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Abstract: Graft-versus-host disease (GVHD) is still a major complication of allogeneic stem cell transplantation (allo-SCT). The pathophysiology of GVHD is a multistep process initiated by tissue damage and proinflammatory cytokine cascades induced by the pretransplantation conditioning therapy. This eventually results in Th1-driven tissue damage. However, increasing evidence indicates the involvement of IL17-producing T cells in GVHD pathogenesis. Both CD4+ and CD8+ IL17-producing T cells are suspected of initiating the Th1 response and aggravating tissue inflammation, resulting in full-blown GVHD. In this review, we discuss the involvement of IL17-producing T cells in GVHD and the factors involved in their expansion, differentiation, and activation. Different dendritic cell (DC) subsets, such as plasmacytoid DCs and DC NK lectin group receptor 1+ myeloid DCs have the capability to stimulate Th/Tc17 responses through the release of cytokines. Pivotal cytokines include IL1β, IL6, IL23, and TGFβ, which are known to drive differentiation and expansion of IL17-producing T cells, and these cytokines are highly elevated in patients after allo-SCT. Potent activators of these DC subsets are motifs that are released upon tissue damage and microbial exposure during allo-SCT. These motifs aggravate the Th/Tc17 response via the activation of various pathogen recognition receptors, thereby initiating and perpetuating GVHD. A more comprehensive understanding of the factors and DC subsets driving the IL17 pathway will result in developing and testing novel therapeutic approaches for the prevention of GVHD. [Copyright &y& Elsevier]

Abstract: A role for gut bacteria in the pathogenesis of graft-versus-host disease (GVHD) has been firmly established; however, the role of Candida spp, which form part of the mycobiome, remains unknown. In a homogenous group of patients who underwent allogeneic stem cell transplantation (SCT), we found a significant impact of Candida colonization on the occurrence of acute GVHD. Patients colonized with Candida spp developed significantly more grade II-IV acute GVHD compared with noncolonized patients (50% vs 32%; P = .03), as well as more gastrointestinal (GI)-GVHD (33% vs 19%; P = .05). Colonization with Candida spp was more frequent in patients bearing the loss-of-function polymorphism Y238X, which results in dectin-1 dysfunction, compared with patients with the wild-type allele (73% vs 31%; P = .002). There was no direct effect of dectin-1 dysfunction on acute GVHD, although it did influence the occurrence of GVHD indirectly through Candida colonization. The exact mechanism of GVHD induction by Candida spp colonization of the mucosa is unknown, but the link might prove to be the induction of Th 17/IL-23 responses through activation of pattern recognition receptors by fungal motifs, including β-d-glucan and mannans. These data indicate a role for the mycobiome in the pathogenesis of GVHD and suggest that altering the mycobiome by antifungal drugs can help ameliorate GI-GVHD. In addition, given that the genetic constitution of patients affects susceptibility to both Candida colonization and GVHD, whether identifying gene polymorphisms will facilitate personalized treatment of SCT recipients remains to be determined. [Copyright &y& Elsevier]

Abstract: Dectin-1 plays an important role in antifungal immunity. The dectin-1 Y238X polymorphism, which results in decreased Th17 responses, is associated with increased Candida colonization of stem cell transplantation (SCT) recipients. In this study we found no impact of the polymorphism on the incidence of graft-versus-host disease (GvHD), or on disease-free and overall survival in these SCT recipients. However, patients from patient–donor pairs bearing the wild-type allele who where colonized with Candida had a significant increased incidence of acute GvHD compared to non-colonized patients (OR=2.6, P =0.04). The fact that this was not the case in patients from pairs with the Y238X polymorphism (OR=1.2, ns) suggests that despite increased colonization defective dectin-1 signaling might have prevented an impact of Candida colonization on the incidence of acute GvHD to occur. These are the first human data showing a role for Candida in the pathogenesis of acute GvHD. The mechanism could involve C-type lectin receptor mediated Th17 responses. [Copyright &y& Elsevier]

