Phosphoinositide 3-kinase gamma (PI3Kγ), the only class IB PI3 kinase, is a cell-extrinsic immunotherapy target in solid tumors. PI3Kγ inhibition reprograms immunosuppressive myeloid cells to acquire immunostimulatory phenotypes, which promote antitumor cytotoxic T-cell activity. Although PI3Kγ inhibition has no direct effect on solid tumor cells, several new studies have nominated PI3Kγ as a cell-intrinsic target in various leukemias, particularly acute myeloid leukemia. Intrinsic dependency on PI3Kγ is present at baseline in leukemias with specific pathological characteristics, is inducible by extrinsic inflammation in others, and may also be acquired with resistance to certain therapies. The discovery of leukemia PI3Kγ dependency has generated enthusiasm for immediate clinical trial evaluation of inhibitor monotherapy and combinations. Parallel laboratory evaluation is needed to develop an improved understanding of leukemia disease features associated with clinical inhibitor sensitivity that might suggest biomarker-directed patient enrichment strategies. In this review, we discuss recent progress credentialing PI3Kγ as a bona fide target in leukemia. We also highlight open questions, including a need to understand the mechanism of acquired resistance to PI3Kγ inhibition, how to optimally prioritize combination therapies to enhance PI3Kγ inhibitor utility, and how cell-extrinsic effects of PI3Kγ inhibition in the leukemia microenvironment might also contribute to clinical activity.

Emerging evidence indicates that CD4+ T cells contribute to antitumor immunity beyond their traditional roles as helpers or regulators. However, the specific subset of CD4+ T cells mediating beneficial outcomes in patients with multiple myeloma remains unclear. Here, we performed single-cell RNA sequencing and T-cell receptor sequencing on CD4+ T cells sorted from the bone marrow of patients across the stages of myeloma progression. We identified several distinct states of CD4+ cytotoxic T lymphocytes (CTLs) that were significantly increased and clonally expanded in patients with myeloma. CD4+ CTLs displayed transcriptional and phenotypic characteristics indicative of cytotoxicity, demonstrating their ability to directly kill myeloma cells. This cytotoxicity, however, was abrogated by NKG2D blockade. Notably, the abundance of NKG2D+CD4+ CTLs correlated with improved survival in patients with myeloma. Our findings suggest that harnessing CD4+ CTLs could lead to novel strategies for enhancing immunotherapy outcomes in multiple myeloma.

The half-life of recombinant human von Willebrand factor (rVWF) expressed in CHO cells (CHO-rVWF; Vonicog alfa; and Vonvendi/Veyvondi) is significantly longer than that of plasma-derived VWF (pdVWF). This finding is intriguing because CHO cells do not generate α2-6 sialylation, which constitutes the majority of human pdVWF sialylation. We hypothesized that glycan differences might regulate the longer half-life of CHO-rVWF. In lectin plate-binding assays and liquid chromatography-mass spectrometry analysis, we confirmed that CHO-rVWF lacked α2-6-linked sialylation. Conversely, however, α2-3-linked sialylation was significantly increased on CHO-rVWF, which also had reduced exposed β-galactose (β-Gal) compared to pdVWF. Consistent with human data, CHO-rVWF clearance was significantly (P < .001) reduced in VWF-/- mice compared to pdVWF. However, clearance of asialo-pdVWF and asialo-CHO-rVWF were identical. In keeping with the in vivo half-life prolongation, CHO-rVWF binding to murine macrophages (P = .012) and HepG2 cells (P = .001) was significantly decreased compared to pdVWF. Furthermore, CHO-rVWF binding to purified macrophage-galactose-type lectin (MGL) receptor and asialoglycoprotein receptor (ASGPR) was also significantly reduced. In contrast to pdVWF, in vivo studies in MGL1-/- mice and Asgr1-/- mice demonstrated that neither MGL nor ASGPR plays significant roles in regulating CHO-rVWF clearance. Together, our findings demonstrate that enhanced α2-3-linked sialylation on CHO-rVWF is responsible for its extended half-life.

We used single-cell genomics to characterize a patient with T-cell acute lymphoblastic leukemia treated in the Children's Oncology Group AALL0434 trial with poor clinical outcome despite favorable genomic features, identifying a STAT1-mediated interferon-related transcriptional signature and inflammatory microenvironment associated with sensitivity to small-molecule JAK inhibition.

