Risk-Adapted Preemptive Tocilizumab to Prevent Severe Cytokine Release Syndrome After CTL019 for Pediatric B-Cell Acute Lymphoblastic Leukemia: A Prospective Clinical Trial

Outpatient Administration of Chimeric Antigen Receptor T-Cell Therapy Using Remote Patient Monitoring

Chimeric antigen receptor T-cell (CAR-T) therapies are standard of care for the treatment of several hematologic malignancies. Although patients receiving CAR-T therapies are frequently hospitalized given risks of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), there is increasing interest and evidence for the safety of their outpatient administration. We review various models of care and provide operational considerations for centers that are interested in developing outpatient CAR-T programs, with a particular emphasis on using remote patient monitoring (RPM) to facilitate outpatient care. Safe and high-quality outpatient care requires involvement of a multidisciplinary team with clinical pathways for rapid triage and evaluation for CRS and ICANS and their management and, if necessary, timely transition of patients to a higher level of acute care. RPM can facilitate scaling an outpatient program in a cost-effective manner, especially across multiple sites of care, and can reduce the time patients spend in an acute care setting. Overall minimizing hospital-based care and an outpatient approach can alleviate capacity challenges treatment centers have faced that have partly impacted access to CAR-T therapies and have the potential to positively impact patient and caregiver experience and quality of life.

CD22-targeted chimeric antigen receptor-modified T cells for children and adults with relapse of B-cell acute lymphoblastic leukemia after CD19-directed immunotherapy

BACKGROUND

Relapse of B-cell acute lymphoblastic leukemia (B-ALL) with CD19-antigen loss after CD19-targeted chimeric antigen receptor (CAR) T-cell therapy has a dismal prognosis. Novel immunotherapeutic strategies for this patient population are urgently needed.

METHODS

We tested a novel, fully human anti-CD22/4-1BB CAR T-cell construct, CART22-65s, in parallel phase I studies for pediatric and adult B-ALL. After lymphodepletion, CART22-65s was infused using a 3-day fractionated dosing scheme, allowing for omission of the second and third doses in cases of early cytokine release syndrome (CRS).

RESULTS

Twenty-two patients, all with relapse after prior CD19-directed immunotherapy, were enrolled. Of 19 infused patients (pediatric, n=17; adult, n=2), 14 (74%) achieved a complete remission (CR), including 4 of 6 (67%) patients refractory to prior inotuzumab. Five of 14 patients in a CR proceeded to consolidative hematopoietic cell transplantation (HCT). With a median follow-up of 38 months, the 12-month relapse-free survival rate was 38.4% (95% CI 19.3% to 76.5%) and overall survival rate was 52.6% (95% CI 34.3% to 80.6%). Two patients received additional CART22-65s treatments for subsequent CD22-positive relapses; one achieved another CR. All CRS (n=17, 89%) and neurotoxicity (n=4, 21%) events after initial infusion were grades 1-2. The only grade 3 CRS/neurotoxicity and the only high-grade immune effector cell-associated hemophagocytic lymphohistocytosis-like syndrome occurred in the retreatment setting. In vivo cellular kinetic data revealed robust CART22-65s proliferation by quantitative PCR peaking at a median of 20 days postinfusion, with the cells persisting out to month 42 in one patient who achieved a long-term remission with CART22-65s alone.

CONCLUSIONS

The favorable safety profile and high remission rates in exceedingly refractory B-ALL support the continued development of CART22-65s but also highlight the need to use the product in combination with HCT or other novel strategies.

TRIAL REGISTRATION NUMBERS

NCT02650414 and NCT03620058.

Deep insight into cytokine storm: from pathogenesis to treatment

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

Siltuximab for the treatment of early complications after chimeric antigen receptor T-cell therapy for acute lymphoblastic leukemia in children, adolescents, and young adults

BACKGROUND

Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are complications associated with CAR T-cell therapy. Siltuximab directly binds interleukin-6 (IL-6) and may be safe and effective as first-line therapy for CRS or ICANS.

METHODS

A retrospective study was conducted on pediatric, adolescent and young adult (AYA) patients treated with siltuximab after CAR T-cell therapy for B-ALL.

RESULTS

A total of 118 patients treated were included: 97 patients developed CRS (82%), and 26 patients (22%) developed ICANS. Sixty-five of those that developed CRS (55%), received treatment. In 46/65 (71%), tocilizumab was administered as anti-IL-6 drug, and 19/65 (29%) patients received siltuximab to treat tocilizumab-refractory CRS (n = 13, 68%), or as first-line CRS treatment (n = 6, 32%). Nine patients treated with siltuximab (47%) developed ICANS. With a median follow-up of 12.1 months, 7 patients remained alive.

CONCLUSIONS

To the best of our knowledge, we present the largest reported cohort of patients treated with siltuximab for CRS following CAR T-cell therapy for B-ALL. Siltuximab's safety profile and its inhibition of IL-6 effects suggest that it should be investigated as first-line therapy in prospective clinical trials.

Inconsistent Reporting and Definitions of Time-to-Event Endpoints in CAR T Clinical Trials: A Review

Clinical trials evaluating chimeric antigen receptor T-cell therapy (CAR T) commonly report time-to-event (TTE) endpoints. However, definitions are not necessarily comparable across studies and variability can lead to misinterpretation of results or inappropriate comparisons across products and studies. Amid the rapidly increasing number of published CAR T trials-many of which were used for regulatory approval-this study aims to summarize the variation in the use and reporting of TTE endpoints in CAR T trials. We include CAR T trials published January 2008 to January 2023 on PubMed that reported at least one of these TTE endpoints: overall survival (OS), progression-free survival (PFS), duration of response/remission (DOR), disease-free survival, event-free survival (EFS), relapse-free survival (RFS), time to relapse, time to progression, or time to treatment failure. We abstracted and summarized endpoint definitions, including the time origin, events, competing events, and censoring. We assessed the completeness of endpoint reporting, overall and by subgroups such as study phase, publication year, and the journal's impact factor. We included 116 publications in the analysis. The most frequently reported TTEs were OS (83%,), PFS (56%), DOR (55%), and EFS (23%). Complete reporting of endpoints was poor overall: 32%, 24%, 25%, and 56% for OS, PFS, DOR, and EFS respectively. Complete reporting was lower in articles published before 2018, in lower impact factor journals, and in phase I trials. There was also a large variability in TTE definitions among those reported. For example, among 64 studies reporting DOR, 48% used the date of response as the time origin while 20% used the date of infusion, and 31% did not report a time origin. There is substantial heterogeneity and incompleteness of TTE endpoint definitions in CAR T trials that could impact the interpretation of the study results. Improving TTE reporting, by stating the time origin, event(s) of interest, competing event(s) if any, and censoring, is required to ensure valid assessment of clinical benefit and cross-trial comparison.

