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

A Bump in the Road: How the Hostile AML Microenvironment Affects CAR T Cell Therapy

Chimeric antigen receptor (CAR) T cells targeting CD19 have been successful treating patients with relapsed/refractory B cell acute lymphoblastic leukemia (ALL) and B cell lymphomas. However, relapse after CAR T cell therapy is still a challenge. In addition, preclinical and early clinical studies targeting acute myeloid leukemia (AML) have not been as successful. This can be attributed in part to the presence of an AML microenvironment that has a dampening effect on the antitumor activity of CAR T cells. The AML microenvironment includes cellular interactions, soluble environmental factors, and structural components. Suppressive immune cells including myeloid derived suppressor cells and regulatory T cells are known to inhibit T cell function. Environmental factors contributing to T cell exhaustion, including immune checkpoints, anti-inflammatory cytokines, chemokines, and metabolic alterations, impact T cell activity, persistence, and localization. Lastly, structural factors of the bone marrow niche, secondary lymphoid organs, and extramedullary sites provide opportunities for CAR T cell evasion by AML blasts, contributing to treatment resistance and relapse. In this review we discuss the effect of the AML microenvironment on CAR T cell function. We highlight opportunities to enhance CAR T cell efficacy for AML through manipulating, targeting, and evading the anti-inflammatory leukemic microenvironment.

Neurotoxicity associated with cancer immunotherapy: immune checkpoint inhibitors and chimeric antigen receptor T-cell therapy

PURPOSE OF REVIEW

Immune checkpoint inhibitors (ICPI) and chimeric antigen receptor T cells (CAR-T) represent novel therapies recently approved to treat a number of human cancers. As both approaches modulate the immune system, they can generate a number of immune-related adverse events (irAEs), including a large spectrum of novel neurological toxicities. These are of special interest given their potential severity and risk of compromising further oncologic treatment. We aim to provide a comprehensive review of the literature and discuss their optimal management.

RECENT FINDINGS

In contrast to irAEs involving other organs, neurological complications of ICPI are uncommon, may present throughout the course of treatment and involve the peripheral and central nervous system, including polyneuropathy, myositis, myasthenia gravis, demyelinating polyradiculopathy, myelitis, encephalitis and others. If started early, ICPI-related neurologic irAEs are usually responsive to steroids. In contrast, as many as 40% of patients undergoing CAR-T therapy will develop neurologic complications in the form of a cytokine-release-associated encephalopathy. It includes delirium, aphasia, tremor/myoclonus, seizure and seizure-like activity.

SUMMARY

irAEs associated with CAR-T and ICPI therapy constitute new entities. Early identification and treatment are essential to optimize the functional outcome and further oncologic management of the patient.

Next Generation of Cancer Treatments: Chimeric Antigen Receptor T-Cell Therapy and Its Related Toxicities: A Review for Perioperative Physicians

Cancer immunotherapy has entered a new era with the recent introduction of genetically engineered T-cells that express chimeric antigen receptors (CARs) capable of recognizing and destroying tumor cells. Several clinical trials in patients with relapsed or refractory B-cell malignancies have demonstrated complete remission rates ranging from 50% to 90%, with long-term data suggestive of a possible curative response. CAR T-cell therapy is currently under investigation for earlier use in these disease processes and in various other solid and liquid tumors. CAR T-cell therapy is associated with a unique postinfusion toxicity profile including cytokine-release syndrome and neurotoxicity. These toxicities are usually reversible but can be fatal, requiring close vigilance and prompt treatment often in an intensive care unit (ICU) setting. CAR T-cell therapy is currently restricted to designated centers possessing expertise in acute toxicity management, but wider use is likely if early therapeutic successes are replicated. As perioperative and critical care physicians, anesthesiologists may encounter such patients in the perioperative or ICU setting and should become familiar with this unique and novel therapeutic modality capable of causing extreme cardiovascular and respiratory compromise. This review will describe the immunobiology of CAR T-cells, their relevance to cancer treatment, clinical aspects of their therapeutic use in cancer chemotherapy, toxicities related to CAR T-cell use, and their therapeutic management.

Safety and feasibility of anti-CD19 CAR T cells with fully human binding domains in patients with B-cell lymphoma

Anti-CD19 chimeric antigen receptor (CAR)-expressing T cells are an effective treatment for B-cell lymphoma, but often cause neurologic toxicity. We treated 20 patients with B-cell lymphoma on a phase I, first-in-human clinical trial of T cells expressing the new anti-CD19 CAR Hu19-CD828Z (NCT02659943). The primary objective was to assess safety and feasibility of Hu19-CD828Z T-cell therapy. Secondary objectives included assessments of blood levels of CAR T cells, anti-lymphoma activity, second infusions and immunogenicity. All objectives were met. Fifty-five percent of patients who received Hu19-CD828Z T cells obtained complete remission. Hu19-CD828Z T cells had clinical anti-lymphoma activity similar to that of T cells expressing FMC63-28Z, an anti-CD19 CAR tested previously by our group, which contains murine binding domains and is used in axicabtagene ciloleucel. However, severe neurologic toxicity occurred in only 5% of patients who received Hu19-CD828Z T cells, whereas 50% of patients who received FMC63-28Z T cells experienced this degree of toxicity (P = 0.0017). T cells expressing Hu19-CD828Z released lower levels of cytokines than T cells expressing FMC63-28Z. Lower levels of cytokines were detected in blood from patients who received Hu19-CD828Z T cells than in blood from those who received FMC63-28Z T cells, which could explain the lower level of neurologic toxicity associated with Hu19-CD828Z. Levels of cytokines released by CAR-expressing T cells particularly depended on the hinge and transmembrane domains included in the CAR design.

Adoptive Cell Therapy: A Novel and Potential Immunotherapy for Glioblastoma

Glioblastoma multiforme (GBM) is the most common primary brain tumor in adults with very poor prognosis and few advances in its treatment. Recently, fast-growing cancer immunotherapy provides a glimmer of hope for GBM treatment. Adoptive cell therapy (ACT) aims at infusing immune cells with direct anti-tumor activity, including tumor-infiltrating lymphocyte (TIL) transfer and genetically engineered T cells transfer. For example, complete regressions in patients with melanoma and refractory lymphoma have been shown by using naturally tumor-reactive T cells and genetically engineered T cells expressing the chimeric anti-CD19 receptor, respectively. Recently, the administration of ACT showed therapeutic potentials for GBM treatment as well. In this review, we summarize the success of ACT in the treatment of cancer and provide approaches to overcome some challenges of ACT to allow its adoption for GBM treatment.

