Transplant-associated Microangiopathy Research Articles

Endoscopic manifestation of intestinal transplant-associated microangiopathy after stem cell transplantation

BackgroundEndoscopic features of intestinal transplant-associated microangiopathy (iTAM) have not been comprehensively investigated. This study aimed to examine the endoscopic characteristics of patients diagnosed with iTAM.MethodsThis retrospective analysis included 14 patients pathologically diagnosed with iTAM after stem cell transplantation for hematolymphoid neoplasms (n = 13) or thalassemia (n = 1). The sex, age at diagnosis, endoscopic features, and prognosis of each patient were assessed. Serological markers for diagnosing transplant-associated thrombotic microangiopathy were also evaluated.ResultsThe mean age at the time of iTAM diagnosis was 40.2 years. Patients diagnosed based on the pathognomonic pathological changes of iTAM presented with diverse symptoms at the times of endoscopic examinations, including diarrhea (n = 10), abdominal pain (n = 5), nausea (n = 4), appetite loss (n = 2), bloody stools (n = 2), abdominal discomfort (n = 1), and vomiting (n = 1). At the final follow-up, six patients survived, while eight patients succumbed, with a median time of 100.5 days (range: 52–247) post-diagnosis. Endoscopic manifestations included erythematous mucosa (n = 14), erosions (n = 13), ulcers (n = 9), mucosal edema (n = 9), granular mucosa (n = 9), and villous atrophy (n = 4). Erosions and/or ulcers were primarily observed in the colon (10/14, 71%), followed by the ileum (9/13, 69%), stomach (4/10, 40%), cecum (5/14, 36%), duodenum (3/10, 30%), rectum (4/14, 29%), and esophagus (1/10, 10%). Cytomegalovirus infection (n = 4) and graft-versus-host disease (n = 2) coexisted within the gastrointestinal tract. Patients had de novo prolonged or progressive thrombocytopenia (6/14, 43%), decreased hemoglobin concentration (4/14, 29%), reduced serum haptoglobin level (3/14, 21%), and a sudden and persistent increase in lactate dehydrogenase level (2/14, 14%). Peripheral blood samples from 12 patients were evaluated for schistocytes, with none exceeding 4%.ConclusionsThis study provides a comprehensive exploration of the endoscopic characteristics of iTAM. Notably, all patients exhibited erythematous mucosa throughout the gastrointestinal tract, accompanied by prevalent manifestations, such as erosions (93%), ulcers (64%), mucosal edema (64%), granular mucosa (64%), and villous atrophy (29%). Because of the low positivity for serological markers of transplant-associated thrombotic microangiopathy in patients with iTAM, endoscopic evaluation and biopsy of these lesions are crucial, even in the absence of these serological features.

Haploidentical Hematopoietic Stem Cell Transplantation in Pediatric Patients with Acquired Hypocellular Bone Marrow Failure

Children with acquired hypocellular bone marrow failure of unknown cause (AHBMF) are usually diagnosed either with severe aplastic anemia (SAA) or refractory cytopenia of childhood (RCC). Patients with AHBMF who lack a matched donor and who failed or relapsed after immunosuppressive therapy (IST) need alternative therapies. Haploidentical hematopoietic stem cell transplantation (haplo-HSCT) offers a curative treatment for these patients. We report a multicenter Spanish experience with haplo-HSCT in pediatric patients with AHBMF. Eleven pediatric patients (SAA, n=9; RCC, n=2) underwent haplo-HSCT with different lymphodepletion strategies. Most patients (10 of 11) had previously failed to respond or relapsed after IST. The conditioning regimen was reduced intensity in SAA and myeloablative in RCC. Patients with SAA received low-dose radiotherapy as part of their conditioning regimen. All patients engrafted. Viral reactivation was common (8 of 11). Acute GVHD grade ≥II was seen in 5 patients. Chronic GVHD was diagnosed in 4 of the long-term survivors. Transplantation-associated microangiopathy was a frequent complication in SAA patients and was related to worse outcome. Two patients died of transplantation-related complications. Overall survival was 81%, with a median follow-up of 36 months. Haplo-HSCT can be a successful salvage curative treatment for pediatric patients with AHBMF, but with significant toxicities that must be addressed. Transplantation-associated microangiopathy was the most critical complication.

