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Findings of retrospective studies suggest that sorafenib maintenance post-transplantation might reduce relapse in patients with FLT3 internal tandem duplication (FLT3-ITD) acute myeloid leukaemia undergoing allogeneic haematopoietic stem-cell transplantation. We investigated the efficacy and tolerability of sorafenib maintenance post-transplantation in this population. We did an open-label, randomised phase 3 trial at seven hospitals in China. Eligible patients (aged 18–60 years) had FLT3-ITD acute myeloid leukaemia, were undergoing allogeneic haematopoietic stem-cell transplantation, had an Eastern Cooperative Oncology Group performance status of 0–2, had composite complete remission before and after transplantation, and had haematopoietic recovery within 60 days post-transplantation. Patients were randomly assigned (1:1) to sorafenib maintenance (400 mg orally twice daily) or non-maintenance (control) at 30–60 days post-transplantation. Randomisation was done with permuted blocks (block size four) and implemented through an interactive web-based randomisation system. The primary endpoint was the 1-year cumulative incidence of relapse in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02474290; the trial is complete. Between June 20, 2015, and July 21, 2018, 202 patients were enrolled and randomly assigned to sorafenib maintenance (n=100) or control (n=102). Median follow-up post-transplantation was 21·3 months (IQR 15·0–37·0). The 1-year cumulative incidence of relapse was 7·0% (95% CI 3·1–13·1) in the sorafenib group and 24·5% (16·6–33·2) in the control group (hazard ratio 0·25, 95% CI 0·11–0·57; p=0·0010). Within 210 days post-transplantation, the most common grade 3 and 4 adverse events were infections (25 [25%] of 100 patients in the sorafenib group vs 24 [24%] of 102 in the control group), acute graft-versus-host-disease (GVHD; 23 [23%] of 100 vs 21 [21%] of 102), chronic GVHD (18 [18%] of 99 vs 17 [17%] of 99), and haematological toxicity (15 [15%] of 100 vs seven [7%] of 102). There were no treatment-related deaths. Sorafenib maintenance post-transplantation can reduce relapse and is well tolerated in patients with FLT3-ITD acute myeloid leukaemia undergoing allogeneic haematopoietic stem-cell transplantation. This strategy could be a suitable therapeutic option for patients with FLT3-ITD acute myeloid leukaemia. None.

Currently, the diagnosis of acute graft-versus-host disease (aGVHD) is mainly based on clinical symptoms and biopsy results. This study was designed to further explore new no noninvasive biomarkers for aGVHD prediction/diagnosis. We profiled miRNAs in serum pools from patients with aGVHD (grades II–IV) ( n  = 9) and non-aGVHD controls ( n  = 9) by real-time qPCR-based TaqMan MicroRNA arrays. Then, predictive models were established using related miRNAs ( n  = 38) and verified by a double-blind trial ( n  = 54). We found that miR-411 was significantly down regulated when aGVHD developed and recovered when aGVHD was controlled, which demonstrated that miR-411 has potential as an indicator for aGVHD monitoring. We developed and validated a predictive model and a diagnostic model for aGVHD. The predictive model included two miRNAs ( miR-26b and miR-374a ), which could predict an increased risk for aGVHD 1 or 2 weeks in advance, with an AUC, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of 0.722, 76.19 %, and 69.70 %, respectively. The diagnostic model included three miRNAs ( miR-28-5p , miR-489 , and miR-671-3p ) with an AUC, PPV, and NPV of 0.841, 85.71 % and 83.33 %, respectively. Our results show that circulating miRNAs ( miR-26b and miR-374a , miR-28-5p , miR-489 and miR-671-3p ) may serve as biomarkers for the prediction and diagnosis of grades II–IV aGVHD.

Steroid refractory acute GVHD (SR aGVHD) is associated with high morbidity and mortality. This study attempted to generate a risk model for SR aGVHD using 259 single nucleotide polymorphisms (SNPs) in 53 genes of recipients and donors. A total of 268 patients with aGVHD who were treated with systemic steroids were included. Patients were randomly divided into training ( n =180) and validation sets ( n =88). Clinical risk factors were also evaluated. In the training set, 85 (47.2%) developed SR aGVHD. Gastrointestinal involvement ( P <0.0001) and donor genotypes of IL6 (rs1800797; P =6.2 × 10 −4 ) and IFNG (rs2069727; P =4.4 × 10 −4 ) were significant risk factors. Scores were assigned to the above risk factors. Patients were divided into low (score 0, n =74) vs high risk (scores 1–3; n =106) in risk model. Higher incidence of SR aGVHD was noted in the high risk (61.3%) vs the low-risk group (27%; P <0.0001, odds ratio (OR) 4.28). Predictive effect of risk model was replicated in the validation set ( P =0.0045, OR 3.74). This risk model was associated with response to therapy, overall and GVHD-specific survival and non-relapse mortality. Our study suggested that this risk model could identify patients at high risk of SR aGVHD with donor genotype of IL6 (rs1800797) and IFNG (rs2069727) along with gastrointestinal involvement of aGVHD.

