Graft-versus-host Disease Outcomes Research Articles

Pre-transplant hepatic steatosis (fatty liver) is associated with chronic graft-vs-host disease but not mortality.

Allogeneic-HCT (allo-HCT), while potentially curative, can result in significant complications including graft versus host disease (GVHD). Prior studies suggest that metabolic syndrome may be one risk factor for GVHD. We hypothesized that hepatic steatosis on pre-HCT computed tomography (CT) scans may be a marker for development of GVHD and poor outcomes in allo-HCT. In this retrospective study, we reviewed the pre-HCT CT scans and transplant outcome data of patients who underwent allo-HCT at Duke University Medical Center from 2009 to 2017. The presence of steatosis was confirmed using CT attenuation measurements. We then assessed the association between pre-HCT hepatic steatosis and HCT-related outcomes including GVHD. 80 patients who had pre-HCT CT scans were included in the study. Pre-transplant hepatic steatosis was associated with the development of chronic GVHD (OR 4.2, p = 0.02), but was not associated with acute GVHD (OR 1.3, p = 0.7), non-relapse mortality (p = 0.81) or overall survival (p = 0.74). Based on this single center retrospective study, pre-transplant hepatic steatosis is associated with development of chronic GVHD. Further, prospective study with other imaging modalities including non-contrasted CT scans is needed to determine if this association is reproducible.

Treating From the Inside Out: Relevance of Fecal Microbiota Transplantation to Counteract Gut Damage in GVHD and HIV Infection.

The gastrointestinal (GI) tract is a complex and well-balanced milieu of anatomic and immunological barriers. The epithelial surface of the GI tract is colonized by trillions of microorganisms, known as the gut microbiota, which is considered an “organ” with distinctive endocrine and immunoregulatory functions. Dysregulation of the gut microbiota composition, termed dysbiosis, has been associated with epithelial damage and translocation of microbial products into the circulating blood. Dysbiosis, increased gut permeability and chronic inflammation play a major role on the clinical outcome of inflammatory bowel diseases, graft-vs.-host disease (GVHD) and HIV infection. In this review, we focus on GVHD and HIV infection, conditions sharing gut immune damage leading to dysbiosis. The degree of dysbiosis and level of epithelial gut damage predict poor clinical outcome in both conditions. Emerging interventions are therefore warranted to promote gut microbiota homeostasis and improve intestinal barrier function. Interventions such as anti-inflammatory medications, and probiotics have toxicity and/or limited transitory effects, justifying innovative approaches. Fecal microbiota transplantation (FMT) is one such approach where fecal microorganisms are transferred from healthy donors into the GI tract of the recipient to restore microbiota composition in patients with Clostridium difficile-induced colitis or inflammatory bowel diseases. Preliminary findings point toward a beneficial effect of FMT to improve GVHD and HIV-related outcomes through the engraftment of beneficial donor bacteria, notably those producing anti-inflammatory metabolites. Herein, we critically review the potential for FMT in alleviating dysbiosis and gut damage in patients with GVHD or HIV-infection. Understanding the underlying mechanism by which FMT restores gut function will pave the way toward novel scalable and targeted interventions.

Anaerobic Antibiotics and the Risk of Graft-versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation.

Certain anaerobic bacteria are important for maintenance of gut barrier integrity and immune tolerance and may influence the risk of graft-versus-host disease (GVHD) after allogeneic hematopoietic stem cell transplantation (HSCT). We conducted a single-center retrospective cohort study of allogeneic HSCT recipients to evaluate associations between receipt of antibiotics with an anaerobic spectrum of activity and GVHD outcomes. We identified 1214 children and adults who developed febrile neutropenia between 7 days before and 28 days after HSCT and compared GVHD risk and mortality among patients who received anaerobic antibiotics (piperacillin-tazobactam or carbapenems; n=491) to patients who received only antibiotics with minimal activity against anaerobes (aztreonam, cefepime, or ceftazidime; n=723). We performed metagenomic sequencing of serial fecal samples from 36 pediatric patients to compare the effects of specific antibiotics on the gut metagenome. Receipt of anaerobic antibiotics was associated with higher hazards of acute gut/liver GVHD (hazard ratio [HR], 1.26; 95% confidence interval [CI], 1.03 to 1.54) and acute GVHD mortality (HR, 1.63; 95% CI, 1.08 to 2.46), but not chronic GVHD diagnosis (HR, 1.04; 95% CI: .84 to 1.28) or chronic GVHD mortality (HR, .88; 95% CI, .53 to 1.45). Anaerobic antibiotics resulted in decreased gut bacterial diversity, reduced abundances of Bifidobacteriales and Clostridiales, and loss of bacterial genes encoding butyrate biosynthesis enzymes from the gut metagenome. Acute gut/liver GVHD was preceded by a sharp decline in bacterial butyrate biosynthesis genes with antibiotic treatment. Our findings demonstrate that exposure to anaerobic antibiotics is associated with increased risks of acute gut/liver GVHD and acute GVHD mortality after allogeneic HSCT. Use of piperacillin-tazobactam or carbapenems should be reserved for febrile neutropenia cases in which anaerobic or multidrug-resistant infections are suspected.

Preconditioning Absolute Lymphocyte Count and Transplantation Outcomes in Matched Related Donor Allogeneic Hematopoietic Stem Cell Transplantation Recipients with Reduced-Intensity Conditioning and Antithymocyte Globulin Treatment.