Efficacy and safety of tocilizumab in managing cytokine release syndrome after CD19 CAR-T therapy for relapsed or refractory B-cell acute lymphoblastic leukemia

Purpose

CD19 chimeric antigen receptor T (CAR-T) cell therapy has shown promise in treating relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL), but cytokine release syndrome (CRS) remains a significant side effect.

Methods

This retrospective cohort study investigated the use of tocilizumab for managing CAR-T-related CRS in 45 R/R B-ALL patients.

Results

Of these, 17 patients received tocilizumab, resulting in a significant reduction in the duration of grade 3 CRS compared to those who did not receive the drug. Additionally, 10 patients showed decreased cytokine levels.Importantly, tocilizumab did not impair CAR-T cell expansion or efficacy, nor did it increase the incidence of adverse events.

Conclusion

These findings suggest that tocilizumab may be an effective and safe strategy for mitigating CAR-T-related CRS in R/R B-ALL patients, potentially improving patient outcomes and survival.

Co-targeting of the thymic stromal lymphopoietin receptor to decrease immunotherapeutic resistance in CRLF2-rearranged Ph-like and Down syndrome acute lymphoblastic leukemia

CRLF2 rearrangements occur in >50% of Ph-like and Down syndrome (DS)-associated B-acute lymphoblastic leukemia (ALL) and induce constitutive kinase signaling targetable by the JAK1/2 inhibitor ruxolitinib under current clinical investigation. While chimeric antigen receptor T cell (CART) immunotherapies have achieved remarkable remission rates in children with relapsed/refractory B-ALL, ~50% of CD19CART-treated patients relapse again, many with CD19 antigen loss. We previously reported preclinical activity of thymic stromal lymphopoietin receptor-targeted cellular immunotherapy (TSLPRCART) against CRLF2-overexpressing ALL as an alternative approach. In this study, we posited that combinatorial TSLPRCART and ruxolitinib would have superior activity and first validated potent TSLPRCART-induced inhibition of leukemia proliferation in vitro in CRLF2-rearranged ALL cell lines and in vivo in Ph-like and DS-ALL patient-derived xenograft (PDX) models. However, simultaneous TSLPRCART/ruxolitinib or CD19CART/ruxolitinib treatment during initial CART expansion diminished T cell proliferation, blunted cytokine production, and/or facilitated leukemia relapse, which was abrogated by time-sequenced/delayed ruxolitinib co-exposure. Importantly, ruxolitinib co-administration prevented fatal TSLPRCART cytokine-associated toxicity in ALL PDX mice. Upon ruxolitinib withdrawal, TSLPRCART functionality recovered in vivo with clearance of subsequent ALL rechallenge. These translational studies demonstrate an effective two-pronged therapeutic strategy that mitigates acute CART-induced hyperinflammation and provides potential anti-leukemia 'maintenance' relapse prevention for CRLF2-rearranged Ph-like and DS-ALL.

Novel strategies to manage CAR-T cell toxicity

The immune-related adverse events associated with chimeric antigen receptor (CAR)-T cell therapy result in substantial morbidity as well as considerable cost to the health-care system, and can limit the use of these treatments. Current therapeutic strategies to manage immune-related adverse events include interleukin-6 receptor (IL-6R) blockade and corticosteroids. However, because these interventions do not always address the side effects, nor prevent progression to higher grades of adverse events, new approaches are needed. A deeper understanding of the cell types involved, and their associated signalling pathways, cellular metabolism and differentiation states, should provide the basis for alternative strategies. To preserve treatment efficacy, cytokine-mediated toxicity needs to be uncoupled from CAR-T cell function, expansion, long-term persistence and memory formation. This may be achieved by targeting CAR or independent cytokine signalling axes transiently, and through novel T cell engineering strategies, such as low-affinity CAR-T cells, reversible on-off switches and versatile adaptor systems. We summarize the current management of cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome, and review T cell- and myeloid cell-intrinsic druggable targets and cellular engineering strategies to develop safer CAR-T cells.

EASIX and m-EASIX predict CRS and ICANS in pediatric and AYA patients after CD19-CAR T-cell therapy

ABSTRACT

Cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are complications of CD19-directed chimeric antigen receptor (CD19-CAR) T-cell therapy. The Endothelial Activation and Stress Index (EASIX) and modified EASIX (m-EASIX) scores have been retrospectively proven to be predictive of CRS and ICANS in adult CAR T-cell recipients. However, these scores have not been evaluated in pediatric cohorts. We retrospectively report on 76 pediatric and adolescent and young adult (AYA) patients with relapsed/refractory B-cell acute lymphoblastic leukemia treated with CD19-CAR T cells at St. Jude Children's Research Hospital or Johns Hopkins Hospital. Data included patient, disease, and treatment characteristics. EASIX and m-EASIX scores were calculated at days -5 before, 0, and +3 after CAR T-cell infusion. CRS and ICANS occurred in 47 and 17 patients, respectively. At all evaluated time points, the median EASIX scores were higher for patients who developed severe CRS and any grade ICANS, and the median m-EASIX scores were higher in patients who developed severe CRS and severe ICANS than those with no/mild CRS/ICANS. Receiver operating characteristic curve analysis showed that both scores were strong predictors of CRS, especially severe CRS, at all time points. Any grade and severe ICANS were best predicted by both scores at day +3. m-EASIX uniformly outperformed EASIX, except for predicting any grade ICANS. Our results validate the potential utility of EASIX and m-EASIX scores for predicting CAR T-cell-related complications for pediatric and AYA patients.

How I treat postimmunotherapy relapsed B-ALL

ABSTRACT

Despite significant advancements in single-antigen targeted therapies for B-cell acute lymphoblastic leukemia (B-ALL), nonresponse and relapse persist as major challenges. Antigen escape after blinatumomab or CD19-directed chimeric antigen receptor (CAR) T cells (CD19-CAR), as CD19-negative B-ALL or lineage switch (LS) to acute myeloid leukemia, present diagnostic and treatment complexities. Given the poor outcomes for patients experiencing a postinfusion relapse, particularly those with loss of the target antigen, a strategic approach to diagnosis and treatment is imperative. In this discussion, we outline a systematic approach to managing postimmunotherapy events, categorized by CD19-positive relapse, CD19-negative relapse, and LS. We explore treatment modalities including CD19-CAR reinfusions, humanized CAR constructs, combinatorial strategies, and alternative antigen-targeted therapies, such as blinatumomab and inotuzumab. Challenges in diagnosis, particularly with antigen-escape, are addressed, highlighting the role of next-generation sequencing and multiparameter flow cytometry for myeloid marker monitoring.

