Acute graft-versus-host disease (aGVHD) is a major cause of death after allogeneic hematopoietic cell transplantation (allo-HCT) and patients with steroid-refractory aGVHD have a dismal prognosis. We have previously shown that the enteroendocrine hormone glucagon-like peptide-2 (GLP-2) has tissue regenerative activity in the lower GI in mice and patients with steroid-refractory aGVHD. Here we explored the tissue protective effect of the enteroendocrine hormone gastrin for aGVHD of the stomach. We observed that aGVHD caused a loss of gastrin-producing G-cells and parietal cells (PCs) and an increase of pH in the stomach, while allogeneic T cells infiltrated the stomach wall. Pentagastrin treatment of aGVHD mice rescued the loss of PCs, normalized the pH in the stomach, increased stomach stem cell marker expression and abundance of LGR5+ cells, and changes in the stomach microbiome. Gastrin also increased the viability of stomach and small intestine organoids in vitro. Gast-/- mice experienced more severe aGVHD in the intestine and liver compared to WT mice, which was rescued by pentagastrin-treatment. In patients developing aGVHD, low gastrin levels in stomach biopsies were connected to reduced survival. Moreover, gastrin expression in the stomach correlated with aGVHD severity and tissue damage scores in independent patient cohorts. This study delineates the protective role of gastrin in aGVHD of the stomach in mice and patients and provides a rationale for therapeutic use of pentagastrin in a clinical trial for patients with aGVHD.

BACKGROUND:Acute graft-versus-host disease (aGvHD) remains a major complication after allogeneic hematopoietic cell transplantation (alloHCT). Adoptive regulatory T-cell (Treg) therapy may suppress alloreactive T-cell responses, but clinical implementation has been limited by donor-specific manufacturing, prolonged ex vivo expansion, and logistical complexity. OBJECTIVE:We developed ATreg, a cell therapy product consisting of gp120-activated, polyclonal Tregs derived from HLA-unmatched third-party donors. The primary objective was to assess the safety, tolerability and toxicity of ATreg, hypothesizing that this would be feasable and safe for aGvHD prevention early after alloHCT in patients with hematologic malignancies. STUDY DESIGN:ATreg-001 is a first-in-human, prospective, open-label, single-arm, multi-center phase 1/2 trial (EU CT number 2024-516599-14-00) conducted at four German centers (Mainz, Dresden, Münster, Dortmund). ATreg was generated from standard non-mobilized apheresis products by Treg isolation followed by 16 hours of gp120-mediated activation in the presence of IL-2, without ex vivo expansion, thereby enhancing suppressive function and (potentially) enabling a therapeutic effect at substantially lower Treg doses. Ten patients received ATreg at 0.1-1.0 × 10⁶ cells/kg body weight on day +10 ± 5 after alloHCT, in addition to standard GvHD prophylaxis, in a dose-escalation design across three cohorts. ATreg was administered within 24 hours after manufacturing. The primary endpoint was the type, incidence, and severity of ATreg-related serious adverse events within 14 days after administration. Secondary endpoints included manufacturing feasibility, aGvHD incidence/severity within 100 days, engraftment, and infections. RESULTS:ATreg administration was well tolerated, with no infusion-related toxicities or other safety signals attributable to ATreg. All treated patients achieved hematopoietic engraftment and full donor chimerism. Within 100 days after alloHCT, no grade 3-4 aGvHD occurred, the cumulative incidence of grade 2-4 aGvHD was 10%, and no non-relapse mortality was observed. CONCLUSION:These first clinical data support the feasibility and favorable safety profile of ATreg, a third-party, gp120-activated Treg product requiring no ex vivo expansion, and warrant further evaluation in larger prospective clinical trials. MAIN POINTS:

Hepatocellular carcinoma (HCC) is the fastest growing cause of cancer-related mortality and there are limited therapies1. Although endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) are implicated in HCC, the involvement of the UPR transducer ATF6α remains unclear2. Here we demonstrate the function of ATF6α as an ER-stress-inducing tumour driver and metabolic master regulator restricting cancer immunosurveillance for HCC, in contrast to its well-characterized role as an adaptive response to ER stress3. ATF6α activation in human HCC is significantly correlated with an aggressive tumour phenotype, characterized by reduced patient survival, enhanced tumour progression and local immunosuppression. Hepatocyte-specific ATF6α activation in mice induced progressive hepatitis with ER stress, immunosuppression and hepatocyte proliferation. Concomitantly, activated ATF6α increased glycolysis and directly repressed the gluconeogenic enzyme FBP1 by binding to gene regulatory elements. Restoring FBP1 expression limited ATF6α-activation-related pathologies. Prolonged ATF6α activation in hepatocytes triggered hepatocarcinogenesis, intratumoural T cell infiltration and nutrient-deprived immune exhaustion. Immune checkpoint blockade (ICB)4 restored immunosurveillance and reduced HCC. Consistently, patients with HCC who achieved a complete response to immunotherapy displayed significantly increased ATF6α activation compared with those with a weaker response. Targeting Atf6 through germline ablation, hepatocyte-specific ablation or therapeutic hepatocyte delivery of antisense oligonucleotides dampened HCC in preclinical liver cancer models. Thus, prolonged ATF6α activation drives ER stress, leading to glycolysis-dependent immunosuppression in liver cancer and sensitizing to ICB. Our findings suggest that persistently activated ATF6α is a tumour driver, a potential stratification marker for ICB response and a therapeutic target for HCC.

The landscape of Allogeneic Haematopoietic Cell Transplantation (allo-HCT) for Chronic Myeloid Leukaemia (CML) remains dynamic with the advent of tyrosine kinase inhibitors (TKIs). There remains an absence of widely agreed evidence-based guidelines for post-transplant monitoring and relapse management. To evaluate current real-world practices for ‘high risk’ CML, the CML subcommittee of the Chronic Malignancies Working Party (CMWP) of the European Blood and Marrow Transplantation (EBMT) society developed an electronic survey, which was distributed to 39 EBMT-registered transplant centres in April 2024. Centres were chosen based on CML allo-HCT activity. Twenty-three centres (59%) responded, providing clinical perspectives into pre-transplant chemotherapy regimens, TKI use, ABL1 kinase domain mutation analysis, post-transplant monitoring, and their practice regarding sequencing/ integration of TKIs with donor lymphocyte infusions (DLI). Most centres conduct monthly BCR::ABL1 transcript monitoring during the first three months post-transplant, transitioning to quarterly assessments upon achieving a deep molecular response. TKI maintenance is widely adopted across centres, with treatment duration guided by molecular response, and TKIs are generally preferred over DLI for managing molecular relapse. However, DLI remains a valid option for TKI-refractory chronic-phase (CP)-CML relapse. Survey findings illustrate significant heterogeneity in practice, offering insights to inform research aimed at improving allo-HCT outcomes in CML.