The MCL35 gene expression assay encompasses key risk features and stratified older patients with mantle cell lymphoma (MCL) using routine biopsies. In the SHINE trial, high-risk patients had poor outcomes despite adding ibrutinib to bendamustine-rituximab, highlighting an urgent need for novel strategies in high-risk MCL.

Tyrosine kinase inhibitors (TKIs) are the mainstay of treatment for patients with chronic myeloid leukemia. The standard dose has been established for each drug according to the indication for the various stages of the disease and whether as initial therapy or after failure of previous therapies. The recommended doses are fixed for all patients and dose adjustments are mostly recommended for management of adverse events. The standard doses have been derived largely from phase 1 studies, but as we discuss in this review, the current model may not be optimal for this purpose for drugs such as TKIs that are meant to be used for extended periods of time. Subsequent studies have led to changes in the initial recommendations for some drugs. In others, experience and real-world data have led to the use of TKIs using doses and adjustments that may be different than what clinical trials have recommended. In other scenarios, available data suggest that the current standard dose may need to be revisited. It may also be time to reconsider the standard approach of starting therapy with the standard dose and adjusting merely based on adverse events. We propose a flexible model that perhaps reflects more accurately what is being done frequently in the clinic.

G protein-coupled receptor, class C, group 5, member D (GPRC5D) has emerged as a novel target for chimeric antigen receptor (CAR) T-cell therapy, demonstrating promising efficacy in multiple myeloma (MM). However, disease relapse is still common, and the mechanism of resistance remains poorly understood. In this study, we conducted whole-genome sequencing and whole-genome bisulfite sequencing on MM samples from 10 patients who relapsed after GPRC5D CAR T-cell therapy. Among these patients, 8 had GPRC5D loss, whereas 2 presented mixed expression (GPRC5D+/-). Genetic alterations were identified in 3 cases: one had a homozygous deletion in the GPRC5D gene, another had a biallelic loss in the regulatory regions of GPRC5D, and the third had homozygous deletions in both TNFRSF17 and GPRC5D after sequential anti-B-cell maturation antigen and anti-GPRC5D CAR T-cell therapies. No genetic changes were detected at GPRC5D locus in the remaining 7 cases. However, multiple hypermethylation sites were present in the transcriptional regulatory elements of the GPRC5D gene in 5 post-treatment MM samples. In MM cell lines, GPRC5D expression was inversely correlated with methylation levels in its regulatory regions. Furthermore, azacitidine treatment induced GPRC5D messenger RNA and protein expression in hypermethylated MM cell lines. Our findings highlight that biallelic genetic inactivation and hypermethylation-driven epigenetic silencing are key mechanisms contributing to GPRC5D loss and treatment resistance.

Rilzabrutinib is a covalent, reversible Bruton tyrosine kinase inhibitor targeting multiple immune thrombocytopenia (ITP)-related mechanisms. The phase 3 LUNA3 study in previously treated adults with persistent/chronic ITP evaluated oral rilzabrutinib 400 mg twice daily (n = 133) vs placebo (n = 69) for 24 weeks. At baseline overall, median age was 47 years, 63% female, 7.7 year median ITP duration, and 28% prior splenectomy. Overall (N = 202), 85 (64%) rilzabrutinib and 22 (32%) placebo patients achieved platelet response (≥50 × 109/L or 30 × 109/L to <50 × 109/L and doubled from baseline) during the first 12 weeks and were eligible to continue. The primary end point, durable platelet response (platelet count ≥50 × 109/L for ≥two-thirds of ≥8 of the last 12 of 24 weeks without rescue therapy), was observed in 31 (23%) rilzabrutinib vs 0 placebo patients (P < .0001). All secondary efficacy end points were significantly superior for rilzabrutinib (P < .05). Median time to first platelet response was 15 days in rilzabrutinib responders. Rilzabrutinib significantly reduced rescue therapy use by 52% (P = .0007) and improved week 25 bleeding scores (P = .0006). Improved physical fatigue was sustained from week 13 (P = .01) through 25 (P = .0003). Treatment-related adverse events were mainly grade 1/2. One rilzabrutinib patient with multiple risk factors had serious treatment-related grade 3 peripheral embolism (lower left leg), and another died from unrelated pneumonia. Rilzabrutinib in patients who failed multiple previous ITP therapies showed rapid and durable platelet response, reduced rescue medication and bleeding, improved physical fatigue, and favorable safety. Trial registration: www.clinicaltrials.gov (#NCT04562766) and www.clinicaltrialsregister.eu (#2020-002063-60).

