Next generation treatment of acute graft-versus-host disease

Azacitidine combined with interferon-α for pre-emptive treatment of AML/MDS after allogeneic peripheral blood stem cell transplantation: A prospective phase II study

This prospective clinical study aimed to evaluate the efficacy and safety of the pre-emptive treatment modality of azacitidine in combination with interferon-α (IFN-α) in AML/MDS patients post-transplantation. Forty-seven patients aged 17-62 were enrolled with 14 patients having completed the planned 12 cycles. Following initiation, 72.3% responded positively after the first cycle, peaking at 77.2% by the fifth cycle. Notably, 24 patients maintained sustained responses throughout a median follow-up of 1050 days (range, 866-1234). Overall survival, leukaemia-free survival and event-free survival probabilities at 3 years were 69.5%, 60.4% and 35.7% respectively. Cumulative incidences of relapse and non-relapse mortality were 36.5% and 4.3% respectively. Multivariate analysis identified that receiving pre-emptive treatment for fewer than six cycles and the absence of chronic graft-versus-host disease after intervention was significantly associated with poorer clinical outcomes. The combination of azacitidine with IFN-α was well-tolerated with no observed severe myelotoxicity, and the majority of adverse events were reversible and manageable. In conclusion, the use of azacitidine in conjunction with IFN-α as pre-emptive therapy is a safe and effective treatment to prevent disease progression in AML/MDS patients with MRD positivity post-allo-HSCT.

Donor T cell STAT3 deficiency enables tissue PD-L1-dependent prevention of graft-versus-host disease while preserving graft-versus-leukemia activity

STAT3 deficiency (STAT3-/-) in donor T cells prevents graft-versus-host disease (GVHD), but the impact on graft-versus-leukemia (GVL) activity and mechanisms of GVHD prevention remains unclear. Here, using murine models of GVHD, we show that STAT3-/- donor T cells induced only mild reversible acute GVHD while preserving GVL effects against nonsusceptible acute lymphoblastic leukemia (ALL) cells in a donor T cell dose-dependent manner. GVHD prevention depended on programmed death ligand 1/programmed cell death protein 1 (PD-L1/PD-1) signaling. In GVHD target tissues, STAT3 deficiency amplified PD-L1/PD-1 inhibition of glutathione (GSH)/Myc pathways that regulate metabolic reprogramming in activated T cells, with decreased glycolytic and mitochondrial ATP production and increased mitochondrial ROS production and dysfunction, leading to tissue-specific deletion of host-reactive T cells and prevention of GVHD. Mitochondrial STAT3 deficiency alone did not reduce GSH expression or prevent GVHD. In lymphoid tissues, the lack of host-tissue PD-L1 interaction with PD-1 reduced the inhibition of the GSH/Myc pathway despite reduced GSH production caused by STAT3 deficiency and allowed donor T cell functions that mediate GVL activity. Therefore, STAT3 deficiency in donor T cells augments PD-1 signaling-mediated inhibition of GSH/Myc pathways and augments dysfunction of T cells in GVHD target tissues while sparing T cells in lymphoid tissues, leading to prevention of GVHD while preserving GVL effects.

Efficacy of azacitidine in preventing relapse after hematopoietic stem cell transplantation for advanced myeloid malignancies: a systematic review and meta-analysis

BACKGROUND

Relapse is the leading cause of death from myeloid malignancies after allogeneic hematopoietic stem cell transplantation (HSCT). Azacitidine has gained attention in recent years in the prophylaxis of relapsed refractory hematologic malignancies. This study evaluated the efficacy of AZA in preventing relapse after HSCT in patients with myeloid malignancies.

METHODS

A systematic review and meta-analysis of all available cohort studies were performed regarding the application of AZA for prophylaxis of relapse after HSCT for advanced MDS and AML. Databases were searched for relevant studies. Endpoints included 2-year relapse rate, survival, relapse-related mortality, as well as the incidence of graft-versus-host disease (GVHD).