Impact of pre-infusion disease burden on outcomes in pediatric relapsed/refractory B-cell lymphoblastic leukemia following anti-CD19 CAR T-cell therapy

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapies have demonstrated high efficacy in pediatric patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). Despite this success, the challenge of post-infusion relapse persists. In our study, we evaluate 116 children with R/R B-ALL who received anti-CD19 CAR T-cell therapy at our center. All patients were included in the response analysis and assessed for survival and toxicity. The CR rate was 98.3%, with 90.5% achieving minimal residual disease negative (MRD)- CR by day 28 (d28). The overall survival (OS) and event-free survival (EFS) were 69.3%±4.5% and 59.0%±4.6%, respectively, with a median follow-up duration of 47.9 months. The patients with pre-infusion MRD ≥ 1% was associated with lower 4-year OS (p = 0.006) and EFS (p = 0.027) comparing to those with MRD < 1%. The incidences of grade ≥ 3 cytokine release syndrome (CRS) and neurotoxicity were21.6 and 5.0%, respectively. Therefore, pre-infusion disease burden is a predictor of long-term outcome following anti-CD19 CAR T-cell therapy for pediatric R/R B-ALL.

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.

Cardiovascular toxicities associated with novel cellular immune therapies

ABSTRACT

Over the past decade, T-cell-directed therapies, including chimeric antigen receptor T-cell (CAR-T) and bispecific T-cell engager (BTE) therapies, have reshaped the treatment of an expanding number of hematologic malignancies, whereas tumor-infiltrating lymphocytes, a recently approved cellular therapy, targets solid tumor malignancies. Emerging data suggest that these therapies may be associated with a high incidence of serious cardiovascular toxicities, including atrial fibrillation, heart failure, ventricular arrhythmias, and other cardiovascular toxicities. The development of these events is a major limitation to long-term survival after these treatments. This review examines the current state of evidence, including reported incidence rates, risk factors, mechanisms, and management strategies of cardiovascular toxicities after treatment with these novel therapies. We specifically focus on CAR-T and BTE therapies and their relation to arrhythmia, heart failure, myocarditis, bleeding, and other major cardiovascular events. Beyond the relationship between cytokine release syndrome and cardiotoxicity, we describe other potential mechanisms and highlight key unanswered questions and future directions of research.

Evolving strategies for addressing CAR T-cell toxicities

The field of chimeric antigen receptor (CAR) T-cell therapy has grown from a fully experimental concept to now boasting a multitude of treatments including six FDA-approved products targeting various hematologic malignancies. Yet, along with their efficacy, these therapies come with side effects requiring timely and thoughtful interventions. In this review, we discuss the most common toxicities associated with CAR T-cells to date, highlighting risk factors, prognostication, implications for critical care management, patient experience optimization, and ongoing work in the field of toxicity mitigation. Understanding the current state of the field and standards of practice is critical in order to improve and manage potential toxicities of both current and novel CAR T-cell therapies as they are applied in the clinic.

Cytokines in hematopoietic cell transplantation and related cellular therapies

Cytokines are pleiotropic molecules involved in hematopoiesis, immune responses, infections, and inflammation. They play critical roles in hematopoietic cell transplantation (HCT) and immune effector cell (IEC) therapies, mediating both therapeutic and adverse effects. Thus, cytokines contribute to the immunopathology of graft-versus-host disease (GVHD), cytokine release syndrome (CRS), and immune effector cell-associated neurotoxicity syndrome (ICANS). This review examines cytokine functions in these contexts, their influence on engraftment and immune recovery post-transplantation, and their role in mediating toxicities. We focus on current and potential uses of cytokines to enhance engraftment and potentiate IEC therapies, as well as strategies to mitigate cytokine-mediated complications using cytokine blockers (e.g., tocilizumab, anakinra) and JAK inhibitors (e.g., ruxolitinib). We discuss new insights into GVHD physiology that have led to novel treatments, such as CSF1R blockade, which is effective in refractory chronic GVHD.

Early tocilizumab treatment was associated with survival benefits in hospitalized kidney transplants with severe COVID-19 infection: A prospective cohort study

BACKGROUND

The potential of Tocilizumab (TCZ) in preventing the cytokine storm caused by COVID-19 infection has been observed, while the survival benefits were inconclusive in solid-organ transplant recipients. We aimed to explore whether the timing of TCZ administration holds significance in the clinical course of COVID-19 infection and identify predicative factors of TCZ efficacy.

METHODS

We conducted a prospective cohort study between December 2022, and January 2023. Early TCZ use referred to administration within 6 days after symptoms onset, while late TCZ use indicated administration after 6 days. The primary endpoint was 30-day mortality.

RESULTS

Twenty-seven kidney transplant recipients with severe COVID-19 infection were enrolled, with 10 in the early use group and 17 in the late use group. In the early use group, ferritin, lactate dehydrogenase (LDH), C-reactive protein (CRP) and brain natriuretic peptide(BNP) levels had shown significant inhibitions comparing to the late use group, and those inflammatory cytokines demonstrated a noticeable decreasing trend after TCZ administration, whereas only CRP levels decreased in the late use group. The Kaplan-Meier survival curve demonstrated that the early use group had a higher likelihood of survival (P = 0.0078). Receiver Operating Characteristic (ROC) analyses revealed that the time from symptoms to TCZ use (AUC: 0.645), LDH (AUC: 0.803), CRP (AUC: 0.787), and IL-6 (AUC: 0.725) were potential predictive factors of TCZ efficacy. TCZ use within 6 days from symptoms onset, with CRP < 73.5 mg/L, LDH < 435.5 IU/L, and IL-6 < 103.5 pg/mL, had higher survival rates (P = 0.008, P = 0.009, P < 0.001, P < 0.001).

CONCLUSION

This study highlights the survival benefits of early TCZ use and the predicative role of cytokines levels in predicting TCZ efficacy in kidney transplant recipients with severe COVID-19 infection.

CAR-T Cells for the Treatment of Central Nervous System Tumours: Known and Emerging Neurotoxicities

The advent of chimeric antigen receptor (CAR)-T cells has recently changed the prognosis of relapsing/refractory diffuse large B-cell lymphomas, showing response rates as high as 60 to 80%. Common toxicities reported in the pivotal clinical trials include the cytokine release syndrome (CRS) and the Immune effector Cell-Associated Neurotoxicity Syndrome (ICANS), a stereotyped encephalopathy related to myeloid cell activation and blood-brain barrier dysfunction, presenting with a distinctive cascade of dysgraphia, aphasia, disorientation, attention deficits, vigilance impairment, motor symptoms, seizures, and diffuse brain oedema. The tremendous oncological efficacy of CAR-T cells observed in systemic B-cell malignancies is leading to their growing use in patients with primary or secondary central nervous system (CNS) lymphomas and in patients with solid tumours, including several CNS cancers. Early studies conducted in adult and paediatric patients with solid CNS tumours reported a distinct profile of neurotoxicity referred to as Tumour inflammation-associated neurotoxicity (TIAN), corresponding to local inflammation at the tumour site manifesting with focal neurological deficits or mechanical complications (e.g., obstructive hydrocephalus). The present review summarises available data on the efficacy and safety of CAR-T cells for solid and haematological CNS malignancies, emphasising known and emerging phenotypes, ongoing challenges, and future perspectives.

