Chimeric antigen receptor T cell therapy for autoimmune disease.

Infusion of T cells engineered to express chimeric antigen receptors (CARs) that target B cells has proven to be a successful treatment for B cell malignancies. This success inspired the development of CAR T cells to selectively deplete or modulate the aberrant immune responses that underlie autoimmune disease. Promising results are emerging from clinical trials of CAR T cells targeting the B cell protein CD19 in patients with B cell-driven autoimmune diseases. Further approaches are being designed to extend the application and improve safety of CAR T cell therapy in the setting of autoimmunity, including the use of chimeric autoantibody receptors to selectively deplete autoantigen-specific B cells and the use of regulatory T cells engineered to express antigen-specific CARs for targeted immune modulation. Here, we highlight important considerations, such as optimal target cell populations, CAR construct design, acceptable toxicities and potential for lasting immune reset, that will inform the eventual safe adoption of CAR T cell therapy for the treatment of autoimmune diseases.

Current understanding and management of CAR T cell-associated toxicities.

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

Transient responses and significant toxicities of anti-CD30 CAR T cells for CD30+ lymphomas: results of a phase 1 trial.

ABSTRACT: New treatments are needed for relapsed and refractory CD30-expressing lymphomas. We developed a novel anti-CD30 chimeric antigen receptor (CAR), designated 5F11-28Z. Safety and feasibility of 5F11-28Z-transduced T cells (5F11-Ts) were evaluated in a phase 1 dose escalation clinical trial. Patients with CD30-expressing lymphomas received 300 mg/m2 or 500 mg/m2 of cyclophosphamide and 30 mg/m2 of fludarabine on days -5 to -3, followed by infusion of 5F11-Ts on day 0. Twenty-one patients received 5F11-T infusions. Twenty patients had classical Hodgkin lymphoma, and 1 had anaplastic large-cell lymphoma. Patients were heavily pretreated, with a median of 7 prior lines of therapy and substantial tumor burden, with a median metabolic tumor volume of 66.1 mL (range, 6.4-486.7 mL). The overall response rate was 43%; 1 patient achieved a complete remission. Median event-free survival was 13 weeks. Eleven patients had cytokine release syndrome (CRS; 52%). One patient had grade 3 CRS, and there was no grade 4/5 CRS. Neurologic toxicity was minimal. Nine patients (43%) had new-onset rashes. Two patients (9.5%) received extended courses of corticosteroids for prolonged severe rashes. Five patients (24%) had grade 3/4 cytopenias, with recovery time of ≥30 days, and 2 of these patients (9.5%) had prolonged cytopenias with courses complicated by life-threatening sepsis. The trial was halted early because of toxicity. Median peak blood CAR+ cells per µL was 26 (range, 1-513 cells per µL), but no infiltration of CAR+ cells was detected in lymph node biopsies. 5F11-Ts had low efficacy and substantial toxicities, which limit further development of 5F11-Ts. This trial was registered at www.clinicaltrials.gov as #NCT03049449.

Rapid anti-myeloma activity by T cells expressing an anti-BCMA CAR with a human heavy-chain-only antigen-binding domain.

Multiple myeloma (MM) is a rarely curable malignancy of plasma cells. MM expresses B cell maturation antigen (BCMA). We developed a fully human anti-BCMA chimeric antigen receptor (CAR) with a heavy-chain-only antigen-recognition domain, a 4-1BB domain, and a CD3ζ domain. The CAR was designated FHVH33-CD8BBZ. We conducted the first-in-humans clinical trial of T cells expressing FHVH33-CD8BBZ (FHVH-T). Twenty-five patients with relapsed MM were treated. The stringent complete response rate (sCR) was 52%. Median progression-free survival (PFS) was 78 weeks. Of 24 evaluable patients, 6 (25%) had a maximum cytokine-release syndrome (CRS) grade of 3; no patients had CRS of greater than grade 3. Most anti-MM activity occurred within 2-4 weeks of FHVH-T infusion as shown by decreases in the rapidly changing MM markers serum free light chains, urine light chains, and bone marrow plasma cells. Blood CAR+ cell levels peaked during the time that MM elimination was occurring, between 7 and 15 days after FHVH-T infusion. C-C chemokine receptor type 7 (CCR7) expression on infusion CD4+ FHVH-T correlated with peak blood FHVH-T levels. Single-cell RNA sequencing revealed a shift toward more differentiated FHVH-T after infusion. Anti-CAR antibody responses were detected in 4 of 12 patients assessed. FHVH-T has powerful, rapid, and durable anti-MM activity.