The integration of antithymocyte globulin (ATG) into therapy has significantly reduced the incidence of graft-versus-host disease (GVHD) and is being actively used in allogeneic hematopoietic stem cell transplantation (allo-HSCT). The ATG dosage is determined by the recipient's body weight, but some insist that this approach does not reflect the actual target of ATG. In this respect, weight-based dosing may lead to ATG overdose, particularly in recipients with a relatively low absolute lymphocyte count (ALC). We retrospectively analyzed 84 patients with acute leukemia or myelodysplastic syndrome who underwent matched related donor (MRD) allo-HSCT with reduced-intensity conditioning (RIC) at a single institution. Patients were dichotomized according to the ALC measured on the first day of conditioning (day -7) to investigate the associations of the ALC with GVHD and survival outcomes. The median duration of follow-up was 29 months. The preconditioning ALC was closely correlated with the ALC at the first ATG administration (day -3). The cumulative incidences of both acute GVHD and chronic GVHD were significantly lower in the preconditioning ALC <500/μL group compared with the ALC ≥500/μL group. There was no significant difference in disease relapse incidence between the 2 groups; however, mortality was significantly higher in the ALC <500/μL group. Multivariate analysis including disease status, modified European Blood and Marrow Transplantation score, and preconditioning ALC (≥500/μL versus <500/μL) identified disease status and ALC as being independently associated with overall survival (OS). In particular, infection was the most common cause of death in the ALC <500/μL group. Our data suggest that uniform weight-based ATG dosing in MRD allo-HSCT with RIC is associated with an increase in nonrelapse mortality and a relatively inferior OS in patients with a significantly low preconditioning ALC. Therefore, alternative strategies for the integration of ATG should be considered in allo-HSCT, at least for patients with a substantially low preconditioning ALC.

Evolving Therapeutic Options for Chronic Graft-versus-Host Disease.

Despite improvements in prevention and treatment of acute graft-versus-host disease (GVHD), chronic GVHD (cGVHD) remains a significant contributor to morbidity and mortality of allogeneic transplant patients. Chronic GVHD remains a leading cause of late complications posttransplant and is impacted by donor-, patient-, and transplant-related (hematopoietic cell transplant [HCT]) factors. Advances in the biological understanding of cGVHD have provided opportunities to improve clinical interventions for prevention and treatment. Expansion of posttransplantation cyclophosphamide beyond haploidentical HCTs has transformed alternative donor, matched, and mismatch GVHD outcomes and is currently being investigated in two upcoming clinical trials network prophylaxis studies. Although corticosteroids remain the cornerstone therapy, several clinical trials are prospectively investigating the utility of using novel agents in combination with corticosteroids as upfront therapy to mitigate prolonged steroid exposure. Several treatment options for patients with steroid-refractory cGVHD are currently being investigated, and advances have resulted in ibrutinib becoming the first cGVHD agent approved by the U.S. Food and Drug Administration. We review recent advances in understanding of cGVHD pathophysiology and new approaches for the prevention and treatment of cGVHD.

Association between P2X7 Polymorphisms and Post-Transplant Outcomes in Allogeneic Haematopoietic Stem Cell Transplantation.

Allogeneic stem cell transplantation (alloSCT) is a highly effective treatment method for haematologic malignancies. However, infection of acute organ dysfunction and graft versus host disease (GVHD) impact negatively on patient outcomes. Pre-transplant conditioning regimes are associated with high levels of immunogenic cell death and the release of extracellular ATP, which binds to the P2X7 receptor. It has been proposed that signaling through the P2X7 receptor may lead to activation of downstream effectors that influence alloSCT outcome. In this study, we examined the effect of gain-of-function (GOF) or loss-of-function (LOF) P2X7 Single Nucleotide Polymorphisms (SNP) in 453 paired alloSCT donors and recipients and correlated their presence or absence to the major post-transplant outcomes of acute GVHD, relapse free survival and overall survival. The allelic frequency of P2X7 SNP in recipients and donors was not different from those SNP for which there is published population data. The LOF SNP Glu496Ala was overrepresented in recipients who did not develop severe acute GVHD and was associated with improved overall survival in rare homozygous recipients, whereas the LOF SNP Ile568Asn was more common in patients with grade 1–4 GVHD but lost statistical association in patients with grade 2–4 aGVHD, and was associated with reduced overall survival in heterozygotes due to an excess of infection-related deaths. The GOF variant haplotype (homozygous Gln460Arg-Ala348Thr) had no impact on post-alloSCT outcomes. Overall, our data indicate that allelic variations in recipients or donors occurs at the same frequency as the general population and may have a minor, but clinically nominal, impact on post-alloSCT outcomes.

Diverse IL-6 signalling modalities drive pathogenic T cell differentiation and graft-versus-host-disease after allotransplantation

Abstract Allogeneic stem cell transplantation (alloSCT) and graft-versus-host disease (GVHD) are characterized by systemic interleukin 6 (IL-6) dysregulation, which plays a significant role in shaping donor immune responses and T cell polarization. GVHD is a T cell-mediated disease and the severity and tissue distribution is heavily influenced by T cell-derived cytokines, therefore it is critical to understand the factors that drive T cell polarization in this context to inform therapeutic strategies. IL-6 has a unique receptor system composed of IL-6Ra and the signal transducing molecule gp130, in which signaling occurs via multiple pathways either directly (classical), indirectly via a soluble IL-6 receptor (trans), or presented via antigen presenting cells (cluster). We examined the influence of IL-6 signaling modalities on T cell polarization following allotransplantation, where we found specific targeting of these pathways modulates GVHD outcomes. Using donor grafts composed of IL-6Ra deficient T cells resulted in a profound loss of pathogenic Th17/Th22 differentiation and increased GVHD survival, demonstrating these populations are highly dependent upon classical IL-6 signaling post-transplant. Whilst targeting cluster signaling through IL-6Ra deficient DC had no effect on T cell cytokine responses, trans-signaling inhibition via soluble gp130-Fc resulted in severe skin GVHD. This effect was due to significant expansion of pathogenic donor Th22 and was prevented by donor IL-22 deficiency. These data demonstrate an important role for IL-6 trans signaling in regulating pathogenic T cell polarization pathways following allotransplantation and support IL-6 classical signaling as an important target for GVHD prevention.