New insights into CAR T-cell hematological toxicities: manifestations, mechanisms, and effective management strategies

Chimeric antigen receptor (CAR) T-cell therapy represents a highly efficacious treatment modality demonstrated to enhance outcomes in patients afflicted with malignancies, particularly those enduring relapsed or refractory hematological malignancies. However, the escalating adoption of CAR T-cell therapy has unveiled several life-threatening toxicities, notably cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), infections, and hematological toxicities (HTs), thereby hindering the broad implementation of CAR T-cell therapy. HTs encompass a spectrum of adverse effects, including cytopenias, hemophagocytic lymphohistiocytosis (HLH), coagulopathies, and B-cell aplasia. While our comprehension of the underlying mechanisms governing CRS and ICANS is advancing, the intricate pathophysiology of HTs remains inadequately elucidated. Such knowledge gaps may precipitate suboptimal therapeutic decisions, potentially culminating in substantial medical resource depletion and detriment to patients' quality of life. In this comprehensive review, based on recent updated findings, we delineate various mechanisms contributing to HTs subsequent to CAR T-cell therapy, explicate manifestations of HTs, and proffer strategic interventions to mitigate this relevant clinical challenge.

[The new generations of CAR-T cells]

Chimeric antigen receptor (CAR)-T is one of the most promising modern cancer immunotherapies. In the recent years, impressive results have been obtained in the treatment of cancer which led to FDA approval for the treatment of liquid tumors. In this cell-based therapy, immune cells (e.g. T and NK cells) are engineered to express a synthetic receptor CAR to specifically recognize and eliminate cells expressing a target antigen. CAR has evolved through different generations aiming to boost its biological activity and overcome limitations such as low persistence, limited potency, life-threatening toxicity and inefficient activity against solid tumor. The present review provides an overview of the different CAR generations, starting from the 1st generation with limited cytotoxic activity until the latest generation, the 5th generation or new generation, developed to overcome various limitations of CAR T therapy. The current ongoing clinical trials in cancer and autoimmune diseases, and the limitation associated with CAR-T cells in cancer therapy, are also discussed.

Precision Medicine for Acute Lymphoblastic Leukemia in Children: A Review

The clinical outcome for children diagnosed with acute lymphoblastic leukemia is a testimony to the success of modern medicine. Over the past few decades, survival has climbed from ∼10% to >90% for certain subgroups. Yet, the outcome for those with relapsed disease is often poor, and survivors struggle with a multitude of healthcare issues, some of which are lifelong. In recent years, the advent of the widespread sequencing of tumors has made available patients with previously unrecognized subtypes of leukemia, who have the potential to benefit from the addition of targeted therapies. Indeed, the promise of precision medicine, encompassing a person's environment, genetics and lifestyle, is likely to have profound impact on further tailoring therapies that are likely to improve outcomes, diminish toxicity and ultimately pave the pathway for a healthier population.

Directed evolution-based discovery of ligands for in vivo restimulation of CAR-T cells

Chimeric antigen receptor (CAR) T cell therapy targeting CD19 elicits remarkable clinical efficacy in B-cell malignancies, but many patients relapse due to failed expansion and/or progressive loss of CAR-T cells. We recently reported a strategy to potently restimulate CAR-T cells in vivo, enhancing their functionality by administration of a vaccine-like stimulus comprised of surrogate peptide ligands for a CAR linked to a lymph node-targeting amphiphilic PEG-lipid (termed CAR-T-vax). Here, we demonstrate a general strategy to generate and optimize peptide mimotopes enabling CAR-T-vax generation for any CAR. Using the clinical CD19 CAR FMC63 as a test case, we employed yeast surface display to identify peptide binders to soluble IgG versions of FMC63, which were subsequently affinity matured by directed evolution. CAR-T vaccines using these optimized mimotopes triggered marked expansion of both murine CD19 CAR-T cells in a syngeneic model and human CAR-T cells in a humanized mouse model of B cell acute lymphoblastic leukemia (B-ALL), and enhanced control of leukemia progression. This approach thus enables vaccine boosting to be applied to any clinically-relevant CAR-T cell product.

Cardiovascular toxicities of immune therapies for cancer - a scientific statement of the Heart Failure Association (HFA) of the ESC and the ESC Council of Cardio-Oncology

The advent of immunological therapies has revolutionized the treatment of solid and haematological cancers over the last decade. Licensed therapies which activate the immune system to target cancer cells can be broadly divided into two classes. The first class are antibodies that inhibit immune checkpoint signalling, known as immune checkpoint inhibitors (ICIs). The second class are cell-based immune therapies including chimeric antigen receptor T lymphocyte (CAR-T) cell therapies, natural killer (NK) cell therapies, and tumour infiltrating lymphocyte (TIL) therapies. The clinical efficacy of all these treatments generally outweighs the risks, but there is a high rate of immune-related adverse events (irAEs), which are often unpredictable in timing with clinical sequalae ranging from mild (e.g. rash) to severe or even fatal (e.g. myocarditis, cytokine release syndrome) and reversible to permanent (e.g. endocrinopathies).The mechanisms underpinning irAE pathology vary across different irAE complications and syndromes, reflecting the broad clinical phenotypes observed and the variability of different individual immune responses, and are poorly understood overall. Immune-related cardiovascular toxicities have emerged, and our understanding has evolved from focussing initially on rare but fatal ICI-related myocarditis with cardiogenic shock to more common complications including less severe ICI-related myocarditis, pericarditis, arrhythmias, including conduction system disease and heart block, non-inflammatory heart failure, takotsubo syndrome and coronary artery disease. In this scientific statement on the cardiovascular toxicities of immune therapies for cancer, we summarize the pathophysiology, epidemiology, diagnosis, and management of ICI, CAR-T, NK, and TIL therapies. We also highlight gaps in the literature and where future research should focus.

Quadriparesis and paraparesis following chimeric antigen receptor T-cell therapy in children and adolescents

ABSTRACT

Immune effector cell-associated neurotoxicity syndrome (ICANS) is a common but potentially severe adverse event associated with chimeric antigen receptor T-cell (CART) therapy, characterized by the development of acute neurologic symptoms following CART infusion. ICANS encompasses a wide clinical spectrum typified by mild to severe encephalopathy, seizures, and/or cerebral edema. As more patients have been treated with CART, new ICANS phenomenology has emerged. We present the clinical course of 5 children who developed acute onset of quadriparesis or paraparesis associated with abnormal brain and/or spine neuroimaging after infusion of CD19- or CD22-directed CART, adverse events not previously reported in children. Orthogonal data from autopsy studies, cerebrospinal fluid (CSF) flow cytometry, and CSF proteomics/cytokine profiling demonstrated chronic white matter destruction, but a notable lack of inflammatory pathologic changes and cell populations. Instead, children with quadriparesis or paraparesis post-CART therapy had lower levels of proinflammatory cytokines, such as interferon gamma, CCL17, CCL23, and CXCL10, than those who did not develop quadriparesis or paraparesis. Taken together, these findings imply a noninflammatory source of this newly described ICANS phenomenon in children. The pathophysiology of some neurologic symptoms following CART may therefore have a more complex etiology than exclusive T-cell activation and excessive cytokine production.