CAR-T Cell Therapy in Cancer: Tribulations and Road Ahead

Chimeric antigen receptor- (CAR-) T cell therapy is one of the most recent innovative immunotherapies and is rapidly evolving. Like other technologies, CAR-T cell therapy has undergone a long development process, and persistent explorations of the actions of the intracellular signaling domain and make several improvements have led to the superior efficacy when anti-CD19 CAR-T cell treatments in B cell cancers. At present, CAR-T cell therapy is developing rapidly, and many clinical trials have been established on a global scale, which has great commercial potential. This review mainly describes the toxicity of CAR-T cell therapy and the challenges of CAR-T cells in the treatment of solid tumors, and looks forward to future development and opportunities for immunotherapy and reviews major breakthroughs in CAR-T cell therapy.

Leptomeningeal malignancy of childhood: sharing learning between childhood leukaemia and brain tumour trials

Leptomeningeal malignancy complicates childhood cancers, including leukaemias, brain tumours, and solid tumours. In leukaemia, such malignancy is thought to invade leptomeninges via the vascular route. In brain tumours, dissemination from the primary tumour, before or after surgery, via CSF pathways is assumed; however, evidence exists to support the vascular route of dissemination. Success in treating leptomeningeal malignancy represents a rate-limiting step to cure, which has been successfully overcome in leukaemia with intensified systemic therapy combined with intra-CSF therapy, which replaced cranial radiotherapy for many patients. This de-escalated CNS-directed therapy is still associated with some neurotoxicity. The balanced benefit justifies exploration of ways to further de-escalate CNS-directed therapy. For primary brain tumours, standard therapy is craniospinal radiotherapy, but attendant risk of acute and delayed brain injury and endocrine deficiencies compounds post-radiation impairment of spinal growth. Alternative ways of treating leptomeninges by intensifying drug therapy delivered to CSF are being investigated-preliminary evidence suggests improved outcomes. This Review seeks to describe methods of intra-CSF drug delivery and drugs in use, and consider how the technique could be modified and additional drugs might be selected for this route of administration.

Patient-Reported Neuropsychiatric Outcomes of Long-Term Survivors after Chimeric Antigen Receptor T Cell Therapy

CD19-targeted chimeric antigen receptor (CAR) modified T cell immunotherapy is a novel treatment with promising results in patients with relapsed/refractory lymphoid malignancies. CAR T cell therapy has known early toxicities of cytokine release syndrome and neurotoxicity, but little is known about long-term neuropsychiatric adverse effects. We have used patient-reported outcomes, including Patient-Reported Outcomes Measurement Information System (PROMIS) measures, to assess neuropsychiatric and other patient-reported outcomes of 40 patients with relapse/refractory chronic lymphocytic leukemia, non-Hodgkin lymphoma, and acute lymphoblastic leukemia 1 to 5 years after treatment with CD19-targeted CAR T cells. Mean T scores of PROMIS domains of global mental health, global physical health, social function, anxiety, depression, fatigue, pain, and sleep disturbance were not clinically meaningfully different from the mean in the general US population. However, 19 patients (47.5%) reported at least 1 cognitive difficulty and/or clinically meaningful depression and/or anxiety, and 7 patients (17.5%) scored ≤40 in global mental health, indicating at least 1 standard deviation worse than the general population mean. Younger age was associated with worse long-term global mental health (P = .02), anxiety (P = .001), and depression (P= .01). Anxiety before CAR T cell therapy was associated with increased likelihood of anxiety after CAR T cell therapy (P = .001). Fifteen patients (37.5%) reported cognitive difficulties after CAR T cell therapy. Depression before CAR T cell therapy was statistically significantly associated with higher likelihood of self-reported post-CAR T cognitive difficulties (P = .02), and there was a trend for an association between acute neurotoxicity and self-reported post-CAR T cognitive difficulties (P = .08). Having more post-CAR T cognitive difficulties was associated with worse global mental health and global physical health. Our study demonstrates overall good neuropsychiatric outcomes in 40 long-term survivors after CAR T cell therapy. However, nearly 50% of patients in the cohort reported at least 1 clinically meaningful negative neuropsychiatric outcome (anxiety, depression, or cognitive difficulty), indicating that a significant number of patients would likely benefit from mental health services following CAR T cell therapy. Younger age, pre-CAR T anxiety or depression, and acute neurotoxicity may be risk factors for long-term neuropsychiatric problems in this patient population. Larger studies are needed to confirm these findings.

Engineering strategies to overcome the current roadblocks in CAR T cell therapy

T cells genetically engineered to express chimeric antigen receptors (CARs) have proven — and impressive — therapeutic activity in patients with certain subtypes of B cell leukaemia or lymphoma, with promising efficacy also demonstrated in patients with multiple myeloma. Nevertheless, various barriers restrict the efficacy and/or prevent the widespread use of CAR T cell therapies in these patients as well as in those with other cancers, particularly solid tumours. Key challenges relating to CAR T cells include severe toxicities, restricted trafficking to, infiltration into and activation within tumours, suboptimal persistence in vivo, antigen escape and heterogeneity, and manufacturing issues. The evolution of CAR designs beyond the conventional structures will be necessary to address these limitations and to expand the use of CAR T cells to a wider range of malignancies. Investigators are addressing the current obstacles with a wide range of engineering strategies in order to improve the safety, efficacy and applicability of this therapeutic modality. In this Review, we discuss the innovative designs of novel CAR T cell products that are being developed to increase and expand the clinical benefits of these treatments in patients with diverse cancers.

