Clinical and Biological Correlates of Neurotoxicity Associated with CAR T-cell Therapy in Patients with B-cell Acute Lymphoblastic Leukemia

Biomarkers associated with blinatumomab outcomes in acute lymphoblastic leukemia

This study aimed to identify biomarkers for clinical outcomes in a phase 3 clinical study of blinatumomab or chemotherapy in adults with Philadelphia chromosome-negative relapsed/refractory B-cell precursor acute lymphoblastic leukemia. Patients were randomized 2:1 to receive blinatumomab, a BiTE^® therapy, for 4 weeks (9 μg/day cycle 1 week 1, 28 μg/day thereafter) every 6 weeks, or chemotherapy. Baseline blood samples were evaluated to identify biomarkers prognostic (both treatment groups) or predictive (either treatment groups) for overall survival, event-free survival, hematologic remission, minimal residual disease (MRD) response, duration of response, or adverse events. Baseline values were balanced between treatment groups. Prognostic biomarkers were platelets, tumor burden, and percentage of T cells: each 1-log increase in platelets at baseline was prognostic for improved 6-month survival; lower tumor burden was prognostic for hematologic remission; and a higher percentage of CD3⁺ T-cells was prognostic for MRD response. Consistent with the BiTE mechanism of action, higher percentage of CD45⁺ CD3⁺ CD8⁺ T cells was associated with hematologic remission following blinatumomab. No examined biomarkers were significant for the risk of grade ≥3 adverse events. Incorporating baseline biomarkers into future studies may help to identify subgroups most likely to benefit from blinatumomab.

A Review of Acute and Long-Term Neurological Complications Following Haematopoietic Stem Cell Transplant for Paediatric Acute Lymphoblastic Leukaemia

Despite advances in haematopoietic stem cell transplant (HSCT) techniques, the risk of serious side effects and complications still exists. Neurological complications, both acute and long term, are common following HSCT and contribute to significant morbidity and mortality. The aetiology of neurotoxicity includes infections and a wide variety of non-infectious causes such as drug toxicities, metabolic abnormalities, irradiation, vascular and immunologic events and the leukaemia itself. The majority of the literature on this subject is focussed on adults. The impact of the combination of neurotoxic drugs given before and during HSCT, radiotherapy and neurological complications on the developing and vulnerable paediatric and adolescent brain remains unclear. Moreover, the age-related sensitivity of the nervous system to toxic insults is still being investigated. In this article, we review current evidence regarding neurotoxicity following HSCT for acute lymphoblastic leukaemia in childhood. We focus on acute and long-term impacts. Understanding the aetiology and long-term sequelae of neurological complications in children is particularly important in the current era of immunotherapy for acute lymphoblastic leukaemia (such as chimeric antigen receptor T cells and bi-specific T-cell engager antibodies), which have well-known and common neurological side effects and may represent a future treatment modality for at least a fraction of HSCT-recipients.

CAR-T cell therapy and infection: a review

Introduction: Chimeric antigen receptor T-cell therapy (CAR-T cell therapy) is a novel immunotherapy with promising results in the treatment of relapsed or refractory B cell malignancies. Patients undergoing CAR-T cell therapy are at increased risk of infection due to prior immunosuppression, lymphodepleting chemotherapy, treatment of unique toxicities with tocilizumab and/or steroids, on-target effects of hypogammaglobulinaemia, and prolonged cytopenias.Areas covered: A narrative review of infections (PubMed, August 2020) occurring in patients undergoing CAR-T cell therapy is described, and the evidence for infection prevention strategies is presented.Expert commentary: The rapid adoption of CAR-T cell therapy into clinical practice presents many challenges for the diagnosis, management, and prevention of infection. Ongoing surveillance of the spectrum of infectious complications and effectiveness of prophylaxis is required to support safe and effective patient care.

Lymphodepletion strategies to potentiate adoptive T-cell immunotherapy - what are we doing; where are we going?

INTRODUCTION

Adoptive immunotherapy of cancer has evolved from the use of ex vivo expanded lymphokine-activated killer cells and tumor-infiltrating lymphocytes to an increasing array of approaches involving genetically engineered T-cells. A pivotal advance in the enablement of these therapies has been the conditioning of patients with lymphodepleting chemotherapy.A broad range of lymphodepleting regimens has been employed in an effort to improve response rates, without any single consistent approach having emerged. Only a limited number of studies involving small numbers of patients has directly compared two or more regimens, making it challenging to infer which are the preferred agents and dosing schedules. This difficulty is compounded by the fact that both response rate and toxicity appear to be disease-, patient- and T-cell product specific.

EXPERT OPINION

This article surveys clinical experience with lymphodepleting regimens that have been used in conjunction with adoptive T-cell immunotherapy, focussing in particular on studies where different approaches have been employed. Harnessing this limited and evolving clinical experience, we set out to provide potential insights into how an optimal balance may be achieved between efficacy and safety. Intermediate dose fludarabine-based regimens are emerging as an increasingly popular option in an attempt to achieve this goal, although further studies are required to provide definitive evidence.

Overcoming key challenges in cancer immunotherapy with engineered T cells

PURPOSE OF REVIEW

A number of clinical trials are currently testing chimeric antigen receptor (CAR) and T cell receptor (TCR) engineered T cells for the treatment of haematologic malignancies and selected solid tumours, and CD19-CAR-T cells have produced impressive clinical responses in B-cell malignancies. Here, we summarize the current state of the field, highlighting the key aspects required for the optimal application of CAR and TCR-engineered T cells for cancer immunotherapy.

RECENT FINDINGS

Toxicities, treatment failure and disease recurrence have been observed at different rates and kinetics. Several strategies have been designed to overcome these hurdles: the identification and combination of known and new antigens, together with the combination of immunotherapeutic and classical approaches may overcome cancer immune evasion. New protocols for genetic modification and T cell culture may improve the overall fitness of cellular products and their resistance to hostile tumour immunomodulatory signals. Finally, the schedules of T cell administration and toxicity management have been adapted to improve the safety of this transformative therapeutic approach.

SUMMARY

In order to develop effective adoptive T cell treatments for cancer, therapeutic optimization of engineered CAR and TCR T cells is crucial, by simultaneously focusing on intrinsic and extrinsic factors. This review focuses on the innovative approaches designed and tested to overcome the hurdles encountered so far in the clinical practice, with new excitement on novel laboratory insights and ongoing clinical investigations.

Investigational drugs for the treatment of diffuse large B-cell lymphoma

Introduction: Diffuse large B cell lymphoma (DLBCL) is the most frequent lymphoma in adults. 30-40% DLBCL eventually relapse and 10% are primary refractory, posing an unmet clinical need, especially in patients not eligible for hematopoietic stem cell transplant. Knowledge of DLBCL molecular pathogenesis has identified druggable molecular pathways. Surface antigens can be targeted by novel antibodies and innovative cell therapies. Areas covered: This review illuminates those investigational drugs and cell therapies that are currently in early phase clinical trials for the treatment of DLBCL. New small molecules that modulate the pathways involved in the molecular pathogenesis of DLBCL, monospecific and bispecific monoclonal antibodies, drug-immunoconjugates, and cellular therapies are placed under the spotlight. A futuristic perspective concludes the paper. Expert opinion: A precision medicine strategy based on robust molecular predictors of outcome is desirable in the development of investigational small molecules for DLBCL. Novel monoclonal and bispecific antibodies may be offered to (i) relapsed/refractory patients ineligible for CAR-T cells because of comorbidities, and (ii) younger patients before CAR-T cell infusion to reduce a high tumor burden. A focus on the optimal sequencing of the emerging DLBCL drugs is appropriate and necessary.

