Kinetics of immune reconstitution after anti-CD19 chimeric antigen receptor T cell therapy in relapsed or refractory acute lymphoblastic leukemia patients

Managing Infection Complications in the Setting of Chimeric Antigen Receptor T cell (CAR-T) Therapy

Chimeric antigen receptor T-cell (CAR T-cell) therapy has changed the paradigm of management of non-Hodgkin's lymphoma (NHL) and Multiple Myeloma. Infection complications have emerged as a concern that can arise in the setting of therapy and lead to morbidity and mortality. In this review, we classified infection complications into three categories, pre-infusion phase from the time pre- lymphodepletion (LD) up to day zero, early phase from day of infusion to day 30 post-infusion, and late phase after day 30 onwards. Infections arising in the pre-infusion phase are closely related to previous chemotherapy and bridging therapy. Infections arising in the early phase are more likely related to LD chemo and the expected brief period of grade 3-4 neutropenia. Infections arising in the late phase are particularly worrisome because they are associated with adverse risk features including prolonged neutropenia, dysregulation of humoral and adaptive immunity with lymphopenia, hypogammaglobinemia, and B cell aplasia. Bacterial, respiratory and other viral infections, protozoal and fungal infections can occur during this time . We recommend enhanced supportive care including prompt recognition and treatment of neutropenia with growth factor support, surveillance testing for specific viruses in the appropriate instance, management of hypogammaglobulinemia with repletion as appropriate and extended antimicrobial prophylaxis in those at higher risk (e.g. high dose steroid use and prolonged cytopenia). Finally, we recommend re-immunizing patients post CAR-T based on CDC and transplant guidelines.

High-Specificity CRISPR-Mediated Genome Engineering in Anti-BCMA Allogeneic CAR T Cells Suppresses Allograft Rejection in Preclinical Models

Allogeneic chimeric antigen receptor (CAR) T cell therapies hold the potential to overcome many of the challenges associated with patient-derived (autologous) CAR T cells. Key considerations in the development of allogeneic CAR T cell therapies include prevention of graft-vs-host disease (GvHD) and suppression of allograft rejection. Here, we describe preclinical data supporting the ongoing first-in-human clinical study, the CaMMouflage trial (NCT05722418), evaluating CB-011 in patients with relapsed/refractory multiple myeloma. CB-011 is a hypoimmunogenic, allogeneic anti-B-cell maturation antigen (BCMA) CAR T cell therapy candidate. CB-011 cells feature 4 genomic alterations and were engineered from healthy donor-derived T cells using a Cas12a CRISPR hybrid RNA-DNA (chRDNA) genome-editing technology platform. To address allograft rejection, CAR T cells were engineered to prevent endogenous HLA class I complex expression and overexpress a single-chain polyprotein complex composed of beta-2 microglobulin (B2M) tethered to HLA-E. In addition, T-cell receptor (TCR) expression was disrupted at the TCR alpha constant locus in combination with the site-specific insertion of a humanized BCMA-specific CAR. CB-011 cells exhibited robust plasmablast cytotoxicity in vitro in a mixed lymphocyte reaction in cell cocultures derived from patients with multiple myeloma. In addition, CB-011 cells demonstrated suppressed recognition by and cytotoxicity from HLA-mismatched T cells. CB-011 cells were protected from natural killer cell-mediated cytotoxicity in vitro and in vivo due to endogenous promoter-driven expression of B2M-HLA-E. Potent antitumor efficacy, when combined with an immune-cloaking armoring strategy to dampen allograft rejection, offers optimized therapeutic potential in multiple myeloma. See related Spotlight by Caimi and Melenhorst, p. 385.

Early CAR- CD4+ T-lymphocytes recovery following CAR-T cell infusion: A worse outcome in diffuse large B cell lymphoma