RESULTS

A total of 444 patients from 13 studies were included in this analysis. The pooled estimate of the cumulative incidence of relapse after two years in enrolled patients was 25% (95% confidence interval [CI], 18%-33%). The pooled estimates of 2-year survival probabilities were 65% (95% CI, 50%-79%). The pooled cumulative incidence of relapse-related mortality was 28% (95% CI, 22%-34%). The pooled estimated incidence of acute and chronic GVHD, respectively, were 28% (95% CI, 22%-34%) and 38% (95% CI, 27%-49%).

CONCLUSION

AZA administration is efficacious for relapse prevention after HSCT in myeloid malignancies.

T Helper Cell Lineage-Defining Transcription Factors: Potent Targets for Specific GVHD Therapy?

Allogenic hematopoietic stem cell transplantation (allo-HSCT) represents a potent and potentially curative treatment for many hematopoietic malignancies and hematologic disorders in adults and children. The donor-derived immunity, elicited by the stem cell transplant, can prevent disease relapse but is also responsible for the induction of graft-versus-host disease (GVHD). The pathophysiology of acute GVHD is not completely understood yet. In general, acute GVHD is driven by the inflammatory and cytotoxic effect of alloreactive donor T cells. Since several experimental approaches indicate that CD4 T cells play an important role in initiation and progression of acute GVHD, the contribution of the different CD4 T helper (Th) cell subtypes in the pathomechanism and regulation of the disease is a central point of current research. Th lineages derive from naïve CD4 T cell progenitors and lineage commitment is initiated by the surrounding cytokine milieu and subsequent changes in the transcription factor (TF) profile. Each T cell subtype has its own effector characteristics, immunologic function, and lineage specific cytokine profile, leading to the association with different immune responses and diseases. Acute GVHD is thought to be mainly driven by the Th1/Th17 axis, whereas Treg cells are attributed to attenuate GVHD effects. As the differentiation of each Th subset highly depends on the specific composition of activating and repressing TFs, these present a potent target to alter the Th cell landscape towards a GVHD-ameliorating direction, e.g. by inhibiting Th1 and Th17 differentiation. The finding, that targeting of Th1 and Th17 differentiation appears more effective for GVHD-prevention than a strategy to inhibit Th1 and Th17 cytokines supports this concept. In this review, we shed light on the current advances of potent TF inhibitors to alter Th cell differentiation and consecutively attenuate GVHD. We will focus especially on preclinical studies and outcomes of TF inhibition in murine GVHD models. Finally, we will point out the possible impact of a Th cell subset-specific immune modulation in context of GVHD.

LYG1 Deficiency Attenuates the Severity of Acute Graft-Versus-Host Disease via Skewing Allogeneic T Cells Polarization Towards Treg Cells

Acute graft-versus-host disease (aGVHD) is a lethal complication after allogeneic hematopoietic stem cell transplantation. The mechanism involves the recognition of host antigens by donor-derived T cells which induces augmented response of alloreactive T cells. In this study, we characterized the role of a previously identified novel classical secretory protein with antitumor function-LYG1 (Lysozyme G-like 1), in aGVHD. LYG1 deficiency reduced the activation of CD4⁺ T cells and Th1 ratio, but increased Treg ratio in vitro by MLR assay. By using major MHC mismatched aGVHD model, LYG1 deficiency in donor T cells or CD4⁺ T cells attenuated aGVHD severity, inhibited CD4⁺ T cells activation and IFN-γ expression, promoted FoxP3 expression, suppressed CXCL9 and CXCL10 expression, restrained allogeneic CD4⁺ T cells infiltrating in target organs. The function of LYG1 in aGVHD was also confirmed using haploidentical transplant model. Furthermore, administration of recombinant human LYG1 protein intraperitoneally aggravated aGVHD by promoting IFN-γ production and inhibiting FoxP3 expression. The effect of rhLYG1 could partially be abrogated with the absence of IFN-γ. Furthermore, LYG1 deficiency in donor T cells preserved graft-versus-tumor response. In summary, our results indicate LYG1 regulates aGVHD by the alloreactivity of CD4⁺ T cells and the balance of Th1 and Treg differentiation of allogeneic CD4⁺ T cells, targeting LYG1 maybe a novel therapeutic strategy for preventing aGVHD.