Cytokine storm (CS) is a severe systemic inflammatory syndrome characterized by the excessive activation of immune cells and a significant increase in circulating levels of cytokines. This pathological process is implicated in the development of life-threatening conditions such as fulminant myocarditis (FM), acute respiratory distress syndrome (ARDS), primary or secondary hemophagocytic lymphohistiocytosis (HLH), cytokine release syndrome (CRS) associated with chimeric antigen receptor-modified T (CAR-T) therapy, and grade III to IV acute graft-versus-host disease following allogeneic hematopoietic stem cell transplantation. The significant involvement of the JAK-STAT pathway, Toll-like receptors, neutrophil extracellular traps, NLRP3 inflammasome, and other signaling pathways has been recognized in the pathogenesis of CS. Therapies targeting these pathways have been developed or are currently being investigated. While novel drugs have demonstrated promising therapeutic efficacy in mitigating CS, the overall mortality rate of CS resulting from underlying diseases remains high. In the clinical setting, the management of CS typically necessitates a multidisciplinary team strategy encompassing the removal of abnormal inflammatory or immune system activation, the preservation of vital organ function, the treatment of the underlying disease, and the provision of life supportive therapy. This review provides a comprehensive overview of the key signaling pathways and associated cytokines implicated in CS, elucidates the impact of dysregulated immune cell activation, and delineates the resultant organ injury associated with CS. In addition, we offer insights and current literature on the management of CS in cases of FM, ARDS, systemic inflammatory response syndrome, treatment-induced CRS, HLH, and other related conditions.

Combining the kinase inhibitor sorafenib with allogeneic stem cell transplantation boosts immune responses against a subtype of acute myelogenous leukemia, suggesting potential clinical benefit. Individuals with acute myeloid leukemia (AML) harboring an internal tandem duplication (ITD) in the gene encoding Fms-related tyrosine kinase 3 (FLT3) who relapse after allogeneic hematopoietic cell transplantation (allo-HCT) have a 1-year survival rate below 20%. We observed that sorafenib, a multitargeted tyrosine kinase inhibitor, increased IL-15 production by FLT3-ITD + leukemia cells. This synergized with the allogeneic CD8 + T cell response, leading to long-term survival in six mouse models of FLT3-ITD + AML. Sorafenib-related IL-15 production caused an increase in CD8 + CD107a + IFN-γ + T cells with features of longevity (high levels of Bcl-2 and reduced PD-1 levels), which eradicated leukemia in secondary recipients. Mechanistically, sorafenib reduced expression of the transcription factor ATF4, thereby blocking negative regulation of interferon regulatory factor 7 (IRF7) activation, which enhanced IL-15 transcription. Both IRF7 knockdown and ATF4 overexpression in leukemia cells antagonized sorafenib-induced IL-15 production in vitro . Human FLT3-ITD + AML cells obtained from sorafenib responders following sorafenib therapy showed increased levels of IL-15, phosphorylated IRF7, and a transcriptionally active IRF7 chromatin state. The mitochondrial spare respiratory capacity and glycolytic capacity of CD8 + T cells increased upon sorafenib treatment in sorafenib responders but not in nonresponders. Our findings indicate that the synergism of T cells and sorafenib is mediated via reduced ATF4 expression, causing activation of the IRF7–IL-15 axis in leukemia cells and thereby leading to metabolic reprogramming of leukemia-reactive T cells in humans. Therefore, sorafenib treatment has the potential to contribute to an immune-mediated cure of FLT3-ITD-mutant AML relapse, an otherwise fatal complication after allo-HCT.

Tregs are critical for maintaining immune homeostasis, and their adoptive transfer can treat murine inflammatory disorders. In patients, Treg therapies have been variably efficacious. Therefore, new strategies to enhance Treg therapeutic efficacy are needed. Tregs predominantly depend on oxidative phosphorylation (OXPHOS) for energy and suppressive function. Fatty acid oxidation (FAO) contributes to Treg OXPHOS and can be important for Treg “effector” differentiation, but FAO activity is inhibited by coordinated activity of the isoenzymes acetyl-CoA carboxylase-1 and -2 (ACC1 and ACC2). Here, we show that small-molecule inhibition or Treg-specific genetic deletion of ACC1 significantly increases Treg suppressive function in vitro and in mice with established chronic graft-versus-host disease. ACC1 inhibition skewed Tregs toward an “effector” phenotype and enhanced FAO-mediated OXPHOS, mitochondrial function, and mitochondrial fusion. Inhibiting mitochondrial fusion diminished the effect of ACC1 inhibition. Reciprocally, promoting mitochondrial fusion, even in the absence of ACC1 modulation, resulted in a Treg functional and metabolic phenotype similar to that seen with ACC1 inhibition, indicating a key role for mitochondrial fusion in Treg-suppressive potency. Ex vivo–expanded, ACC1 inhibitor–treated human Tregs similarly augmented suppressor function, as observed with murine Tregs. Together, these data suggest that ACC1 manipulation may be exploited to modulate Treg function in patients.