The impact of race, ethnicity, and obesity on CAR T-cell therapy outcomes.

Cancer outcomes with chemotherapy are inferior in patients of minority racial/ethnic groups and those with obesity. Chimeric antigen receptor (CAR) T-cell therapy has transformed outcomes for relapsed/refractory hematologic malignancies, but whether its benefits extend commensurately to racial/ethnic minorities and patients with obesity is poorly understood. With a primary focus on patients with B-cell acute lymphoblastic leukemia (B-ALL), we retrospectively evaluated the impact of demographics and obesity on CAR T-cell therapy outcomes in adult and pediatric patients with hematologic malignancies treated with CAR T-cell therapy across 5 phase 1 clinical trials at the National Cancer Institute from 2012 to 2021. Among 139 B-ALL CAR T-cell infusions, 28.8% of patients were Hispanic, 3.6% were Black, and 29.5% were overweight/obese. No significant associations were found between race, ethnicity, or body mass index (BMI) and complete remission rates, neurotoxicity, or overall survival. Hispanic patients were more likely to experience severe cytokine release syndrome compared with White non-Hispanic patients even after adjusting for leukemia disease burden and age (odds ratio, 4.5; P = .001). A descriptive analysis of patients with multiple myeloma (n = 24) and non-Hodgkin lymphoma (n = 23) displayed a similar pattern to the B-ALL cohort. Our findings suggest CAR T-cell therapy may provide substantial benefit across a range of demographics characteristics, including for those populations who are at higher risk for chemotherapy resistance and relapse. However, toxicity profiles may vary. Therefore, efforts to improve access to CAR therapy for underrepresented populations and elucidate mechanisms of differential toxicity among demographic groups should be prioritized.

Acute and delayed cytopenias following CAR T-cell therapy: an investigation of risk factors and mechanisms.

Prolonged myelosuppression after chimeric antigen receptor (CAR) T-cell therapy is common and poorly understood. A retrospective analysis of 43 patients was conducted to investigate factors contributing to CAR T-cell-related cytopenias. Thirty-five patients were evaluable for analysis of delayed cytopenias occurring after initial hematologic recovery. Time to hematologic recovery (TTHR) was defined as number of days after CAR T-cell infusion for recovery to hemoglobin ≥8.0 g/dL, platelets ≥50.0 k/µL, and neutrophil count ≥1.0 k/µL without transfusions or growth factors for 7 days. Baseline percent bone marrow (BM) malignancy involvement correlated with TTHR (p = .0047). Patients with grades 3-4 cytokine-release syndrome (CRS) had longer TTHR than those with grades 0-2 CRS (p = .0479). Patients who developed prolonged or delayed cytopenias after anti-BCMA CAR T cells had a higher percentage of BM aspirate CAR+ cells at 2 months (n = 10; p = .0159).

Critically Ill Patients Treated for Chimeric Antigen Receptor-Related Toxicity: A Multicenter Study.

OBJECTIVES: To report the epidemiology, treatments, and outcomes of adult patients admitted to the ICU after cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome. DESIGN: Retrospective cohort study. SETTING: Nine centers across the U.S. part of the chimeric antigen receptor-ICU initiative. PATIENTS: Adult patients treated with chimeric antigen receptor T-cell therapy who required ICU admission between November 2017 and May 2019. INTERVENTIONS: Demographics, toxicities, specific interventions, and outcomes were collected. RESULTS: One-hundred five patients treated with axicabtagene ciloleucel required ICU admission for cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome during the study period. At the time of ICU admission, the majority of patients had grade 3-4 toxicities (66.7%); 15.2% had grade 3-4 cytokine release syndrome and 64% grade 3-4 immune effector cell-associated neurotoxicity syndrome. During ICU stay, cytokine release syndrome was observed in 77.1% patients and immune effector cell-associated neurotoxicity syndrome in 84.8% of patients; 61.9% patients experienced both toxicities. Seventy-nine percent of patients developed greater than or equal to grade 3 toxicities during ICU stay, however, need for vasopressors (18.1%), mechanical ventilation (10.5%), and dialysis (2.9%) was uncommon. Immune Effector Cell-Associated Encephalopathy score less than 3 (69.7%), seizures (20.2%), status epilepticus (5.7%), motor deficits (12.4%), and cerebral edema (7.9%) were more prevalent. ICU mortality was 8.6%, with only three deaths related to cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome. Median overall survival time was 10.4 months (95% CI, 6.64-not available mo). Toxicity grade or organ support had no impact on overall survival; higher cumulative corticosteroid doses were associated to decreased overall and progression-free survival. CONCLUSIONS: This is the first study to describe a multicenter cohort of patients requiring ICU admission with cytokine release syndrome or immune effector cell-associated neurotoxicity syndrome after chimeric antigen receptor T-cell therapy. Despite severe toxicities, organ support and in-hospital mortality were low in this patient population.