Novel Therapies in the Treatment of Adult Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

Acute lymphoblastic leukemia (ALL) is a rare hematologic malignancy. Advances in multi-agent chemotherapy have resulted in dramatic improvements in the number of pediatric cases that result in a cure; however, until recently, treatment options for older adults or patients with relapsed and refractory disease were extremely limited. This review seeks to describe in greater detail a number of emerging novel treatment modalities recently approved for this cancer.

RECENT FINDINGS

In this review, we discuss a number of recently approved novel therapies for ALL, including new approaches with targeted tyrosine kinase inhibitors, novel immune-based therapies including the bispecific antibody blinatumomab and the antibody-drug conjugate inotuzumab ozogamicin, and the role of cellular therapeutics such as chimeric antigen receptor (CAR) T cells. We also discuss the impact that advances in diagnostics and disease classification and monitoring have had on treatment. A number of advances in ALL have resulted in dramatic changes to the treatment landscape and therapeutic options both at the time of diagnosis and in salvage. These findings are reshaping our treatment paradigms throughout the course of disease.

Advances in Supportive Care for Acute Lymphoblastic Leukemia

PURPOSE OF REVIEW

Tremendous advances have been made in the treatment armamentarium for acute lymphoblastic leukemia in recent years, which have substantially improved outcomes for these patients. At the same time, unique toxicities have emerged, and without early intervention, are life-threatening. This article will review the novel therapies in acute leukemias and highlight the clinically relevant supportive care advances.

RECENT FINDINGS

The American Society for Transplantation and Cellular Therapy (ASTCT) has put forth the most recent recommendations in managing the cytokine release syndrome and neurotoxicity after chimeric antigen receptor T cells (CAR-T) and blinatumomab. The hepatic injury incurred by inotuzumab, and the vascular toxicity of tyrosine kinase inhibitors, other relatively novel agents, require subspecialist intervention and multidisciplinary care. Asparaginase, a long-established and key element of pediatric regimens, has made a comeback in the young adult leukemia population. Updated guidelines have been outlined for management of asparaginase thrombotic complications. Lastly, although there have been few changes in the applications of growth factor, antimicrobial prophylaxis, and management of neuropathy, these encompass exceedingly important aspects of care. While the rapidly changing treatment paradigms for acute lymphoblastic leukemia have transformed leukemia-specific outcomes, treatment emergent toxicities have forced much necessary attention to better definitions of these toxicities and on improving supportive care guidelines in acute lymphoblastic leukemia.

The International Prognostic Index Is Associated with Outcomes in Diffuse Large B Cell Lymphoma after Chimeric Antigen Receptor T Cell Therapy

CD19-targeted chimeric antigen receptor (CAR) T cells have shown excellent activity against relapsed and refractory (R/R) diffuse large B cell lymphoma (DLBCL). CAR T cell therapy is associated with early toxicities, including cytokine release syndrome and neurotoxicity. The incidence and severity of these toxicities has been associated in part with baseline disease and patient characteristics, which also may impact overall survival (OS) and progression-free survival (PFS). However, there are limited data on patient selection and how to better predict toxicities or outcomes. Indexes used in patients with DLBCL, such as the International Prognostic Index (IPI and age-adjusted IPI [aaIPI]) and in transplantation recipients, such as the Hematopoietic Cell Transplantation Comorbidity Index (HCT-CI), have not been evaluated in this setting. Here we evaluated 4 indices- IPI, aaIPI, HCT-CI, and the Charlson Comorbidity Index (CCI)-and their associations with early CAR T cell related-toxicities and outcomes. We demonstrated an association between high-risk IPI or aaIPI and inferior PFS in patients with R/R DLBCL treated with CAR T cell therapy. We also found an association between aaIPI and IPI with OS and neurotoxicity, respectively. CCI was not associated with toxicities or outcomes, and owing to the small sample size, we could not draw a conclusion regarding associations with the HCT-CI. Both the IPI and aaIPI are widely used tools that can now provide better information to guide selection of patients who would best benefit from CD19 CAR T cell therapy.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immune effector cell-related adverse events

Immune effector cell (IEC) therapies offer durable and sustained remissions in significant numbers of patients with hematological cancers. While these unique immunotherapies have improved outcomes for pediatric and adult patients in a number of disease states, as 'living drugs,' their toxicity profiles, including cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS), differ markedly from conventional cancer therapeutics. At the time of article preparation, the US Food and Drug Administration (FDA) has approved tisagenlecleucel, axicabtagene ciloleucel, and brexucabtagene autoleucel, all of which are IEC therapies based on genetically modified T cells engineered to express chimeric antigen receptors (CARs), and additional products are expected to reach marketing authorization soon and to enter clinical development in due course. As IEC therapies, especially CAR T cell therapies, enter more widespread clinical use, there is a need for clear, cohesive recommendations on toxicity management, motivating the Society for Immunotherapy of Cancer (SITC) to convene an expert panel to develop a clinical practice guideline. The panel discussed the recognition and management of common toxicities in the context of IEC treatment, including baseline laboratory parameters for monitoring, timing to onset, and pharmacological interventions, ultimately forming evidence- and consensus-based recommendations to assist medical professionals in decision-making and to improve outcomes for patients.

Cytokines in CAR T Cell-Associated Neurotoxicity

Chimeric antigen receptor (CAR) T cells provide new therapeutic options for patients with relapsed/refractory hematologic malignancies. However, neurotoxicity is a frequent, and potentially fatal, complication. The spectrum of manifestations ranges from delirium and language dysfunction to seizures, coma, and fatal cerebral edema. This novel syndrome has been designated immune effector cell-associated neurotoxicity syndrome (ICANS). In this review, we draw an arc from our current understanding of how systemic and potentially local cytokine release act on the CNS, toward possible preventive and therapeutic approaches. We systematically review reported correlations of secreted inflammatory mediators in the serum/plasma and cerebrospinal fluid with the risk of ICANS in patients receiving CAR T cell therapy. Possible pathophysiologic impacts on the CNS are covered in detail for the most promising candidate cytokines, including IL-1, IL-6, IL-15, and GM-CSF. To provide insight into possible final common pathways of CNS inflammation, we place ICANS into the context of other systemic inflammatory conditions that are associated with neurologic dysfunction, including sepsis-associated encephalopathy, cerebral malaria, thrombotic microangiopathy, CNS infections, and hepatic encephalopathy. We then review in detail what is known about systemic cytokine interaction with components of the neurovascular unit, including endothelial cells, pericytes, and astrocytes, and how microglia and neurons respond to systemic inflammatory challenges. Current therapeutic approaches, including corticosteroids and blockade of IL-1 and IL-6 signaling, are reviewed in the context of what is known about the role of cytokines in ICANS. Throughout, we point out gaps in knowledge and possible new approaches for the investigation of the mechanism, prevention, and treatment of ICANS.

Neurotoxicity of Cancer Therapies

PURPOSE OF REVIEW

This article reviews neurologic complications associated with chemotherapy, radiation therapy, antiangiogenic therapy, and immunotherapy.

RECENT FINDINGS

Cancer therapies can cause a wide range of neurologic adverse effects and may result in significant patient morbidity and mortality. Although some treatment-associated neurologic complications manifest acutely and are often reversible and transient, others occur with delayed onset, can be progressive, and are uniquely challenging to patient management. With an increase in multimodality and combination therapies, including targeted therapies and immunotherapies, and prolonged patient survival, novel and unique patterns of neurologic complications have emerged.