The CREBBP lysine acetyltransferase (KAT) is frequently mutated in follicular lymphoma and diffuse large B-cell lymphoma and has been studied using gene knockout in murine and human cells. However, most CREBBP mutations encode amino acid substitutions within the catalytic KAT domain (CREBBP KAT-PM) that retain an inactive protein and have not been extensively characterized. Using CRISPR gene editing and extensive epigenomic characterization of lymphoma cell lines, we found that CREBBP KAT-PM lead to unloading of CREBBP from chromatin, loss of enhancer acetylation, and prevention of EP300 compensation. These enhancers were enriched for those that are dynamically loaded by CREBBP in the normal centroblast-to-centrocyte transition in the germinal center, including enhancers activated in response to CD40 signaling, leading to blunted molecular response to CD40 ligand in lymphoma cells. We provide evidence that CREBBP KAT-PM inhibits EP300 function by binding limiting quantities nuclear transcription factor (TF), thereby preventing its compensatory activity. This effect can be experimentally overcome by expressing saturating quantities of TF or biologically attenuated by strong stimulation of CD40 signaling that increases nuclear TF abundance. Importantly, epigenetic responses to CD40 signaling can be induced by enforcing CD4 T-cell engagement using a bispecific antibody, leading to CD40-dependent restoration of antigen presentation machinery in CREBBP KAT-PM cells and cell death. Therefore, we provide a mechanistic basis for enhancer deregulation by CREBBP KAT-PM and highlight enforced CD4 T-cell engagement as a potential approach for overcoming these effects.

Chronic granulomatous disease (CGD) is an inborn error of immunity characterized by defective NAD phosphate oxidase function, leading to impaired microbial killing, recurrent infections, and granulomatous inflammation. Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for CGD, particularly effective when a fully HLA-matched donor is available. However, the place of HLA-haploidentical HSCT remains less established. This retrospective multicenter study analyzed outcomes of 64 patients with CGD (53 males; 46 with X-linked CGD) who underwent a first HSCT with HLA-haploidentical family donors, with either in vitro T-cell receptor (TCR)αβ/CD19 depletion or in vivo depletion using posttransplant cyclophosphamide (PTCY). The mean age at transplant was 5.8 years (range, 0-33). Patients exhibited a high disease burden before HSCT, with 45% experiencing infections in the 6 months before HSCT and 67% exhibiting inflammation. Outcomes in the entire cohort showed a 3-year overall survival, event-free survival (EFS), and grade 3 to 4 graft-versus-host disease (GVHD)-free EFS of 75.9%, 70.2%, and 56.1%, respectively, and were not affected by the type of depletion or age. The cumulative incidence (CI) of primary graft failure (PGF) was 20.6%. The CI of grade 2 to 4 acute GVHD was higher in the PTCY group (P = .04), whereas the CI of grade 3 to 4 GVHD was not. These results indicate that HLA-haploidentical HSCT is a feasible transplant option for patients with CGD lacking HLA-matched donors. Further refinement of transplant protocols is necessary to mitigate graft failure and acute GVHD, ultimately improving access and outcomes for this life-saving therapy.