Does Lymphocyte Count Impact Dosing of Anti-Thymocyte Globulin in Unrelated Donor Stem Cell Transplantation?

Anti-thymocyte globulin (ATG) is used to reduce the incidence and severity of graft-versus-host disease (GVHD) with hematopoietic cell transplantation, yet optimum dosing has yet to be determined. We have previously demonstrated that 2.5 mg/kg ATG in conditioning can reduce the incidence of GVHD in unrelated donor transplants. Recent literature has suggested that ATG dosing based on absolute lymphocyte count (ALC) could lead to more optimum exposure of the drug. We sought to determine if ALC at the time of transplant could impact clinical outcomes. We conducted a retrospective single-center study analyzing all consecutive patients at The Ottawa Hospital who received a matched unrelated donor stem cell transplant with ATG between 2009 and 2014. Patients received rabbit ATG (thymoglobulin) at 0.5 mg/kg on day -2 and 2.0 mg/kg on day -1. Univariate and multivariate analyses were used to determine if any patient- or transplant-related factors, including weight, ALC, and total ATG dose given, impacted GVHD, relapse, or mortality. In total, 111 patients met inclusion, with a median age of 50 years (range, 19 to 70). The most common diagnoses were acute myelogenous leukemia (43%), Myelodysplasia/myeloproliferative neoplasms (13%), and lymphoma (12%). The median weight at time of conditioning was 80.3 kg (range, 45 to 216). The median ALC on the first day of ATG administration was 0.1×109/L (range, 0 to 190). The median total dose of ATG received was 201 mg (range, 112 to 540 mg). The incidence of acute and chronic GVHD was 35.1% and 21.6%, respectively. In the multivariate model, the actual dose of ATG given to patients was not associated with GVHD (hazard ratio [HR], 1.11; 95% confidence interval [CI], 0.99 to 1.25; P=.07), relapse (HR, 1.13; 95% CI, 0.98 to 1.30; P=.1), or mortality (HR, 1.09; 95% CI, 0.92 to 1.28; P=.32). Similarly, the pretransplant ALC was not associated with GVHD (HR, 1; P=.82), relapse (HR, 1; P=.90), or mortality (HR, 1; P=.39). If patients had received ALC-based dosing according to previously published work (Admiraal et al., Lancet Haematol 2017), the mean total dose of ATG received would have been 1205 mg, more than 5 times the mean dose that was actually given based on weight. With GVHD outcomes being similar to that published by Admiraal et al. and ALC not independently associated with outcomes in our study, further studies are still needed to compare standard weight-based dosing to ALC-based dosing of ATG in matched unrelated donor stem cell transplant.

Pediatric Late-Onset Acute and Chronic Graft-Versus-Host Disease: A Single Center Cohort Study 2007-2017

<h3>Objectives</h3> Late acute graft-versus-host-disease (GVHD) in children is not well described. The 2014 NIH Chronic GVHD Consensus Criteria have not been studied in pediatric populations. We examined the incidence, organ involvement, severity by 2014 NIH criteria, and outcomes of late acute GVHD (L-aGVHD), overlap cGVHD, (O-cGVHD) and classic-chronic GVHD (C-cGVHD) in children. <h3>Methods</h3> We retrospectively reviewed 573 children, median age 7 (range 0.1-17.9) years who underwent first allogeneic hematopoietic cell transplant (HCT) at the University of Minnesota (2007-2017). 377 (66%) had a non-malignant disease. Graft sources included bone marrow (47%), peripheral blood (2%) and cord blood (51%). The majority (76%) received myeloablative regimens. GVHD prophylaxis was calcineurin-based (93%), sirolimus-based (2%) or ex vivo T-cell depletion (5%). <h3>Results</h3> While 79 patients (14%; 95%CI: 11–17) developed early onset (ie, ≤ day +100 after HCT) acute GVHD by 3 years, 9 patients had developed L-aGVHD (> day +100; cumulative incidence 2%, 95%CI: 1–3), 16 patients developed O-cGVHD (3%; 95%CI: 1–4) and 6 patients C-cGVHD (1%; 95%CI: 0–2) (Figure 1). Patients with prior grade II–IV early onset acute GVHD had a higher incidence of O-cGVHD or C-cGVHD (8% vs. 3%, p=0.02). No other patients or graft characteristics were associated with the 32 patients with L-aGVHD, O-cGVHD, or C-cGVHD. Skin was the most common involved organ at GVHD diagnosis across all the GVHD subtypes (Figure 2). No cases with joint or genitourinary chronic GVHD were reported. 6 patients had mild, 4 moderate and 13 severe chronic GVHD. 24/32 patients with L-aGVHD, O-cGVHD, or C-cGVHD received systemic therapy as initial treatment. Systemic therapies included steroids alone (17%, 4/24), steroids and sirolimus (8%, 2/24), steroids and cyclosporine (58%, 14/24), and CSA alone (17%, 4/24). At 6 months, CR/PR was achieved in 78% L-aGVHD patients, 44% O-cGVHD patients, and 43% C-cGVHD patients. 2 year CR/PR was achieved in 89% L-aGVHD patients, 63% O-cGVHD patients, and 71% C-cGVHD patients. The 1-year non-relapse mortality (NRM) was 11% (95%CI: 0–30) for L-aGVHD, 13% (95%CI: 0–29) for O-cGVHD, and 14% (95%CI: 1–28) for C-cGVHD as compared to 34% (95%CI: 23–47) for early onset acute GVHD. Patients with L-aGVHD, O-cGVHD and/or C-cGVHD had higher 2-year NRM than those without (Hazard Ratio: 2.8, 95%CI: 1.0–7.9, p=0.049). <h3>Conclusion</h3> Patients with L-aGVHD, O-cGVHD, and/or C-cGVHD had a higher likelihood of poor NRM. These data suggest that pediatric patients with L-aGVHD may respond better to treatment than those with O-cGVHD or C-cGVHD. Future research should further investigate the risks and nature of L-aGVHD, O-cGVHD and C-cGVHD to better understand how to prevent and treat GVHD in children.