SUMMARY

Both conventional and novel cancer therapies can adversely affect the nervous system, thereby producing a wide range of neurologic complications. Increased awareness among neurologists and early recognition of cancer therapy-induced neurotoxic syndromes is critically important to minimize patient morbidity, prevent permanent injury, and improve patient outcomes.

CAR T cells vs allogeneic HSCT for poor-risk ALL

For subgroups of children with B-cell acute lymphoblastic leukemia (B-ALL) at very high risk of relapse, intensive multiagent chemotherapy has failed. Traditionally, the field has turned to allogeneic hematopoietic stem cell transplantation (HSCT) for patients with poor outcomes. While HSCT confers a survival benefit for several B-ALL populations, often HSCT becomes standard-of-care in subsets of de novo ALL with poor risk features despite limited or no data showing a survival benefit in these populations, yet the additive morbidity and mortality can be substantial. With the advent of targeted immunotherapies and the transformative impact of CD19-directed chimeric antigen receptor (CAR)-modified T cells on relapsed or refractory B-ALL, this approach is currently under investigation in frontline therapy for a subset of patients with poor-risk B-ALL: high-risk B-ALL with persistent minimal residual disease at the end of consolidation, which has been designated very high risk. Comparisons of these 2 approaches are fraught with issues, including single-arm trials, differing eligibility criteria, comparisons to historical control populations, and vastly different toxicity profiles. Nevertheless, much can be learned from available data and ongoing trials. We will review data for HSCT for pediatric B-ALL in first remission and the efficacy of CD19 CAR T-cell therapy in relapsed or refractory B-ALL, and we will discuss an ongoing international phase 2 clinical trial of CD19 CAR T cells for very-high-risk B-ALL in first remission.

Safety and clinical efficacy of BCMA CAR-T-cell therapy in multiple myeloma

Background

B-cell maturation antigen (BCMA)-targeted chimeric antigen receptor (CAR)-T-cell therapy is an emerging treatment option for multiple myeloma. The aim of this systematic review and meta-analysis was to determine its safety and clinical activity and to identify factors influencing these outcomes.

Methods

We performed a database search using the terms “BCMA,” “CAR,” and “multiple myeloma” for clinical studies published between 01/01/2015 and 01/01/2020. The methodology is further detailed in PROSPERO (CRD42020125332).

Results

Twenty-three different CAR-T-cell products have been used so far in 640 patients. Cytokine release syndrome was observed in 80.3% (69.0–88.2); 10.5% (6.8–16.0) had neurotoxicity. A higher neurotoxicity rate was reported in studies that included more heavily pretreated patients: 19.1% (13.3–26.7; I² = 45%) versus 2.8% (1.3–6.1; I² = 0%) (p < 0.0001). The pooled overall response rate was 80.5% (73.5–85.9); complete responses (CR) were observed in 44.8% (35.3–54.6). A pooled CR rate of 71.9% (62.8–79.6; I² = 0%) was noted in studies using alpaca/llama-based constructs, whereas it was only 18.0% (6.5–41.1; I² = 67%) in studies that used retroviral vectors for CAR transduction. Median progression-free survival (PFS) was 12.2 (11.4–17.4) months, which compared favorably to the expected PFS of 1.9 (1.5–3.7) months (HR 0.14; p < 0.0001).

Conclusions

Although considerable toxicity was observed, BCMA-targeted CAR-T-cell therapy is highly efficacious even in advanced multiple myeloma. Subgroup analysis confirmed the anticipated inter-study heterogeneity and identified potential factors contributing to safety and efficacy. The results of this meta-analysis may assist the future design of CAR-T-cell studies and lead to optimized BCMA CAR-T-cell products.

Role of blinatumomab, inotuzumab, and CAR T-cells: Which to choose and how to sequence for patients with relapsed disease

Recent approval of several novel agents has dramatically improved outcomes for patients with relapsed and refractory (R/R) B-cell acute lymphoblastic leukemia. Blinatumomab, a bi-specific T-cell engager targeted to CD3 and CD19, inotuzumab ozogamicin (InO), an antibody-drug conjugate to CD22, and tisagenlecleucel, a CD19 chimeric antigen receptor T-cell with a 4-1BB costimulatory domain, have all demonstrated impressive response rates in R/R B-ALL as compared to historic controls. However, important considerations when choosing among these novel agents include clinical features that may impact efficacy, such as relative disease burden, antigen expression, and T-cell function, as well as patient and disease characteristics that may contribute to risk of toxicity. In addition, suitability of the patient for hematopoietic stem cell transplant (HSCT) as well as patient preference must also be considered. This review will focus on factors to weigh when choosing an agent in the setting of R/R disease and important challenges moving forward.

A giant step forward: chimeric antigen receptor T-cell therapy for lymphoma

The combination of the immunotherapy (i.e., the use of monoclonal antibodies) and the conventional chemotherapy increases the long-term survival of patients with lymphoma. However, for patients with relapsed or treatment-resistant lymphoma, a novel treatment approach is urgently needed. Chimeric antigen receptor T (CAR-T) cells were introduced as a treatment for these patients. Based on recent clinical data, approximately 50% of patients with relapsed or refractory B-cell lymphoma achieved complete remission after receiving the CD19 CAR-T cell therapy. Moreover, clinical data revealed that some patients remained in remission for more than two years after the CAR-T cell therapy. Other than the CD19-targeted CAR-T, the novel target antigens, such as CD20, CD22, CD30, and CD37, which were greatly expressed on lymphoma cells, were studied under preclinical and clinical evaluations for use in the treatment of lymphoma. Nonetheless, the CAR-T therapy was usually associated with potentially lethal adverse effects, such as the cytokine release syndrome and the neurotoxicity. Therefore, optimizing the structure of CAR, creating new drugs, and combining CAR-T cell therapy with stem cell transplantation are potential solutions to increase the effectiveness of treatment and reduce the toxicity in patients with lymphoma after the CAR-T cell therapy.

CART Cell Toxicities: New Insight into Mechanisms and Management

T cells genetically engineered with chimeric antigen receptors (CART) have become a potent class of cancer immunotherapeutics. Numerous clinical trials of CART cells have revealed remarkable remission rates in patients with relapsed or refractory hematologic malignancies. Despite recent clinical success, CART cell therapy has also led to significant morbidity and occasional mortality from associated toxicities. Cytokine release syndrome (CRS) and Immune effector cell-associated neurotoxicity syndrome (ICANS) present barriers to the extensive use of CART cell therapy in the clinic. CRS can lead to fever, hypoxia, hypotension, coagulopathies, and multiorgan failure, and ICANS can result in cognitive dysfunction, seizures, and cerebral edema. The mechanisms of CRS and ICANS are becoming clearer, but many aspects remain unknown. Disease type and burden, peak serum CART cell levels, CART cell dose, CAR structure, elevated pro-inflammatory cytokines, and activated myeloid and endothelial cells all contribute to CART cell toxicity. Current guidelines for the management of toxicities associated with CART cell therapy vary between clinics, but are typically comprised of supportive care and treatment with corticosteroids or tocilizumab, depending on the severity of the symptoms. Acquiring a deeper understanding of CART cell toxicities and developing new management and prevention strategies are ongoing. In this review, we present findings in the mechanisms and management of CART cell toxicities.