IL-22-dependent dysbiosis and mononuclear phagocyte depletion contribute to steroid-resistant gut graft-versus-host disease in mice

Efforts to improve the prognosis of steroid-resistant gut acute graft-versus-host-disease (SR-Gut-aGVHD) have suffered from poor understanding of its pathogenesis. Here we show that the pathogenesis of SR-Gut-aGVHD is associated with reduction of IFN-γ+ Th/Tc1 cells and preferential expansion of IL-17-IL-22+ Th/Tc22 cells. The IL-22 from Th/Tc22 cells causes dysbiosis in a Reg3γ-dependent manner. Transplantation of IFN-γ-deficient donor CD8+ T cells in the absence of CD4+ T cells produces a phenocopy of SR-Gut-aGVHD. IFN-γ deficiency in donor CD8+ T cells also leads to a PD-1-dependent depletion of intestinal protective CX3CR1hi mononuclear phagocytes (MNP), which also augments expansion of Tc22 cells. Supporting the dual regulation, simultaneous dysbiosis induction and depletion of CX3CR1hi MNP results in full-blown Gut-aGVHD. Our results thus provide insights into SR-Gut-aGVHD pathogenesis and suggest the potential efficacy of IL-22 antagonists and IFN-γ agonists in SR-Gut-aGVHD therapy.

5-Aminolevulinic acid combined with sodium ferrous citrate (5-ALA/SFC) ameliorated liver injury in a murine acute graft-versus-host disease model by reducing inflammation responses through PGC1-α activation

Acute graft-versus-host disease (aGvHD) remains lethal as a life-threatening complication after allogeneic hematopoietic stem cell transplantation (HSCT). Inflammatory responses play an important role in aGvHD. 5-Aminolevulinic acid combined with sodium ferrous citrate (5-ALA/SFC) has been widely reported to have a major effect on the anti-inflammatory response; however, these effects in aGvHD models have never been reported. In this study, a murine aGvHD model was developed by transferring spleen cells from donor B6/N (H-2kb) mice into recipient B6D2F1 (H-2kb/d) mice. In addition to evaluating manifestations in aGvHD mice, we analyzed the serum ALT/AST levels, liver pathological changes, infiltrating cells and mRNA expression of inflammation-related cytokines and chemokines. 5-ALA/SFC treatment significantly ameliorated liver injury due to aGvHD and decreased the population of liver-infiltrating T cells, resulting in a reduced expression of pro-inflammatory cytokines and chemokines. Furthermore, the mRNA expression proliferator-activated receptor-γcoactivator (PGC-1α) was enhanced, which might explain why 5-ALA/SFC treatment downregulates inflammatory signaling pathways. Our results indicated that 5-ALA/SFC can ameliorate liver injury induced by aGvHD through the activation of PGC-1α and modulation of the liver mRNA expression of inflammatory-related cytokines and chemokines. This may be a novel strategy for treating this disease.