ZUSAMMENFASSUNG Hyperpolarisierte (HP) 13 C Kernspinresonanzspektroskopie (NMR) ermöglicht die Beobachtung metabolischer Prozesse in Echtzeit, ist jedoch aufgrund komplexer Präparationsverfahren und eines geringen experimentellen Durchsatzes typischerweise auf Einzelmessungen beschränkt. In dieser Arbeit demonstrieren wir einen schnellen und experimentell zugänglichen Workflow für zeitlich kontrollierte HP‐NMR Messungen in lebenden Zellen. Mittels SABRE‐SHEATH bei 0.4 µT, konnten wir 7.7 ± 0.2 % 13 C Polarisation bei 50 mM [1‐ 13 C]Pyruvate in 60 s erreichen. Eine einfache 1:50‐Verdünnung mit phosphatgepuffertem D 2 O ergab eine zellverträgliche Lösung die, ohne mehrstufigen Aufreinigungsprozess, 1,3 mM Pyruvat mit 5,3 ± 0,4 % Polarisation enthielt. In Kombination mit einem vereinfachten Agarosekügelchen‐Immobilisierungsansatz ermöglichte dies vier Injektionen von hyperpolarisiertem Pyruvat in dieselbe HeLa‐Zellpopulation innerhalb von 7 Minuten. Bei schnellen Injektionsintervallen (≈2 min) nahm die Pyruvat‐zu‐Laktat‐Umwandlung schrittweise ab, während bei 20‐minütigen Intervallen mit intermittierender Perfusion des Zellmediums eine stabile metabolische Umsetzung erhalten blieb. Diese Ergebnisse demonstrieren, dass eine schnelle, wiederholte Substratzufuhr die metabolische Umsetzungsfähigkeit der Zellen vorübergehend beeinträchtigen kann. Dieser experimentell gut zugängliche Ansatz ermöglicht die Untersuchung kurzzeitiger Stoffwechseldynamiken, welche mit herkömmlichen Einzelmessungen der HP‐NMR oder langen, thermisch polarisierten NMR‐Experimenten nicht möglich ist.

Single-cell studies have revealed substantial microglial diversity in development, homeostasis and disease. However, a framework enabling comparison and stratification of microglial states across contexts is needed. Here we generated an atlas of myeloid cell states by single-cell RNA sequencing more than one million central nervous system cells from more than 30 physiological and pathological conditions. This atlas enables us to establish a comprehensive taxonomy of myeloid cell states across brain disorders and related mouse models, comprising 27 superclusters and 192 clusters that are prevalent across diseases and largely conserved. We augment this taxonomic framework with spatial transcriptomics to map how immune cell states are organized within tissue and interact with their local cellular environment. Using in vivo perturbations, we also show that activation-associated microglial states are dependent on interferon and colony-stimulating factor 1 receptor signaling. Together, these findings provide a spatially aware taxonomic framework for central nervous system immune cells in health and disease.

Relapse of acute myeloid leukemia (AML) following allogeneic hematopoietic cell transplantation (allo-HCT) remains a life-threatening complication and is influenced by the underlying biology of the AML and possibly by genetic alterations. In this retrospective multicenter study, we evaluated mutational dynamics of AML cells in 57 patients with relapse after allo-HCT. We observed that 68% of patients exhibited genetic instability, characterized by acquisition or loss of mutations, most frequently involving FLT3-ITD, NRAS, and KRAS, while founding lesions such as DNMT3A were usually retained. Clonal evolution patterns varied, with constant profiles (35.0%), linear (29.8%), branching (22.8%), and parallel (12.3%) evolution. However, these evolutionary categories were not associated with differences in progression-free or overall survival. In contrast, relapse timing was highly prognostic: early relapse ( ≤ 6 months) conferred a significant higher mortality risk compared to late relapse, independent of evolution model. Our findings indicate that while relapse after allo-HCT in AML is genetically diverse, timing of recurrence remains the most critical determinant of outcome. Given that certain genetic changes may inform therapeutic options, these findings highlight the relevance of longitudinal molecular monitoring especially during the early post-transplant period.

In this issue of Cell Chemical Biology, Uible et al.1 uncover a previously unknown non-proteolytic role for caspase-1 (CASP1) in leukemia. CASP1 sustains leukemic growth by coordinating mTORC1-NF-κB signaling as scaffold for RPTOR, rather than regulating IL-1β and pyroptosis. CASP1’s scaffolding function was found as a therapeutic vulnerability in leukemia.