Cytokine release syndrome after CAR T-cell therapy for B-cell acute lymphoblastic leukemia in children and young adolescents: storms make trees take deeper roots

INTRODUCTION

Chimeric antigen receptor (CAR) T-cells have revolutionized cancer treatment, showing significant success, including treatment of pediatric B-cell acute lymphoblastic leukemia (B-ALL). Despite their efficacy, cytokine release syndrome (CRS) emerges as a common early adverse effect that can be life threatening in severe cases, resulting from the immune system's targeted activation against tumors.

AREAS COVERED

This review concentrates on CRS in children and young adults undergoing CAR T-cell therapy for B-ALL. It explores CRS pathophysiology, clinical presentation, and incidence, emphasizing the importance of a consensus definition and grading to homogenize the treatment according to the severity of symptoms. We will discuss the standard of care treatment of CRS but also novel approaches. We will highlight the importance of managing CRS without compromising the efficacy of immune cell activation against tumors.

EXPERT OPINION

As CAR T-cell therapy in pediatric B-ALL become increasingly available and used, optimal management of CRS becomes increasingly important. Early recognition and timely management has improved. Further information will aid us to identify optimal timing of tocilizumab and corticosteroids. Continued bench research coupled with clinical studies and biomarker discovery will allow for valuable insights into CRS pathophysiology and patient and/or cell-targeted treatments.

The Kinetics of Inflammation-Related Proteins and Cytokines in Children Undergoing CAR-T Cell Therapy-Are They Biomarkers of Therapy-Related Toxicities?

CD19-targeted CAR-T cell therapy has revolutionized the treatment of relapsed/refractory (r/r) pre-B acute lymphoblastic leukemia (ALL). However, it can be associated with acute toxicities related to immune activation, particularly cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). Cytokines released from activated immune cells play a key role in their pathophysiology. This study was a prospective analysis of proinflammatory proteins and cytokines in children treated with tisagenlecleucel. Serial measurements of C-reactive protein, fibrinogen, ferritin, IL-6, IL-8, IL-10, IFNγ, and TNFα were taken before treatment and on consecutive days after infusion. The incidence of CRS was 77.8%, and the incidence of ICANS was 11.1%. No CRS of grade ≥ 3 was observed. All complications occurred within 14 days following infusion. Higher biomarker concentrations were found in children with CRS grade ≥ 2. Their levels were correlated with disease burden and CAR-T cell dose. While cytokine release syndrome was common, most cases were mild, primarily due to low disease burden before lymphodepleting chemotherapy (LDC). ICANS occurred less frequently but exhibited various clinical courses. None of the toxicities were fatal. All of the analyzed biomarkers rose within 14 days after CAR-T infusion, with most reaching their maximum around the third day following the procedure.

Riding the storm: managing cytokine-related toxicities in CAR-T cell therapy

The advent of chimeric antigen receptor T cells (CAR-T) has been a paradigm shift in cancer immunotherapeutics, with remarkable outcomes reported for a growing catalog of malignancies. While CAR-T are highly effective in multiple diseases, salvaging patients who were considered incurable, they have unique toxicities which can be life-threatening. Understanding the biology and risk factors for these toxicities has led to targeted treatment approaches which can mitigate them successfully. The three toxicities of particular interest are cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and immune effector cell-associated hemophagocytic lymphohistiocytosis (HLH)-like syndrome (IEC-HS). Each of these is characterized by cytokine storm and hyperinflammation; however, they differ mechanistically with regard to the cytokines and immune cells that drive the pathophysiology. We summarize the current state of the field of CAR-T-associated toxicities, focusing on underlying biology and how this informs toxicity management and prevention. We also highlight several emerging agents showing promise in preclinical models and the clinic. Many of these established and emerging agents do not appear to impact the anti-tumor function of CAR-T, opening the door to additional and wider CAR-T applications.

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 critical role of endothelial cell in the toxicity associated with chimeric antigen receptor T cell therapy and intervention strategies

Chimeric antigen receptor (CAR)-T cell therapy has shown promising results in patients with hematological malignancies. However, many patients still have poor prognoses or even fatal outcomes due to the life-threatening toxicities associated with the therapy. Moreover, even after improving the known influencing factors (such as number or type of CAR-T infusion) related to CAR-T cell infusion, the results remain unsatisfactory. In recent years, it has been found that endothelial cells (ECs), which are key components of the organization, play a crucial role in various aspects of immune system activation and inflammatory response. The levels of typical markers of endothelial activation positively correlated with the severity of cytokine release syndrome (CRS) and immune effector cell-associated neurotoxic syndrome (ICANS), suggesting that ECs are important targets for intervention and toxicity prevention. This review focuses on the critical role of ECs in CRS and ICANS and the intervention strategies adopted.

Reactions and adverse events induced by T-cell engagers as anti-cancer immunotherapies, a comprehensive review

T-cell engagers (TCE) are cancer immunotherapies that have recently demonstrated meaningful benefit for patients with hematological malignancies and solid tumors. The anticipated widespread use of T cell engagers poses implementation challenges and highlights the need for guidance to anticipate, mitigate, and manage adverse events. By mobilizing T-cells directly at the contact of tumor cells, TCE mount an obligatory and immediate anti-tumor immune response that could result in diverse reactions and adverse events. Cytokine release syndrome (CRS) is the most common reaction and is largely confined to the first drug administrations during step-up dosage. Cytokine release syndrome should be distinguished from infusion related reaction by clinical symptoms, timing to occurrence, pathophysiological aspects, and clinical management. Other common reactions and adverse events with TCE are immune effector Cell-Associated Neurotoxicity Syndrome (ICANS), infections, tumor flare reaction and cytopenias. The toxicity profiles of TCE and CAR-T cells have commonalities and distinctions that we sum-up in this review. As compared with CAR-T cells, TCE are responsible for less frequently severe CRS or ICANS. This review recapitulates terminology, pathophysiology, severity grading system and management of reactions and adverse events related to TCE.

Efficacy and Safety of Children With Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia After Anti-CD19 CAR T-Cell Therapy Without Bridging Transplantation

BACKGROUND

Anti-CD19 chimeric antigen receptor (CAR) T-cell therapies have demonstrated significant efficacy in achieving complete remission (CR) in pediatric patients with relapsed/refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). However, a considerable number of patients experience relapse within 1 year after CAR T-cell therapy, leading to an extremely poor prognosis, particularly in patients without bridging transplantation.

MATERIALS AND METHODS

In our study, we investigated 42 children with R/R B-ALL who underwent anti-CD19 CAR T-cell therapy without bridging transplantation at our center. All patients were included in the response analysis and evaluated for survival and toxicity.

