Graft-versus-host disease after anti-CD19 chimeric antigen receptor T-cell therapy following allogeneic hematopoietic cell transplantation: a transplant complications and paediatric diseases working parties joint EBMT study.

In patients diagnosed with B-acute lymphoblastic leukemia (B-ALL) or B-non-Hodgkin's lymphoma (B-NHL) relapsing after allogeneic stem cell transplantation (allo-HCT), it is a standard practice to perform anti-CD19 chimeric antigen receptor (CAR) T-cell therapy. When collected from the patient after allo-HCT, the produced CAR-T cells are likely to be donor T-cell-derived, creating unknown safety risks due to their potential allo-reactivity. We therefore performed an EBMT registry-based study on the incidence of graft-versus-host disease (GvHD) in this setting.

Pediatric adapted risk index to predict 2-year transplant-related mortality post-HSCT in children.

Several attempts have been made to optimize pretransplant risk assessment to improve hematopoietic stem cell transplantation (HSCT) decision-making and to predict post-HSCT outcomes. However, the relevance of pretransplant risk assessment to the pediatric population remains unclear. We report the results of revalidation of the hematopoietic cell transplantation comorbidity index (HCT-CI) in 874 children who received 944 HSCTs for malignant or nonmalignant diseases at a single center.

Outcomes of allogeneic haematopoietic cell transplantation for myelofibrosis in children and adolescents: the retrospective study of the EBMT Paediatric Diseases WP.

This retrospective study evaluated 35 children (median age 5.2 years; range 0.4-18) with myelofibrosis (MF), including 33 with primary myelofibrosis and 2 with secondary myelofibrosis transplanted from matched sibling donor (MSD) (n = 17) or non-MSD (n = 18) between 2000 and 2022.

Intention-to-treat outcomes utilising a stringent event definition in children and young people treated with tisagenlecleucel for r/r ALL through a national access scheme.

CAR T-cell therapy has transformed relapsed/refractory (r/r) B-cell precursor acute lymphoblastic leukaemia (B-ALL) management and outcomes, but following CAR T infusion, interventions are often needed. In a UK multicentre study, we retrospectively evaluated tisagenlecleucel outcomes in all eligible patients, analysing overall survival (OS) and event-free survival (EFS) with standard and stringent definitions, the latter including measurable residual disease (MRD) emergence and further anti-leukaemic therapy. Both intention-to-treat and infused cohorts were considered.

Anti-CD45 PBD-based antibody-drug conjugates are effective targeted conditioning agents for gene therapy and stem cell transplant.

Stem cell gene therapy and hematopoietic stem cell transplantation (SCT) require conditioning to ablate the recipient's hematopoietic stem cells (HSCs) and create a niche for gene-corrected/donor HSCs. Conventional conditioning agents are non-specific, leading to off-target toxicities and resulting in significant morbidity and mortality. We developed tissue-specific anti-human CD45 antibody-drug conjugates (ADCs), using rat IgG2b anti-human CD45 antibody clones YTH24.

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

Although CD19-directed chimeric antigen receptor (CAR) T cell therapy (CAR-T) for relapsed/refractory B cell acute lymphoblastic leukemia (B-ALL) has been transformative in inducing and sustaining remission, relapse rates remain unacceptably high, with approximately 50% of children and young adults experiencing relapse within the first year postinfusion. Emerging strategies to extend the durability of remission involve the use of prognostic biomarkers to identify those at high risk of relapse or incorporate strategies aimed to enhancing functional CAR T cell persistence. Nonetheless, with antigen loss/down-regulation or evolution to lineage switch as major mechanisms of relapse, optimizing single antigen targeting alone is insufficient.

CD19/CD22 targeting with cotransduced CAR T cells to prevent antigen-negative relapse after CAR T-cell therapy for B-cell ALL.