PRMT5 regulates T cell interferon response and is a target for acute graft-versus-host disease

Acute graft-versus-host disease (aGVHD) is a T cell-mediated immunological disorder and the leading cause of nonrelapse mortality in patients who receive allogeneic hematopoietic cell transplants. Based on recent observations that protein arginine methyltransferase 5 (PRMT5) and arginine methylation are upregulated in activated memory T cells, we hypothesized that PRMT5 is involved in the pathogenesis of aGVHD. Here, we show that PRMT5 expression and enzymatic activity were upregulated in activated T cells in vitro and in T cells from mice developing aGVHD after allogeneic transplant. PRMT5 expression was also upregulated in T cells of patients who developed aGVHD after allogeneic hematopoietic cell transplant compared with those who did not develop aGVHD. PRMT5 inhibition using a selective small-molecule inhibitor (C220) substantially reduced mouse and human allogeneic T cell proliferation and inflammatory IFN-γ and IL-17 cytokine production. Administration of PRMT5 small-molecule inhibitors substantially improves survival, reducing disease incidence and clinical severity in mouse models of aGVHD without adversely affecting engraftment. Importantly, we show that PRMT5 inhibition retained the beneficial graft-versus-leukemia effect by maintaining cytotoxic CD8+ T cell responses. Mechanistically, we show that PRMT5 inhibition potently reduced STAT1 phosphorylation as well as transcription of proinflammatory genes, including interferon-stimulated genes and IL-17. Additionally, PRMT5 inhibition deregulates the cell cycle in activated T cells and disrupts signaling by affecting ERK1/2 phosphorylation. Thus, we have identified PRMT5 as a regulator of T cell responses and as a therapeutic target in aGVHD.

Extracorporeal Photopheresis (ECP) and the Potential of Novel Biomarkers in Optimizing Management of Acute and Chronic Graft vs. Host Disease (GvHD)

As the use of hematopoietic stem cell transplantation (HSCT) has become a more widespread and effective treatment for hematological malignant and non-malignant conditions, the need to minimize the harmful effects of graft- vs.-host disease (GvHD) has become more important in achieving good outcomes. With diagnosis of GvHD reliant on its clinical manifestations, research into biomarkers for the diagnosis, progression, and even for the prediction of disease, is imperative to combating the high levels of morbidity and mortality post-HSCT. Despite the development of novel treatment approaches to GvHD, corticosteroids remain the standard first-line treatment, with immunosuppressant therapies as second-line options. These strategies however have significant limitations and associated complications. Extracorporeal Photopheresis (ECP) has shown to be effective and safe in treating patients with symptomatic GvHD. ECP has been shown to have varied effects on multiple parts of the immune system and does not appear to increase the risk of relapse or infection in the post HSCT setting. Even so, ECP can be logistically more complex to organize and requires patients to be sufficiently stable. This review aims to summarize the potential role of biomarkers to help guide individualized treatment decisions in patients with acute and chronic GvHD. In relation to ECP, robust biomarkers of GvHD will be highly useful in informing patient selection, intensity and duration of the ECP schedule, monitoring of response and other treatment decisions alongside the concurrent administration of other GvHD therapies. Further research is warranted to establish how GvHD biomarkers are best incorporated into ECP treatment pathways with the goal of tailoring ECP to the needs of individual patients and maximizing benefit.

Salvianolic acid B ameliorates liver injury in a murine aGvHD model by decreasing inflammatory responses via upregulation of HO-1

Acute graft-versus-host disease (aGvHD) remains lethal, even after allogeneic hematopoietic stem cell transplantation. Inflammatory responses play an important role in aGvHD. Salvianolic acid B (Sal B) has been widely reported to have a major effect on the anti-inflammatory response, but these effects in an aGvHD model have never been reported. B6 donor splenocytes were transplanted into unirradiated BDF1 recipients and liver and serum were collected on day 14 after transplantation with or without Sal B administration. We measured the expression of pro-inflammatory cytokines and chemokines and other manifestations in aGvHD mice after Sal B treatment. Sal B ameliorated liver injury in aGvHD and promoted survival in mice. Sal B treatment resulted in decreased expression of pro-inflammatory cytokines and chemokines whose expressions in liver are normally elevated by aGvHD. Furthermore, Sal B treatment also enhanced PGC-1α expression in liver tissue and HO-1 expression in nonparenchymal cells. In addition, HO-1 inhibitor abrogated the improvement of survival rate of mice with aGvHD. These results indicated that the protective effect of Sal B relies on suppressing the inflammatory response phase in the aGvHD model, presumably by inducing HO-1. Taken together our data showed that Sal B ameliorates liver injury in aGvHD by decreasing inflammatory responses via upregulation of HO-1. It may provide a novel way to deal with this disease.