Yearlong COVID-19 Infection Reveals Within-Host Evolution of SARS-CoV-2 in a Patient With B-Cell Depletion.

B-cell-depleting therapies may lead to prolonged disease and viral shedding in individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and this viral persistence raises concern for viral evolution. We report sequencing of early and late samples from a 335-day infection in an immunocompromised patient. The virus accumulated a unique deletion in the amino-terminal domain of the spike protein, and complete deletion of ORF7b and ORF8, the first report of its kind in an immunocompromised patient. Unique viral mutations found in this study highlight the importance of analyzing viral evolution in protracted SARS-CoV-2 infection, especially in immunosuppressed hosts.

Year-long COVID-19 infection reveals within-host evolution of SARS-CoV-2 in a patient with B cell depletion.

BACKGROUND: B-cell depleting therapies may lead to protracted disease and prolonged viral shedding in individuals infected with SARS-CoV-2. Viral persistence in the setting of immunosuppression raises concern for viral evolution. METHODS: Amplification of sub-genomic transcripts for the E gene (sgE) was done on nasopharyngeal samples over the course of 355 days in a patient infected with SARS-CoV-2 who had previously undergone CAR T cell therapy and had persistently positive SARS-CoV-2 nasopharyngeal swabs. Whole genome sequencing was performed on samples from the patient's original presentation and 10 months later. RESULTS: Over the course of almost a year, the virus accumulated a unique in-frame deletion in the amino-terminal domain of the spike protein, and complete deletion of ORF7b and ORF8, the first report of its kind in an immunocompromised patient. Also, minority variants that were identified in the early samples-reflecting the heterogeneity of the initial infection-were found to be fixed late in the infection. Remdesivir and high-titer convalescent plasma treatment were given, and the infection was eventually cleared after 335 days of infection. CONCLUSIONS: The unique viral mutations found in this study highlight the importance of analyzing viral evolution in protracted SARS-CoV-2 infection, especially in immunosuppressed hosts, and the implication of these mutations in the emergence of viral variants. SUMMARY: We report an immunocompromised patient with persistent symptomatic SARS-CoV-2 infection for 335 days. During this time, the virus accumulated a unique in-frame deletion in the spike, and a complete deletion of ORF7b and ORF8 which is the first report of its kind in an immunocompromised patient.

CAR T-Cell Therapy in Hematologic Malignancies: Clinical Role, Toxicity, and Unanswered Questions.

At the time of writing, five anti-CD19 CAR T-cell products are approved by the U.S. Food and Drug Administration for seven different indications in lymphoid malignancies, including B-cell non-Hodgkin lymphoma, pediatric B-cell acute lymphoblastic leukemia, and multiple myeloma. CAR T cells for chronic lymphocytic leukemia, acute myeloid leukemia, and less common malignancies such as T-cell lymphomas and Hodgkin lymphoma are being tested in early-phase clinical trials worldwide. The purpose of this overview is to describe the current landscape of CAR T cells in hematologic malignancies, outline their outcomes and toxicities, and explain the outstanding questions that remain to be addressed.

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.

The chimeric antigen receptor-intensive care unit (CAR-ICU) initiative: Surveying intensive care unit practices in the management of CAR T-cell associated toxicities.