Multiple myeloma (MM) is a complex hematological malignancy characterized by genomic changes and transcriptomic dysregulation. Initial exome sequencing approaches have failed to identify any single, frequent (>25%) mutation in the coding genome. However, using whole-genome sequencing, we found that one of the genomic regions most frequently mutated (62% of the patients with MM) was the 5' untranslated region and/or intron 1 of the BCL7A gene. RNA-sequencing data from a large cohort suggest a loss of BCL7A expression in a large majority of patients with MM as compared with normal plasma cells. BCL7A loss of function in a panel of MM cell lines led to a highly proliferative phenotype in vitro and in vivo, whereas its ectopic expression significantly reduced cell viability, suggesting a tumor suppressor function for BCL7A in MM. We studied the cellular and molecular effects of BCL7A loss and observed that it endows myeloma cells with proliferative potential in cooperation with the plasma cell-defining transcription factor IRF4. BCL7A is involved in a direct protein-protein interaction with IRF4, limiting its DNA-binding activity. Loss of BCL7A thus enhances the expression of IRF4-associated cytokines and reduces mitochondrial metabolism and reactive oxygen species levels. Our study therefore suggests that BCL7A loss provides the necessary molecular change to allow IRF4-mediated transcriptional activity and MM cell growth and survival.

Relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL) remains a challenging disease with dismal prognosis. Despite the revolutionary impact of CD19-directed chimeric antigen receptor (CAR19) T-cell therapy, >50% of patients relapse within a year. Both leukemia cell-intrinsic factors favoring immune escape and poor CAR T-cell persistence contribute to clinical failure. Moreover, the expression of immune checkpoint receptors (ICRs) and their ligands within the bone marrow (BM) microenvironment may contribute to leukemia progression and therapy resistance. Here, we characterized the expression of ICRs and their ligands in leukemic blasts, T cells, and mesenchymal stromal cells (MSCs) from B-ALL BM samples at diagnosis and relapse, comparing them with age-matched healthy BM controls. Our findings reveal a significantly upregulated expression of TIM-3 in T cells and its ligand, galectin-9, in both blasts and MSCs throughout disease progression. The expression of galectin-9 in B-ALL blasts and TIM-3 in CAR19 T cells negatively correlates with clinical outcome. Furthermore, we demonstrate that galectin-9 impairs CAR19 T-cell homeostasis and cytotoxicity. Notably, an engineered TIM-3-Fc decoy receptor, delivered either by primary T cells coadministered with CAR19 T cells or via a bicistronic all-in-one CAR19-TIM-3-Fc construct, improved the antileukemia efficacy and persistence of CAR19 T cells in B-ALL xenograft models. Mechanistically, CAR19-TIM-3-Fc T-cell treatment promotes the in vivo expansion of transduced and bystander effector and memory T cells, as determined by spectral flow cytometry. Collectively, these TIM-3-Fc decoy-armored CAR19 T cells offer a promising therapeutic strategy for patients with R/R B-ALL.

Cytokine release syndrome (CRS) and immune effector cell (IEC)-associated neurotoxicity syndrome (ICANS) are common complications after IEC therapy for hematologic malignancies. This 2-part phase 2 study (INCB 39110-211) investigated the safety and efficacy of itacitinib, a potent, highly selective Janus kinase 1 inhibitor with broad anti-inflammatory activity, for the prevention of CRS and ICANS in patients who received commercial CD19-directed IEC therapy. Patients in part 1 received 200 mg itacitinib once daily 3 days before IEC therapy (axicabtagene ciloleucel [axi-cel], brexucabtagene autoleucel, or tisagenlecleucel) through day 26 with guidelines for use of other CRS/ICANS interventions. In part 2 (double-blind), patients were randomized to receive 200 mg itacitinib twice daily or placebo 3 days before IEC therapy with axi-cel. The primary end point was the proportion of patients with CRS grade ≥2 by day 14 using the American Society for Transplantation and Cellular Therapy consensus grading system. Overall, 111 patients were enrolled (63 in part 1; 48 in part 2); 109 patients were analyzed for efficacy and 110 for safety. By day 14, grade ≥2 CRS occurred in fewer patients on 200 mg twice daily itacitinib (17.4%) than on placebo (56.5%; P = .003). The proportion of patients with grade ≥2 ICANS by day 28 was lower than with placebo (8.7% vs 21.7%). Itacitinib was well tolerated, with pyrexia being the most common treatment-emergent adverse event (200 mg itacitinib twice daily, 43.5%; placebo, 50.0%), and itacitinib-related cytopenias were manageable. Itacitinib did not affect IEC therapy efficacy (objective response rate at 6 months, 39.1% [200 mg itacitinib twice daily] vs 26.1% [placebo]). This study was registered at www.clinicaltrials.gov as #NCT04071366.