Impact of cumulative steroid dose on infectious diseases after allogenic hematopoietic stem cell transplantation

BACKGROUND

Systemic steroid is used to treat various transplant-related complications after allogenic hematopoietic stem cell transplantation (allo-HSCT). However, measures to evaluate its impact on infections are still limited. Hence, we examined the cumulative steroid dose used within 30 days after transplant as a predictor of future risk of infections.

METHODS

This study included 226 patients who underwent their first allo-HSCT at Kyoto University Hospital between 2005 and 2015.

RESULTS

Sixty-one patients received transplantation from related donors, 106 received unrelated BMT and 59 received unrelated single-unit CBT. Patients were categorized into three groups according to the cumulative steroid dose in terms of prednisolone: no-steroid group (n = 174), low-dose group (≤7 mg/kg) (n = 22) and high-dose group (>7 mg/kg) (n = 30). In a multivariate analysis, high-dose steroid administration was associated with cytomegalovirus (CMV) antigenemia (HR 1.91, P = 0.037) and bacteremia (HR 2.59, P = 0.053). No impact was found on the occurrence of invasive fungal infection.

CONCLUSION

High-dose cumulative steroid could predict high risks of bacteremia and CMV antigenemia. Additional anti-bacterial agents for fever and regular measurement of CMV antigen are recommended for whom with systemic steroid administration even after neutrophil engraftment.

Protein dysregulation in graft versus host disease

Allogeneic hematopoietic stem cell transplantation is a well-established treatment for many malignant and non-malignant hematological disorders. As a frequent complication in up to 50% of all patients, graft-versus-host disease is still the main cause for morbidity and non-relapse mortality. Diagnosis is usually done clinically, even though confirmation by pathology is often used to support the clinical findings. Effective treatment requires intensified immunosuppression as early as possible. Although several promising biomarkers have been proposed for an early diagnosis, no internationally-recognized consensus has yet been established. Protein-based biomarkers represent an interesting tool since they have been recently reported to be an important regulator of various cells, including immune cells such as T cells. Therefore, we assume that protein dysregulation is important in the pathogenesis of acute graft versus host disease and their detection might be an possibility in the early diagnosis and monitoring. In this review, we aim to summarize the previous reports of protein biomarkers, focusing on the pathogenesis of the disease and possible implications in diagnostic approaches.

Extracorporeal photopheresis for graft versus host disease: Identifying a clinical pathway and associated resource utilization

Extracorporeal photopheresis (ECP) is an established therapy for the treatment of graft-versus-host-disease (GVHD) following an allogeneic stem cell transplant. We performed a prospective analysis of patients receiving ECP treatment for GVHD to identify a clinical pathway and resource utilization of this process. The cohort included consecutive allogeneic stem cell recipients with GVHD. ECP was performed using the CELLEX Photopheresis System or the UVAR XTS Photopheresis System (Therakos, Inc, Exton, PA). A clinical pathway was developed and a time and motion study was conducted to define the resource utilization and costs associated with ECP. Patients were treated with either CELLEX (n = 18 procedures) or UVAR (n = 4 procedures). Total time commitment for each procedure for the 2 machines differed. The time for ECP was 117 min (median, range: 91-164 min) using CELLEX and 161 min (median; range: 140-210) using the UVAR-XTS machine. Total costs of each ECP procedure were $3420.50. There is a considerable time commitment of the patient and the clinical staff when employing ECP to treat GVHD. ECP costs are significant considering this is a prolonged therapy continued for several months. With this finalized pathway and costs, we have a standardized clinical pathway for the treatment of GVHD. We are addressing minimizing resource utilization while emphasizing quality care for these patients.