Evaluation of Tacrolimus Levels and Risk of Graft-Versus-Host Disease, Relapse and Non-Relapse Mortality after Haploidentical Transplantation with Post-Transplant Cyclophosphamide

Following haploidentical hematopoietic cell transplantation (haplo-HCT) with post-transplant cyclophosphamide (PTCy), the range of target tacrolimus blood levels is wide (5-15 ng/ml). This fact, combined with pharmacogenomic variation and effects of drug interactions, leads to significant variability in tacrolimus serum concentrations. In the setting of matched related or unrelated donor transplantation using conventional graft-versus-host disease (GVHD) prophylaxis, several published studies have correlated higher post-transplant tacrolimus levels with a lower risk of GVHD. Therefore, we hypothesized that early post-transplant tacrolimus levels following haplo-HCT might impact the incidence of GVHD and other post-transplant endpoints and that more precise tacrolimus level targeting may improve post-transplant outcomes. To this end, we analyzed the relationship between mean weekly tacrolimus levels and acute and chronic GVHD, relapse, non-relapse mortality (NRM) and survival in 158 consecutive patients with hematologic malignancies receiving haplo-HCT using PTCy, tacrolimus and mycophenolate for GVHD prophylaxis between 2013-2018. Transplanted patients had a median age of 51 years (range, 19-75) and comorbidity index was ≥3 in 97 (61%). Peripheral blood was the graft source in 142 (90%), and regimen intensity was myeloablative in 90 (57%). Mean weekly tacrolimus levels were calculated each week for the first 4 weeks starting on day +7 and ending day +35 post-transplant, as well as aggregate mean tacrolimus level for 2- and 4-week intervals. Table 1 depicts a summary of the univariate analysis of weekly mean tacrolimus levels and various clinical endpoints (hazard ratios are depicted for each 1 ng/ml increment in mean tacrolimus levels). In this analysis, there were no significant associations between higher mean weekly tacrolimus levels and acute GVHD, chronic GVHD, relapse, NRM, or survival. Using tertiles, mean tacrolimus levels during weeks 1-4 were divided into <10.9 ng/ml, 10.9-13 ng/ml, and ≥13 ng/ml subgroups. In univariate analysis, there were no significant differences between mean weekly tacrolimus level subgroups and cumulative incidence of acute GVHD, chronic GVHD, relapse or NRM (Figure 1). In conclusion, following haplo-HCT with PTCy, there were no significant associations found between serum tacrolimus concentrations and the incidence of GVHD or other post-transplant outcomes. Given the lack of an obvious detrimental effect of lower tacrolimus levels, combined with the known toxicities associated with tacrolimus use (i.e. renal, neurologic, cardiovascular, diabetes mellitus), we speculate that lower target tacrolimus serum concentrations may be preferable following PTCy-based haplo-HCT.

Microbial-Derived Metabolites Drive Protective Type-I Interferon Responses in Models of Gut Epithelial Damage and Limit Graft-Versus-Host Disease

Background: Graft-versus-host disease (GVHD) is a dreaded complication after stem-cell transplantation (SCT). Standard treatment relies on immunosuppressants but is associated with an increased risk of infection and relapse. Up 50% of patients develop steroid-refractory GVHD, with dismal impact on SCT outcomes. New studies in mice suggest that induction of type-I interferon (IFN-I) signalling or activation of IFN-I inducing pathways such as cGAS/STING or RIG-I/MAVS can promote gut barrier integrity and limit GVHD. However, the endogenous ligands that drive this "protective" IFN-I response are poorly defined. Recent data in mice and humans suggest that microbial-derived metabolites such as small-chain fatty acids or indoles can decrease GHVD mortality. Here, we describe IFN-I inducing metabolites that improve outcomes in mouse models of gut epithelial damage and acute GVHD via a mechanism dependent on STING signalling. Methods: To investigate which cell types mediate protection and how, we generated intestinal organoids and antigen presenting cells (APC) from bone marrow of WT or genetically deficient mice (MAVS-/-, STING-/-, IFNAR-/-) under steady state conditions versus chemotherapy, total body irradiation and after allogeneic SCT in the presence or absence of microbial metabolites. Analysis was performed by microscopy, immunoblotting, qPCR, ELISA and flow cytometry. Outcomes of gut-injured mice were assessed by clinical scoring, histopathology, flow cytometry and organoid recovery. Results: Metabolite treatment promoted regeneration of intestinal organoids as assayed by organoid numbers as well as proliferation. These effects were dependent on IFN-I and STING signalling. In addition, we found activated pro-inflammatory NFkB signalling and decreased apoptosis as evidenced by reduced caspase-3 cleavage. In APCs, IFN-I responses were enhanced in the presence of metabolites including increased IFN-β production and upregulation of IFN stimulated genes. Metabolite-treated mice showed improved recovery of intestinal stem cells following gut injury by chemotherapy and irradiation and increased survival in acute GVHD. Conclusions: Our findings uncover a mechanism by which microbial metabolites amplify IFN-I signals, promote tissue regeneration and thereby prevent allo-activation and GVHD. We show for the first time that these IFN-I inducing metabolites are protective in diverse models of gut damage -- from chemotherapy and radiation to immune-mediated damage -- via a STING-dependent mechanism. Perhaps the poor prognosis of GVHD patients exhibiting a loss of microbiota diversity can be explained in part by an absence of "protective" metabolites able to amplify critical IFN signals. We are currently studying whether metabolite levels correlate with severity and outcome of GVHD in humans. Figure Disclosures No relevant conflicts of interest to declare.