PURPOSE: A task force of experts from 11 United States (US) centers, sought to describe practices for managing chimeric antigen receptor (CAR) T-cell toxicity in the intensive care unit (ICU). MATERIALS AND METHODS: Between June-July 2019, a survey was electronically distributed to 11 centers. The survey addressed: CAR products, toxicities, targeted treatments, management practices and interventions in the ICU. RESULTS: Most centers (82%) had experience with commercial and non-FDA approved CAR products. Criteria for ICU admission varied between centers for patients with Cytokine Release Syndrome (CRS) but were similar for Immune Effector Cell Associated Neurotoxicity Syndrome (ICANS). Practices for vasopressor support, neurotoxicity and electroencephalogram monitoring, use of prophylactic anti-epileptic drugs and tocilizumab were comparable. In contrast, fluid resuscitation, respiratory support, methods of surveillance and management of cerebral edema, use of corticosteroid and other anti-cytokine therapies varied between centers. CONCLUSIONS: This survey identified areas of investigation that could improve outcomes in CAR T-cell recipients such as fluid and vasopressor selection in CRS, management of respiratory failure, and less common complications such as hemophagocytic lymphohistiocytosis, infections and stroke. The variability in specific treatments for CAR T-cell toxicities, needs to be considered when designing future outcome studies of critically ill CAR T-cell patients.

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

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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.

Effects of starting cellular material composition on chimeric antigen receptor T-cell expansion and characteristics.

BACKGROUND: When manufacturing chimeric antigen receptor (CAR) T cells using anti-CD3/anti-CD28 beads, ex vivo T-cell expansion is dependent on the composition of leukocytes used in the manufacturing process. We investigated the effects of leukocyte composition on CAR T-cell expansion and characteristics using an alternative manufacturing method. METHODS: Anti-B-cell maturation antigen and CD19-CAR T cells were manufactured using autologous peripheral blood mononuclear cell (PBMNC) concentrates. The PBMNCs were enriched for lymphocytes using density gradient separation, which were used for CAR T-cell culture initiation. T-cell expansion was stimulated with soluble anti-CD3 and interleukin-2. RESULTS: Fifty-one CAR T-cell products were evaluated; 28 anti-B-cell maturation antigen (BCMA) CAR T cells produced for 24 patients and 27 CD19 CAR T cells produced for 24 patients. CAR T-cell expansion was reduced when greater quantities of monocytes were present in the post-density gradient separation PBMNCs. In addition, the ratio of CD4 to CD8 cells in the CAR T-cell products after 7 days of culture was dependent on the quantity of monocytes, RBCs, and neutrophils in the post-density gradient separation PBMNCs. Greater quantities of monocytes and RBCs were associated with a greater proportion of CD4+ cells and greater quantities of neutrophils were associated with a greater proportion of CD8+ cells. CONCLUSIONS: The composition of leukocytes used to manufacture CAR T cells can affect cell expansion and the composition of CAR T-cell products. More uniform or complete lymphocyte enrichment of PBMNCs improves the consistency of final CAR T-cell products.

Recent advances in CAR T-cell toxicity: Mechanisms, manifestations and management.

Chimeric antigen receptor (CAR) T-cell therapy is an effective new treatment for hematologic malignancies. Two CAR T-cell products are now approved for clinical use by the U.S. FDA: tisagenlecleucel for pediatric acute lymphoblastic leukemia (ALL) and adult diffuse large B-cell lymphoma subtypes (DLBCL), and axicabtagene ciloleucel for DLBCL. CAR T-cell therapies are being developed for multiple myeloma, and clear evidence of clinical activity has been generated. A barrier to widespread use of CAR T-cell therapy is toxicity, primarily cytokine release syndrome (CRS) and neurologic toxicity. Manifestations of CRS include fevers, hypotension, hypoxia, end organ dysfunction, cytopenias, coagulopathy, and hemophagocytic lymphohistiocytosis. Neurologic toxicities are diverse and include encephalopathy, cognitive defects, dysphasias, seizures, and cerebral edema. Our understanding of the pathophysiology of CRS and neurotoxicity is continually improving. Early and peak levels of certain cytokines, peak blood CAR T-cell levels, patient disease burden, conditioning chemotherapy, CAR T-cell dose, endothelial activation, and CAR design are all factors that may influence toxicity. Multiple grading systems for CAR T-cell toxicity are in use; a universal grading system is needed so that CAR T-cell products can be compared across studies. Guidelines for toxicity management vary among centers, but typically include supportive care, plus immunosuppression with tocilizumab or corticosteroids administered for severe toxicity. Gaining a better understanding of CAR T-cell toxicities and developing new therapies for these toxicities are active areas of laboratory research. Further clinical investigation of CAR T-cell toxicity is also needed. In this review, we present guidelines for management of CRS and CAR neurotoxicity.