This study aimed to describe the absolute oral bioavailability of the solid oral formulation of posaconazole and the impact of severe intestinal mucositis in haematology patients. This study also aimed to describe posaconazole protein binding in haematology patients. A pharmacokinetic study was performed of patients receiving induction chemotherapy or a haematopoietic cell transplantation who were randomized to receive 7 days of intravenous posaconazole therapy followed by 9 days of oral therapy, or vice versa. Patients received a posaconazole licensed dose until day 12, after which a reduced once-daily dose of 200 mg was given. At days 7, 12, and 16, blood samples were obtained for pharmacokinetic curves, and trough samples were collected on all other days. Total and unbound posaconazole pharmacokinetics were analyzed by population pharmacokinetic modelling. The presence of severe intestinal mucositis was assessed by plasma citrulline levels and analyzed as a binary covariate using 10 μmol/L as the cut-off. Monte Carlo simulations were performed to simulate posaconazole exposure at a steady state. Twenty-three patients were included for analysis, with 581 total posaconazole concentrations and 91 paired unbound concentrations. Absolute bioavailability in the final model was estimated at 51.4% (percentage relative standard error (%RSE): 56.5) and 67.6% (%RSE: 75.0) in patients with and without severe intestinal mucositis, respectively. Posaconazole unbound fraction was estimated at 2.7% (%RSE: 3.9). Posaconazole bioavailability is reduced in haematological patients with severe intestinal mucositis, requiring an increase in oral posaconazole dose to 400 mg twice daily on day 1, followed by 400 mg once daily or a switch to intravenous therapy. [ABSTRACT FROM AUTHOR]

Allogeneic hematopoietic cell transplantation (HCT) offers the possibility of curative therapy for patients with myelodysplastic syndromes (MDS), chronic myelomonocytic leukemia (CMML), and acute myelogenous leukemia (AML). However, post-HCT relapse remains a major problem, particularly in patients with high-risk cytogenetics and in patients who cannot tolerate consolidation chemotherapy (eg, due to previous toxicity). We assessed the toxicity and efficacy of 10-day decitabine (Dec), fludarabine (Flu), and 2 Gy total body irradiation (TBI) as a new conditioning regimen for allogeneic HCT in patients with MDS, CMML, or AML. Thirty patients were enrolled, including 11 with MDS, 2 with CMML, and 17 with AML. Patients received 20 mg/m 2 /day Dec on days -11 to -2, 30 mg/m 2 /day Flu on days -4 to -2, and 2 Gy TBI on day -1, followed by infusion of a donor stem cell graft on day 0. Postgrafting immunosuppression consisted of cyclosporin A and mycophenolate mofetil. At a median follow-up of 443 days, the overall survival was 53%, relapse incidence was 27%, and nonrelapse mortality was 27%. The incidence of severe acute (grade III/IV) graft-versus-host disease (GVHD) was 27%, and that of (predominantly mild) chronic GVHD was 60%. Immunomonitoring studies revealed that specific CD8 + T cell responses against epigenetically silenced tumor-associated antigens (TAAs), including cancer-testis antigens (MAGE-A1/A2/A3 and PRAME) and RHAMM, occurred more frequently in patients who had received Dec/Flu/TBI conditioning (8 of 11 patients) compared with a control group of patients who had received only Flu/TBI conditioning (2 of 9 patients). In summary, Dec/Flu/TBI conditioning proved feasible and effective and enhanced the induction of TAA-reactive CD8 + T cell responses in vivo, which may contribute to disease control post-transplantation. [ABSTRACT FROM AUTHOR]

Although the Bacille-Calmette-Guérin (BCG) vaccine is used to prevent tuberculosis, it also offers protection against a diverse range of non-mycobacterial infections. However, the underlying protective mechanisms in humans are not yet fully understood. Here, we surveyed at single-cell resolution the gene expression and chromatin landscape of human bone marrow, aspirated before and 90 days after BCG vaccination or placebo. We showed that BCG alters both the gene expression and epigenetic profiles of human hematopoietic stem and progenitor cells (HSPCs). Changes in gene expression occurred primarily within uncommitted stem cells. By contrast, changes in chromatin accessibility were most prevalent within differentiated progenitor cells at sites influenced by Kruppel-like factor (KLF) and early growth response (EGR) transcription factors and were highly correlated (r > 0.8) with the interleukin (IL)-1β secretion capacity of paired peripheral blood mononuclear cells (PBMCs). Our findings shed light on BCG vaccination's profound and lasting effects on HSPCs and its influence on innate immune responses and trained immunity. [Display omitted] • BCG persistently alters gene expression in human hematopoietic stem cells (HSCs) • HSCs maintain a differentiation bias toward the myeloid lineage after 90 days • BCG alters chromatin accessibility (CA), but not gene expression, of progenitors • CA changes in myeloid progenitors correlate with IL-1β secretion by paired PBMCs The BCG vaccine for tuberculosis protects against non-mycobacterial infections, but the mechanisms are unclear. Sun et al. found that BCG alters gene expression and chromatin accessibility in hematopoietic stem and progenitor cells (HSPCs), predicting cytokine secretion in peripheral blood mononuclear cells. This research highlights BCG's lasting, multimodal effects on HSPCs and the regulation of innate immune responses. [ABSTRACT FROM AUTHOR]