CAR- CD4+ T cell lymphopenia is an emerging issue following CAR-T cell therapy. We analyzed the determinants of CD4+ T cell recovery and a possible association with survival in 31 consecutive patients treated with commercial CAR-T for diffuse large B-cell (DLBCL) or mantle cell lymphoma. Circulating immune subpopulations were characterized through multiparametric-flow cytometry. Six-month cumulative incidence of CAR- CD4+ T cell recovery (≥200 cells/μL) was 0.43 (95% confidence interval [CI]: 0.28-0.65). Among possible determinants of CD4+ T cell recovery, we recognized infusion of a 4-1BB product (tisagenlecleucel, TSA) in comparison with a CD28 (axicabtagene/brexucabtagene, AXI/BRX) (hazard ratio [HR] [95% CI]: 5.79 [1.16-24.12] p = 0.016). Higher CD4+ T cell counts resulted with TSA at month-1, -2 and -3. Moderate-to-severe infections were registered with prolonged CD4+ T cell lymphopenia. Early, month-1 CD4+ T cell recovery was associated with a worse outcome in the DLBCL cohort, upheld in a multivariate regression model for overall survival (HR: 4.46 [95% CI: 1.12-17.71], p = 0.03). We conclude that a faster CAR- CD4+ T cell recovery is associated with TSA as compared to AXI/BRX. Month-1 CAR- CD4+ T cell subset recovery could represent a "red flag" for CAR-T cell therapy failure in DLBCL patients.

Pneumocystis jirovecii Pneumonia Secondary to Blinatumomab Therapy: A Case Report

INTRODUCTION

With the increasing use of blinatumomab in relapsed or refractory B-cell precursor acute lymphoblastic leukemia (ALL), including minimal residual disease (MRD)-positive cases, awareness of its adverse effects has gradually improved. Pneumocystis jirovecii pneumonia (PCP) associated with blinatumomab therapy is rare.

CASE PRESENTATION

We present a case of PCP in a patient undergoing blinatumomab therapy. A 70-year-old female diagnosed with Philadelphia-like CRLF2 overexpression B-cell precursor ALL received blinatumomab as consolidation therapy after achieving complete remission with prior induction chemotherapy. On the second day of blinatumomab infusion, she developed intermittent low-grade fever, and chest computed tomography (CT) revealed subtle infiltrates and nodules. Despite empiric trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis, she progressed to significant shortness of breath and type I respiratory failure, with increased lactate dehydrogenase and β-D-glucan assays. Chest CT showed diffuse ground-glass opacities with scattered small nodules. The dry cough prompted next-generation sequencing of peripheral blood, which tested positive for pneumocystis jirovecii without evidence of other pathogens. Consequently, the patient was diagnosed with PCP. The first cycle of blinatumomab had to be discontinued, and therapeutic dosages of TMP-SMX and dexamethasone were administered, resulting in full recovery and stable condition during follow-ups.

CONCLUSION

PCP is rare in B-cell precursor ALL patients receiving blinatumomab therapy but manifests with early onset and rapid disease progression. Despite prophylaxis, PCP infection cannot be ignored during blinatumomab therapy. Therefore, heightened attention is warranted when using blinatumomab therapy.

CAR T cells and time-limited ibrutinib as treatment for relapsed/refractory mantle cell lymphoma: the phase 2 TARMAC study

ABSTRACT

CD19-directed chimeric antigen receptor T cells (CAR-T) achieve high response rates in patients with relapsed/refractory mantle cell lymphoma (MCL). However, their use is associated with significant toxicity, relapse concern, and unclear broad tractability. Preclinical and clinical data support a beneficial synergistic effect of ibrutinib on apheresis product fitness, CAR-T expansion, and toxicity. We evaluated the combination of time-limited ibrutinib and CTL019 CAR-T in 20 patients with MCL in the phase 2 TARMAC study. Ibrutinib commenced before leukapheresis and continued through CAR-T manufacture for a minimum of 6 months after CAR-T administration. The median prior lines of therapy was 2; 50% of patients were previously exposed to a Bruton tyrosine kinase inhibitor (BTKi). The primary end point was 4-month postinfusion complete response (CR) rate, and secondary end points included safety and subgroup analysis based on TP53 aberrancy. The primary end point was met; 80% of patients demonstrated CR, with 70% and 40% demonstrating measurable residual disease negativity by flow cytometry and molecular methods, respectively. At 13-month median follow-up, the estimated 12-month progression-free survival was 75% and overall survival 100%. Fifteen patients (75%) developed cytokine release syndrome; 12 (55%) with grade 1 to 2 and 3 (20%) with grade 3. Reversible grade 1 to 2 neurotoxicity was observed in 2 patients (10%). Efficacy was preserved irrespective of prior BTKi exposure or TP53 mutation. Deep responses correlated with robust CAR-T expansion and a less exhausted baseline T-cell phenotype. Overall, the safety and efficacy of the combination of BTKi and T-cell redirecting immunotherapy appears promising and merits further exploration. This trial was registered at www.ClinicalTrials.gov as #NCT04234061.