Chimeric antigen receptor (CAR) T cell therapy, the first approved therapeutic approach with a genetic engineering component, holds substantial promise in the treatment of a range of cancers but is nevertheless limited by various challenges, including toxicities, intrinsic and acquired resistance mechanisms, and manufacturing issues. In this Review, the authors describe the innovative approaches to the engineering of CAR T cell products that are providing solutions to these challenges and therefore have the potential to considerably improve the safety and effectiveness of treatment.

Chimeric antigen receptor (CAR) T cells have induced remarkable responses in patients with certain haematological malignancies, yet various barriers restrict the efficacy and/or prevent the widespread use of this treatment.

Investigators are addressing these challenges with engineering strategies designed to improve the safety, efficacy and applicability of CAR T cell therapy.

CARs have modular components, and therefore the optimal molecular design of the CAR can be achieved through many variations of the constituent protein domains.

Toxicities currently associated with CAR T cell therapy can be mitigated using engineering strategies to make CAR T cells safer and that potentially broaden the range of tumour-associated antigens that can be targeted by overcoming on-target, off-tumour toxicities.

CAR T cell efficacy can be enhanced by using engineering strategies to address the various challenges relating to the unique biology of diverse haematological and solid malignancies.

Strategies to address the manufacturing challenges can lead to an improved CAR T cell product for all patients.

Preemptive mitigation of CD19 CAR T-cell cytokine release syndrome without attenuation of antileukemic efficacy

Immunotherapy with the adoptive transfer of T cells redirected with CD19-specific chimeric antigen receptors (CARs) for B-lineage acute lymphoblastic leukemia (ALL) can salvage >80% of patients having relapsed/refractory disease. The therapeutic index of this emerging modality is attenuated by the occurrence of immunologic toxicity syndromes that occur upon CAR T-cell engraftment. Here, we report on the low incidence of severe cytokine release syndrome (CRS) in a subject treated with a CAR T-cell product composed of a defined ratio CD4:CD8 T-cell composition with a 4-1BB:zeta CAR targeting CD19 who also recieved early intervention treatment. We report that early intervention with tocilizumab and/or corticosteroids may reduce the frequency at which subjects transition from mild CRS to severe CRS. Although early intervention doubled the numbers of subjects dosed with tocilizumab and/or corticosteroids, there was no apparent detrimental effect on minimal residual disease-negative complete remission rates or subsequent persistence of functional CAR T cells compared with subjects who did not receive intervention. Moreover, early intervention therapy did not increase the proportion of subjects who experience neurotoxicity or place subjects at risk for infectious sequelae. These data support the contention that early intervention with tocilizumab and/or corticosteroids in subjects with early signs of CRS is without negative impact on the antitumor potency of CD19 CAR T cells. This intervention serves to enhance the therapeutic index in relapsed/refractory patients and provides the rationale to apply CAR T-cell therapy more broadly in ALL therapy. This trial was registered at www.clinicaltrials.gov as #NCT020284.

Immunotherapy in pediatric acute lymphoblastic leukemia

The 5-year survival rate for children and adolescents with acute lymphoblastic leukemia (ALL) has improved to more than 90% in high-income countries. However, further increases in the intensity of conventional chemotherapy would be associated with significant adverse effects; therefore, novel approaches are necessary. The last decade has seen significant advances in targeted therapy with immunotherapy and molecular therapeutics, as well as advances in risk stratification for therapy based on somatic and germline genetic analysis and monitoring of minimal residual disease. For immunotherapy, the approval of antibody-based therapy (with blinatumomab in 2014 and inotuzumab ozogamicin in 2017) and T cell-based therapy (with tisagenlecleucel in 2017) by the US Food and Drug Administration has significantly improved the response rate and outcomes in patients with relapsed/refractory B-ALL. These strategies have also been tested in the frontline setting, and immunotherapy against a new ALL-associated antigen has been developed. Incorporating effective immunotherapy into ALL therapy would enable the intensity of conventional chemotherapy to be decreased and thereby reduce associated toxicity, leading to further improvement in survival and quality of life for patients with ALL.

Salsolinol-neurotoxic or Neuroprotective?

Salsolinol (6,7-dihydroxy-1-methyl-1,2,3,4-tetrahydroisoquinoline), widely available in many edibles, is considered to alter the function of dopaminergic neurons in the central nervous system and thus, multiple hypotheses on its either physiological and/or pathophysiological role have emerged. The aim of our work was to revisit its potentially neurotoxic and/or neuroprotective role through a series of both in vitro and in vivo experiments. Salsolinol in the concentration range 10-250 μM did not show any significant release of lactate dehydrogenase from necrotic SH-SY5Y cells and was able in the concentration of 50 and 100 μM to rescue SH-SY5Y cells from death induced by H₂O₂. Its neuroprotective effect against neurotoxin 6-hydroxydopamine was also determined. Salsolinol was found to decrease significantly the reactive oxygen species level in SH-SY5Y cells treated by 500 μM H₂O₂ and the caspase activity induced by 300 μM of H₂O₂ or 100 μM of 6-hydroxydopamine. Serum levels of TNFα and CRP of salsolinol-treated rats were not significantly different from control animals. Both TNFα and CRP served as indirect markers of neurotoxicity and/or neuroprotection. Although the neurotoxic properties of salsolinol have numerously been emphasized, its neuroprotective properties should not be neglected and need greater consideration.

Role of CAR-T cell therapy in B-cell acute lymphoblastic leukemia

Chimeric antigen receptor (CAR) T cells are genetically engineered cells containing fusion proteins combining an extracellular epitope-specific binding domain, a transmembrane and signaling domains of the T cell receptor. The CD19-CAR T cell product tisagenlecleucel has been approved by the US Food and Drug Administration and the European Medicines Agency for therapy of children and young adults under 25 years with relapsed/refractory B‑cell acute lymphoblastic leukemia (ALL) due to a high overall response rate of 81% at 3 months after therapy. The rates of event-free and overall survival were 50 and 76% at 12 months. Despite the high initial response rate with CD19-CAR‑T cells in B‑ALL, relapses occur in a significant fraction of patients. Current strategies to improve CAR‑T cell efficacy focus on improved persistence of CAR‑T cells in vivo, use of multispecific CARs to overcome immune escape and new CAR designs. The approved CAR‑T cell products are from autologous T cells generated on a custom-made basis with an inherent risk of production failure. For large scale clinical applications, universal CAR‑T cells serving as “off-the-shelf” agents would be of advantage. During recent years CAR‑T cells have been frequently used for bridging to allogeneic hematopoietic stem cell transplantation (HSCT) in patients with relapsed/refractory B‑ALL since we currently are not able to distinguish those CAR‑T cell induced CRs that will persist without further therapy from those that are likely to be short-lived. CAR‑T cells are clearly of benefit for treatment following relapse after allogeneic HSCT. Future improvements in CAR‑T cell constructs may allow longer term remissions without additional HSCT.