Invariant Natural Killer T Cells As Suppressors of Graft-versus-Host Disease in Allogeneic Hematopoietic Stem Cell Transplantation

Invariant natural killer T (iNKT) cells serve as a bridge between innate and adaptive immunity and have been shown to play an important role in immune regulation, defense against pathogens, and cancer immunity. Recent data also suggest that this compartment of the immune system plays a significant role in reducing graft-versus-host disease (GVHD) in the setting of allogeneic hematopoietic stem cell transplantation. Murine studies have shown that boosting iNKT numbers through certain conditioning regimens or adoptive transfer leads to suppression of acute or chronic GVHD. Preclinical work reveals that iNKT cells exert their suppressive function by expanding regulatory T cells in vivo, though the exact mechanism by which this occurs has yet to be fully elucidated. Human studies have demonstrated that a higher number of iNKT cells in the graft or in the peripheral blood of the recipient post-transplantation are associated with a reduction in GVHD risk, importantly without a loss of graft-versus-tumor effect. In two separate analyses of many immune cell subsets in allogeneic grafts, iNKT cell dose was the only parameter associated with a significant improvement in GVHD or in GVHD-free progression-free survival. Failure to reconstitute iNKT cells following allogeneic transplantation has also been associated with an increased risk of relapse. These data demonstrate that iNKT cells hold promise for future clinical application in the prevention of GVHD in allogeneic stem cell transplantation and warrant further study of the immunoregulatory functions of iNKT cells in this setting.

Therapeutic Effects of a NEDD8-Activating Enzyme Inhibitor, Pevonedistat, on Sclerodermatous Graft-versus-Host Disease in Mice

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the sole treatment option for highly malignant hematologic disease; however, the major complication-graft-versus-host disease (GVHD)-still hinders its clinical application. In addition, chronic GVHD remains the major cause of long-term morbidity and mortality after allo-HSCT. Previously we showed that bortezomib, a proteasome inhibitor, can ameliorate the sclerodermatous GVHD response while maintaining graft-versus-tumor (GVT) effects. Here we report that pevonedistat (MLN4924), an inhibitor of the Nedd8-activating enzyme, which functions upstream of the proteasome in the ubiquitin-proteasome pathway, can also show similar protective effects. Recipient mice treated with pevonedistat demonstrated inhibitory effects on sclerodermatous GVHD pathogenesis. The beneficial effect of pevonedistat was observed to be temporally dependent. Whereas treatment given at the time of allo-HSCT administration or before the onset of symptoms worsened the scleroderma response, therapeutic administration starting at 20 days post-transplantation ameliorated the sclerodermatous GVHD. Flow cytometry analysis revealed differential effects on immune subsets, with inhibition of only antigen-presenting cells and not of donor T cells. Finally, pevonedistat preserved GVT effects in a sclerodermatous murine model of B cell lymphoma. Taken together, these data suggest that inhibition of neddylation with pevonedistat can serve as an alternative approach for the treatment of GVHD while maintaining GVT effects in a murine model of sclerodermatous GVHD.

Advances in understanding the pathogenesis of graft-versus-host disease

Allogeneic haematopoietic stem cell transplantation (HCT) is a potent immunotherapy with curative potential for several haematological disorders. Overcoming the immunological barrier of acute graft-versus-host disease (GVHD) remains a fundamental impediment to expanding the efficacy of HCT. GVHD reflects a complex pathological interaction between the innate and adaptive immune systems of the host and donor. Over the past decade there has been a tremendous advancement in our understanding of the cellular and molecular underpinnings of this devastating disease. In this review, we cover several recently appreciated facets of GVHD pathogenesis including novel extracellular mediators of inflammation, immune subsets, intracellular signal transduction, post-translation modifications and epigenetic regulation. We begin to develop general themes regarding the immunological pathways in GVHD pathogenesis, discuss critical outstanding questions, and explore new avenues for GVHD treatment and prevention.