Complications after CD19+ CAR T-Cell Therapy

Simple Summary

CD19+ Chimeric antigen receptor (CAR) T-cells are used against CD19+ hematologic malignancies, such as high-grade B-cell lymphoma and acute lymphoblastic leukemia. Since this is a relatively new treatment approach, not all potential side effects are well described, and the underlying pathobiology is often not well defined. Here, we summarize current data on the incidence and the current management of CD19+ CAR T-cell complications. We discuss frequently occurring toxicities and we highlight evidence for the occurrence of rarer side effects affecting different organ systems. In addition, we highlight new findings that shed light on the pathophysiology of CAR T-cell-related complications.

Abstract

Clinical trials demonstrated that CD19+ chimeric antigen receptor (CAR) T-cells can be highly effective against a number of malignancies. However, the complete risk profile of CAR T-cells could not be defined in the initial trials. Currently, there is emerging evidence derived from post approval studies in CD19+ CAR T-cells demonstrating both short-term and medium-term effects, which were unknown at the time of regulatory approval. Here, we review the incidence and the current management of CD19+ CAR T-cell complications. We highlight frequently occurring events, such as cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, cardiotoxicity, pulmonary toxicity, metabolic complications, secondary macrophage-activation syndrome, and prolonged cytopenia. Furthermore, we present evidence supporting the hypothesis that CAR T-cell-mediated toxicities can involve any other organ system and we discuss the potential risk of long-term complications. Finally, we discuss recent pre-clinical and clinical data shedding new light on the pathophysiology of CAR T-cell-related complications.

Gene Modified CAR-T Cellular Therapy for Hematologic Malignancies

With advances in the understanding of characteristics of molecules, specific antigens on the surface of hematological malignant cells were identified and multiple therapies targeting these antigens as neoplasm treatments were developed. Among them, chimeric antigen receptor (CAR) T-cell therapy, which got United States Food and Drug Administration (FDA) approval for relapsed/refractory (r/r) diffuse large B-cell lymphoma (DLBCL) as well as for recurrent acute lymphoblastic leukemia (ALL) within the past five years, and for r/r mantle cell lymphoma (MCL) this year, represents one of the most rapidly evolving immunotherapies. Nevertheless, its applicability to other hematological malignancies, as well as its efficacy and persistence are fraught with clinical challenges. Currently, more than one thousand clinical trials in CAR T-cell therapy are ongoing and its development is changing rapidly. This review introduces the current status of CAR T-cell therapy in terms of the basic molecular aspects of CAR T-cell therapy, its application in hematological malignancies, adverse reactions during clinical use, remaining challenges, and future utilization.

The Application of CAR-T Cells in Haematological Malignancies

Chimeric antigen receptor (CAR)-T cells (CART) remain one of the most advanced and promising forms of adoptive T-cell immunotherapy. CART represent autologous, genetically engineered T lymphocytes expressing CAR, i.e. fusion proteins that combine components and features of T cells as well as antibodies providing their more effective and direct anti-tumour effect. The technology of CART construction is highly advanced in vitro and every element of their structure influence their mechanism of action in vivo. Patients with haematological malignancies are faced with the possibility of disease relapse after the implementation of conventional chemo-immunotherapy. Since the most preferable result of therapy is a partial or complete remission, cancer treatment regimens are constantly being improved and customized to individual patients. This individualization could be ensured by CART therapy. This paper characterized CART strategy in details in terms of their structure, generations, mechanism of action and published the results of clinical trials in haematological malignancies including acute lymphoblastic leukaemia, diffuse large B-cell lymphoma, chronic lymphocytic leukaemia and multiple myeloma.

Filgrastim associations with CAR T-cell therapy

Little is known about the benefits and risks of myeloid growth factor administration after chimeric antigen receptor (CAR) T‐cell therapy for diffuse large B‐cell lymphoma (DLBCL). We present a retrospective analysis among 22 relapsed/refractory DLBCL patients who received CAR T‐cell therapy with axicabtagene ciloleucel. Filgrastim was administered by physician discretion to seven patients (31.8%), and the median duration of neutropenia after lymphodepleting therapy was significantly shorter for those patients who received filgrastim (5 vs 15 days, P = .016). Five patients (22.7%) developed infection in the 30 days post‐CAR T‐cell therapy with three patients being Grade 3 or higher. There was no difference in the incidence and severity of infection based on filgrastim use (P = .274, P = .138). Among the seven patients that received filgrastim, six patients (85.7%) and four patients (57.1%) had evidence of cytokine release syndrome (CRS) and immune effector cell‐associated neurotoxicity syndrome (ICANS), respectively. Among the 15 patients that did not receive filgrastim, 8 patients (53.3%) and 7 patients (46.7%) had evidence of CRS and ICANS, respectively. There was no significant difference in the incidence of developing CRS or ICANS between the group of patients that received filgrastim and those that did not (P = .193, P = .647). However, there was a significant increase in the severity of CRS for patients that received filgrastim compared to those that did not (P = .042). Filgrastim administration after CAR T‐cell therapy may lead to an increase in severity of CRS without decreasing infection rates.

What's new

Chimeric antigen receptor (CAR) T‐cell therapy in patients with relapsed/refractory diffuse large B‐cell lymphoma is limited by associated cytokine release syndrome, neurotoxicity, and cytopenias. Little is known about the benefits and risks of myeloid growth factor administration in CAR T‐cell therapy. This retrospective analysis reveals a significant increase in the severity but not the incidence of cytokine release syndrome in those patients that received filgrastim. There was no association of filgrastim use with the severity or incidence of neurotoxicity and infection rates. The findings call for caution in the use of myeloid growth factors in patients undergoing CAR T‐cell therapy.

Description of neurotoxicity in a series of patients treated with CAR T-cell therapy

Chimeric antigen receptor-modified T (CAR T) cell therapy is a highly promising treatment for haematological malignancies but is frequently associated with cytokine release syndrome and neurotoxicity. Between July 2018 and July 2019, all patients treated with CD19-targeted CAR T-cell therapy for relapsing lymphoma were followed-up longitudinally to describe neurological symptoms and their evolution over time. Four different French centres participated and 84 patients (median age 59 years, 31% females) were included. Neurotoxicity, defined as the presence of at least one neurological symptom appearing after treatment infusion, was reported in 43% of the patients. The median time to onset was 7 days after infusion with a median duration of 6 days. More than half of the patients (64%) had grade 1–2 severity and 34% had grade 3–4. CRS was observed in 80% of all patients. The most frequent neurological symptoms were cognitive signs, being severe in 36%, and were equally distributed between language disorders and cognitive disorders without language impairment. Non-pyramidal motor disorders, severe in 11%, were reported in 42% of the patients. Elevation of C-reactive protein (CRP) within 4 days after treatment was significantly correlated with the occurrence of grade 3–4 neurotoxicity. Although sometimes severe, neurotoxicity was almost always reversible. The efficacy of steroids and antiepileptic drugs remains unproven in the management of neurotoxicity. Neurotoxicity associated with CAR T-cell therapies occurs in more than 40% of patients. The clinical pattern is heterogeneous but cognitive disorders (not limited to language disorders) and, to a minor degree, non-pyramidal motor disorders, appeared as a signature of severe neurotoxicity.

Neurological updates: neurological complications of CAR-T therapy

Chimeric antigen receptor (CAR)-expressing T cells now offer an effective treatment option for people with previously refractory B cell malignancies and are under development for a wide range of other tumours. However, neurological toxicity is a common complication of CAR-T cell therapy, seen in over 50% of recipients in some cohorts. Since 2018, the term immune effector cell-associated neurotoxicity syndrome (ICANS) has been used to describe and grade neurotoxicity seen after CAR-T cells and other similar therapies. ICANS following CAR-T therapy is usually self-limiting but can necessitate admission to the intensive care unit and is rarely fatal. As CAR-T therapies enter routine clinical practice, it is important for neurologists to be aware of the nature of neurological complications. Here, we summarise the clinical manifestations, mechanisms, investigations and recommended treatment of CAR-T-related neurotoxicity, focusing on the licensed CD19 products.