CD19 chimeric antigen receptor-T cells in B-cell leukemia and lymphoma: current status and perspectives

The approval of tisagenlecleucel and axicabtagene ciloleucel represents a breakthrough in the field of immune and cellular therapy for hematologic malignancies. These anti-CD19 chimeric antigen receptor-T cells (CAR) proved to be highly effective in the treatment of relapsed/refractory B-cell acute lymphoblastic leukemia (B-ALL) and specific histologic subtypes of B-cell non-Hodgkin lymphomas. This expert review aims to summarize the current available research evidence in this field, with a special focus on the different challenges faced by treating physicians, and we also provide future perspectives.

Axicabtagene Ciloleucel: The First FDA-Approved CAR T-Cell Therapy for Relapsed/Refractory Large B-Cell Lymphoma

Axicabtagene ciloleucel (axi-cel) is an anti-CD19 CAR T-cell therapy that has demonstrated efficacy in relapsed and refractory diffuse large B-cell lymphoma (DLBCL) patients who have had suboptimal responses to conventional therapies. The immune activation that confers the efficacy of axi-cel comes at the price of potentially devastating adverse phenomena: cytokine release syndrome and neurotoxicity. This article serves as an overview of axi-cel, including a review of the available clinical evidence, mechanism of action, and management of some of the unique toxicities of axi-cel.

Primary Bone Tumors: Challenges and Opportunities for CAR-T Therapies

Primary malignant bone tumors are rare, occur in all age groups, and include distinct entities such as osteosarcoma, Ewing sarcoma, and chondrosarcoma. Traditional treatment with some combination of chemotherapy, surgery, and radiation has reached the limit of efficacy, with substantial room for improvement in patient outcome. Furthermore, genomic characterization of these tumors reveals a paucity of actionable molecular targets. Against this backdrop, recent advances in cancer immunotherapy represent a silver lining in the treatment of primary bone cancer. Major strategies in cancer immunotherapy include stimulating naturally occurring anti-tumor T cells and adoptive transfer of tumor-specific cytotoxic T cells. Chimeric antigen receptor T cells (CAR-T cells) belong to the latter strategy and are an impressive application of both insights into T cell biology and advances in genetic engineering. In this review, we briefly describe the CAR-T approach and discuss its applications in primary bone tumors. © 2019 American Society for Bone and Mineral Research.

Central nervous system emergencies in haematological malignancies

Neurological emergencies are frequently catastrophic events in the course of haematological malignancies (HM) that, if not promptly recognized and treated, may lead to lethal outcomes or chronic sequelae. They may occur at any time during the disease course, but are more frequently observed following relapse. Practice guidelines are lacking in the management of most central nervous system (CNS) complications in HM. Herein we review the pathophysiology, presentation and treatment of elevated intracranial pressure, spinal cord compression, status epilepticus, neurovascular complications, CNS infection, leucostasis and hyperviscosity. Further, we discuss the expanding spectrum of neurological complications of old and novel treatments in HM.

Use of Chimeric Antigen Receptor T Cell Therapy in Clinical Practice for Relapsed/Refractory Aggressive B Cell Non-Hodgkin Lymphoma: An Expert Panel Opinion from the American Society for Transplantation and Cellular Therapy

Axicabtagene ciloleucel (YESCARTA; Kite Pharma, a Gilead Company, Los Angeles CA) and tisagenlecleucel (KYMRIAH; Novartis Pharmaceuticals Corp., Basel, Switzerland) are two CD19-directed chimeric antigen receptor (CAR) T cell products currently approved by the US Food and Drug Administration; the European Medicines Agency; Health Canada; Ministry of Health, Labor and Welfare (Japan); and Therapeutic Goods Administration (Australia) for treatment of specific subtypes of relapsed/refractory aggressive B cell non-Hodgkin lymphoma (NHL). Although this approval has been transformative in the use of cellular immunotherapy in lymphoma, there are concerns regarding appropriate use of this novel therapy and of short- and long-term toxicities. To address these issues, representatives of the American Society of Transplantation and Cellular Therapy convened to recognize and address key issues surrounding the clinical application of CD19 CAR T cell therapy in B cell lymphomas, in collaboration with worldwide experts. The aim of this article is to provide consensus opinion from experts in the fields of hematopoietic cell transplantation, cellular immunotherapy, and lymphoma regarding key clinical questions pertinent to the use of CD19 CAR T cell products for the treatment of NHL. As the clinical practice using CAR T cells grows worldwide, we anticipate that this guidance will be relevant for hematology/oncology physicians who care for patients with lymphomas.

CD19 CAR T cells following autologous transplantation in poor-risk relapsed and refractory B-cell non-Hodgkin lymphoma

High-dose chemotherapy and autologous stem cell transplantation (HDT-ASCT) is the standard of care for relapsed or primary refractory (rel/ref) chemorefractory diffuse large B-cell lymphoma. Only 50% of patients are cured with this approach. We investigated safety and efficacy of CD19-specific chimeric antigen receptor (CAR) T cells administered following HDT-ASCT. Eligibility for this study includes poor-risk rel/ref aggressive B-cell non-Hodgkin lymphoma chemosensitive to salvage therapy with: (1) positron emission tomography-positive disease or (2) bone marrow involvement. Patients underwent standard HDT-ASCT followed by 19-28z CAR T cells on days +2 and +3. Of 15 subjects treated on study, dose-limiting toxicity was observed at both dose levels (5 × 106 and 1 × 107 19-28z CAR T per kilogram). Ten of 15 subjects experienced CAR T-cell-induced neurotoxicity and/or cytokine release syndrome (CRS), which were associated with greater CAR T-cell persistence (P = .05) but not peak CAR T-cell expansion. Serum interferon-γ elevation (P < .001) and possibly interleukin-10 (P = .07) were associated with toxicity. The 2-year progression-free survival (PFS) is 30% (95% confidence interval, 20% to 70%).  Subjects given decreased naive-like (CD45RA+CCR7+) CD4+ and CD8+ CAR T cells experienced superior PFS (P = .02 and .04, respectively). There was no association between CAR T-cell peak expansion, persistence, or cytokine changes and PFS. 19-28z CAR T cells following HDT-ASCT were associated with a high incidence of reversible neurotoxicity and CRS. Following HDT-ASCT, effector CD4+ and CD8+ immunophenotypes may improve disease control. This trial was registered at www.clinicaltrials.gov as #NCT01840566.