Improved Gvhd Free, Relapse Free Survival Using Dual T-Cell Depletion with ATG and Ptcy in Matched Unrelated Donor RIC Allo-HSCT

Introduction The combination of anti-thymoglobulin (ATG), post-transplant cyclophosphamide (PTCy) and cyclosporine (CsA) provides an effective control of graft-versus host disease (GVHD) in allo-HSCT using peripheral blood stem cell (PBSC) grafts, as has been reported by Dr. Viswabandya et al. We aim to report a large, single center experience in reduced intensity conditioning (RIC) allo-HSCT using dual T-cell depletion with ATG and PTCy combined with CsA for GVHD prophylaxis using grafts from 10/10 matched unrelated donors. Patients and methods Between October 2015 and April 2019, 167 adult patients diagnosed with hematological malignancies underwent first 10/10 MUD RIC allo-HSCT. RIC regimen was composed by fludarabine, busulfan, and 200cGy of total body irradiation. For GVHD prophylaxis all recipients received rabbit-ATG, PTCy 50mg/m2/day on day +3 and +4, and CsA since day +5. One hundred sixteen (69.5%) recipients, transplanted between 2015 and May 2018, received a total dose of 4.5mg/kg of rabbit-ATG (given on day -3,-2 and -1). In May 2018, the dose of ATG was lowered to a total of 2mg/kg (given on day -3 and -2). A total of 51 (30.5%) recipients received the lowered dose of ATG. The median follow-up of the entire cohort was 14 months (range: 0.4-44.5). For those patients who got a higher dose of ATG was 20 months and for those who received a lower dose of ATG was 8.8 months. Data was collected retrospectively and updated on July 2019. Cumulative incidence (Cum.Inc) of GVHD analysis was assessed accounting relapse and death as competing events. Results Baseline and post-transplant information are summarized in the Table 1 and 2. Ninety-three (55.7%) recipients were diagnosed with acute myeloid leukemia (AML). The cum.Inc of grade II-IV and grade III-IV acute GVHD at day +100 was respectively 15.6% (95% confidence interval (CI) 10.6-21.6) and 3.6% (95% CI 1.5-7.3). The cum.Inc of acute GVHD was not significantly affected by the dose of ATG (P&gt;0.05). The cum.Inc of chronic GVHD was 10.9% (95% CI 6.6-16.4). Due to the shorter median follow up of the cohort that received a lower dose of ATG, the impact of the reduction of the dose in the cum.Inc of chronic GVHD was not explored. Overall, 48 (28.7%) recipients died and 35 (20.4%) relapsed. Main causes of death were relapse (14.4%) and infection (9.6%). Outcome information is reported in the Table 2 and Plot A, B and C. One-year overall survival (OS), relapse-free survival (RFS) and GVHD-free/RFS (GFRFS) were respectively 75.6%, 70.3%, 60.4%. Table 3 summarizes the impact of the use of a different dose of ATG in acute GVHD and post-transplant outcome. No significant differences were found between the two groups that receive a different dose of ATG. However, median follow-up was shorter in the cohort that received 2mg/kg of ATG. Table 4 reports the main post-allo-HSCT information of patients diagnosed with AML. One-year OS, RFS and GRFRS for this subgroup of patients were 76.8%, 71.9% and 65.9%. Conclusion The unique and modern combination of RIC PB allo-HSCT using ATG, PTCY and CsA for GVHD prophylaxis results in impressive post-transplant outcomes using 10/10 MUD. The use of dual T-cell depletion with ATG and PTCy is safe and provides an extraordinary control of GVHD with acceptable relapse rates using PB stem cell 10/10 MUD grafts. ATG of only 2mg/kg when it is combined with PTCy and CsA, results in an effective control of acute GVHD rates. The optimal dose of ATG for GVHD prophylaxis is not well established. Further investigations need to be done to determine the efficacy of a lower dose of ATG controlling chronic GVHD in this setting. For patients diagnosed with AML, this protocol is safe and an effective approach when a 10/10 MUD is available. Disclosures Michelis: CSL Behring: Other: Financial Support. Mattsson:Celgene: Honoraria; Gilead: Honoraria; Therakos: Honoraria.