Neurological complications of pediatric cancer

Both the onset of various malignancies as well as the treatment of cancer can lead to neurologic symptoms which can be difficult to diagnose. In this review, we highlight the varied ways in which neurologic sequelae of cancer and its treatment manifest in children. Initial neurologic presentation may be secondary to mass effect or to immune-mediated paraneoplastic syndromes. Treatment effects on the nervous system may arise from surgery, chemotherapy, radiation, or bone marrow transplantation. In addition, the rapidly expanding field of immunotherapies for cancer has generated numerous new approaches to eradicating cancer including monoclonal antibodies, checkpoint inhibitors, and chimeric antigen receptor T cells (CAR-T cells), which have neurologic side effects mediated by immune responses that are also being recognized. Here we review common consult questions to the neurologist and our general approach to these scenarios including altered mental status, headaches, seizures, and sensorimotor complaints, considering the multifactorial nature of each.

CAR T-cell therapy-related neurotoxicity in paediatric acute lymphocytic leukaemia

BACKGROUND

The advent of chimeric antigen receptor (CAR) T-cell therapy has created a paradigm shift in the management of patients with refractory B-cell acute lymphocytic leukaemia (ALL). The aim of this study is to correlate imaging findings of CAR T-cell therapy related neurotoxicity with clinical course and eventual clinical outcome, with the hope that it will bring us a step closer to the identification of potential imaging biomarkers that may allow more accurate prognostication and risk stratification of patients.

PROCEDURE

Our imaging database was queried from January 2018 to April 2020 to identify paediatric patients who fulfil the following criteria: (a) diagnosed with ALL, (b) underwent CAR T-cell therapy, and (c) had magnetic resonance imaging (MRI) brain studies performed before and after CAR T-cell therapy. A total of seven patients were included and all MRI studies were analysed by a paediatric neuroradiologist for the presence of acute neuroimaging findings post CAR T-cell infusion. Acute neuroimaging findings are defined as new imaging findings detected within 28 days of CAR T-cell infusion.

RESULTS

Three out of four patients with acute neuroimaging findings had sustained complete remission for more than 6 months, while all three patients without acute neuroimaging findings had positive minimal residual disease (MRD) within 1 month. Both patients with acute diffuse leptomeningeal enhancement showed clinical improvement within 1-2 days.

CONCLUSIONS

Acute neuroimaging findings may be a potential imaging biomarker for peak neurotoxicity and treatment response, and it is not necessarily associated with poor outcome, as previously reported.

The incidence of cytokine release syndrome and neurotoxicity of CD19 chimeric antigen receptor-T cell therapy in the patient with acute lymphoblastic leukemia and lymphoma

Our objective was to summarize the side effect of chimeric antigen receptor (CAR)-T cell therapy in patients with acute lymphocytic leukemia (ALL) and lymphoma. Two independent reviewers extracted relevant data. A total of 35 hematologic malignancy studies with CD19 CAR-T cell were included (1412 participants). Severe cytokine release syndrome (sCRS) proportion was experienced by 18.5% (95% confidence interval [CI], 0.128-0.259; P = 0.000) of 982 patients with the National Cancer Institute/Lee/common terminology criteria for adverse events grading system. The pooled neurotoxicity proportion was 21.7% (95% CI, 0.167-0.287; P = 0.000) of 747 patients with the same grading system. For all of the 25 clinical trials with the same grading system, subgroup analysis was performed. Based on the different disease type, a pooled prevalence of 35.7% was observed with event rate (ER) of 0.358 (95% CI, 0.289-0.434; P = 0.000) for ALL in 12 clinical trials. For lymphoma, a pooled prevalence of 13% was observed with ER of 0.073 (95% CI, 0.028-0.179; P = 0.000) in eight clinical trials. It was demonstrated that the patients who were older than 18 years of age have the lower sCRS incidence of 16.1% (95% CI, 0.110-0.250; P = 0.000) compared with 28.6% of the remaining population who were younger than 18 years of age (95% CI, 0.117-0.462: P = 0.023) in our analysis. Based on the different co-stimulatory domain, the sCRS of 16.5% was observed with ER of 0.175 (95% CI, 0.090-0.312; P = 0.000) for 4-1BB. The sCRS of 22.2% was observed with ER of 0.193 (95% CI, 0.107-0.322; P = 0.000) for CD28. For both the CD28 and 4-1BB, the sCRS of 17.3% was observed with ER of 0.170 (95% CI, 0.067-0.369; P = 0.003). Sub-analysis sCRS of the impact with cell dose and specific disease indication were also demonstrated. Limitations include heterogeneity of study populations, as well as high risk of bias of included studies. These results are helpful for physicians, patients and the other stakeholders to understand the adverse events and to further promote the improvement of CAR-T cell therapy in the future.

Toxicities Associated with Immunotherapy and Approach to Cardiotoxicity with Novel Cancer Therapies

In recent years, major advances in oncology especially the advent of targeted agents and immunotherapies (immune checkpoint inhibitors [ICIs] and chimeric antigen receptor [CAR] T-cell therapy) have led to improved quality of life and survival rates in patients with cancer. This article focuses on the clinical features, and grading and management of toxicities associated with ICIs and CAR T-cell therapy. In addition, because cardiotoxicity is one of the most harmful effects of anticancer therapeutics, we describe the risk factors and mechanisms of cardiovascular injury associated with newer agents, screening technologies for at-risk patients, and preventive and treatment strategies.

The Cerebroventricular Environment Modifies CAR T Cells for Potent Activity against Both Central Nervous System and Systemic Lymphoma

Lymphomas with central nervous system (CNS) involvement confer a worse prognosis than those without CNS involvement, and patients currently have limited treatment options. T cells genetically engineered with CD19-targeted chimeric antigen receptors (CAR) are effective against B-cell malignancies and show tremendous potential in the treatment of systemic lymphoma. We aimed to leverage this strategy toward a more effective therapy for patients with lymphoma with CNS disease. NOD-scid IL2Rgamma^null (NSG) mice with CNS and/or systemic lymphoma were treated with CD19-CAR T cells via intracerebroventricular (ICV) or intravenous (IV) injection. CAR T cells isolated after treatment were rigorously examined for phenotype, gene expression, and function. We observed that CAR T cells infused ICV, but not IV, completely and durably eradicated both CNS and systemic lymphoma. CAR T cells delivered ICV migrated efficiently to the periphery, homed to systemic tumors, and expanded in vivo, leading to complete elimination of disease and resistance to tumor rechallenge. Mechanistic studies indicated that ICV-delivered CAR T cells are conditioned by exposure to cerebrospinal fluid in the ICV environment for superior antilymphoma activity and memory function compared with IV-delivered CAR T cells. Further analysis suggested that manipulating cellular metabolism or preactivating therapeutic CAR T cells with antigen ex vivo may improve the efficacy of CAR T cells in vivo Our demonstration that ICV-delivered CD19-CAR T cells had activity against CNS and systemic lymphoma could offer a valuable new strategy for treatment of B-cell malignancies with CNS involvement.

