as a regulator of CD19 expression in B-ALL

Despite massive improvements in the treatment of B-ALL through CART-19 immunotherapy, a large number of patients suffer a relapse due to loss of the targeted epitope. Mutations in the CD19 locus and aberrant splicing events are known to account for the absence of surface antigen. However, early molecular determinants suggesting therapy resistance as well as the time point when first signs of epitope loss appear to be detectable are not enlightened so far. By deep sequencing of the CD19 locus, we identified a blast-specific 2-nucleotide deletion in intron 2 that exists in 35% of B-ALL samples at initial diagnosis. This deletion overlaps with the binding site of RNA binding proteins (RBPs) including PTBP1 and might thereby affect CD19 splicing. Moreover, we could identify a number of other RBPs that are predicted to bind to the CD19 locus being deregulated in leukemic blasts, including NONO. Their expression is highly heterogeneous across B-ALL molecular subtypes as shown by analyzing 706 B-ALL samples accessed via the St. Jude Cloud. Mechanistically, we show that downregulation of PTBP1, but not of NONO, in 697 cells reduces CD19 total protein by increasing intron 2 retention. Isoform analysis in patient samples revealed that blasts, at diagnosis, express increased amounts of CD19 intron 2 retention compared to normal B cells. Our data suggest that loss of RBP functionality by mutations altering their binding motifs or by deregulated expression might harbor the potential for the disease-associated accumulation of therapy-resistant CD19 isoforms.

Failure of ALL recognition by CAR T cells: a review of CD 19-negative relapses after anti-CD 19 CAR-T treatment in B-ALL

The use of chimeric antigen receptor (CAR) T lymphocytes in the treatment of refractory or relapsed (R/R) B cell acute lymphoblastic leukemia (B-ALL) has meant a radical change in the prognosis of these patients, whose chances of survival with conventional treatment are very low. The current probability of event-free survival by R/R B-ALL patients treated using anti-CD 19 CART cell therapy is as high as 50-60% at 1.5 years, which is a very important advance for this group of very ill patients. Although most patients (70 to 94%) achieve complete remission (CR), the main problem continues to be relapse of the disease. Most relapses, both in clinical trials and real-world evidence, are due to failure of CAR-T cell expansion or limited CAR-T persistence. However, despite the adequate functioning of infused CART lymphocytes, the tumor cells of an important group of patients manage to evade CAR-T attack, resulting in a CD 19-negative relapse. Several mechanisms have been described that may be able to produce the escape of leukemic cells, such as acquired mutations and alternative splicing of the CD19 antigen, CD19 epitope loss or masking, leukemia lineage switching, and trogocytosis. In the present review, we comprehensively analyze the leukemic cell escape mechanisms, the incidence of CD19-negative relapse reported in clinical trials and real-world evidence (outside clinical trials), and provide an update on the main lines of current research into the prevention of leukemia evasion.

A systematic review and meta-analysis of CD22 CAR T-cells alone or in combination with CD19 CAR T-cells

Chimeric antigen receptor (CAR) T-cells are an emerging therapy for the treatment of relapsed/refractory B-cell malignancies. While CD19 CAR-T cells have been FDA-approved, CAR T-cells targeting CD22, as well as dual-targeting CD19/CD22 CAR T-cells, are currently being evaluated in clinical trials. This systematic review and meta-analysis aimed to evaluate the efficacy and safety of CD22-targeting CAR T-cell therapies. We searched MEDLINE, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials from inception to March 3rd 2022 for full-length articles and conference abstracts of clinical trials employing CD22-targeting CAR T-cells in acute lymphocytic leukemia (ALL) and non-Hodgkin's lymphoma (NHL). The primary outcome was best complete response (bCR). A DerSimonian and Laird random-effects model with arcsine transformation was used to pool outcome proportions. From 1068 references screened, 100 were included, representing 30 early phase studies with 637 patients, investigating CD22 or CD19/CD22 CAR T-cells. CD22 CAR T-cells had a bCR of 68% [95% CI, 53-81%] in ALL (n= 116), and 64% [95% CI, 46-81%] in NHL (n= 28) with 74% and 96% of patients having received anti-CD19 CAR T-cells previously in ALL and NHL studies respectively. CD19/CD22 CAR T-cells had a bCR rate of 90% [95% CI, 84-95%] in ALL (n= 297) and 47% [95% CI, 34-61%] in NHL (n= 137). The estimated incidence of total and severe (grade ≥3) CRS were 87% [95% CI, 80-92%] and 6% [95% CI, 3-9%] respectively. ICANS and severe ICANS had an estimated incidence of 16% [95% CI, 9-25%] and 3% [95% CI, 1-5%] respectively. Early phase trials of CD22 and CD19/CD22 CAR T-cells show high remission rates in ALL and NHL. Severe CRS or ICANS were (1)rare and dual-targeting did not increase toxicity. Variability in CAR construct, dose, and patient factors amongst studies limits comparisons, with long-term outcomes yet to be reported.

Systematic review registration

https://www.crd.york.ac.uk/prospero, identifier CRD42020193027.