Hematopoiesis and immune reconstitution after CD19 directed chimeric antigen receptor T-cells (CAR-T): A comprehensive review on incidence, risk factors and current management

Impaired function of hematopoiesis after treatment with chimeric antigen T-cells (CAR-T) is a frequent finding and can interest a wide range of patients, regardless of age and underlying disease. Trilinear cytopenias, as well as hypogammaglobulinemia, B-cell aplasia, and T-cell impairment, can severely affect the infectious risk of CAR-T recipients, as well as their quality of life. In this review, we provide an overview of defects in hematopoiesis after CAR-T, starting with a summary of different definitions and thresholds. We then move to summarize the main pathogenetic mechanisms of cytopenias, and we offer insight into cytomorphological aspects, the role of clonal hematopoiesis, and the risk of secondary myeloid malignancies. Subsequently, we expose the major findings and reports on T-cell and B-cell quantitative and functional impairment after CAR-T. Finally, we provide an overview of current recommendations and leading experiences regarding the management of cytopenias and defective B- and T-cell function.

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

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

Early and Late Toxicities of Chimeric Antigen Receptor T-Cells

As chimeric antigen receptor (CAR) T-cell therapy is increasingly integrated into clinical practice across a range of malignancies, identifying and treating inflammatory toxicities will be vital to success. Early experiences with CD19-targeted CAR T-cell therapy identified cytokine release syndrome and neurotoxicity as key acute toxicities and led to unified initiatives to mitigate the influence of these complications. In this section, we provide an update on the current state of CAR T-cell-related toxicities, with an emphasis on emerging acute toxicities affecting additional organ systems and considerations for delayed toxicities and late effects.

Long-term analysis of cellular immunity in patients with RRMM treated with CAR-T cell therapy

Chimeric antigen receptor T (CAR-T) cell therapy exhibits remarkable efficacy against refractory or relapsed multiple myeloma (RRMM); however, the immune deficiency following CAR-Ts infusion has not been well studied. In this study, 126 patients who achieved remission post-CAR-Ts infusion were evaluated for cellular immunity. Following lymphodepletion (LD) chemotherapy, the absolute lymphocyte count (ALC) and absolute counts of lymphocyte subsets were significantly lower than baseline at D0. Grade ≥ 3 lymphopenia occurred in 99% of patients within the first 30 days, with most being resolved by 180 days. The median CD4+ T-cell count was consistently below baseline and the lower limit of normal (LLN) levels at follow-up. Conversely, the median CD8+ T-cell count returned to the baseline and LLN levels by D30. The median B-cell count remained lower than baseline level at D60 and returned to baseline and LLN levels at D180. In the first 30 days, 27 (21.4%) patients had 29 infections, with the majority being mild to moderate in severity (21/29; 72.4%). After day 30, 44 (34.9%) patients had 56 infections, including 20 severe infections. One patient died from bacteremia at 3.8 months post-CAR-Ts infusion. In conclusion, most patients with RRMM experienced cellular immune deficiency caused by LD chemotherapy and CAR-Ts infusion. The ALC and most lymphocyte subsets gradually recovered after day 30 of CAR-Ts infusion, except for CD4+ T cells. Some patients experience prolonged CD4+ T-cell immunosuppression without severe infection.

Prevention and management of hepatitis B virus reactivation in patients with hematological malignancies in the targeted therapy era

Hepatitis due to hepatitis B virus (HBV) reactivation can be serious and potentially fatal, but is preventable. HBV reactivation is most commonly reported in patients receiving chemotherapy, especially rituximab-containing therapy for hematological malignancies and those receiving stem cell transplantation. Patients with inactive and even resolved HBV infection still have persistence of HBV genomes in the liver. The expression of these silent genomes is controlled by the immune system. Suppression or ablation of immune cells, most importantly B cells, may lead to reactivation of seemingly resolved HBV infection. Thus, all patients with hematological malignancies receiving anticancer therapy should be screened for active or resolved HBV infection by blood tests for hepatitis B surface antigen (HBsAg) and antibody to hepatitis B core antigen. Patients found to be positive for HBsAg should be given prophylactic antiviral therapy. For patients with resolved HBV infection, there are two approaches. The first is pre-emptive therapy guided by serial HBV DNA monitoring, and treatment with antiviral therapy as soon as HBV DNA becomes detectable. The second approach is prophylactic antiviral therapy, particularly for patients receiving high-risk therapy, especially anti-CD20 monoclonal antibody or hematopoietic stem cell transplantation. Entecavir and tenofovir are the preferred antiviral choices. Many new effective therapies for hematological malignancies have been introduced in the past decade, for example, chimeric antigen receptor (CAR)-T cell therapy, novel monoclonal antibodies, bispecific antibody drug conjugates, and small molecule inhibitors, which may be associated with HBV reactivation. Although there is limited evidence to guide the optimal preventive measures, we recommend antiviral prophylaxis in HBsAg-positive patients receiving novel treatments, including Bruton's tyrosine kinase inhibitors, B-cell lymphoma 2 inhibitors, and CAR-T cell therapy. Further studies are needed to determine the risk of HBV reactivation with these agents and the best prophylactic strategy.