FMS-like tyrosine kinase-3 internal tandem duplication (FLT3-ITD) mutations are frequent in acute myeloid leukemia (AML) and are associated with a high risk of relapse. CKLF-like MARVEL transmembrane domain containing member 6 (CMTM6) stabilizes PD-L1 surface expression and modulates tumor immunity in solid cancer. In this study, we found a role for FLT3-induced CMTM6 in hematologic malignancies. FLT3 drove CMTM6 and PD-L1 expression in AML cells, whereas FLT3 inhibition reduced expression of CMTM6 and PD-L1. In three distinct allogeneic hematopoietic cell transplantation mouse models, transplantation of Cmtm6-deficient FLT3-ITD+ leukemia cells resulted in prolonged survival, reduced leukemia burden, enhanced T-cell effector function, and decreased expression of T-cell exhaustion markers compared with Cmtm6-proficient FLT3-ITD+ leukemia cells. Furthermore, combination therapy with anti-PD-L1 and tandutinib significantly improved survival, suppressed leukemia cell expansion, and augmented the anti-leukemia T-cell response in mice bearing FLT3-ITD+ leukemia. Mechanistically, protein-protein interaction of FLT3 and CMTM6 within their transmembrane domains, which was not phosphorylation dependent, enhanced CMTM6 stability in leukemia cells, whereas FLT3-ITD did not increase CMTM6 and PD-L1 expression at the RNA level. Furthermore, CMTM6 upregulation and protein interaction with FLT3 were validated in primary leukemia cells from two independent cohorts of patients with FLT3-ITD+ AML. Collectively, these findings uncover FLT3-mediated stabilization of CMTM6 in AML cells, which results in enhanced PD-L1 cell surface expression and leukemia immune escape.Significance: Activation of the CMTM6/PD-L1 axis in FLT3-ITD-driven acute myeloid leukemia mediates immunosuppression, providing the basis for potential inhibition of this pathway to harness antitumor immunity.

Introduction Axatilimab (AXA), a monoclonal antibody targeting colony-stimulating factor 1 receptor (CSF-1R), depletes CSF-1R–dependent monocytes and macrophages that mediate fibrosis and end-organ damage in chronic graft-versus-host disease (cGVHD). Ruxolitinib (RUX) is a selective inhibitor of Janus kinase (JAK)1/JAK2, which drive cytokine signaling, T-cell activation, and inflammation in cGVHD. Both AXA and RUX have demonstrated tolerability and clinically meaningful efficacy as single agents in previously treated cGVHD. Given their distinct mechanisms of action, combining AXA and RUX may improve efficacy without overlapping safety concerns. Objectives To report an interim safety analysis of AXA in combination with RUX in patients with newly diagnosed cGVHD. Methods In this ongoing, open-label, phase 2 study (NCT06388564), eligible patients were aged ≥12 years with new onset, moderate or severe cGVHD and no prior systemic cGVHD treatment. Patients were randomized 1:1:1 to receive AXA 0.3 mg/kg every 2 weeks in combination with RUX 10 mg twice daily (BID; AXA+RUX), RUX 10 mg BID alone, or corticosteroids alone for up to 24 months. The primary endpoint is overall response (including complete or partial response) at 6 months in the absence of a new systemic cGVHD therapy. Safety assessments include treatment-emergent adverse events (TEAEs), physical examinations, and laboratory assessments. A pre-specified interim safety analysis was planned to occur after approximately 30 patients receive ≥1 cycle of study treatment. Results As of the interim analysis, 44 patients have enrolled (AXA+RUX, n=15; RUX, n=15; corticosteroids, n=14), and 43 patients have received study treatment (Table). Eight patients discontinued treatment (AXA+RUX, n=1 [relapse or progression of underlying hematologic disease, considered unrelated to AXA+RUX]; RUX, n=1 [death due to bronchospastic crisis, considered unrelated to RUX]; corticosteroids, n=6 [received a new systemic therapy due to insufficient response to treatment, n=5; patient withdrawal, n=1]). Among all treated patients, 32 experienced TEAEs (AXA+RUX, n=11 [73.3%]; RUX, n=12 [80.0%]; corticosteroids, n=9 [69.2%]). TEAEs occurring in >1 patient in a group were diarrhea, fatigue, hyperkalemia, increased amylase, and decreased neutrophil count (all n=2) in the AXA+RUX group; anemia, increased amylase, upper respiratory tract infection (each n=3), diarrhea, fatigue, increased blood alkaline phosphatase, peripheral edema, pollakiuria, and vertigo (each n=2) in the RUX group; and constipation and insomnia (each n=3) in the corticosteroid group. Five patients experienced a grade ≥3 TEAE (AXA+RUX, n=2 [13.3%]; RUX, n=2 [13.3%]; corticosteroids, n=1 [7.7%]). Conclusion In this interim analysis of a randomized phase 2 trial, AXA+RUX was well tolerated with no evidence of additive toxicity.