RESULTS

The cohort that received the CAR T-cell infusion exhibited a 100% CR rate by day 28 (d28). The overall survival (OS) at 4 years was 61.3% ± 8.5%, and the event-free survival (EFS) was 55.9% ± 7.9%, with a median follow-up duration of 50.1 months. Minimal residual disease (MRD) ≥1% was associated with inferior outcomes, resulting in lower 4-year OS (P = .033) and EFS (P = .014) compared to MRD<1%. The incidences of grade ≥3 cytokine release syndrome (CRS) and neurotoxicity were 26.8% and 23.8%, respectively. Furthermore, MRD≥1% was identified as an independent factor associated with increased severity of CRS and occurrence of neurotoxicity.

CONCLUSION

These findings suggest that reducing the pre-infusion MRD could serve as an effective treatment strategy to enhance the outcomes of CAR T-cell therapy.

Development of a chimeric cytokine receptor that captures IL-6 and enhances the antitumor response of CAR-T cells

The efficacy of chimeric antigen receptor (CAR)-engineered T cell therapy is suboptimal in most cancers, necessitating further improvement in their therapeutic actions. However, enhancing antitumor T cell response inevitably confers an increased risk of cytokine release syndrome associated with monocyte-derived interleukin-6 (IL-6). Thus, an approach to simultaneously enhance therapeutic efficacy and safety is warranted. Here, we develop a chimeric cytokine receptor composed of the extracellular domains of GP130 and IL6RA linked to the transmembrane and cytoplasmic domain of IL-7R mutant that constitutively activates the JAK-STAT pathway (G6/7R or G6/7R-M452L). CAR-T cells with G6/7R efficiently absorb and degrade monocyte-derived IL-6 in vitro. The G6/7R-expressing CAR-T cells show superior expansion and persistence in vivo, resulting in durable antitumor response in both liquid and solid tumor mouse models. Our strategy can be widely applicable to CAR-T cell therapy to enhance its efficacy and safety, irrespective of the target antigen.

Mechanisms and management of CAR T toxicity

Chimeric antigen receptor (CAR) T cell therapies have dramatically improved treatment outcomes for patients with relapsed or refractory B-cell acute lymphoblastic leukemia, large B-cell lymphoma, follicular lymphoma, mantle cell lymphoma, and multiple myeloma. Despite unprecedented efficacy, treatment with CAR T cell therapies can cause a multitude of adverse effects which require monitoring and management at specialized centers and contribute to morbidity and non-relapse mortality. Such toxicities include cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, neurotoxicity distinct from ICANS, immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome, and immune effector cell-associated hematotoxicity that can lead to prolonged cytopenias and infectious complications. This review will discuss the current understanding of the underlying pathophysiologic mechanisms and provide guidelines for the grading and management of such toxicities.

Unraveling resistance mechanisms in anti-CD19 chimeric antigen receptor-T therapy for B-ALL: a novel in vitro model and insights into target antigen dynamics

BACKGROUND

Cellular immunotherapy, represented by the chimeric antigen receptor T cell (CAR-T), has exhibited high response rates, durable remission, and safety in vitro and in clinical trials. Unfortunately, anti-CD19 CAR-T (CART-19) treatment alone is prone to relapse and has a particularly poor prognosis in relapsed/refractory (r/r) B-ALL patients. To date, addressing or reducing relapse remains one of the research priorities to achieve broad clinical application.

METHODS

We manufactured second generation CART-19 cells and validated their efficacy and safety in vitro and in vivo. Through co-culture of Nalm-6 cells with short-term cultured CART-19 cells, CD19-negative Nalm-6 cells were detected by flow cytometry, and further investigation of the relapsed cells and their resistance mechanisms was evaluated in vitro.

RESULTS

In this study, we demonstrated that CART-19 cells had enhanced and specific antileukemic activities, and the survival of B-ALL mouse models after CART-19 treatment was significantly prolonged. We then shortened the culture time and applied the serum-free culture to expand CAR-T cells, followed by co-culturing CART-19 cells with Nalm-6 cells. Surprisingly, we observed the proliferation of CD19-negative Nalm-6 cells around 28 days. Identification of potential resistance mechanisms showed that the relapsed cells express truncated CD19 proteins with decreased levels and, more importantly, CAR expression was detected on the relapsed cell surface, which may ultimately keep them antigen-negative. Furthermore, it was validated that CART-22 and tandem CART-22/19 cells could effectively kill the relapsed cells, but neither could completely eradicate them.

CONCLUSIONS

We successfully generated CART-19 cells and obtained a CD19-negative refractory relapsed B-ALL cell line, providing new insights into the underlying mechanisms of resistance and a new in vitro model for the treatment of r/r B-ALL patients with low antigen density.

Reinfusion of CD19 CAR T cells for relapse prevention and treatment in children with acute lymphoblastic leukemia

ABSTRACT

Relapse after CD19-directed chimeric antigen receptor (CAR)-modified T cells remains a substantial challenge. Short CAR T-cell persistence contributes to relapse risk, necessitating novel approaches to prolong durability. CAR T-cell reinfusion (CARTr) represents a potential strategy to reduce the risk of or treat relapsed disease after initial CAR T-cell infusion (CARTi). We conducted a retrospective review of reinfusion of murine (CTL019) or humanized (huCART19) anti-CD19/4-1BB CAR T cells across 3 clinical trials or commercial tisagenlecleucel for relapse prevention (peripheral B-cell recovery [BCR] or marrow hematogones ≤6 months after CARTi), minimal residual disease (MRD) or relapse, or nonresponse to CARTi. The primary endpoint was complete response (CR) at day 28 after CARTr, defined as complete remission with B-cell aplasia. Of 262 primary treatments, 81 were followed by ≥1 reinfusion (investigational CTL019, n = 44; huCART19, n = 26; tisagenlecleucel, n = 11), representing 79 patients. Of 63 reinfusions for relapse prevention, 52% achieved CR (BCR, 15/40 [38%]; hematogones, 18/23 [78%]). Lymphodepletion was associated with response to CARTr for BCR (odds ratio [OR], 33.57; P = .015) but not hematogones (OR, 0.30; P = .291). The cumulative incidence of relapse was 29% at 24 months for CR vs 61% for nonresponse to CARTr (P = .259). For MRD/relapse, CR rate to CARTr was 50% (5/10), but 0/8 for nonresponse to CARTi. Toxicity was generally mild, with the only grade ≥3 cytokine release syndrome (n = 6) or neurotoxicity (n = 1) observed in MRD/relapse treatment. Reinfusion of CTL019/tisagenlecleucel or huCART19 is safe, may reduce relapse risk in a subset of patients, and can reinduce remission in CD19+ relapse.