Multifunctional nanoparticles for genetic engineering and bioimaging of natural killer (NK) cell therapeutics

Recently, natural killer (NK)-based immunotherapy has attracted attention as a next-generation cell-based cancer treatment strategy due to its mild side effects and excellent therapeutic efficacy. Here, we describe multifunctional nanoparticles (MF-NPs) capable of genetically manipulating NK cells and tracking them in vivo through non-invasive magnetic resonance (MR) and fluorescence optical imaging. The MF-NPs were synthesized with a core-shell structure by conjugation of a cationic polymer labeled with a near-infrared (NIR) fluorescent molecule, with the aid of a polydopamine (PDA) coating layer. When administered to NKs, the MF-NPs exhibited excellent cytocompatibility, efficiently delivered genetic materials into the immune cells, and induced target protein expression. In particular, the MF-NPs could induce the expression of EGFR targeting chimeric antigen receptors (EGFR-CARs) on the NK cell surface, which improved the cells' anti-cancer cytotoxic effect both in vitro and in vivo. Finally, when NK cells labeled with MF-NPs were injected into live mice, MF-NP-labeled NK cells could be successfully imaged using fluorescence and MR imaging devices. Our findings indicate that MF-NPs have great potential for application of NK cells, as well as other types of cell therapies involving genetic engineering and in vivo monitoring of cell trafficking.

Tocilizumab for the treatment of chimeric antigen receptor T cell-induced cytokine release syndrome

Introduction: Cancer-directed immunotherapies are transforming the landscape in oncology as new and exciting therapies move from the laboratory to the bedside. Chimeric antigen receptor T (CAR-T) cells are one of these novel therapies, demonstrating impressive efficacy against B-cell malignancies. With the development of new therapies, it is not uncommon to identify new and unanticipated toxicities. CAR-T cells cause unique toxicities not typically found with traditional cytotoxic chemotherapy or small molecule inhibitors. Areas covered: CAR-T cell associated toxicities include cytokine release syndrome (CRS) and CAR-T cell-related encephalopathy syndrome (CRES), alternatively known as immune effector cell-associated neurotoxicity syndrome (ICANS). Prompt identification and management of CRS and CRES are imperative for the prevention of life-threatening complications of these innovative therapies. This literature review describes the seminal trials of CD19-directed immunotherapy and the pathophysiology and management of the toxicities found with CAR-T cells. In addition, the use of the interleukin-6 receptor antibody tocilizumab for CRS is reviewed. Expert opinion: This review describes the recommended management of CRS and CRES and examines the current limitations in management. Alternative therapies for the treatment of CAR-T cell related toxicities are also explored. Furthermore, the review proposes future directions for research.

Novel and emerging therapies for B cell lymphoma

Lymphomas are a heterogeneous group of lymphoproliferative disorders, with unique clinical and biological characteristics that exhibit variable response to therapy. Advances in chemo-immunotherapy have improved outcomes in a number of lymphoma subtypes; however, the prognosis for many patients with relapsed and refractory disease remains poor. Novel therapies including several small molecule inhibitors and chimeric antigen receptor T cells have been approved for the treatment of different lymphoma subtypes at relapse, changing the therapy landscape and further improving survival in many of these diseases. This has led to a focus on the development of new cellular therapy, antibody-based therapy, and small molecule inhibitors for relapsed and refractory disease that offer an alternative approach to cytotoxic chemotherapy. We will review these promising novel therapies and discuss their safety and efficacy in first in human studies.

CAR-T cells secreting BiTEs circumvent antigen escape without detectable toxicity

Chimeric antigen receptor (CAR)-T-cell therapy for solid tumors is limited due to heterogeneous target antigen expression and outgrowth of tumors lacking the antigen targeted by CAR-T cells directed against single antigens. Here, we developed a bicistronic construct to drive expression of a CAR specific for EGFRvIII, a glioblastoma-specific tumor antigen, and a bispecific T-cell engager (BiTE) against EGFR, an antigen frequently overexpressed in glioblastoma but also expressed in normal tissues. CART.BiTE cells secreted EGFR-specific BiTEs that redirect CAR-T cells and recruit untransduced bystander T cells against wild-type EGFR. EGFRvIII-specific CAR-T cells were unable to completely treat tumors with heterogenous EGFRvIII expression, leading to outgrowth of EGFRvIII-negative, EGFR-positive glioblastoma. However, CART.BiTE cells eliminated heterogenous tumors in mouse models of glioblastoma. BiTE-EGFR was locally effective but was not detected systemically after intracranial delivery of CART.BiTE cells. Unlike EGFR-specific CAR-T cells, CART.BiTE cells did not result in toxicity against human skin grafts in vivo.