Comparable Outcomes between Unrelated Donor (8/8 or 7/8 matched) and Haploidentical Donor for Allogeneic Stem Cell Transplantation in Adult Patients with Severe Aplastic Anemia

Background Either allogeneic hematopoietic stem cell transplantation (SCT) from HLA-matched sibling donor or immunosuppressive therapy (IST) has been recommended as one of the standard treatments for severe aplastic anemia (SAA). Regarding only 30% of chance finding HLA‐matched sibling donor, SCT from an alternative donor including unrelated (URD) or haplo-identical related donor (HAPLO) is considered to be a treatment option after failure to IST in patients who lack of a HLA-matched sibling donor. The aim of this study was to compare the outcomes of URD SCT and HAPLO SCT for SAA patients. Method Consecutive 152 adult patients with SAA who received first SCT between March 2002 and May 2018 were included: 73 of HLA-well-matched (8/8) URD (WM-URD), 34 of HLA-mismatched URD (MM-URD), and 45 of HAPLO. With the intention to have a follow-up period at least 1 year, data were analyzed at May 2019. A conditioning regimen with total body irradiation (TBI) and cyclophosphamide was used for URD-SCT, whereas that with TBI and fludarabine was administered for HAPLO-SCT (Lee et al, BBMT 2011;17:101, Park et al, BBMT 2017;23:1498, Lee et al, Am J Hematol 2018;93:1368). The combination of tacrolimus and methotrexate were used as graft-versus-host disease (GVHD) prophylaxis. Results The median follow-up was 53.4 (range, 0.2-174.1) months. The median age of URD and HAPLO cohort was 30 (range 18-59) and 34 (range 18-59) years, respectively. Except for one and three patients who failed respective a neutrophil and platelet engraftment, other patients achieved neutrophil and platelet engraftments with median 11 and 15 days for WM-URD, 13 and 16.5 days for MM-URD, and 12 and 14 days for HAPLO, respectively. The five-years overall survival (OS), failure-free survival (FFS), and cumulative incidences (CIs) of graft-failure and transplant-related mortality were similar among three groups: 88.3%, 85.5%, 2.7%, and 11.7% for WM-URD; 81.7%, 81.7%, 0%, and 18.3% for MM-URD, and 86.3%, 84.1%, 6.7%, and 9.2% for HAPLO. The 180-days CI of grade II-IV acute GVHD in WM-URD, MM-URD and HAPLO were 35.6%, 52.9%, and 28.9%, respectively; and moderate to severe chronic GVHD were 28.7%, 38.7% and 11.8% in respective cohort. The CI of grade II-IV acute GVHD and moderate to severe chronic GVHD were significantly higher in MM-URD than those in HAPLO (both, p=0.026). ATG is the only factor affecting both grade II-IV acute GVHD (Hazard ratio 0.511, p=0.01) and moderate to severe chronic GVHD (Hazard ratio 0.378, p=0.003) in multivariate analysis. Other complications including CMV DNAemia, hemorrhagic cystitis, invasive fungal disease, secondary malignancy, and sinusoidal obstruction syndrome were similar among three groups. Survival outcomes of a subgroup of ≥ 2 allele MM-URD (n=16) extracted form MM-URD were inferior that of other donor types (n=136): 75.0% vs. 86.9% (p=0.163) for 5-year OS and 75.0% vs. 84.7% (p=0.272) for 5-year FFS. Conclusion This study shows that there were no significant differences between alternative donor sources in the absence of suitable matched sibling donor. Host/donor features and urgency of transplant should drive physician towards the best choice among alternative donor sources for SAA patients treated with SCT. However, selection of ≥ 2 allele MM-URD should not be recommended due to high incidence of GVHD and inferior outcomes. Figure Disclosures Kim: Celgene: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Hanmi: Consultancy, Honoraria; AGP: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; SL VaxiGen: Consultancy, Honoraria; Novartis: Consultancy; Amgen: Honoraria; Chugai: Honoraria; Yuhan: Honoraria; Sanofi-Genzyme: Honoraria, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Handok: Honoraria; Janssen: Honoraria; Daiichi Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; BL &amp; H: Research Funding; Otsuka: Honoraria. Lee:Alexion: Consultancy, Honoraria, Research Funding; Achillion: Research Funding.

Clostridium Difficile Infection Among Hematopoietic Stem Cell Transplant Recipients and Subsequent Development of Graft-Versus-Host Disease

Introduction: Clostridium difficile (C. difficile) is an anaerobic gram positive rod that colonizes 20-40 % of hospitalized patients and the most common cause of antibiotic-associated diarrhea. The clinical manifestations of C. difficile infection (CDI) range from asymptomatic carriage to severe fulminant infection, leading to bowel perforation and death. Stem cell transplantation (SCT) recipients are at risk of CDI due to prolonged neutropenia, use of broad-spectrum antibiotics, mucosal damage and changes in intestinal microbiota induced by cytotoxic chemotherapy, microbial co-infection and possibly graft-versus-host disease (GVHD). The incidence of CDI amongst patients undergoing autologous SCT varies between five and 15 % and among those undergoing allogenic SCT 12 and 34% in literature1-5. Some studies have found a strong association between CDI and GVHD, gut GVHD and/or severe GVHD1-4 but this was not universally demonstrated5. Many studies looking at CDI in the SCT setting are limited by the ubiquity of traditional risk factors for CDI and small sample sizes. Methods: In this retrospective observational study, we aimed to review the epidemiology and clinical management of CDI in our autologous and allogeneic SCT recipients and subsequent clinical outcomes including development of GVHD. All recipients of autologous and allogeneic SCT at Vancouver General Hospital over the 10-year period between January 1, 2008 and December 31, 2017, who had diarrhoea and at least one positive stool test for C. difficile toxin by polymerase chain reaction were eligible for inclusion. Patient demographics, transplant details including GVHD prophylaxis, treatment for CDI, complications from CDI and subsequent development of acute and chronic GVHD and survival outcomes were collected by means of review of their electronic and written clinical records. An ethics approval was obtained from the hospital ethics committee. Results: Out of the 2104 patients who underwent SCT during the study period, 277 (13.2%) had at least one episode of C. difficile positive diarrhea. The incidence was higher among recipients of allogeneic SCT (19.6%) compared to autologous SCT recipients (9.6%). The majority of the patients (86.7%) were treated with oral metronidazole as a first line therapy and 18.9% required a second line treatment, with oral vancomycin in most cases, due to persistent symptoms with toxin positivity. 21% had recurrence of CDI after an initial successful treatment and 9.4% had two or more recurrences. There was no death directly attributable to acute CDI and the rate of major complications was low. Two patients required an intensive care unit admission with fulminant CDI and one patient underwent bowel resection. 57% of allogeneic SCT patients with post-transplant CDI subsequently developed acute GVHD (45.8% grade 2 or higher acute GVHD, 34% gut GVHD). 60.6% developed chronic GVHD (46.9% moderate to severe GVHD, 19.2% gut chronic GVHD). The median progression free survival was 670.5 days (range 1-3938) and the overall survival time was 984.5 days (range 10-3938). The commonest cause of death was malignancy relapse. Conclusion: The incidence of CDI among autologous and allogeneic SCT recipients in British Columbia was 9.6% and 19.6% respectively. There was no death immediately attributable to CDI and few patients developed fulminant CDI. Of the SCT patients who had CDI, 57% and 60.6% subsequently developed acute and chronic GVHD respectively.