Emerging Strategies for the Prevention of Immune Toxicities Associated with T cell-Engaging Cancer Therapies

SUMMARY

Immune-related toxicities including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) are common side effects of bispecific antibody and chimeric antigen receptor (CAR) T-cell therapies of hematologic malignancies. As anti-inflammatory therapy (the standard of care) is variably effective in mitigating these toxicities after onset, here we discuss emerging evidence for shifting the strategy from mitigation to prevention.

Current and emerging pharmacotherapies for cytokine release syndrome, neurotoxicity, and hemophagocytic lymphohistiocytosis-like syndrome due to CAR T cell therapy

INTRODUCTION

Chimeric antigen receptor (CAR) T cells have revolutionized the treatment of multiple hematologic malignancies. Engineered cellular therapies now offer similar hope to transform the management of solid tumors and autoimmune diseases. However, toxicities can be serious and often require hospitalization.

AREAS COVERED

We review the two chief toxicities of CAR T therapy, cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), and the rarer immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome. We discuss treatment paradigms and promising future pharmacologic strategies. Literature and therapies reviewed were identified by PubMed search, cited references therein, and review of registered trials.

EXPERT OPINION

Management of CRS and ICANS has improved, aided by consensus definitions and guidelines that facilitate recognition and timely intervention. Further data will define optimal timing of tocilizumab and corticosteroids, current foundations of management. Pathophysiologic understanding has inspired off-label use of IL-1 receptor antagonism, IFNγ and IL-6 neutralizing antibodies, and janus kinase inhibitors, with data emerging from ongoing clinical trials. Further strategies to reduce toxicities include novel pharmacologic targets and safety features engineered into CAR T cells themselves. As these potentially curative therapies are used earlier in oncologic therapy and even in non-oncologic indications, effective accessible strategies to manage toxicities are critical.

Optimizing CAR-T cell therapy in adults with B-cell acute lymphoblastic leukemia

Chimeric antigen receptor T-cell (CAR-T) therapy has demonstrated unprecedented success in the treatment of various hematologic malignancies including relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL). Currently, there are two FDA-approved CD19-directed CAR-T cell products for the treatment of adults with R/R B-ALL. Despite high remission rates following CD19 CAR-T cell therapy in R/R B-ALL, remission durability remains limited in most adult patients, with relapse observed frequently in the absence of additional consolidation therapy. Furthermore, the burden of CAR-T cell toxicity remains significant in adults with R/R B-ALL and further limits the wide utilization of this effective therapy. In this review, we discuss patient and disease factors that are linked to CAR-T cell therapy outcomes in R/R B-ALL and strategies to optimize durability of response to reduce relapse and mitigate toxicity in the adult population. We additionally discuss future approaches being explored to maximize the benefit of CAR-T in adults with B-ALL.

INSPIRED Symposium Part 3: Prevention and Management of Pediatric Chimeric Antigen Receptor T Cell-Associated Emergent Toxicities

Chimeric antigen receptor (CAR) T cell (CAR-T) therapy has emerged as a revolutionary cancer treatment modality, particularly in children and young adults with B cell malignancies. Through clinical trials and real-world experience, much has been learned about the unique toxicity profile of CAR-T therapy. The past decade brought advances in identifying risk factors for severe inflammatory toxicities, investigating preventive measures to mitigate these toxicities, and exploring novel strategies to manage refractory and newly described toxicities, infectious risks, and delayed effects, such as cytopenias. Although much progress has been made, areas needing further improvements remain. Limited guidance exists regarding initial administration of tocilizumab with or without steroids and the management of inflammatory toxicities refractory to these treatments. There has not been widespread adoption of preventive strategies to mitigate inflammation in patients at high risk of severe toxicities, particularly children. Additionally, the majority of research related to CAR-T toxicity prevention and management has focused on adult populations, with only a few pediatric-specific studies published to date. Given that children and young adults undergoing CAR-T therapy represent a unique population with different underlying disease processes, physiology, and tolerance of toxicities than adults, it is important that studies be conducted to evaluate acute, delayed, and long-term toxicities following CAR-T therapy in this younger age group. In this pediatric-focused review, we summarize key findings on CAR-T therapy-related toxicities over the past decade, highlight emergent CAR-T toxicities, and identify areas of greatest need for ongoing research.

Practice Preferences for Consolidative Hematopoietic Stem Cell Transplantation Following Tisagenlecleucel in Children and Young Adults with B Cell Acute Lymphoblastic Leukemia

Treatment with tisagenlecleucel (tisa-cel) achieves excellent complete remission rates in children and young adults with relapsed or refractory B cell acute lymphoblastic leukemia (B-ALL), but approximately 50% maintain long-term remission. Consolidative hematopoietic stem cell transplantation (cHSCT) is a potential strategy to reduce relapse risk, but it carries substantial short- and long-term toxicities. Additionally, several strategies for management of B cell recovery (BCR) and next-generation sequencing (NGS) positivity post-tisa-cel exist, without an accepted standard. We hypothesized that practice preferences surrounding cHSCT, as well as management of BCR and NGS positivity, varies across tisa-cel-prescribing physicians and sought to characterize current practice preferences. A survey focusing on preferences regarding the use of cHSCT, management of BCR, and NGS positivity was distributed to physicians who prescribe tisa-cel for children and young adults with B-ALL. Responses were collected from August 2022 to April 2023. Fifty-nine unique responses were collected across 43 institutions. All respondents prescribed tisa-cel for children and young adults. The clinical focus of respondents was HSCT in 71%, followed by leukemia/lymphoma in 24%. For HSCT-naive patients receiving tisa-cel, 57% of respondents indicated they made individualized decisions for cHSCT based on patient factors, whereas 22% indicated they would avoid cHSCT and 21% indicated they would pursue cHSCT when feasible. Certain factors influenced >50% of respondents towards recommending cHSCT (either an increased likelihood of recommending or always recommending), including preinfusion disease burden >25%, primary refractory B-ALL, M3 bone marrow following reinduction for relapse, KMT2A-rearranged B-ALL, history of blinatumomab nonresponse, and HSCT-naive status. Most respondents indicated they would pursue HSCT for HSCT-naive, total body irradiation (TBI) recipients with BCR before 6 months post-tisa-cel or with NGS positivity at 1 or 3 months post-tisa-cel, although there was variability in responses regarding whether to proceed to HSCT directly or provide intervening therapy prior to HSCT. Fewer respondents recommended HSCT for BCR or NGS positivity in patients with a history of HSCT, in noncandidates for TBI, and in patients with trisomy 21. The results of this survey indicate there exists significant practice variability regarding the use of cHSCT, as well as interventions for post-tisa-cel BCR or NGS positivity. These results highlight areas in which ongoing clinical trials could inform more standardized practice.