Cellular therapy: Immune-related complications

The advent of chimeric antigen receptor T (CAR-T) and the burgeoning field of cellular therapy has revolutionized the treatment of relapsed/refractory leukemia and lymphoma. This personalized "living therapy" is highly effective against a number of malignancies, but this efficacy is tempered by side effects relatively unique to immunotherapies, including CAR-T. The overwhelming release of cytokines and chemokines by activated CAR-T and other secondarily activated immune effector cells can lead to cytokine release syndrome (CRS), which can have clinical and pathophysiology similarities to systemic inflammatory response syndrome and macrophage activating syndrome/hemophagocytic lymphohistiocytosis. Tocilizumab, an anti-IL6 receptor antibody, was recently FDA approved for treatment of CRS after CAR-T based on its ability to mitigate CRS in many patients. Unfortunately, some patients are refractory and additional therapies are needed. Patients treated with CAR-T can also develop neurotoxicity and, as the biology is poorly understood, current therapeutic interventions are limited to supportive care. Nevertheless, a number of recent studies have shed new light on the pathophysiology of CAR-T-related neurotoxicity, which will hopefully lead to effective treatments. In this review we discuss some of the mechanistic contributions intrinsic to the CAR-T construct, the tumor being treated, and the individual patient that impact the development and severity of CRS and neurotoxicity. As CAR-T and cellular therapy have redefined the concept of personalized medicine, so too will personalization be necessary in managing the unique side effects of these therapies.

CAR T cells for brain tumors: Lessons learned and road ahead

Malignant brain tumors, including glioblastoma, represent some of the most difficult to treat of solid tumors. Nevertheless, recent progress in immunotherapy, across a broad range of tumor types, provides hope that immunological approaches will have the potential to improve outcomes for patients with brain tumors. Chimeric antigen receptors (CAR) T cells, a promising immunotherapeutic modality, utilizes the tumor targeting specificity of any antibody or receptor ligand to redirect the cytolytic potency of T cells. The remarkable clinical response rates of CD19-targeted CAR T cells and early clinical experiences in glioblastoma demonstrating safety and evidence for disease modifying activity support the potential of further advancements ultimately providing clinical benefit for patients. The brain, however, is an immune specialized organ presenting unique and specific challenges to immune-based therapies. Remaining barriers to be overcome for achieving effective CAR T cell therapy in the central nervous system (CNS) include tumor antigenic heterogeneity, an immune-suppressive microenvironment, unique properties of the CNS that limit T cell entry, and risks of immune-based toxicities in this highly sensitive organ. This review will summarize preclinical and clinical data for CAR T cell immunotherapy in glioblastoma and other malignant brain tumors, including present obstacles to advancement.

Evaluating tisagenlecleucel and its potential in the treatment of relapsed or refractory diffuse large B cell lymphoma: evidence to date

Chimeric antigen receptor (CAR) T cells have changed the treatment landscape of relapsed or refractory diffuse large B cell lymphoma. This review focuses on the biology of tisagenlecleucel and the clinical data that support its use in this setting. In addition, we discuss how it compares to other CAR T products, the financial implications for payers, and ongoing trials.

Cytokine release syndrome and neurologic toxicities associated with chimeric antigen receptor T-cell therapy: A comprehensive review of emerging grading models

Advances in the fields of immuno-oncology and T-cell engineering have brought autologous chimeric antigen receptor T-cell (CART) therapies from the bench to the bedside. At present, two CART products that target CD19 are commercially available: tisagenlecleucel and axicabtagene ciloleucel. They have demonstrated remarkable efficacy for their particular indications. One challenge is to compare the safety among commercially available and clinical trial CART treatments due to the use of different grading models to assess the severity of cytokine release syndrome and neurotoxicity. An unmet need exists to harmonize current grading models in order to develop uniform treatment strategies to manage these toxicities. Here, we attempt to summarize the evolution of the various grading systems for cytokine release syndrome and neurotoxicity and also highlight the major differences among them, whenever applicable.

T cells engrafted with a UniCAR 28/z outperform UniCAR BB/z-transduced T cells in the face of regulatory T cell-mediated immunosuppression

Adoptive transfer of chimeric antigen receptor (CAR)-equipped T cells have demonstrated astonishing clinical efficacy in hematological malignancies recently culminating in the approval of two CAR T cell products. Despite this tremendous success, CAR T cell approaches have still achieved only moderate efficacy against solid tumors. As a major obstacle, engineered conventional T cells (Tconvs) face an anti-inflammatory, hostile tumor microenvironment often infiltrated by highly suppressive regulatory T cells (Tregs). Thus, potent CAR T cell treatment of solid tumors requires efficient activation of Tconvs via their engrafted CAR to overcome Treg-mediated immunosuppression. In that regard, selecting an optimal intracellular signaling domain might represent a crucial step to achieve best clinical efficiency. To shed light on this issue and to investigate responsiveness to Treg inhibition, we engrafted Tconvs with switchable universal CARs (UniCARs) harboring intracellularly the CD3ζ domain alone or in combination with costimulatory CD28 or 4-1BB. Our studies reveal that UniCAR ζ-, and UniCAR BB/ζ-engineered Tconvs are strongly impaired by activated Tregs, whereas UniCARs providing CD28 costimulation overcome Treg-mediated suppression both in vitro and in vivo. Compared to UniCAR ζ- and UniCAR BB/ζ-modified cells, UniCAR 28/ζ-armed Tconvs secrete significantly higher amounts of Th1-related cytokines and, furthermore, levels of these cytokines are elevated even upon exposure to Tregs. Thus, in contrast to 4-1BB costimulation, CD28 signaling in UniCAR-transduced Tconvs seems to foster a pro-inflammatory milieu, which contributes to enhanced resistance to Treg suppression. Overall, our results may have significant implications for CAR T cell-based immunotherapies of solid tumors strongly invaded by Tregs.

Glial injury in neurotoxicity after pediatric CD19-directed chimeric antigen receptor T cell therapy

OBJECTIVE

To test whether systemic cytokine release is associated with central nervous system inflammatory responses and glial injury in immune effector cell-associated neurotoxicity syndrome (ICANS) after chimeric antigen receptor (CAR)-T cell therapy in children and young adults.

METHODS

We performed a prospective cohort study of clinical manifestations as well as imaging, pathology, CSF, and blood biomarkers on 43 subjects ages 1 to 25 who received CD19-directed CAR/T cells for acute lymphoblastic leukemia (ALL).