This study identified an increased risk of lymphoid malignancy in Shwachman-Diamond syndrome (SDS) with an observed risk 38-fold higher than expected based on population data. Increased toxicity was observed with standard therapies in patients with SDS.

The Csa blood group antigen was identified >50 years ago, but its genetic basis has yet to be elucidated. All our recent genomic investigation has failed to resolve the genetic basis of this enigmatic antigen. By investigating the association of the human neutrophil antigen (HNA)-3a/b polymorphism (rs2288904-G/A) in SLC44A2 with clinical features of sickle cell disease, we incidentally discovered that rare subjects with the homozygous HNA-3b/b genotype also carry the uncommon Cs(a-) phenotype. We genotyped this single-nucleotide polymorphism in a cohort of 25 Cs(a-) subjects and found that all of them showed an HNA-3b/b genotype. This result suggests that the high-prevalence allele with rs2288904 (HNA-3a; 455G) encoding Arg152 encodes the high-prevalence Csa. Accordingly, anti-Csa does not react with solute carrier (SLC)44A2null red blood cells (RBCs), SLC44A2 knockout K562 cells, and K562 cells expressing HNA-3b, confirming that the Csa and Csb antigens are carried on this protein. Furthermore, mass spectrometry analysis of SLC44A2 from neutrophils and RBCs, along with serological investigation, showed that, despite HNA-3a and Csa having the same genetic basis, anti-HNA-3a and anti-Csa recognize different epitopes on the SLC44A2 protein. Overall, our data resolve the genetic bases of the Cs(a-) and Cs(b-) blood phenotypes, with new insights on the anti-HNA-3a specificity.

Congenital thrombotic thrombocytopenic purpura (cTTP) is an ultrarare disorder characterized by thrombocytopenia, microangiopathic hemolytic anemia, and ischemic organ damage caused by pathogenic ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13) variants. ADAMTS13-containing product, including fresh-frozen plasma (FFP), and plasma-derived factor VIII concentrates are commonly used to supply ADAMTS13; however, frequent hospital visits and allergic reactions are major drawbacks. A recombinant ADAMTS13 (rADAMTS13) was recently developed to address these issues. However, real-world evidence has not been reported owing to the rarity of this condition. This study compared the efficacy and safety of FFP and rADAMTS13 in 14 Japanese patients, including 5 patients with end-stage renal disease who were excluded from the phase 3 trial. The median peak level of ADAMTS13 activity 15 minutes after rADAMTS13 administration was significantly higher than that after FFP (68.4% vs 15.9%; P < .001). ADAMTS13 activity 1 week after rADAMTS13 administration was well maintained compared with FFP infusion (11.6% vs 5.1%; P < .001). Patients reported no allergic reactions after rADAMTS13 administration and appreciated the convenience of a single infusion of rADAMTS13, suggesting that rADAMTS13 is a safe and effective alternative to FFP in patients with cTTP. To our knowledge, this is the first publication of patients with cTTP who switched FFP to novel rADAMTS13 from Japanese real-world data.

Hemophagocytic lymphohistiocytosis (HLH) is a severe hyperinflammatory syndrome, and the overall survival (OS) of adult patients is poor. Ruxolitinib, a Janus kinase 1/2 (JAK1/2) inhibitor, has shown promise in treating HLH and exerts synergistic effects when combined with dexamethasone. Our pilot study preliminarily demonstrated that the combination of ruxolitinib and dexamethasone (Ru-D regimen) had a high response rate and led to favorable short-term survival outcomes in adult patients with HLH. In this prospective phase 2 clinical trial, we propose the Ru-D regimen as a first-line treatment for adults newly diagnosed as having HLH with unknown triggers. A total of 28 Chinese patients were enrolled, and the median follow-up time was 25.1 months (range, 0.87-34.0). The 2-month OS rate (the primary end point) was 85.7%, which exceeded our expected 2-month OS rate of 75%. The 6-month and 2-year OS rates were 67.9% (19/28) and 53.6% (15/28), respectively. The median OS of patients with lymphoma-associated HLH (LAHS) was 5.8 months, and most of these patients had natural killer/T-cell lymphoma. In contrast, the 2-year OS rate of patients without LAHS was 75%. The overall response rate was 85.7% (24/28); of 28 patients, 5 (17.9%) achieved a complete response during the Ru-D regimen. Overall, the Ru-D regimen was well tolerated in patients with HLH. This study demonstrates the efficacy and safety of the Ru-D regimen in adults newly diagnosed as having HLH with unknown triggers and warrants a phase 3 randomized controlled study. This trial was registered at www.chictr.org.cn as #ChiCTR2100049996).