IL-6 Blockade in Cytokine Storm Syndromes

Interleukin-6 (IL-6) is a pro-inflammatory cytokine elevated in cytokine storm syndromes, including hemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS). It is also elevated in cytokine release syndrome (CRS) after immune activating cancer therapies such as chimeric antigen receptor (CAR) T-cells or bispecific T-cell engagers (BITEs) and in some patients after infection with SARS-CoV-2. The interaction of IL-6 with its receptor complex can happen in several forms, making effectively blocking this cytokine's effects clinically challenging. Fortunately, effective clinical agents targeting the IL-6 receptor (tocilizumab) and IL-6 directly (siltuximab) have been developed and are approved for use in humans. IL-6 blockade has now been used to safely and effectively treat several cytokine storm syndromes (CSS). Other methods of investigation in effective IL-6 blockade are underway.

Advancing Diagnostics and Therapy to Reach Universal Cure in Childhood ALL

Systemic combination chemotherapy and intrathecal chemotherapy markedly increased the survival rate of children with ALL. In the past two decades, the use of minimal (measurable) residual disease (MRD) measurements early in therapy improved risk group stratification with subsequent treatment intensifications for patients at high risk of relapse, and enabled a reduction of treatment for low-risk patients. The recent development of more sensitive MRD technologies may further affect risk stratification. Molecular genetic profiling has led to the discovery of many new subtypes and their driver genetic alterations. This increased our understanding of the biological basis of ALL, improved risk classification, and enabled implementation of precision medicine. In the past decade, immunotherapies, including bispecific antibodies, antibody-drug conjugates, and cellular therapies directed against surface proteins, led to more effective and less toxic therapies, replacing intensive chemotherapy courses and allogeneic stem-cell transplantation in patients with relapsed and refractory ALL, and are now being tested in newly diagnosed patients. It has taken 50-60 years to increase the cure rate in childhood ALL from 0% to 90% by stepwise improvements in chemotherapy. This review provides an overview of how the developments over the past 10-15 years mentioned above have significantly changed the diagnostic and treatment approach in ALL, and discusses how the integrated use of molecular and immunotherapeutic insights will very likely direct efforts to cure those children with ALL who are not cured today, and improve the quality of life for survivors who should have decades of life ahead. Future efforts must focus on making effective, yet very expensive, new technologies and therapies available to children with ALL worldwide.

[Effect of early tocilizumab intervention on patients with cytokine release syndrome following chimeric antigen receptor T cell therapy]

Objective: This study aimed to evaluate the effect of early tocilizumab intervention to relieve cytokine release syndrome (CRS) following chimeric antigen receptor T cell (CAR-T) therapy. Methods: Twenty-two patients with acute lymphoblastic leukemia who received tocilizumab to relieve CRS response after CAR-T cell infusion in our research center from October 2015 to July 2021 were retrospectively analyzed. According to the timing of tocilizumab intervention, patients were divided into the conventional and early intervention groups. Patients who received tocilizumab treatment after sustained high fever for 4 h were included in the early intervention group. The clinical data, CRS grade, and event-free survival (EFS) between the two groups were evaluated. Results: Compared with patients who used tocilizumab after severe CRS, no patients in the early intervention group died from CRS, and there was no increased risk of neurotoxicity. Eleven patients (84.62%) achieved complete remission with minimal residual lesions. The median EFS of patients in the early intervention and conventional groups was 2 (95% CI 0-5) and 7 (95% CI 3-11) months, respectively. Conclusion: Early tocilizumab intervention in patients with CRS reduces severe CRS and provides a more optimized therapeutic strategy for CRS caused by CAR-T cell therapy.

The Current State of Chimeric Antigen Receptor T Cell Therapy for B Lymphoblastic Leukemia

Over the past decade, CAR T cell therapy has transformed the treatment of relapsed or refractory B-ALL in children and adults. CD19-directed CAR T cells can induce complete remissions in a large majority of patients with B-ALL, and up to half of these patients will go on to maintain durable remissions. However, significant challenges remain for patients who relapse or do not respond. This review will discuss the history of CAR T cell therapy for B-ALL, the treatment considerations for CAR T cell recipients, and current clinical trials and future directions for CAR T cell therapy in B-ALL.

Four challenges to CAR T cells breaking the glass ceiling

Cell-based therapies using chimeric antigen receptor T cells (CAR T) have had dramatic efficacy in the clinic and can even mediate curative responses in patients with hematologic malignancies. As living drugs, engineered cells can still be detected in some patients even years after the original infusion. The excitement around the cell therapy field continues to expand as recent reports have shown that CAR T cells can induce remission in patients with autoimmune disease. While these promising advances in the field garner hope for wide-spread utility of CAR T therapies across diseases, several roadblocks exist that currently limit the access and efficacy of this therapy in the clinic. Herein, we will discuss four major obstacles that the CAR T field faces, including toxicity, identifying tumor-specific antigens, improving function in solid tumors, and reducing manufacturing complexity and cost. CAR T cells have potential for a multitude of diseases, but these glass ceilings will need to be broken in order to improve clinical responses and make this potentially life-saving therapy accessible to a larger patient population.

INSPIRED Symposium Part 2: Prevention and Management of Relapse Following Chimeric Antigen Receptor T Cell Therapy for B Cell Acute Lymphoblastic Leukemia

Although CD19-directed chimeric antigen receptor (CAR) T cell therapy (CAR-T) for relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) has been transformative in inducing and sustaining remission, relapse rates remain unacceptably high, with approximately 50% of children and young adults experiencing relapse within the first year postinfusion. Emerging strategies to extend the durability of remission involve the use of prognostic biomarkers to identify those at high risk of relapse or incorporate strategies aimed to enhancing functional CAR T cell persistence. Nonetheless, with antigen loss/down-regulation or evolution to lineage switch as major mechanisms of relapse, optimizing single antigen targeting alone is insufficient. Here, with a focus on relapse prevention strategies, including postinfusion surveillance and treatment approaches being explored to optimize post-CAR-T management (eg, combinatorial antigen targeting strategies, preemptive hematopoietic cell transplantation), we review the current state of the art in the prevention and management of post CAR-T relapse. We highlight the advancements in the field and identify gaps in the literature to guide future research in optimizing the prevention and management of post-CAR-T relapse in children and young adults with B-ALL.

CAR T-Cells for the Treatment of B-Cell Acute Lymphoblastic Leukemia

B-cell acute lymphoblastic leukemia (B-ALL) is the most common subtype of acute leukemia in the pediatric population. The prognosis and treatment of B-ALL have dramatically improved over the past decade with the adoption of intensive and prolonged combination chemotherapy regimens. The advent of novel immunologic agents such as blinatumomab and inotuzumab has changed the treatment landscape of B-ALL. However, patients have continued to relapse, raising the need for novel therapies. Chimeric antigen receptor (CAR) T-cells have achieved a milestone in the treatment of B-ALL. Two CD19-targeting CAR T-cells were approved by the Food and Drug Administration and the European Medicines Agency for the treatment of relapsed and/or refractory B-ALL. In this review, we review the available data regarding CD19-targeting CAR T-cells with their safety profile as well as the mechanism of resistance to these agents and the way to overcome this resistance.