Genome-wide single-nucleotide polymorphism analysis revealed SUFU suppression of acute graft-versus-host disease through downregulation of HLA-DR expression in recipient dendritic cells

Graft-versus-host disease (GVHD) is a major cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). To identify recipient risk factors, a genome-wide study was performed including 481,820 single-nucleotide polymorphisms (SNPs). Two GVHD susceptibility loci (rs17114803 and rs17114808) within the SUFU gene were identified in the discovery cohort (p = 2.85 × 10⁻⁵). The incidence of acute GVHD among patients homozygous for CC at SUFU rs17114808 was 69%, which was significantly higher than the 8% rate observed in CT heterozygous patients (p = 0.0002). In an independent validation cohort of 100 patients, 50% of the patients with the CC genotype developed GVHD compared to 8% of the patients with either CT or TT genotype (p = 0.01). In comparison to CC dendritic cells, those from CT expressed higher levels of SUFU mRNA and protein, had lower levels of surface HLA-DR, and induced less allogeneic mixed leukocyte response (MLR). Ectopic expression of SUFU in THP-1 derived DCs reduced HLA-DR expression and suppressed MLR, whereas silencing of SUFU enhanced HLA-DR expression and increased MLR. Thus our findings provide novel evidence that recipient SUFU germline polymorphism is associated with acute GVHD and is a novel molecular target for GVHD prevention and treatment.

Third-party CD4+ invariant natural killer T cells protect from murine GVHD lethality

Graft-versus-host disease (GVHD) is driven by extensive activation and proliferation of alloreactive donor T cells causing significant morbidity and mortality following allogeneic hematopoietic cell transplantation (HCT). Invariant natural killer T (iNKT) cells are a potent immunoregulatory T-cell subset in both humans and mice. Here, we explored the role of adoptively transferred third-party CD4(+) iNKT cells for protection from lethal GVHD in a murine model of allogeneic HCT across major histocompatibility barriers. We found that low numbers of CD4(+) iNKT cells from third-party mice resulted in a significant survival benefit with retained graft-versus-tumor effects. In vivo expansion of alloreactive T cells was diminished while displaying a T helper cell 2-biased phenotype. Notably, CD4(+) iNKT cells from third-party mice were as protective as CD4(+) iNKT cells from donor mice although third-party CD4(+) iNKT cells were rejected early after allogeneic HCT. Adoptive transfer of third-party CD4(+) iNKT cells resulted in a robust expansion of donor CD4(+)CD25(+)FoxP3(+) regulatory T cells (Tregs) that were required for protection from lethal GVHD. However, in vivo depletion of myeloid-derived suppressor cells abrogated both Treg expansion and protection from lethal GVHD. Despite the fact that iNKT cells are a rare cell population, the almost unlimited third-party availability and feasibility of in vitro expansion provide the basis for clinical translation.

Chronic myelomonocytic leukemia prognostic classification and management: evidence base and current practice

Chronic myelomonocytic leukemia is a clonal malignancy of the ageing hematopoietic stem cell characterized by a biased differentiation leading to persistent monocytosis and inconstant hypersensitivity of myeloid progenitors to granulo-monocyte colony-stimulating factor (GM-CSF). Cytogenetic abnormalities identified in 30-40 % of patients and gene mutations detected in every patient can be used to stratify patients into risk groups that guide the therapeutic choices. TET2, SRSF2, ASXL1, and genes of the Ras pathway are the most frequently mutated genes, with ASXL1 mutations negatively affecting the disease outcome. Allogeneic stem cell transplantation is the first option to consider, especially in younger patients with poor prognostic factors. There is no firm clinical guideline in transplant-ineligible patients, but hypomethylating agents might be an interesting option. A consensus prognostic scoring system and specific response criteria are now required to facilitate the evaluation of new therapeutic strategies in clinical trials specifically dedicated to this disease.