Side-effect management of chimeric antigen receptor (CAR) T-cell therapy

Chimeric antigen receptor (CAR) T cells directed against the B-cell marker CD19 are currently changing the landscape for treatment of patients with refractory and/or relapsed B-cell malignancies. Due to the nature of CAR T cells as living drugs, they display a unique toxicity profile. As CAR T-cell therapy is extending towards other diseases and being more broadly employed in hematology and oncology, optimal management strategies of side-effects associated with CAR T-cell therapy are of high relevance. Cytokine release syndrome (CRS), immune effector cell-associated neurotoxicity syndrome (ICANS), and cytopenias constitute challenges in the treatment of patients with CAR T cells. This review summarizes the current understanding of CAR T-cell toxicity and its management.

Encephalopathy in COVID-19 Presenting With Acute Aphasia Mimicking Stroke

Introduction: Neurological manifestations are emerging as relatively frequent complications of corona virus disease 2019 (COVID-19), including stroke and encephalopathy. Clinical characteristics of the latter are heterogeneous and not yet fully elucidated, while the pathogenesis appears related to neuroinflammation in a subset of patients.

Case: A middle-aged man presented with acute language disturbance at the emergency department. Examination revealed expressive aphasia, mild ideomotor slowing, and severe hypocapnic hypoxemia. Multimodal CT assessment and electroencephalogram (EEG) did not reveal any abnormalities. COVID-19 was diagnosed based on chest CT findings and positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription PCR (RT-PCR) on nasopharyngeal swab. The following day, neurological symptoms progressed to agitated delirium and respiratory status worsened, requiring admission to the ICU and mechanical ventilation. Brain MRI and cerebrospinal fluid (CSF) studies were unremarkable. RT-PCR for SARS-CoV-2 on CSF was negative. He received supportive treatment and intravenous low-dose steroids. His neurological and respiratory status resolved completely within 2 weeks.

Conclusions: We report a patient with reversible COVID-19-related encephalopathy presenting as acute aphasia, mimicking stroke or status epilepticus, eventually evolving into delirium. Although large-vessel stroke is frequently encountered in COVID-19, our case suggests that focal neurological deficits may occur as the earliest feature of encephalopathy. Neurological status reversibility and the absence of abnormalities on brain MRI are consistent with a functional rather than a structural neuronal network impairment.

The Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of acute leukemia

Acute leukemia is a constellation of rapidly progressing diseases that affect a wide range of patients regardless of age or gender. Traditional treatment options for patients with acute leukemia include chemotherapy and hematopoietic cell transplantation. The advent of cancer immunotherapy has had a significant impact on acute leukemia treatment. Novel immunotherapeutic agents including antibody-drug conjugates, bispecific T cell engagers, and chimeric antigen receptor T cell therapies have efficacy and have recently been approved by the US Food and Drug Administration (FDA) for the treatment of patients with acute leukemia. The Society for Immunotherapy of Cancer (SITC) convened a panel of experts to develop a clinical practice guideline composed of consensus recommendations on immunotherapy for the treatment of acute lymphoblastic leukemia and acute myeloid leukemia.

Management of a patient with mantle cell lymphoma who developed severe neurotoxicity after chimeric antigen receptor T-cell therapy in ZUMA-2

Cerebral edema following chimeric antigen receptor (CAR) T-cell therapy can be fatal. ZUMA-2 is a pivotal phase 2, multicenter study evaluating KTE-X19, an autologous anti-CD19 CAR T-cell therapy, in relapsed/refractory mantle cell lymphoma. We describe a 65-year-old patient in ZUMA-2 who developed cerebral edema following CAR T-cell therapy and had complete recovery after multimodality clinical intervention including rabbit antithymocyte globulin (ATG). Biomarker results show early and robust CAR T-cell expansion and related induction of inflammatory cytokines, followed by rapid declines in CAR T-cell and proinflammatory cytokine levels after ATG administration. This clinical profile highlights a potential relevance of ATG in treating severe CAR T-cell-related neurotoxicity.

Pharmacology of Chimeric Antigen Receptor-Modified T Cells

Cell-based immunotherapies using T cells that are engineered to express a chimeric antigen receptor (CAR-T cells) are an effective treatment option for several B cell malignancies. Compared with most drugs, CAR-T cell products are highly complex, as each cell product is composed of a heterogeneous mixture of millions of cells. The biodistribution and kinetics of CAR-T cells, following administration, are unique given the ability of T cells to actively migrate as well as replicate within the patient. CAR-T cell therapies also have multiple mechanisms of action that contribute to both their antitumor activity and their toxicity. This review provides an overview of the unique pharmacology of CAR-T cells, with a focus on CD19-targeting and B cell maturation antigen (BCMA)-targeting CAR-T cells.

Intravenous immunoglobulin therapy in COVID-19-related encephalopathy

Objective

To report on efficacy and safety of intravenous immunoglobulin (IVIg) therapy in a case series of patients with COVID-19-related encephalopathy.

Methods

We retrospectively collected data on all patients with COVID-19 hospitalized at two Italian hospitals who developed encephalopathy during disease course and were treated with IVIg.

Results

Five patients (two females, mean age 66.8 years) developed encephalopathy after a mean of 12.6 days, since the onset of respiratory/constitutional symptoms related to COVID-19. Four patients suffered severe respiratory distress, three of which required invasive mechanical ventilation. Neurological manifestations included impaired consciousness, agitation, delirium, pyramidal and extrapyramidal signs. EEG demonstrated diffuse slowing in all patients. Brain MRI showed non-specific findings. CSF analysis revealed normal cell count and protein levels. In all subjects, RT-PCR for SARS-CoV-2 in CSF tested negative. IVIg at 0.4 g/kg/die was commenced 29.8 days (mean, range: 19–55 days) after encephalopathy onset, leading to complete electroclinical recovery in all patients, with an initial improvement of neuropsychiatric symptoms observed in 3.4 days (mean, range: 1–10 days). No adverse events related to IVIg were observed.

Conclusions

Our preliminary findings suggest that IVIg may represent a safe and effective treatment for COVID-19-associated encephalopathy. Clinical efficacy may be driven by the anti-inflammatory action of IVIg, associated with its anti-cytokine qualities.

Electronic supplementary material

The online version of this article (10.1007/s00415-020-10248-0) contains supplementary material, which is available to authorized users.

Characteristics of anti-CD19 CAR T cell infusion products associated with efficacy and toxicity in patients with large B cell lymphomas

Autologous chimeric antigen receptor (CAR) T cell therapies targeting CD19 have high efficacy in large B cell lymphomas (LBCLs), but long-term remissions are observed in less than half of patients, and treatment-associated adverse events, such as immune effector cell-associated neurotoxicity syndrome (ICANS), are a clinical challenge. We performed single-cell RNA sequencing with capture-based cell identification on autologous axicabtagene ciloleucel (axi-cel) anti-CD19 CAR T cell infusion products to identify transcriptomic features associated with efficacy and toxicity in 24 patients with LBCL. Patients who achieved a complete response by positron emission tomography/computed tomography at their 3-month follow-up had three-fold higher frequencies of CD8 T cells expressing memory signatures than patients with partial response or progressive disease. Molecular response measured by cell-free DNA sequencing at day 7 after infusion was significantly associated with clinical response (P = 0.008), and a signature of CD8 T cell exhaustion was associated (q = 2.8 × 10^-149) with a poor molecular response. Furthermore, a rare cell population with monocyte-like transcriptional features was associated (P = 0.0002) with high-grade ICANS. Our results suggest that heterogeneity in the cellular and molecular features of CAR T cell infusion products contributes to variation in efficacy and toxicity after axi-cel therapy in LBCL, and that day 7 molecular response might serve as an early predictor of CAR T cell efficacy.