Accurate prediction of mortality after allogeneic hematopoietic stem cell transplantation (alloHCT) is essential for individualized treatment decisions, yet existing clinical risk scores capture only a limited number of variables and show modest predictive performance. In our single-center retrospective analysis, we included data from 909 adult patients with hematologic malignancies undergoing alloHCT. We used 31 features to build machine-learning models to predict death within the first year after alloHCT. These features included established clinical risk factors together with pre-transplant lymphocyte subsets and inflammatory markers. Among four models, a random forest algorithm showed the best performance (AUC = 0.773) and retained good generalizability in an independent test set (AUC = 0.748). SHapley Additive exPlanations (SHAP)-based interpretation of the machine-learning models showed that age together with five easily measurable pre-transplant immunological and inflammatory parameters influenced the outcome: pre-transplant CD4+, CD8+, and B-lymphocyte counts, albumin, and C-reactive protein (CRP) levels. Based on these features, our random forest approach outperformed established clinical risk scores (HCT-CI, EASIX, rDRI, mGPS) in predicting one-year mortality after alloHCT and more effectively distinguished patients at low and high risk of an adverse outcome. Our study shows that machine-learning-based models can not only predict patient outcomes after alloHCT but also serve as powerful tools for data exploration, confirming the prognostic relevance of pre-transplant inflammation while uncovering the critical role of lymphocyte subsets as previously unknown risk factors. External validation in independent multicenter cohorts will be required to confirm generalizability.

Chronic graft-versus-host disease (cGVHD) remains the leading cause of late morbidity and non-relapse mortality after allogeneic hematopoietic cell transplantation, despite major advances in transplant techniques and supportive care. This European position statement provides a comprehensive and forward-looking synthesis of the evolving biology, epidemiology, diagnosis, and management of cGVHD, while highlighting critical unmet needs that impede progress. cGVHD arises from a complex interplay of immune dysregulation, aberrant tissue repair, and progressive fibrosis, resulting in a heterogeneous clinical spectrum that profoundly impairs quality of life and functional status. Although recent therapeutic innovations-including JAK inhibition, ROCK2 inhibition, and CSF-1R-directed therapies-have expanded options beyond corticosteroids, treatment responses remain variable, and optimal sequencing, biomarkers of activity, and organ-specific strategies are lacking. Persistent challenges in diagnosis, staging reproducibility, integration of patient-reported outcomes, and harmonized clinical trial endpoints further limit clinical and regulatory advancement. The substantial pharmaco-economic burden of cGVHD underscores the urgency of developing more effective, durable, and accessible interventions. This review outlines a collaborative roadmap centered on biomarker-driven precision medicine, harmonized assessment tools, integrated supportive care, and international research networks, aiming to transform cGVHD from a debilitating complication into a predictable, preventable, and ultimately curable condition.