Cytopenias following anti-CD19 chimeric antigen receptor (CAR) T cell therapy: a systematic analysis for contributing factors

BACKGROUND

Cytopenia is one of the most common adverse events following the CAR-T cell infusion, affecting the quality of life and potentially leading to life-threatening bleeding and infection. This study aimed to systematically review the cytopenias following anti-CD19 CAR-T therapy and further analyse the contributing factors.

METHODS

Databases including PubMed, MEDLINE, Embase and Cochrane were systematically searched on 8 May 2022. A random-effect meta-analysis was used to estimate the incidence of cytopenia, and subgroup analyses were applied to explore heterogeneity.

RESULTS

A total of 68 studies involving 2950 patients were included in this study. The overall incidence of all grade anaemia, thrombocytopenia, neutropenia, leukopoenia, lymphocytopenia and febrile neutropenia was 65%, 55%, 78%, 62%, 70% and 27%, respectively, and the corresponding cytopenias of grade 3 or worse were 33%, 31%, 61%, 45%, 46%, and 21%, respectively. Subgroup analysis showed increased incidence of cytopenias in subgroups with lower median age, proportion of males (<65%) and proportion of bridging therapy (<80%) and in the subgroup with a median line of prior therapy ≥3. In terms of disease and therapeutic target, cytopenias were more frequent in ALL patients and in dual-target CAR-T therapies (targeting CD19 in combination with other targets). Furthermore, CAR-T products manufactured by lentiviral vectors and those with the costimulatory domain of CD28 were more likely to cause haematological toxicity. No significant differences were observed in cytopenia between patients treated with CAR-T products with murine and humanized scFv.

CONCLUSION

In conclusion, neutropenia is the most frequent cytopenia after CAR-T therapy, both in all grades or grade ≥3. The incidence of cytopenias following CAR-T therapy is influenced by the age, sex, disease and number of prior therapy lines of the patients, as well as the target and costimulatory domain of CAR-T cells, and viral vectors used for manufacturing.KEY MESSAGESNeutropenia is the most frequent cytopenia after CAR-T therapy.The clinical characteristics of the patients, the design of CAR-T cells and the protocol of CAR-T treatment can influence the occurrence of cytopenias following the CAR-T therapy.

Case Report: Successful engraftment of allogeneic hematopoietic stem cells using CAR-T cell therapy as the conditioning regimen in R/R Ph+ B cell acute lymphoblastic leukemia

Background

Consolidative allogeneic hematopoietic stem cells (allo-HSCs) after chimeric antigen receptor T cells (CAR-T) therapy is an emerging modality in hematologic malignancies. Knowledge about the success of allogeneic hematopoietic stem cell transplantation (allo-HSCT) after CAR-T therapy without a conditioning regimen is limited.

Case presentation

We report a patient with relapsed/refractory (R/R) Ph⁺ B-cell acute lymphoblastic leukemia (ALL) who underwent anti-CD19 CAR-T immunotherapy. After 1 month of treatment, bone marrow hyperplasia remained reduced with no hematopoietic improvements. In line with this, allogeneic hematopoietic stem cells (HSCs) were extracted from an HLA-matched sibling donor and administered to the patient on day 33 after CAR-T cell therapy to support hematopoiesis. On day 40, the level of immature bone marrow lymphocytes was at 0% and minimal residual disease-negative, and the fusion gene BCR/ABL 190 was negative. Chimerism analysis showed full donor chimerism. Three months after CAR-T cells infusion, the patient was still in complete remission with full donor chimerism. However, decreased liver function with skin pigmentation and festering, indicative of acute graft versus host disease, was noted. The treatment was halted owing to financial reasons.

Conclusion

We report the successful engraftment of allogeneic HSCs using CAR-T cell therapy as a conditioning regimen for R/R B-ALL patients.