Towards Novel Gene and Cell Therapy Approaches for Cervical Cancer

Cervical cancer is one of the most common malignancies in women, and the majority of cases are caused by infection with high-risk human papilloma virus (HPV) subtypes. Despite effective preventative measures, such as vaccinations against HPV, over 300,000 women die world-wide from cervical cancer each year. Once cervical cancer is diagnosed, treatment may consist of radial hysterectomy, or chemotherapy and radiotherapy, or a combination of therapies dependent upon the disease stage. Unfortunately, overall prognosis for patients with metastatic or recurrent disease remains poor. In these cases, immunotherapies may be useful based on promising preclinical work, some of which has been successfully translated to the clinic. For example, approaches using monoclonal antibodies directed against surface proteins important for control of immune checkpoints (i.e., immune checkpoint inhibitors) were shown to improve outcome in many cancer settings, including cervical cancer. Additionally, initial clinical studies showed that application of cytotoxic immune cells modified to express chimeric antigen receptors (CAR) or T cell receptors (TCR) for better recognition and elimination of tumor cells may be useful to control cervical cancer. This review explores these important topics, including strengths and limitations of standard and developing approaches, and how some novel treatment strategies may be optimally used to offer the best possible treatment for cervical cancer patients.

CAR-NK as a Rapidly Developed and Efficient Immunotherapeutic Strategy against Cancer

Chimeric antigen receptor (CAR)-modified T cell therapy has been rapidly developing in recent years, ultimately revolutionizing immunotherapeutic strategies and providing significant anti-tumor potency, mainly in treating hematological neoplasms. However, graft-versus-host disease (GVHD) and other adverse effects, such as cytokine release syndromes (CRS) and neurotoxicity associated with CAR-T cell infusion, have raised some concerns about the broad application of this therapy. Natural killer (NK) cells have been identified as promising alternative platforms for CAR-based therapies because of their unique features, such as a lack of human leukocyte antigen (HLA)-matching restriction, superior safety, and better anti-tumor activity when compared with CAR-T cells. The lack of CRS, neurotoxicity, or GVHD, in the case of CAR-NK therapy, in addition to the possibility of using allogeneic NK cells as a CAR platform for "off-the-shelf" therapy, opens new windows for strategic opportunities. This review underlines recent design achievements in CAR constructs and summarizes preclinical studies' results regarding CAR-NK therapies' safety and anti-tumor potency. Additionally, new approaches in CAR-NK technology are briefly described, and currently registered clinical trials are listed.

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.

Efficacy, Safety, and Challenges of CAR T-Cells in the Treatment of Solid Tumors

Immunotherapy has been the fifth pillar of cancer treatment in the past decade. Chimeric antigen receptor (CAR) T-cell therapy is a newly designed adoptive immunotherapy that is able to target and further eliminate cancer cells by engaging with MHC-independent tumor-antigens. CAR T-cell therapy has exhibited conspicuous clinical efficacy in hematological malignancies, but more than half of patients will relapse. Of note, the efficacy of CAR T-cell therapy has been even more disappointing in solid tumors. These challenges mainly include (1) the failures of CAR T-cells to treat highly heterogeneous solid tumors due to the difficulty in identifying unique tumor antigen targets, (2) the expression of target antigens in non-cancer cells, (3) the inability of CAR T-cells to effectively infiltrate solid tumors, (4) the short lifespan and lack of persistence of CAR T-cells, and (5) cytokine release syndrome and neurotoxicity. In combination with these characteristics, the ideal CAR T-cell therapy for solid tumors should maintain adequate T-cell response over a long term while sparing healthy tissues. This article reviewed the status, clinical application, efficacy, safety, and challenges of CAR T-cell therapies, as well as the latest progress of CAR T-cell therapies for solid tumors. In addition, the potential strategies to improve the efficacy of CAR T-cells and prevent side effects in solid tumors were also explored.

Targeting the Siglec-Sialic Acid Immune Axis in Cancer: Current and Future Approaches

The sialic acid-binding immunoglobulin-like lectin (Siglec)-sialic acid immune axis is an evolutionarily conserved immunoregulatory pathway that provides a mechanism for establishing self-recognition and combatting invasive pathogens. Perturbations in the pathway lead to many immune dysregulated diseases, including autoimmunity, neurodegeneration, allergic conditions, and cancer. The purpose of this review is to provide a brief overview of the relationship between Siglecs and sialic acid as they relate to human health and disease, to consider current Siglec-based therapeutics, and to discuss new therapeutic approaches targeting the Siglec-sialic acid immune axis, with a focus on cancer.

Evaluating the Patient with Neurotoxicity after Chimeric Antigen Receptor T-cell Therapy

OPINION STATEMENT

Chimeric antigen receptor (CAR) T-cells are now a well-established treatment for hematologic malignancies. Their use in clinical practice has expanded quite rapidly and hospitals have developed CAR T-cell protocols to evaluate patients for associated toxicities, and particularly for neurotoxicity. There are many variables that influence the risk for developing this complication, many of which are not fully understood. The severity can be related to a particular product. Clinical vigilance is critical to facilitate early recognition of neurotoxicity, hence the importance of pre-CAR T-cell neurological evaluation of each patient. While details of such an evaluation may slightly differ between institutions, generally a comprehensive neurological evaluation including assessment of cognitive abilities along with magnetic resonance imaging (MRI) of the brain is a gold standard. Management of neurotoxicity requires a well-orchestrated team approach with specialists from oncology, neurology, oftentimes neurosurgery and neuro-intensive care. Diagnostic work-up frequently includes detailed neurologic evaluation with comparison to the baseline assessment, imaging of the brain, electroencephalogram, and lumbar puncture. While steroids are uniformly used for treatment, many patients also receive tocilizumab for an underlying and frequently concomitant cytokine release syndrome (CRS) in addition to symptom-driven supportive care. Novel CAR T-cell constructs and other agents allowing for potentially lower risk of toxicity are being explored. While neurotoxicity is predominantly an early, and reversible, event, a growing body of literature suggests that late neurotoxicity with variable clinical presentation can also occur.