Oncogenic KRAS mutations drive metabolic reprogramming in pancreatic ductal adenocarcinoma (PDAC). Src-homology 2 domain-containing phosphatase 2 (SHP2) is essential for full KRAS activity, and promising dual SHP2/mitogen-activated protein kinase (MAPK) inhibition is currently being tested in clinical trials. Exploitable metabolic adaptations may contribute to invariably evolving resistance. To understand the metabolic changes induced by dual inhibition, we comprehensively tested human and murine PDAC cell lines, endogenous tumor models, and patient-derived organoids, which are representative of the full spectrum of PDAC molecular subtypes. We found that dual SHP2/mitogen-activated protein kinase kinase (MEK1/2) inhibition induces major alterations in mitochondrial mass and function, impacts reactive oxygen species (ROS) homeostasis and triggers lipid peroxidase dependency. Anabolic pathways, autophagy and glycolysis were also profoundly altered. However, most strikingly, mitochondrial remodeling was evident, persisting into a therapy-resistant state. The resulting vulnerability to the induction of ferroptotic cell death via the combination of vertical SHP2/MEK1/2 with glutathione peroxidase (GPX4) inhibition was largely independent of the PDAC molecular subtype and was confirmed with direct targeting of RAS. The triple combination of SHP2/MEK1/2 inhibition and the ferroptosis-inducing natural compound withaferin A suppressed tumor progression in an endogenous PDAC tumor model in vivo. Our study offers a metabolic leverage point to reinforce RAS pathway interference for targeted PDAC treatment.

Abstract The combination of hypomethylating agents (HMA) and venetoclax (VEN) has transformed acute myeloid leukemia (AML) treatment. Data on donor lymphocyte infusion (DLI) with HMA/VEN for relapse after allogeneic hematopoietic cell transplantation (alloHCT) remain limited. We retrospectively analyzed 78 adults with relapsed myeloid neoplasms after first alloHCT between 2018 and 2025. DLI was given with HMA, HMA/VEN, or other/no treatments. The primary endpoint was event-free survival (EFS), defined as time to death or second alloHCT. Median time to relapse after alloHCT was 12.9 months (range 2.2-192.4). Initial DLI doses ranged from 0.3 to 8.14 × 10⁶ CD3⁺ cells/kg. Median EFS after first DLI was 15.2 months: with 16.2 (DLI/HMA), 14.3 (DLI/HMA/VEN), and 21.1 (DLI/other), respectively. Death occurred in 25.6% and second alloHCT in 32.1% of patients. GvHD of any kind after DLI treatment manifested in 30.8%, both events comparable across groups. Complete remission (CR) after DLI was achieved in 42.3% after a median of 4.2 months, including patients with TP53 mutations (n = 9). Approximately 40% of patients with relapsed myeloid malignancies were successfully salvaged with DLI and combination treatments. Patients with high-risk features such as morphological relapse were overrepresented in the DLI/HMA/VEN cohort but achieved comparable outcomes to the other treatment groups. This finding suggests successful treatment of even morphological relapse by addition of VEN to DLI/HMA regimens while supporting the need for controlled trials.

The success of allogeneic hematopoietic cell transplantation (allo-HCT) is limited by acute graft-versus-host disease (aGVHD). We have previously reported that neutrophils can exacerbate tissue damage caused by conditioning regimens. Pegtarazimod is a synthetic peptide, derived from the capsid protein of human astrovirus serotype 1, that was shown to reduce neutrophil effector functions. Therefore, we evaluated the therapeutic activity of pegtarazimod against aGVHD. Pegtarazimod significantly reduced aGVHD-related mortality, histological aGVHD severity, and pro-inflammatory cytokines in multiple in vivo mouse models, while maintaining the anti-leukemia effect. Mechanistically, pegtarazimod reduced inflammation by decreasing ROS production as investigated using allo-HCT recipient mice with genetic inactivation of NADPH oxidase (NOX2) in the bone marrow. In addition to the anti-inflammatory effect, pegtarazimod protected intestinal organoids against TNF-induced toxicity and oxidative DNA damage. In the phase-2 clinical trial AURORA, pegtarazimod treatment was well-tolerated in patients with corticosteroid-refractory (SR) aGVHD (NCT06343792) with an overall response rate (ORR) of 4/7 patients at day 28. In summary, pegtarazimod reduced aGVHD in mice by suppressing pro inflammatory neutrophil effector functions and preserving enterocyte integrity. The clinical trial data support tolerability of pegtarazimod in aGVHD patients and further studies are needed to determine efficacy.