Endowing universal CAR T-cell with immune-evasive properties using TALEN-gene editing

Universal CAR T-cell therapies are poised to revolutionize cancer treatment and to improve patient outcomes. However, realizing these advantages in an allogeneic setting requires universal CAR T-cells that can kill target tumor cells, avoid depletion by the host immune system, and proliferate without attacking host tissues. Here, we describe the development of a novel immune-evasive universal CAR T-cells scaffold using precise TALEN-mediated gene editing and DNA matrices vectorized by recombinant adeno-associated virus 6. We simultaneously disrupt and repurpose the endogenous TRAC and B2M loci to generate TCRαβ- and HLA-ABC-deficient T-cells expressing the CAR construct and the NK-inhibitor named HLA-E. This highly efficient gene editing process enables the engineered T-cells to evade NK cell and alloresponsive T-cell attacks and extend their persistence and antitumor activity in the presence of cytotoxic levels of NK cell in vivo and in vitro, respectively. This scaffold could enable the broad use of universal CAR T-cells in allogeneic settings and holds great promise for clinical applications.

Adverse effects in hematologic malignancies treated with chimeric antigen receptor (CAR) T cell therapy: a systematic review and Meta-analysis

Background

Recently, chimeric antigen receptor-modified (CAR) T cell therapy for hematological malignancies has shown clinical efficacy. Hundreds of clinical trials have been registered and lots of studies have shown hematologic toxic effects were very common. The main purpose of this review is to systematically analyze hematologic toxicity in hematologic malignancies treated with CAR-T cell therapy.

Methods

We searched databases including PubMed, Web of Science, Embase and Cochrane up to January 2021. For safety analysis of overall hematologic toxicity, the rate of neutrophil, thrombocytopenia and anemia were calculated. Subgroup analysis was performed for age, pathological type, target antigen, co-stimulatory molecule, history of hematopoietic stem cell transplantation (HSCT) and prior therapy lines. The incidence rate of aspartate transferase (AST) increased, alanine transaminase (ALT) increased, serum creatine increased, APTT prolonged and fibrinogen decreased were also calculated.

Results

Overall, 52 studies involving 2004 patients were included in this meta-analysis. The incidence of any grade neutropenia, thrombocytopenia and anemia was 80% (95% CI: 68–89%), 61% (95% CI: 49–73%), and 68% (95%CI: 54–80%) respectively. The incidences of grade ≥ 3 neutropenia, thrombocytopenia and anemia were 60% (95% CI: 49–70%), 33% (95% CI: 27–40%), and 32% (95%CI: 25–40%) respectively. According to subgroup analysis and the corresponding Z test, hematological toxicity was more frequent in younger patients, in patients with ≥4 median lines of prior therapy and in anti-CD19 cases. The subgroup analysis of CD19 CAR-T cell constructs showed that 41BB resulted in less hematological toxicity than CD28.

Conclusion

CAR-T cell therapy has dramatical efficacy in hematological malignancies, but the relevant adverse effects remain its obstacle. The most common ≥3 grade side effect is hematological toxicity, and some cases die from infections or severe hemorrhage in early period. In long-term follow-up, hematological toxicity is less life-threatening generally and most suffered patients recover to adequate levels after 3 months. To prevent life-threatening infections or bleeding events, clinicians should pay attention to intervention of hematological toxicity in the early process of CAR-T cell therapy.

Targeted Therapy in the Treatment of Pediatric Acute Lymphoblastic Leukemia-Therapy and Toxicity Mechanisms

Targeted therapy has revolutionized the treatment of poor-prognosis pediatric acute lymphoblastic leukemia (ALL) with specific genetic abnormalities. It is still being described as a new landmark therapeutic approach. The main purpose of the use of molecularly targeted drugs and immunotherapy in the treatment of ALL is to improve the treatment outcomes and reduce the doses of conventional chemotherapy, while maintaining the effectiveness of the therapy. Despite promising treatment results, there is limited clinical research on the effect of target cell therapy on the potential toxic events in children and adolescents. The recent development of highly specific molecular methods has led to an improvement in the identification of numerous unique expression profiles of acute lymphoblastic leukemia. The detection of specific genetic mutations determines patients’ risk groups, which allows for patient stratification and for an adjustment of the directed and personalized target therapies that are focused on particular molecular alteration. This review summarizes the knowledge concerning the toxicity of molecular-targeted drugs and immunotherapies applied in childhood ALL.