Cytokine release syndrome-associated encephalopathy in patients with COVID-19

Background and purpose

Neurological manifestations in coronavirus disease (COVID)‐2019 may adversely affect clinical outcomes. Severe COVID‐19 and uremia are risk factors for neurological complications. However, the lack of insight into their pathogenesis, particularly with respect to the role of the cytokine release syndrome (CRS), is currently hampering effective therapeutic interventions. The aims of this study were to describe the neurological manifestations of patients with COVID‐19 and to gain pathophysiological insights with respect to CRS.

Methods

In this longitudinal study, we performed extensive clinical, laboratory and imaging phenotyping in five patients admitted to our renal unit.

Results

Neurological presentation included confusion, tremor, cerebellar ataxia, behavioral alterations, aphasia, pyramidal syndrome, coma, cranial nerve palsy, dysautonomia, and central hypothyroidism. Notably, neurological disturbances were accompanied by laboratory evidence of CRS. Severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) was undetectable in the cerebrospinal fluid (CSF). Hyperalbuminorrachia and increased levels of the astroglial protein S100B were suggestive of blood−brain barrier (BBB) dysfunction. Brain magnetic resonance imaging findings comprised evidence of acute leukoencephalitis (n = 3, one of whom had a hemorrhagic form), cytotoxic edema mimicking ischaemic stroke (n = 1), or normal results (n = 2). Treatment with corticosteroids and/or intravenous immunoglobulins was attempted, resulting in rapid recovery from neurological disturbances in two cases. SARS‐CoV2 was undetectable in 88 of the 90 patients with COVID‐19 who underwent Reverse Transcription‐PCR testing of CSF.

Conclusions

Patients with COVID‐19 can develop neurological manifestations that share clinical, laboratory and imaging similarities with those of chimeric antigen receptor T‐cell‐related encephalopathy. The pathophysiological underpinnings appear to involve CRS, endothelial activation, BBB dysfunction, and immune‐mediated mechanisms.

Bispecific antibodies in acute lymphoblastic leukemia therapy

INTRODUCTION

Blinatumomab, first in a class of bispecific T-cell engagers, revolutionized treatment paradigm of B-cell precursor relapsed/refractory or minimal residual disease positive acute lymphoblastic leukemia (ALL) in adults and children, inducing deep remissions in a proportion of patients. However, significant numbers of patients do not respond or eventually relapse. Strategies for improvement of treatment outcomes are required.

AREAS COVERED

This review discusses the main structural and functional features of blinatumomab, and its place in the treatment of ALL. Furthermore, prospects to increase the efficacy of blinatumomab are addressed. The developments in the field of bispecific antibodies and their possible implications for treatment of ALL are reviewed.

EXPERT OPINION

Better understanding the mechanisms of response and resistance to blinatumomab might help us to identify the group of patients benefiting most from treatment and to spare potentially toxic subsequent treatment strategies. Data emerging from ongoing clinical trials might change the treatment landscape of ALL and beyond. Early use of blinatumomab in frontline protocols with more advantageous treatment sequences and in combination with other targeted therapies might reduce the failure rates. Exponentially increasing number of novel treatment options and their possible combinations might complicate treatment decision-making without data from randomized trials.

CAR-T Cell Therapy-Related Neurotoxicity in Pediatric Acute Lymphoblastic Leukemia: Spectrum of Imaging Findings

The emergence of CD19-targeted chimeric antigen receptor-T (CAR-T) cell therapy has created a new era in the management of pediatric patients with refractory B-cell malignancies such as B-cell acute lymphoblastic leukemia. Immune effector cell-associated neurotoxicity syndrome (ICANS) is frequently encountered in the postinfusion period of CD19-targeted chimeric antigen receptor-T cell therapy and in some cases may be fatal. Knowledge related to the spectrum of imaging findings of CD19-targeted CAR-T cell therapy-related ICANS is, however, still very much lacking, underscoring the need for continued research in this area. In this review, we hope to provide an overview of current knowledge and provide an in-depth literature review related to this topic. A brief discussion of possible imaging differential diagnoses, specifically in children with acute lymphoblastic leukemia, will also be included. Illustrative cases for each imaging phenotype will be provided to facilitate a better understanding. A greater level of insight of the spectrum of imaging findings related to ICANS will improve patients' management and enhance efforts to safely deliver CAR-T cell immunotherapy. It will also facilitate further studies to derive mechanistic insights of ICANS and potentially assist in the testing and monitoring of therapeutic interventions.

CAR T-Cell-Associated Neurotoxicity: Current Management and Emerging Treatment Strategies

Axicabtagene ciloleucel and tisagenlecleucel are 2 chimeric antigen receptor (CAR) T-cell immunotherapies targeting CD19 for the treatment of B-cell acute lymphoblastic leukemia and non-Hodgkin lymphoma. Two commonly recognized complications associated with CAR T-cell therapies are cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS). ICANS can occur in isolation or concomitantly with CRS following CAR T-cell therapy and may be due to disruption of the blood-brain barrier and the effects of elevated cytokine levels on the central nervous system. Presently, the optimum management of ICANS remains elusive, as there lacks consensus guidelines. The objective of this review is to provide a comprehensive summary of ICANS and strategies for prompt identification and management of patients presenting to the intensive care unit with this syndrome.

Immunotherapy in Pediatric B-Cell Acute Lymphoblastic Leukemia: Advances and Ongoing Challenges

Leukemia, most commonly B-cell acute lymphoblastic leukemia (B-ALL), accounts for about 30% of childhood cancer diagnoses. While there have been dramatic improvements in childhood ALL outcomes, certain subgroups-particularly those who relapse-fare poorly. In addition, cure is associated with significant short- and long-term side effects. Given these challenges, there is great interest in novel, targeted approaches to therapy. A number of new immunotherapeutic agents have proven to be efficacious in relapsed or refractory disease and are now being investigated in frontline treatment regimens. Blinatumomab (a bispecific T-cell engager that targets cluster of differentiation [CD]-19) and inotuzumab ozogamicin (a humanized antibody-drug conjugate to CD22) have shown the most promise. Chimeric antigen receptor T (CAR-T) cells, a form of adoptive immunotherapy, rely on the transfer of genetically modified effector T cells that have the potential to persist in vivo for years, providing ongoing long-term disease control. In this article, we discuss the clinical biology and treatment of B-ALL with an emphasis on the role of immunotherapy in overcoming the challenges of conventional cytotoxic therapy. As immunotherapy continues to move into the frontline of pediatric B-ALL therapy, we also discuss strategies to address unique side effects associated with these agents and efforts to overcome mechanisms of resistance to immunotherapy.

Chimeric antigen receptor T cell therapy for pediatric and young adult B cell acute lymphoblastic leukemia

INTRODUCTION

Though 85% of children and young adults with acute lymphoblastic leukemia (ALL) are cured, until recently, the prognosis of relapsed or refractory disease has been dismal. The advent of chimeric antigen receptor (CAR) T-cell therapy has transformed the treatment of relapsed/refractory ALL. The most well-studied, successful CARs are autologous, murine-based anti-CD19 CARs, but new constructs are currently under clinical investigation.

AREAS COVERED

This review describes the history and design of CAR T cells, clinical trial outcomes of anti-CD19 and newer CARs, treatment-related toxicities including cytokine release syndrome and neurotoxicity, and issues with resistance and relapse. A search of PubMed and clinicaltrials.gov spanning from 2012-present was used to select original reports investigating the use of CAR T in pediatric patients.