Abstract: Allogeneic stem cell transplantation (allo-SCT) can induce remission in patients with hematologic malignancies due to graft-versus-tumor (GVT) responses. This immune-mediated antitumor effect is often accompanied by detrimental graft-versus-host disease (GVHD), however. Both GVT and GVHD are mediated by minor histocompatibility antigen (MiHA)-specific T cells recognizing peptide products from polymorphic genes that differ between recipient and donor. In this study, we evaluated whether mismatches in a panel of 17 MiHAs are associated with clinical outcome after partially T cell–depleted allo-SCT. Comprehensive statistical analysis revealed that DNA mismatches for one or more autosomal-encoded MiHAs was associated with increased relapse-free survival in recipients of sibling transplants (P = .04), particularly in those with multiple myeloma (P = .02). Moreover, mismatches for the ubiquitous Y chromosome–derived MiHAs resulted in a higher incidence of acute GVHD grade III-IV (P = .004), whereas autosomal MiHA mismatches, ubiquitous or restricted to hematopoietic cells, were not associated with severe GVHD. Finally, we found considerable differences among MiHAs in their capability of inducing in vivo T cell responses using dual-color tetramer analysis of peripheral blood samples collected after allo-SCT. Importantly, detection of MiHA-specific T cell responses was associated with improved relapse-free survival in recipients of sibling transplants (P = .01). Our findings provide a rationale for further boosting GVT immunity toward autosomal MiHAs with a hematopoietic restriction to improve outcomes after HLA-matched allo-SCT. [Copyright &y& Elsevier]

Highlights • CD3/CD7-IT therapy was effective in treating steroid-refractory acute graft-versus-host disease, with promising 6-month overall survival. • Treatment with CD3/CD7-IT proved safe and was well tolerated. • After CD3/CD7-IT therapy, immune reconstitution with a diversified repertoire occurred. ABSTRACT Effective therapies for treating patients with steroid-refractory acute graft-versus-host-disease (SR-aGVHD), particularly strategies that reduce the duration of immunosuppression following remission, are urgently needed. The investigated immunotoxin combination consists of a mixture of anti-CD3 and anti-CD7 antibodies separately conjugated to recombinant ricin A (CD3/CD7-IT), which induces in vivo depletion of T cells and natural killer (NK) cells and suppresses T cell receptor activation. We conducted a phase I/II trial to examine the safety and efficacy of CD3/CD7-IT in 20 patients with SR-aGVHD; 17 of these patients (85%) had severe SR-aGVHD, and all 20 patients had visceral organ involvement, including 18 (90%) with gastrointestinal (GI) involvement and 5 (25%) with liver involvement. A validated 2-biomarker algorithm classified the majority of patients (11 of 20) as high risk. On day 28 after the start of CD3/CD7-IT therapy, the overall response rate was 60% (12 of 20), with 10 patients (50%) achieving a complete response. The 6-month overall survival rate was 60% (12 of 20), including 64% (7 of 11) classified as high risk by biomarkers. The 1-week course of treatment with CD3/CD7-IT caused profound but transient depletion of T cells and NK cells, followed by rapid recovery of the immune system with a diverse TCR Vβ repertoire, and preservation of Epstein-Barr virus- and cytomegalovirus-specific T cell clones. Furthermore, our results indicate that CD3/CD7-IT appeared to be safe and well tolerated, with a relatively low prevalence of manageable and reversible adverse events, primarily worsening of hypoalbuminemia, microangiopathy, and thrombocytopenia. These encouraging results suggest that CD3/CD7-IT may improve patient outcomes in patients with SR-aGVHD. [ABSTRACT FROM AUTHOR]

