Antigen experience history directs distinct functional states of CD8 CAR T cells during the antileukemia response.

Although chimeric antigen receptor (CAR) T cells are effective against B-lineage malignancies, post-CAR relapse is common, and efficacy in other tumors is limited. These challenges may be addressed through rational manipulations to control CAR T cell function. Here we examine the impact of cognate T cell antigen experience on subsequent CD8 CAR T cell activity.

Co-targeting of the thymic stromal lymphopoietin receptor to decrease immunotherapeutic resistance in CRLF2-rearranged Ph-like and Down syndrome acute lymphoblastic leukemia.

CRLF2 rearrangements occur in >50% of Ph-like and Down syndrome (DS)-associated B-acute lymphoblastic leukemia (ALL) and induce constitutive kinase signaling targetable by the JAK1/2 inhibitor ruxolitinib under current clinical investigation. While chimeric antigen receptor T cell (CART) immunotherapies have achieved remarkable remission rates in children with relapsed/refractory B-ALL, ~50% of CD19CART-treated patients relapse again, many with CD19 antigen loss. We previously reported preclinical activity of thymic stromal lymphopoietin receptor-targeted cellular immunotherapy (TSLPRCART) against CRLF2-overexpressing ALL as an alternative approach.

Targeting TGFβ-activated kinase-1 activation in microglia reduces CAR T immune effector cell-associated neurotoxicity syndrome.

Cancer immunotherapy with chimeric antigen receptor (CAR) T cells can cause immune effector cell-associated neurotoxicity syndrome (ICANS). However, the molecular mechanisms leading to ICANS are not well understood. Here we examined the role of microglia using mouse models and cohorts of individuals with ICANS.

Antigen experience history directs distinct functional states of CD8+ CAR T cells during the anti-leukemia response.

Chimeric antigen receptor T cells are an effective therapy for B-lineage malignancies. However, many patients relapse and this therapeutic has yet to show strong efficacy in other hematologic or solid tumors. One opportunity for improvement lies in the ability to generate T cells with desirable functional characteristics.

FOXP1 and KLF2 reciprocally regulate checkpoints of stem-like to effector transition in CAR T cells.

In cancer and infections, self-renewing stem-like CD8 T cells mediate the response of immunotherapies and replenish terminally exhausted T cells and effector-like T cells. However, the programs governing the lineage choice in chimeric antigen receptor (CAR) T cells are unclear. Here, by simultaneously profiling single-cell chromatin accessibility and transcriptome in the same CAR T cells, we identified heterogeneous chromatin states within CD8 T cell subsets that foreshadowed transcriptional changes and were primed for regulation by distinct transcription factors.

Children's Oncology Group's 2023 blueprint for research: Cellular therapy and stem cell transplantation.

Since the publication of the last Cellular Therapy and Stem Cell Transplant blueprint in 2013, Children's Oncology Group cellular therapy-based trials advanced the field and created new standards of care across a wide spectrum of pediatric cancer diagnoses. Key findings include that tandem autologous transplant improved survival for patients with neuroblastoma and atypical teratoid/rhabdoid brain tumors, one umbilical cord blood (UCB) donor was safer than two UCB donors, killer immunoglobulin receptor (KIR) mismatched donors did not improve survival for pediatric acute myeloid leukemia when in vivo T-cell depletion is used, and the depth of remission as measured by next-generation sequencing-based minimal residual disease assessment pretransplant was the best predictor of relapse for acute lymphoblastic leukemia. Plans for the next decade include optimizing donor selection for transplants for acute leukemia/myelodysplastic syndrome, using novel engineered cellular therapies to target a wide array of malignancies, and developing better treatments for cellular therapy toxicities such as viral infections and graft-vs-host disease.

Chimeric Antigen Receptor T Cells as Salvage Therapy for Post-Chimeric Antigen Receptor T Cell Failure.

Outcomes for post-chimeric antigen receptor (CAR) T cell therapy (CART) relapse are poor. The utilization of a unique CAR T cell construct for post-CART failure is increasing, but this approach is not well described. In this study, with CART-A the first unique CAR T cell construct received and CART-B the second, the primary objective was to characterize outcomes following CART-B.

CD22 CAR T-cell associated hematologic toxicities, endothelial activation and relationship to neurotoxicity.

Background: Hematologic toxicities, including coagulopathy, endothelial activation, and cytopenias, with CD19-targeted chimeric antigen receptor (CAR) T-cell therapies correlate with cytokine release syndrome (CRS) and neurotoxicity severity, but little is known about the extended toxicity profiles of CAR T-cells targeting alternative antigens. This report characterizes hematologic toxicities seen following CD22 CAR T-cells and their relationship to CRS and neurotoxicity.

Methods: We retrospectively characterized hematologic toxicities associated with CRS seen on a phase 1 study of anti-CD22 CAR T-cells for children and young adults with relapsed/refractory CD22+ hematologic malignancies.

Prospective PTCTC trial of myeloablative haplo-BMT with posttransplant cyclophosphamide for pediatric acute leukemias.

Promising results have been reported for adult patients with high-risk hematologic malignancies undergoing haploidentical bone marrow transplant (haploBMT) with posttransplant cyclophosphamide (PTCy). To our knowledge, we report results from the first multicenter trial for pediatric and young adult patients with high-risk acute leukemias and myelodysplastic syndrome (MDS) in the Pediatric Transplantation and Cellular Therapy Consortium. Nine centers performed transplants in 32 patients having acute leukemias or MDS, with myeloablative conditioning (MAC), haploBMT with PTCy, mycophenolate mofetil, and tacrolimus.

Hypoimmune anti-CD19 chimeric antigen receptor T cells provide lasting tumor control in fully immunocompetent allogeneic humanized mice.