When the donor and recipient are mismatched at HLA-DPB1, the risk of graft-versus-host disease is high. The authors found that when the donor has a particular regulatory allele that lowers expression of HLA-DPB1, the risk of GVHD is lower. Hematopoietic-cell transplantation from unrelated donors can cure blood disorders; however, graft-versus-host disease (GVHD) remains a major impediment to successful outcomes. 1 GVHD can occur after HLA-matched transplantation when the donor cells recognize polymorphic peptides (“minor histocompatibility antigens”) presented by the recipient’s HLA. 2 In HLA-mismatched transplantation, direct recognition of the recipient’s mismatched HLA by the donor’s cells provides a potent stimulus for graft-versus-host allorecognition 3 – 7 ; recognition of the donor’s mismatched HLA by the recipient’s immune system leads to graft rejection. 8 , 9 The importance of HLA class II alloantigens was established early in the history of clinical transplantation. 10 Advances in understanding the . . .

Mucosal-associated invariant T (MAIT) cells are a unique innate-like T cell subset that responds to a wide array of bacteria and yeast through recognition of riboflavin metabolites presented by the MHC class I-like molecule MR1. Here, we demonstrate using MR1 tetramers that recipient MAIT cells are present in small but definable numbers in graft-versus-host disease (GVHD) target organs and protect from acute GVHD in the colon following bone marrow transplantation (BMT). Consistent with their preferential juxtaposition to microbial signals in the colon, recipient MAIT cells generate large amounts of IL-17A, promote gastrointestinal tract integrity, and limit the donor alloantigen presentation that in turn drives donor Th1 and Th17 expansion specifically in the colon after BMT. Allogeneic BMT recipients deficient in IL-17A also develop accelerated GVHD, suggesting MAIT cells likely regulate GVHD, at least in part, by the generation of this cytokine. Indeed, analysis of stool microbiota and colon tissue from IL-17A-/- and MR1-/- mice identified analogous shifts in microbiome operational taxonomic units (OTU) and mediators of barrier integrity that appear to represent pathways controlled by similar, IL-17A-dependent mechanisms. Thus, MAIT cells act to control barrier function to attenuate pathogenic T cell responses in the colon and, given their very high frequency in humans, likely represent an important population in clinical BMT.

Despite the curative potential of hematopoietic stem cell transplantation (HSCT), conditioning-associated toxicities preclude broader clinical application. Antibody-drug conjugates (ADCs) provide an attractive approach to HSCT conditioning that minimizes toxicity while retaining efficacy. Initial studies of ADC conditioning have largely focused on syngeneic HSCT. However, to treat acute leukemias or induce tolerance for solid organ transplantation, this approach must be expanded to allogeneic HSCT (allo-HSCT). Using murine allo-HSCT models, we show that pharmacologic Janus kinase 1/2 (JAK1/2) inhibition combined with CD45- or cKit-targeted ADCs enables robust multilineage alloengraftment. Strikingly, myeloid lineage donor chimerism exceeding 99% was achievable in fully MHC-mismatched HSCT using this approach. Mechanistic studies using the JAK1/2 inhibitor baricitinib revealed marked impairment of T and NK cell survival, proliferation, and effector function. NK cells were exquisitely sensitive to JAK1/2 inhibition due to interference with IL-15 signaling. Unlike irradiated mice, ADC-conditioned mice did not develop pathogenic graft-versus-host alloreactivity when challenged with mismatched T cells. Finally, the combination of ADCs and baricitinib balanced graft-versus-host disease and graft-versus-leukemia responses in delayed donor lymphocyte infusion models. Our allo-HSCT conditioning strategy exemplifies the promise of immunotherapy to improve the safety of HSCT for treating hematologic diseases.

Programmed death ligand-1 (PD-L1) interacts with programmed death-1 (PD-1) and the immunostimulatory molecule CD80 and functions as a checkpoint to regulate immune responses. The interaction of PD-L1 with CD80 alone has been shown to exacerbate the severity of graft-versus-host disease (GVHD), whereas costimulation of CD80 and PD-1 ameliorates GVHD. Here we have demonstrated that temporary depletion of donor CD4+ T cells early after hematopoietic cell transplantation effectively prevents GVHD while preserving strong graft-versus-leukemia (GVL) effects in allogeneic and xenogeneic murine GVHD models. Depletion of donor CD4+ T cells increased serum IFN-γ but reduced IL-2 concentrations, leading to upregulation of PD-L1 expression by recipient tissues and donor CD8+ T cells. In GVHD target tissues, the interactions of PD-L1 with PD-1 on donor CD8+ T cells cause anergy, exhaustion, and apoptosis, thereby preventing GVHD. In lymphoid tissues, the interactions of PD-L1 with CD80 augment CD8+ T cell expansion without increasing anergy, exhaustion, or apoptosis, resulting in strong GVL effects. These results indicate that the outcome of PD-L1-mediated signaling in CD8+ T cells depends on the presence or absence of CD4+ T cells, the nature of the interacting receptor expressed by CD8+ T cells, and the tissue environment in which the signaling occurs.