Highlights • 26 patients with overt hematological relapse after allo-HCT were evaluable. • DAC + DLI proved feasible and effective in relapse after allo-HCT. • Overall response rate 19% (CR/CRi (4/26); PR (1/26)), stable disease in 54% (14/26). • Median overall survival was 4.7 months. Abstract The combination of 5-azacytidine (AZA) with donor lymphocyte infusions (DLIs) can induce remissions in patients with relapsed myeloid malignancies after allo-HCT. As decitabine (DAC) is known to be effective also in AML/MDS with leukocytosis, we investigated the combination of DAC with DLIs for relapse after allo-HCT. Between 2006 and 2016, 26 patients (median age 59 years) with AML (n = 18), MDS (n = 6), or MPN (n = 2) and overt hematological relapse after allo-HCT were treated. Median duration from allo-HCT to relapse was 306 days (range, 76–4943). Eighteen patients received DAC + DLIs, 8 DAC-only (median number cycles of DAC: 2, range 1–13, median number of DLIs: 2, range 1–10). The incidence of acute and chronic GvHD in patients receiving DLI was 17% (3/18) and 6% (1/18), respectively. CR/CRi was achieved in 15% (4/26), PR in 4% (1/26), and stable disease in 58% (15/26) of patients. Eight patients received a second allo-HCT. Median overall survival was 4.7 months. Elevated PD-L1 protein expression in bone marrow cells was detected in 4/8 patients with >20% blast infiltration prior to DAC, without a clear association with response. In conclusion, the DAC + DLI regimen proved feasible and effective in relapsed myeloid malignancies after allo-HCT, with efficacy not restricted to patients with low leukemic burden. [ABSTRACT FROM AUTHOR]

Steroid-refractory acute graft-versus-host disease (aGVHD) remains an important cause of morbidity and mortality after allogeneic stem cell transplantation (SCT). A protocol on the management of aGVHD was introduced in our center that incorporated a prospective study on combination therapy with inolimomab (anti-IL-2Rα) and etanercept (anti–tumor necrosis factor-α) for steroid-refractory aGVHD. We evaluated the efficacy and safety in 21 consecutively treated patients. The patients had developed refractory aGVHD after SCT (n = 16) or donor lymphocyte infusion (n = 5), and aGVHD was classified as severe in all patients, mostly due to gastrointestinal involvement stages 2 to 4. No drug-related side effects were observed apart from the infections expected to occur in these severely immunocompromised patients. Overall response at day 28 of second-line therapy was 48% (10/21), with 6 and 4 patients achieving a complete and partial response, respectively. Eventually, 19 patients died (90%), with early mortality (<6 months) predominantly resulting from refractory aGVHD and secondary infections and late mortality resulting from relapse of the underlying disease. With a median follow-up of 55 days, the estimated rates of 6-month and 2-year overall survival were dismal, 29% and 10%, respectively. In conclusion, the combination of inolimomab and etanercept for steroid-refractory aGVHD failed to improve the dismal prognosis of severe steroid-refractory aGVHD. [ABSTRACT FROM AUTHOR]

Abstract: Graft-versus-host disease (GVHD) and fungal infections are frequent complications after allogeneic hematopoietic stem cell transplantation (HSCT). Single nucleotide polymorphisms (SNPs) in genes of the immune system can influence the inflammatory cascade and T cell–driven alloimmune reactions after HSCT, and thus increasing the incidence of GVHD and infectious complications. Here, we investigated the effect of SNPs in IL-23R and CCR6 on posttransplantation outcome in 161 recipients of partially T cell–depleted HSCT. Remarkably, IL-23R SNPs were not associated with clinical outcome, but we found that disparities in the CCR6 tagSNP rs2301436 and SNP rs3093023 are independently associated with the occurrence of chronic GVHD (cGVHD) and invasive fungal disease. In multivariate analysis, patients receiving a transplant from a homozygous rs2301436 G allele donor showed less cGVHD (odds ratio [OR]: 0.16; P = .002), as was the case for a homozygous donor rs3093023 G allele (OR: 0.24; P = .005). In parallel, the GG genotype at rs2301436 in donors was associated with a higher incidence of invasive fungal disease at day 100 after HSCT (OR: 3.59; P = .008). This study shows that CCR6 SNPs can be used to predict clinical outcome, and that polymorphisms in the CCR6 gene may influence T cell–mediated immune reactions after HSCT. [Copyright &y& Elsevier]