Manufacturing autologous chimeric antigen receptor (CAR) T cell therapeutics is complex, and many patients experience treatment delays or cannot be treated at all. Although current allogeneic CAR products have the potential to overcome manufacturing bottlenecks, they are subject to immune rejection and failure to persist in the host, and thus do not provide the same level of efficacy as their autologous counterparts. Here, we aimed to develop universal allogeneic CAR T cells that evade the immune system and produce a durable response.

Digital polymerase chain reaction strategies for accurate and precise detection of vector copy number in chimeric antigen receptor T-cell products.

Background Aims: Vector copy number (VCN), an average quantification of transgene copies unique to a chimeric antigen receptor (CAR) T-cell product, is a characteristic that must be reported prior to patient administration, as high VCN increases the risk of insertional mutagenesis. Historically, VCN assessment in CAR T-cell products has been performed via quantitative polymerase chain reaction (qPCR). qPCR is reliable along a broad range of concentrations, but quantification requires use of a standard curve and precision is limited.

Murine allogeneic CAR T cells integrated before or early after posttransplant cyclophosphamide exert antitumor effects.

Relapse limits the therapeutic efficacy both of chimeric antigen receptor (CAR) T cells and allogeneic hematopoietic cell transplantation (allo-HCT). Patients may undergo these therapies sequentially to prevent or treat relapsed malignancy. However, direct integration of the 2 therapies has been avoided over concerns for potential induction of graft-versus-host disease (GVHD) by allogeneic CAR T cells.

Potent preclinical activity of FLT3-directed chimeric antigen receptor T-cell immunotherapy against - mutant acute myeloid leukemia and -rearranged acute lymphoblastic leukemia.

Chimeric antigen receptor (CAR) T-cell immunotherapies targeting CD19 or CD22 induce remissions in the majority of patients with relapsed/refractory B-cell acute lymphoblastic leukemia (ALL), although relapse due to target antigen loss or downregulation has emerged as a major clinical dilemma. Accordingly, great interest exists in developing CAR T cells directed against alternative leukemia cell surface antigens that may help to overcome immunotherapeutic resistance. The fms-like tyrosine kinase 3 receptor (FLT3) is constitutively activated via FLT3 mutation in acute myeloid leukemia (AML) or wild-type FLT3 overexpression in KMT2A (lysine-specific methyltransferase 2A)-rearranged ALL, which are associated with poor clinical outcomes in children and adults.

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.

CD19/22 CAR T cells in children and young adults with B-ALL: phase 1 results and development of a novel bicistronic CAR.

Remission durability following single-antigen targeted chimeric antigen receptor (CAR) T-cells is limited by antigen modulation, which may be overcome with combinatorial targeting. Building upon our experiences targeting CD19 and CD22 in B-cell acute lymphoblastic leukemia (B-ALL), we report on our phase 1 dose-escalation study of a novel murine stem cell virus (MSCV)-CD19/CD22-4-1BB bivalent CAR T-cell (CD19.22.

Efficacy of second CAR-T (CART2) infusion limited by poor CART expansion and antigen modulation.

Chimeric antigen receptor T-cells (CART) are active in relapsed/refractory (r/r) B-cell acute lymphoblastic leukemia (B-ALL), but relapse remains a substantial challenge. Reinfusion with the same CART product (CART2) in patients with suboptimal response or antigen positive relapse following first infusion (CART1) represents a potential treatment strategy, though early experiences suggest limited efficacy of CART2 with CD19 targeting. We report on our experience with CART2 across a host of novel CAR T-cell trials.

Optimizing CARs for ocular delivery.

Effective methods for treating retinoblastoma while preserving vision are an unmet clinical need. Subretinal delivery of a hydrogel containing T cells that secrete the cytokine IL-15 and express a chimeric antigen receptor directed at the ganglioside protein GD2 completely controls retinoblastoma in immunocompromised mice, with no obvious damage to the surrounding retina.

Infectious complications of CAR T-cell therapy across novel antigen targets in the first 30 days.

Infections are a known complication of chimeric antigen receptor (CAR) T-cell therapy with data largely emerging from CD19 CAR T-cell targeting. As CAR T-cell therapy continues to evolve, infection risks and management thereof will become increasingly important to optimize outcomes across the spectrum of antigens and disease targeted. We retrospectively characterized infectious complications occurring in 162 children and adults treated among 5 phase 1 CAR T-cell clinical trials.

Systematic preclinical evaluation of CD33-directed chimeric antigen receptor T cell immunotherapy for acute myeloid leukemia defines optimized construct design.

Background: Successful development of chimeric antigen receptor (CAR) T cell immunotherapy for children and adults with relapsed/refractory acute myeloid leukemia (AML) is highly desired given their poor clinical prognosis and frequent inability to achieve cure with conventional chemotherapy. Initial experiences with CD19 CAR T cell immunotherapy for patients with B-cell malignancies highlighted the critical impact of intracellular costimulatory domain selection (CD28 vs 4-1BB (CD137)) on CAR T cell expansion and in vivo persistence that may impact clinical outcomes. However, the impact of costimulatory domains on the efficacy of myeloid antigen-directed CAR T cell immunotherapy remains unknown.

Combining Immunocytokine and Activated NK Cells as a Platform for Enhancing Graft-Versus-Tumor Effects Against GD2 Murine Neuroblastoma.

Management for high-risk neuroblastoma (NBL) has included autologous hematopoietic stem cell transplant (HSCT) and anti-GD2 immunotherapy, but survival remains around 50%. The aim of this study was to determine if allogeneic HSCT could serve as a platform for inducing a graft-versus-tumor (GVT) effect against NBL with combination immunocytokine and NK cells in a murine model. Lethally irradiated C57BL/6 (B6) x A/J recipients were transplanted with B6 bone marrow on Day +0.