Comparison of characteristics and outcomes of late acute and NIH chronic GVHD between Japanese and white patients

Although differences in the incidence of chronic graft-versus-host disease (GVHD) across the races have been suggested, these have not been systematically investigated. This study compared the incidence, sites, severity, and outcomes of late acute GVHD and chronic GVHD according to National Institutes of Health (NIH) consensus criteria between Japanese (n = 413) and white (n = 708) patients after first allogeneic hematopoietic cell transplantation. Analysis was stratified according to bone marrow transplantation (BMT) or peripheral blood stem cell transplantation (PBSCT). Japanese patients, compared with white patients, had a similar incidence of late acute GVHD (BMT, 19% vs 16%; PBSCT, 19% vs 16%) but experienced more frequent liver late acute GVHD as defined by transaminase elevation (BMT, 79% vs 8%; PBSCT, 92% vs 33%) and less frequent gastrointestinal late acute GVHD (BMT, 11% vs 58%; PBSCT, 20% vs 68%). Japanese patients were more likely to discontinue systemic immunosuppression after late acute GVHD than white patients (hazard ratio, 3.68; 95% confidence interval, 1.96-6.94; P < .001). Japanese patients, compared with white patients, had a lower incidence of chronic GVHD (BMT, 15% vs 30% [P = .002]; PBSCT, 37% vs 45% [P < .001]) and experienced more frequent chronic GVHD of the mouth, eyes, and liver and less frequent gastrointestinal chronic GVHD. The duration of immunosuppressive treatment of NIH chronic GVHD was similar between the races. These differences could not be entirely attributed to practice variation between the centers. This study shows that the incidence, affected sites, severity, and clinical outcomes of late acute GVHD and NIH chronic GVHD differ between Japanese and white patients.

PS1536 EMPIRICAL ANTIBIOTIC THERAPY FOR NEUTROPENIC FEVER AFTER ALLOGENEIC STEM CELL TRANSPLANTATION INFLUENCES GRAFT‐VERSUS‐HOST DISEASE‐RELATED MORTALITY

Background:Neutropenic fever (NF) after allogeneic hematopoietic stem cell transplantation (allo‐HSCT) is common and treated with a choice of clinically equivalent empirical antibiotics. However, treatment with antibiotics results in loss of bacterial diversity; this loss has been shown to affect graft‐versus‐host disease (GVHD)‐related outcomes. We hypothesized that the differences in the spectrum of activity of antibiotics given for NF can differently affect intestinal microbiota and modulate subsequent frequency and severity of GVHD and related outcomes.Aims:With the aim to evaluate the associations among individual antibiotic treatments and GVHD‐related mortality, we retrospectively examined 340 consecutive adult recipients of allo‐HSCT at our center.Methods:For each antibiotic, we stratified patients into two cohorts: those treated with a certain antibiotic, and those never receiving that antibiotic. We then compared the cumulative incidence of GVHD‐related mortality for the two cohorts and evaluated them for potential differences using the Gray's test. The multivariate analysis was performed using the semi‐parametric proportional hazards model of Fine and Gray.Results:Between January 2011 to December 2017, 198 male and 142 female patients underwent allo‐HSCT at a median age of 47 years (range, 18–67). Among them, most patiens (67%) were treated for myeloid malignancies, while the rest had lymphoproliferative disorders (33%). The donors were related in 120 cases (35%), unrelated in 188 patients (55%) and haploidentical in 32 patients (10%). Most of the patients (69%) received peripheral blood stem cells after a reduced‐intensity conditioning regimen (64%). Most frequently administered antibiotics given between days −7 to +28 relative to allo‐HSCT were vancomycin in 57% patients, piperacillin‐tazobactam in 47% of patients, meropenem in 44% of patients and cefepime in 37% of patients. We found that treatment of NF with piperacillin‐tazobactam and vancomycin was associated with increased GVHD‐related mortality at 5 years (17% in piperacillin‐tazobactam ‐ treated patients vs. 9% in untreated patients, p = 0.03, and 16% in vancomycin ‐ treated patients vs. 8% in untreated patients, p = 0.02). The use of vancomycin was also associated with an increased incidence of grade 2–4 clinical GVHD (18% in vancomycin ‐ treated patients vs. 11% in untreated patients, p = 0.02). On the contrary, two other antibiotics, cefepime and meropenem (usually used as second‐line treatment), were not associated with GVHD‐related mortality (p = 0.52 and p = 0.62, respectively). In the multivariate analysis, the use of vancomycin remained significantly correlated (p = 0.03) with GVHD‐related mortality, after adjusting for other GVHD risk factors (age, disease risk, source of stem cells, conditioning regimen).Image/Pictures:Summary/Conclusion:Microbiota injury in allo‐HSCT patients has been observed in several ways, including reduction in commensal anaerobes, expansion of commensal Enterococcus species and loss of overall diversity. Consistent with these reports, we demonstrate that use of antibiotics such as piperacillin‐tazobactam and vancomycin leads to increased GVHD severity. A full explanation has yet to be revealed but one possible contribution could be the rise of antibiotic‐resistant enterococci; both directly with the use of vancomycin and indirectly through the use piperacillin‐tazobactam and reduction of anaerobes. Our findings raise the question to the ideal choices of antibiotics for NF, causing a reappraisal of the manner in which antibiotics have been used in allo‐HSCT so far.