RESULTS

Neurotoxicity occurred in 19 of 43 (44%) subjects. Nine subjects (21%) had CTCAE grade 3 or 4 neurological symptoms, with no neurotoxicity-related deaths. Reversible delirium, headache, decreased level of consciousness, tremor, and seizures were most commonly observed. Cornell Assessment of Pediatric Delirium (CAPD) scores ≥9 had 94% sensitivity and 33% specificity for grade ≥3 neurotoxicity, and 91% sensitivity and 72% specificity for grade ≥2 neurotoxicity. Neurotoxicity correlated with severity of cytokine release syndrome, abnormal past brain magnetic resonance imaging (MRI), and higher peak CAR-T cell numbers in blood, but not cerebrospinal fluid (CSF). CSF levels of S100 calcium-binding protein B and glial fibrillary acidic protein increased during neurotoxicity, indicating astrocyte injury. There were concomitant increases in CSF white blood cells, protein, interferon-γ (IFNγ), interleukin (IL)-6, IL-10, and granzyme B (GzB), with concurrent elevation of serum IFNγ IL-10, GzB, granulocyte macrophage colony-stimulating factor, macrophage inflammatory protein 1 alpha, and tumor necrosis factor alpha, but not IL-6. We did not find direct evidence of endothelial activation.

INTERPRETATION

Our data are most consistent with ICANS as a syndrome of systemic inflammation, which affects the brain through compromise of the neurovascular unit and astrocyte injury. ANN NEUROL 2019.

Clinical chimeric antigen receptor-T cell therapy: a new and promising treatment modality for glioblastoma

Chimeric antigen receptor (CAR)-T cell therapy is now approved in the United States and Europe as a standard treatment for relapsed/refractory B-cell malignancies. It has also been approved recently by the Therapeutic Goods Administration in Australia and may soon be publicly reimbursed. This advance has accentuated scientific, clinical and commercial interest in adapting this exciting technology for the treatment of solid cancers where it is widely recognised that the challenges of overcoming a hostile tumor microenvironment are most acute. Indeed, CAR-T cell technology may be of the greatest value for those cancers that lack pre-existing immunity because they are immunologically 'cold', or have a low somatic tumor mutation load, or both. These cancers are generally not amenable to therapeutic immune checkpoint blockade, but CAR-T cell therapy may be effective because it provides an abundant supply of autologous tumor-specific T cells. This is achieved by using genetic engineering to re-direct autologous T-cell cytotoxicity towards a tumor-associated antigen, bypassing endogenous T-cell requirements for antigen processing, MHC-dependent antigen presentation and co-stimulation. One of the most challenging solid cancers is glioblastoma, which has among the least permissive immunological milieu of any cancer, and which is almost always fatal. Here, we argue that CAR-T cell technology may counter some glioblastoma defences and provide a beachhead for furthering our eventual therapeutic aims of restoring effective antitumor immunity. Although clinical investigation of CAR-T cell therapy for glioblastoma is at an early stage, we discuss three recently published studies, which feature significant differences in target antigen, CAR-T cell phenotype, route of administration and tumor response. We discuss the lessons, which may be learned from these studies and which may guide further progress in the field.

The Other Side of CAR T-Cell Therapy: Cytokine Release Syndrome, Neurologic Toxicity, and Financial Burden

Immune effector cells, including T cells and natural killer cells, which are genetically engineered to express a chimeric antigen receptor (CAR), constitute a powerful new class of therapeutic agents to treat patients with hematologic malignancies. Several CAR T-cell trials have shown impressive remission rates in patients with relapsed/refractory hematologic cancers. Although the clinical responses of these agents in hematologic malignancies have been very encouraging, they have also produced substantial morbidity and occasionally mortality resulting from toxicity. With more experience and collaboration, hopefully the toxicities and the costs will come down, increasing the availability of CAR T cells to patients in need.

Clinical presentation, management, and biomarkers of neurotoxicity after adoptive immunotherapy with CAR T cells

Chimeric antigen receptor (CAR) T cells have emerged as a promising class of cell-based immunotherapy in refractory malignancies. Neurotoxicity represents a common and potentially life-threatening adverse effect of CAR T cells, and clinical experience is limited. Here, we describe the clinical presentation and management of 25 adult patients who presented with neurotoxic syndromes after CAR T-cell therapy at the Massachusetts General Hospital. This cohort includes 24 patients treated with CD19-directed CAR T cells for non-Hodgkin lymphoma (n = 23) and acute lymphoblastic leukemia (n = 1), and 1 patient treated with α-fetoprotein–directed CAR T cells for hepatocellular carcinoma (n = 1). Twelve of the 25 patients (48%) developed grade 1-2 neurotoxicity and 13 patients (52%) presented with grade 3-4 neurotoxicity. We found that lower platelet counts at time of CAR T-cell infusion were associated with more severe neurotoxicity (P = .030). Cytokine release syndrome occurred in 24 of 25 patients (96%). Serum levels of ferritin peaked with onset of neurologic symptoms, and higher ferritin levels were associated with higher neurotoxicity grade. Grade 3-4 neurotoxicity correlated negatively with overall survival (OS) (P = .013). Median OS of the entire cohort was 54.7 weeks. Eight patients (32%) with grade 3-4 neurotoxicity were deceased at database closure, whereas none died with neurotoxicity grade 1-2. High pretreatment lactate dehydrogenase was frequently encountered in lymphoma patients with grade 3-4 neurotoxicity and correlated negatively with progression-free survival (P = .048). We did not find evidence that steroid use ≥7 days altered the patient’s outcome when compared with &lt;7 days of steroids. Management of CAR T cell–mediated neurotoxicity warrants evaluation in prospective clinical trials.

CARs of the future

CAR T cells have revolutionized the treatment of relapsed and refractory CD19-positive leukemia and lymphoma. Unfortunately, the majority of patients treated will not achieve durable remissions. Reasons for these suboptimal clinical outcomes can be tied back to intrinsic CAR T cell design and manufacturing processes, factors that are highly amenable to modification and improvement. As CAR T cell therapy is being deployed in spaces outside of CD19-positive disease, these limitations, complications, and setbacks need to be overcome, allowing for the full potential of this novel therapy to be realized. Preclinical work has begun tackling these major roadblocks, paving the way for potentially off-the-shelf products that are safer and more potent. In time, a number of these advances will be translated to the clinic and usher in an era of CARs of the future.