Genetic screening for severe congenital immunohematological diseases offers potential for early intervention, particularly through preemptive allogeneic hematopoietic stem cell transplantation (HSCT). However, the clinical value of such screening depends on precise prognostic predictions based on genotype-phenotype correlations and/or functional confirmation. We investigated familial hemophagocytic lymphohistiocytosis type 2 (FHL2), caused by PRF1 variants. Specifically, we evaluated the clinical significance of the frequent PRF1 A91V variant, if present in trans with a predicted loss-of-function (pLOF) PRF1 variant, defined as "disease mutation" listed in the Human Gene Mutation Database. We combined clinical and functional data from our hemophagocytic lymphohistiocytosis (HLH)-network registry with UK Biobank data to evaluate disease penetrance and clinical outcomes. Among 52 individuals with A91V/pLOF genotype in the registry, 39 (72%) showed FHL2-related manifestations with mean onset at 20 years. Four patients had recurrent disease, 15 received transplantation, and 14 died. Among 14 individuals with A91V/pLOF genotype identified by family screening (mean age, 29 years), however, only 1 was symptomatic. Moreover, among 21 A91V/pLOF carriers identified in 200 000 UK Biobank participants, 12 with genotypes identical to symptomatic registry patients, none had developed HLH by age 73 years. Premature stop pLOF alleles appeared more penetrant than missense variants, but functional data including perforin expression or cytotoxicity failed to predict disease manifestation. Our combined registry and population-based approach reveals significant variability in disease penetrance and severity among PRF1 A91V/pLOF carriers, with no clear association between genotype, functional data, and clinical outcomes. This complexity illustrates the challenges of genetic screening and highlights the need for careful clinical decision-making regarding preemptive HSCT in asymptomatic carriers.

Follicular lymphoma (FL) represents a heterogeneous group of B-cell neoplasms with distinct genetic, epigenetic, microenvironmental, and clinical features. It is the most prevalent indolent non-Hodgkin lymphoma, characterized by a relapsing course and risk of transformation to aggressive diffuse large B-cell lymphoma. Recent advances in high-throughput sequencing, spatial transcriptomics, and imaging technologies uncovered genetic, epigenetic, and immunogenetic features underpinning FL, offering insights into its biology and potential therapeutic vulnerabilities. Although FL is primarily driven by the hallmark t(14;18) translocation involving BCL2, its pathogenesis requires additional oncogenic mutations, particularly in genes regulating chromatin and histone modifications. These early genetic and epigenetic alterations promote the persistence and evolution of cancer precursor cells, setting the stage for lymphomagenesis. The tumor microenvironment is also crucial in FL progression and patient prognosis, with T cells, stromal cells, and macrophages playing pivotal roles in facilitating tumor immune escape. Targeted therapies, including B-cell lymphoma 2 (BCL2) inhibitors, epigenetic modulators, and immunotherapies, have emerged from this deeper understanding of FL biology. Achieving a cure for FL will require targeted therapies that selectively eliminate cancer precursor cells with minimal impact on normal cells, thus preventing relapse and avoiding harmful side effects. Eradicating minimal residual disease should be a primary objective rather than waiting for clinical relapse. Future research must prioritize the development of accurate experimental models, the elucidation of FL precursors, and a deeper understanding of its heterogeneity, dependencies, progression, and mechanisms driving transformation. Implementing targeted therapies at FL early stages, instead of the current "watch and wait" approach, will be essential to improve patient outcomes.

We report our single-center experience demonstrating that HLA class I alloimmunization predicts longer time to platelet engraftment, increased bleeding complications, and higher transfusion requirements in patients undergoing gene-modified hematopoietic stem cell transplant for transfusion-dependent β thalassemia.