Graft Versus Host Disease Following HLA-Matched Sibling Donor Compared with Matched Related Donor for Hematopoietic Stem Cell Transplantation for the Treatment of Severe Combined Immunodeficiency Disease.

One of the limiting factors for successful hematopoietic stem cell transplantation (HSCT) is graft versus host disease (GVHD). The EBMT/ESID guidelines for HSCT in severe combined immunodeficiency (SCID) recommend no GVHD prophylaxis for a matched sibling donor (MSD). To determine the risk of GVHD in MSD HSCT for SCID patients compared to matched related donor (MRD). This retrospective cohort study compares MSD with MRD and the outcome of GVHD in all SCID patients who underwent HSCT between 1993 and 2013. All statistical analyses were done using IBM SPSS statistics software. One hundred forty-five SCID patients underwent 152 HSCTs while 82 (54%) received GVHD prophylaxis. GVHD occurred in 48 patients (31.5%); 20/48 (42%) had GVHD prophylaxis compared to 28/48 (58%) that did not, P = 0.022. Acute GVHD occurred at a higher trend in MSD, 37/120 (30.8%), compared to MRD, 6/32 (18.8%), P = 0.17. We also analyzed the outcome according to the period of HSCT. The first period was 1993 to 2003, 48 HSCTs, 43 MSD, 5 MRD; all patients had GVHD prophylaxis, and there was no difference in GVHD. The second period was 2004 to 2013: of 104 HSCTs, 77 had MSD and 27 had MRD; GVHD prophylaxis was used in 22.1% of MSD and 63% of MRD, P = 0.000. GVHD was significantly higher in the MSD (40.2%) compared to MRD (18.5%) patients, P = 0.041. GVHD prophylaxis in MSD transplant should be considered in SCID patients.

Graft Versus Host Disease Clinical Trials: Is it Time for Patients Centered Outcomes to Be the Primary Objective?

Graft versus host disease (GVHD) is a common complication following hematopoietic cell transplant and is associated with a high symptom burden, reduced functional status, and impaired quality of life (QOL). QOL is best assessed by patient-reported outcomes (PRO). Numerous clinical trials for the prevention and treatment of GVHD are available. This review aims to understand the landscape of PRO inclusion in clinical trials for GVHD over the last decade. Consensus bodies, including experts in GVHD, PRO, and clinical trials have made recommendations for a standardized approach for the inclusion of PRO in clinical trials including as primary outcomes, however, these have yet to be implemented in a consistent manner in practice. Consistently applying consensus recommendation in chronic GVHD will ensure that PROs are appropriately included in clinical trials. Development of validated measures in acute GVHD and composite outcomes for all GVHD trials are required.

Immune Regulatory Cell Biology and Clinical Applications to Prevent or Treat Acute Graft-Versus-Host Disease

Abstract The most common approaches to prevent and treat graft-versus-host disease (GVHD) are intended to deplete or suppress the T cells capable of mediating or supporting alloresponses; however, this renders the recipients functionally T cell deficient and hence highly susceptible to infections and tumor recurrence. Depletion is often accomplished through the use of broadly reactive antibodies, while functional impairment is typically achieved by pharmacological agents that require long-term administration (usually six months or more), have significant side effects, and may not result in tolerance (i.e., non-responsiveness) of donor T cells to conditioning regimen-resistant host alloantigen-bearing cells. As our knowledge of immune system homeostasis has increased, cell populations with immune regulatory function have been identified and characterized. Although such cell populations are typically present in low frequencies, methods to isolate and expand these cells have permitted their supplementation to the donor graft or infusion late post-transplant in order to stifle GVHD. This review discusses the biology and preclinical proof of concept of GVHD models, along with GVHD outcomes that focus exclusively on immune regulatory cell therapies that have progressed to clinical testing.

Complement C3a and C5a receptors promote GVHD by suppressing mitophagy in recipient dendritic cells.

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic cell transplantation (HCT). DCs play critical roles in GVHD induction. Modulating autophagy represents a promising therapeutic strategy for the treatment of immunological diseases. Complement receptors C3aR/C5aR expressed on DCs regulate immune responses by translating extracellular signals into intracellular activity. In the current study, we found that C3aR/C5aR deficiency enhanced ceramide-dependent lethal mitophagy (CDLM) in DCs. Cotransfer of host-type C3aR-/-/C5aR-/- DCs in the recipients significantly improved GVHD outcome after allogeneic HCT, primarily through enhancing CDLM in DCs. C3aR/C5aR deficiency in the host hematopoietic compartment significantly reduced GVHD severity via impairing Th1 differentiation and donor T cell glycolytic activity while enhancing Treg generation. Prophylactic treatment with C3aR/C5aR antagonists effectively alleviated GVHD while maintaining the graft-versus-leukemia (GVL) effect. Altogether, we demonstrate that inhibiting C3aR/C5aR induces lethal mitophagy in DCs, which represents a potential therapeutic approach to control GVHD while preserving the GVL effect.