CD19-negative relapse is a leading cause of treatment failure after chimeric antigen receptor (CAR) T-cell therapy for acute lymphoblastic leukemia. We investigated a CAR T-cell product targeting CD19 and CD22 generated by lentiviral cotransduction with vectors encoding our previously described fast-off rate CD19 CAR (AUTO1) combined with a novel CD22 CAR capable of effective signaling at low antigen density. Twelve patients with advanced B-cell acute lymphoblastic leukemia were treated (CARPALL [Immunotherapy with CD19/22 CAR Redirected T Cells for High Risk/Relapsed Paediatric CD19+ and/or CD22+ Acute Lymphoblastic Leukaemia] study, NCT02443831), a third of whom had failed prior licensed CAR therapy.

Transcriptional signatures associated with persisting CD19 CAR-T cells in children with leukemia.

In the context of relapsed and refractory childhood pre-B cell acute lymphoblastic leukemia (R/R B-ALL), CD19-targeting chimeric antigen receptor (CAR)-T cells often induce durable remissions, which requires the persistence of CAR-T cells. In this study, we systematically analyzed CD19 CAR-T cells of 10 children with R/R B-ALL enrolled in the CARPALL trial via high-throughput single-cell gene expression and T cell receptor sequencing of infusion products and serial blood and bone marrow samples up to 5 years after infusion. We show that long-lived CAR-T cells developed a CD4/CD8 double-negative phenotype with an exhausted-like memory state and distinct transcriptional signature.

T-cell replete cord transplants give superior outcomes in high-risk and relapsed/refractory pediatric myeloid malignancy.

Stem cell transplant (SCT) outcomes in high-risk and relapsed/refractory (R/R) pediatric acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) have been historically poor. Cord blood (CB) allows T-cell replete CB transplant (TRCB), enabling enhanced graft-versus-leukemia. We consecutively collected data from 367 patients undergoing TRCB (112 patients) or other cell source (255 patients) SCT for pediatric AML/MDS in the United Kingdom and Ireland between January 2014 and December 2021.

Activation priming and cytokine polyfunctionality modulate the enhanced functionality of low-affinity CD19 CAR T cells.

We recently described a low-affinity second-generation CD19 chimeric antigen receptor (CAR) CAT that showed enhanced expansion, cytotoxicity, and antitumor efficacy compared with the high-affinity (FMC63-based) CAR used in tisagenlecleucel, in preclinical models. Furthermore, CAT demonstrated an excellent toxicity profile, enhanced in vivo expansion, and long-term persistence in a phase 1 clinical study. To understand the molecular mechanisms behind these properties of CAT CAR T cells, we performed a systematic in vitro characterization of the transcriptomic (RNA sequencing) and protein (cytometry by time of flight) changes occurring in T cells expressing low-affinity vs high-affinity CD19 CARs following stimulation with CD19-expressing cells.

High-dimensional functional phenotyping of preclinical human CAR T cells using mass cytometry.

Here, we present a comprehensive protocol for the generation and functional characterization of chimeric antigen receptor (CAR) T cells and their products by mass cytometry in a reproducible and scalable manner. We describe the production of CAR T cells from human peripheral blood mononuclear cells. We then detail a three-step staining protocol with metal-labeled antibodies and the subsequent mass cytometry analysis.

Betibeglogene Autotemcel Gene Therapy for Non-β/β Genotype β-Thalassemia.

Background: Betibeglogene autotemcel (beti-cel) gene therapy for transfusion-dependent β-thalassemia contains autologous CD34+ hematopoietic stem cells and progenitor cells transduced with the BB305 lentiviral vector encoding the β-globin (β) gene.

Methods: In this open-label, phase 3 study, we evaluated the efficacy and safety of beti-cel in adult and pediatric patients with transfusion-dependent β-thalassemia and a non-β/β genotype. Patients underwent myeloablation with busulfan (with doses adjusted on the basis of pharmacokinetic analysis) and received beti-cel intravenously.

CAR T cells with dual targeting of CD19 and CD22 in pediatric and young adult patients with relapsed or refractory B cell acute lymphoblastic leukemia: a phase 1 trial.

Chimeric antigen receptor (CAR) T cells targeting CD19 or CD22 have shown remarkable activity in B cell acute lymphoblastic leukemia (B-ALL). The major cause of treatment failure is antigen downregulation or loss. Dual antigen targeting could potentially prevent this, but the clinical safety and efficacy of CAR T cells targeting both CD19 and CD22 remain unclear.