Biomarkers for early complications post hematopoietic cell transplantation: Insights and challenges.

Hematopoietic cell transplantation is an established curative treatment option for various hematological malignant, and non-malignant diseases. However, the success of HCT is still limited by life-threatening early complications post-HCT, such as Graft Versus Host Disease (GVHD), Sinusoidal Obstruction Syndrome (SOS), and transplant-associated microangiopathy, to name a few. A decade of research in the discovery and validation of novel blood-based biomarkers aims to manage these early complications by using them for diagnosis or prognosis. Advances in this field have also led to predictive biomarkers to identify patients' likelihood of response to therapy. Although biomarkers have been extensively evaluated for different complications, these are yet to be used in routine clinical practice. This review provides a detailed summary of various biomarkers for individual early complications post-HCT, their discovery, validation, ongoing clinical trials, and their limitations. Furthermore, this review also provides insights into the biology of biomarkers and the challenge of obtaining a universal cut-off value for biomarkers.

Hematopoietic Stem Cell Transplantation in ARPC1B Deficiency.

Mutations in the ARPC1B isoform component of human actin-related protein 2/3 complex have been recently associated with an inborn error of immunity characterized by combined immunodeficiency, allergies, autoinflammation, and platelet abnormalities. Currently, indications on the management of this novel disease and information on its outcome are lacking. We report the first case series of 7 children with a homozygous mutation in ARPC1B gene who underwent allogeneic-HSCT (allo-HSCT). All patients presented an early clinical onset, characterized by recurrent infections, failure to thrive and gastrointestinal bleeding episodes complicated with neonatal hemorrhagic enteritis in 3 cases, and macrophage activating syndrome in 2. Allo-HSCT was performed at the median age of 1.83years after a myeloablative conditioning regimen in all cases. Engraftment occurred in all patients with full donor chimerism in 6 out of 7. The clinical course after engraftment was uneventful in 3 out of 7 children; 2 patients developed a grade 1-2 acute graft-versus-host disease (GvHD), and 1 patient a grade 1 chronic-GvHD. JC virus-related progressive multifocal leukoencephalopathy was diagnosed in one patient 13months after haploidentical-HSCT and successfully managed with donor-derived viral-specific T-cell infusion. Only one patient had a fatal outcome 3months after HSCT because of sepsis, after veno-occlusive disease, and transplant-associated microangiopathy. At a median follow-up of 19months (range 3-110), 6 out of 7 patients are alive and disease-free. The severity of the clinical phenotype at diagnosis and the high survival rate, with limited transplant-related morbidity, strongly support the indication to allo-HSCT for patients with this diagnosis.

Rapid Improvement in Jaundice Using Transdermal Isosorbide Tape as a Nitric Oxide Donor in Two Adult Patients with Transplantation-associated Microangiopathy Related to Graft-versus-host Disease.

Two adult patients with acute leukemia developed transplantation-associated microangiopathy (TAM) related to graft-versus-host disease (GVHD). Both patients were resistant to standard therapy for TAM and GVHD, which led to markedly elevated serum total bilirubin levels of 47.5 and 10.6 mg/dL, respectively. Transdermal isosorbide tape as a nitric oxide donor was applied to Patients 1 and 2 on post-transplantation days 60 and 66, respectively, which rapidly improved their jaundice after 1 day. This is the first report to describe the efficacy of transdermal isosorbide tape for adult patients with jaundice associated with TAM related to GVHD.

Pretransplantation EASIX predicts intensive care unit admission in allogeneic hematopoietic cell transplantation