Toxicities of CD19 CAR-T cell immunotherapy

CD19-targeted chimeric antigen receptor (CAR)-modified T (CAR-T) cell immunotherapy has demonstrated impressive results in B-cell malignancies, and CAR-T cell therapies targeting other antigens are in development for other cancers. Cytokine release syndrome (CRS) and neurotoxicity can be life-threatening in a subset of patients. The severity of CRS and neurotoxicity can be impacted by the disease burden, lymphodepletion regimen, and CAR-T cell dose. Tocilizumab and corticosteroids have been used to manage these toxicities, enabling CD19 CAR-T cells to be administered without obvious compromise in efficacy. Consensus criteria for grading and managing toxicities will facilitate the widespread application of this treatment modality.

Chimeric Antigen Receptor T-Cell Therapy: What the Neuroradiologist Needs to Know

Chimeric antigen receptor T-cell therapy is an exciting and rapidly emerging "fifth pillar" treatment for hematologic cancers. Unique treatment-related toxicities and cost remain a major hindrance to its widespread application. The commonly faced challenges with this innovative therapy, its neurotoxicity, and manifestation on neuroimaging studies, are reviewed.

Human CAR NK Cells: A New Non-viral Method Allowing High Efficient Transfection and Strong Tumor Cell Killing

CAR-NK cells may represent a valuable tool, complementary to CAR-T cells, in adoptive immunotherapy of leukemia and solid tumors. However, gene transfer to human NK cells is a challenging task, particularly with non-virus-based techniques. Here, we describe a new procedure allowing efficient electroporation-based transfection of plasmid DNA, including CAR and CCR7 genes, in resting or cytokine-expanded human NK cell populations and NK-92 cell line. This procedure may offer a suitable platform for a safe and effective use of CAR-NK cells in adoptive immunotherapy of cancer.

Adverse Events Following Cancer Immunotherapy: Obstacles and Opportunities

Oncology has recently undergone a revolutionary change with widespread adoption of immunotherapy for many cancers. Immunotherapy using monoclonal antibodies against checkpoint molecules, including programmed death (PD)-1, PD ligand (PD-L)1, and cytotoxic T lymphocyte-associated antigen (CTLA)-4, is effective in a significant subset of patients. However, immune-related adverse events (irAEs) have emerged as frequent complications of checkpoint blockade, likely due to the physiological role of checkpoint pathways in regulating adaptive immunity and preventing autoimmunity. As immunotherapy becomes more common, a better understanding of the etiology of irAEs and ways to limit these events is needed. At the same time, studying these new therapy-related disorders provides an opportunity to better understand naturally occurring human autoimmune and inflammatory disorders, with the potential to improve therapies for cancer and autoimmune diseases.

CAR T Cell Immunotherapy in Human and Veterinary Oncology: Changing the Odds Against Hematological Malignancies

The advent of the genome editing era brings forth the promise of adoptive cell transfer using engineered chimeric antigen receptor (CAR) T cells for targeted cancer therapy. CAR T cell immunotherapy is probably one of the most encouraging developments for the treatment of hematological malignancies. In 2017, two CAR T cell therapies were approved by the US Food and Drug Administration: one for the treatment of pediatric acute lymphoblastic leukemia (ALL) and the other for adult patients with advanced lymphomas. However, despite significant progress in the area, CAR T cell therapy is still in its early days and faces significant challenges, including the complexity and costs associated with the technology. B cell lymphoma is the most common hematopoietic cancer in dogs, with an incidence approaching 0.1% and a total of 20-100 cases per 100,000 individuals. It is a widely accepted naturally occurring model for human non-Hodgkin's lymphoma. Current treatment is with combination chemotherapy protocols, which prolong life for less than a year in canines and are associated with severe dose-limiting side effects, such as gastrointestinal and bone marrow toxicity. To date, one canine study generated CAR T cells by transfection of mRNA for CAR domain expression. While this was shown to provide a transient anti-tumor activity, results were modest, indicating that stable, genomic integration of CAR modules is required in order to achieve lasting therapeutic benefit. This commentary summarizes the current state of knowledge on CAR T cell immunotherapy in human medicine and its potential applications in animal health, while discussing the potential of the canine model as a translational system for immuno-oncology research.

Chimeric antigen receptor T-cell toxicity

PURPOSE OF REVIEW

Chimeric antigen receptor -(CAR) T-cell therapy has become a commonly used immunotherapy originally used in the treatment of B-cell leukemias but which are now applied broadly across tumor classes. Although high rates of remission are associated with CAR T-cell therapy, toxicities associated with these novel treatment regimens can be lethal if not recognized in a timely manner.

RECENT FINDINGS

Cytokine release syndrome and neurotoxicity are the two most common toxicities associated with CAR T-cell therapy. Cytokine release syndrome is characterized by a flu-like illness accompanied by significant hemodynamic instability; treatments include administration of tocilizumab and corticosteroids. Neurotoxicity is associated with nonpattern-specific neurological changes and can rapidly progress to a comatose state from cerebral edema and death. Other potential toxicities from CAR T-cell therapy include tumor lysis syndrome, B-cell aplasia, graft versus host disease, and dermatological eruptions.

SUMMARY

Clinical awareness of CAR T-cell toxicities is important because prompt treatment leads to improved survival and remission rates.

In the Eye of the Storm: Immune-mediated Toxicities Associated With CAR-T Cell Therapy

The success of chimeric antigen receptor (CAR)-T cell therapy with impressive response rates in hematologic malignancies but also promising data in solid tumors came along with the cognition of unexpected, potentially life-threatening immune-mediated toxicities, namely the cytokine release syndrome (CRS) and neurotoxicity recently referred to as "immune effector cell-associated neurotoxicity syndrome" (ICANS). These toxicities require urgent diagnostic and therapeutic interventions and targeted modulation of key cytokine pathways represents the mainstay of CRS treatment. However, as the underlying mechanisms of ICANS are not well understood, treatment options remain limited and further investigation is warranted. Importantly, after the recent market approval of 2 CAR-T cell constructs, the application of CAR-T cells will expand to nonacademic centers with limited experience in the management of CAR-T cell-associated toxicities. Here, we review the current evidence of CRS and ICANS pathophysiology, diagnostics, and treatment.