EXPERT OPINION

CD19-targeted CARs have demonstrated remarkable response rates and produced durable remissions in very high-risk pediatric patient populations. The therapies, however, are limited by unique treatment-related toxicities and considerable rates of antigen-positive and antigen-negative relapses. Current research efforts focused on elucidating mechanisms of resistance/relapse and on developing strategies to prevent and treat relapse are critical to optimizing the use of CAR-T. In addition, ongoing trials testing CARs earlier in therapy and for new indications are key to informing their widespread usage.

Improving safety of cancer immunotherapy via delivery technology

Breakthroughs in molecular mechanisms underlying immune-suppressive tumor microenvironment and paradigm shifts in the cancer-immunity response cycle have profoundly changed the landscape of cancer immunotherapy. However, one of the challenges is to mitigate the serious side effects caused by systemic autoimmunity and autoinflammatory responses following immunotherapy. Thus, restraining the activation of the immune system in healthy tissues is highly desirable to address this problem. Bioengineering and delivery technologies provide a solution to the issue. In this Review, we first introduce immune-related adverse effects of main immunotherapies and the underlying mechanisms, summarize strategies of designingde bioengineering and delivery systems to reduce their immunotoxicities, and highlight the importance of the development of immunotoxicity-related animal models.

Inflammatory leptomeningeal cytokines mediate delayed COVID-19 encephalopathy

SARS-CoV-2 infection induces a wide spectrum of neurologic dysfunction. Here we show that a particularly vulnerable population with neurologic manifestations of COVID-19 harbor an influx of inflammatory cytokines within the cerebrospinal fluid in the absence of viral neuro-invasion. The majority of these inflammatory mediators are driven by type 2 interferon and are known to induce neuronal injury in other disease models. Levels of matrix metalloproteinase-10 within the spinal fluid correlate with the degree of neurologic dysfunction. Furthermore, this neuroinflammatory process persists weeks following convalescence from the acute respiratory infection. These prolonged neurologic sequelae following a systemic cytokine release syndrome lead to long-term neurocognitive dysfunction with a wide range of phenotypes.

A Concise Review of Neurologic Complications Associated with Chimeric Antigen Receptor T-cell Immunotherapy

Chimeric antigen receptor-engineered T (CAR-T) cell immunotherapy has been successful in treating many types of hematological malignancies. CAR-T therapy, however, has been associated with toxicities, including cytokine release syndrome (CRS) as well as immune effector cell-associated neurotoxicity syndrome (ICANS). ICANS presentation is variable, largely reversible, and manifests with encephalopathy and focal neurologic deficits. Treatment strategies largely are supportive. ICANS pathophysiology likely is related to that of CRS. Preclinical studies and clinical experience have shed light on the driving forces of ICANS and have yielded new strategies to mitigate ICANS occurrence.

Insight into mechanisms associated with cytokine release syndrome and neurotoxicity after CD19 CAR-T cell immunotherapy

Adoptive immunotherapy with CD19-targeted chimeric antigen receptor (CAR)-T cells has been successful in producing durable remissions in some patients with relapsed or refractory B cell malignancies. Despite the efficacy of CAR-T cell therapy, significant toxicities can occur. Cytokine release syndrome (CRS) and neurotoxicity are the most common toxicities and can range from self-limited fever to life threatening organ damage and death. Understanding the mechanisms underlying these toxicities can help guide and improve outcomes. In this review we describe CRS and neurotoxicity in patients with B cell malignancies treated with CD19 CAR-T cells in pivotal trials, and also provide insight into potential mechanisms associated with these toxicities based on studies conducted in a phase 1/2 clinical trial at the Fred Hutchinson Cancer Research Center.

Efficacy and safety of CD19 CAR T constructed with a new anti-CD19 chimeric antigen receptor in relapsed or refractory acute lymphoblastic leukemia

Background

Recent evidence suggests that resistance to CD19 chimeric antigen receptor (CAR)-modified T cell therapy may be due to the presence of CD19 isoforms that lose binding to the single-chain variable fragment (scFv) in current use. As such, further investigation of CARs recognize different epitopes of CD19 antigen may be necessary.

Methods

We generated a new CD19 CAR T (HI19α-4-1BB-ζ CAR T, or CNCT19) that includes an scFv that interacts with an epitope of the human CD19 antigen that can be distinguished from that recognized by the current FMC63 clone. A pilot study was undertaken to assess the safety and feasibility of CNCT19-based therapy in both pediatric and adult patients with relapsed/refractory acute lymphoblastic leukemia (R/R B-ALL).

Results

Data from our study suggested that 90% of the 20 patients treated with infusions of CNCT19 cells reached complete remission or complete remission with incomplete count recovery (CR/CRi) within 28 days. The CR/CRi rate was 82% when we took into account the fully enrolled 22 patients in an intention-to-treat analysis. Of note, extramedullary leukemia disease of two relapsed patients disappeared completely after CNCT19 cell infusion. After a median follow-up of 10.09 months (range, 0.49–24.02 months), the median overall survival and relapse-free survival for the 20 patients treated with CNCT19 cells was 12.91 months (95% confidence interval [CI], 7.74–18.08 months) and 6.93 months (95% CI, 3.13–10.73 months), respectively. Differences with respect to immune profiles associated with a long-term response following CAR T cell therapy were also addressed. Our results revealed that a relatively low percentage of CD8⁺ naïve T cells was an independent factor associated with a shorter period of relapse-free survival (p = 0.012, 95% CI, 0.017–0.601).

Conclusions

The results presented in this study indicate that CNCT19 cells have potent anti-leukemic activities in patients with R/R B-ALL. Furthermore, our findings suggest that the percentage of CD8⁺ naïve T cells may be a useful biomarker to predict the long-term prognosis for patients undergoing CAR T cell therapy.

Trial registration

ClinicalTrials.gov: NCT02975687; registered 29 November, 2016. https://clinicaltrials.gov/ct2/keydates/NCT02975687

Neurological Aspects of SARS-CoV-2 Infection: Mechanisms and Manifestations

The human infection of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a public health emergency of international concern that has caused more than 16.8 million new cases and 662,000 deaths as of July 30, 2020. Although coronavirus disease 2019 (COVID-19), which is associated with this virus, mainly affects the lungs, recent evidence from clinical and pathological studies indicates that this pathogen has a broad infective ability to spread to extrapulmonary tissues, causing multiorgan failure in severely ill patients. In this regard, there is increasing preoccupation with the neuroinvasive potential of SARS-CoV-2 due to the observation of neurological manifestations in COVID-19 patients. This concern is also supported by the neurotropism previously documented in other human coronaviruses, including the 2002-2003 SARS-CoV-1 outbreak. Hence, in the current review article, we aimed to summarize the spectrum of neurological findings associated with COVID-19, which include signs of peripheral neuropathy, myopathy, olfactory dysfunction, meningoencephalitis, Guillain-Barré syndrome, and neuropsychiatric disorders. Furthermore, we analyze the mechanisms underlying such neurological sequela and discuss possible therapeutics for patients with neurological findings associated with COVID-19. Finally, we describe the host- and pathogen-specific factors that determine the tissue tropism of SARS-CoV-2 and possible routes employed by the virus to invade the nervous system from a pathophysiological and molecular perspective. In this manner, the current manuscript contributes to increasing the current understanding of the neurological aspects of COVID-19 and the impact of the current pandemic on the neurology field.