AbstractThe Endothelial Activation and Stress Index (EASIX) is a laboratory-based prognosis index defined as creatinine × lactate dehydrogenase/platelets. When measured at pretransplantation evaluation (EASIX-PRE), it predicts allogeneic hematopoietic cell transplantation (alloHCT) mortality. This study explores its ability to predict intensive care unit (ICU) admission and validates EASIX-PRE predictive power for overall survival (OS) and nonrelapse mortality (NRM) in 167 consecutive patients undergoing alloHCT. EASIX-PRE was calculated retrospectively in all patients and transformed into log2 values (log2-EASIX-PRE). Log2-EASIX-PRE predicted ICU admission (hazard ratio [HR], 1.41; P < .001), OS (HR, 1.19; P = .011), and NRM (HR, 1.28; P = .004). The most discriminating EASIX-PRE cutoff value for risk of ICU admission was the 75th percentile (2.795); for OS and NRM, it was the median value (1.703). Patients with EASIX-PRE >2.795 had higher incidence of ICU admission in comparison with patients with lower EASIX-PRE values (day +180, 35.8% vs 12.8%; HR, 2.28; P = .010). Additionally, patients with EASIX-PRE >1.073 had lower OS (2 years, 57.7% vs 68.7%; HR, 1.98; P = .006) and higher NRM (2 years, 38.7% vs 18.5%; HR, 2.92; P = .001) than patients with lower EASIX-PRE results. Log2-EASIX-PRE was not associated with incidence of transplantation-associated microangiopathy, sinusoidal obstruction syndrome, or acute graft-versus-host disease. This study proposes EASIX-PRE as a prognostic tool to identify patients undergoing alloHCT at increased risk of severe organ dysfunction and who would therefore require ICU admission. Early identification of patients at high risk of severe events could contribute to personalized intervention design. Additionally, it validates the association between EASIX-PRE and OS and NRM in those undergoing alloHCT.

Evaluation of Clinical and Morphological Practices in the Diagnosis of Transplant-Associated Microangiopathy: A Study on Behalf of the Complications and Quality of Life Working Party of the EBMT

Introduction: Transplant-associated microangiopathy (TAM) is a severe and frequently life-threatening complication of allogeneic stem cell transplantation (SCT). Thus correct laboratory confirmation and differential diagnosis are important, especially in the context of emerging new therapies, like complement inhibitors. However, among the parameters taken into account when establishing diagnosis, schistocyte count seems to be a subjective and variable one (Zini G. et al., 2012). Therefore, a practice of TAM clinical and morphological diagnosis was investigated in 17 EBMT transplant centers.Methods: The study included two questionnaires, one for transplant physician and one for morphologist, and also a set of 20 blood slide photographs of 20 cases for quantification of proportion of schistocytes. 10 of these cases represented patients with TAM, with diagnosis established based on International Working Group (IWG) criteria at the Pavlov First Saint Petersburg State Medical University and Helsinki university. The remaining 10 were control cases, including diagnosis of myelodysplastic syndrome, autoimmune hemolysis, thalassemia, myelofibrosis and poikilocytosis due to B12 deficiency. 17 EBMT centers participated in the study.Results: Based on physician's questionnaires, 41% of centers use IWG criteria, 41% - “overall TAM” criteria (Cho et al. Transplantation 2010) and 18% physician's decision for the diagnosis of TAM. 88% of centers stated that the differential diagnosis of TAM is complicated and 65% of centers consider schistocyte count a criterion most commonly not fulfilled in suspected cases. For 65% of physicians the percentage of schistocytes required for the diagnosis of TAM is above 4%, for 18% above 1%, for 12% above 2%, and one center considered the level of schistocytes not important for the diagnosis. Based on morphologists's form, the morphological types of abnormal red blood cells that were counted as schistocytes were triangular cells (in 93% of centers), helmet cells (93% of centers), keratocytes (67%), microspherocytes (53%), degmacytes (47%), stomatocytes (13%), acanthocytes (7%) and codocytes (7%). 27% of centers reported that it is impossible to distinguish TAM morphology form autoimmune hemolysis, 13% - from myelodysplastic syndrome, 20% - from poikilocytosis, 7% - from hereditary anemias. 57% of centers considered automated hematology analyzers not applicable for quantification of schistocytes in patients after allogeneic SCT, 36% stated that manual confirmation of results is required, and only one center reported that automated analyzers are accurate for TAM diagnosis. The analysis of blood slides by morphologists revealed significant variability in schistocyte quantification for all the cases. The median number of schistocytes reported was 3% for TAM cases (range 0-19.6%, coefficient of variation 0.83), and 0.6% for control cases (range 0-8.3%, coefficient of variation 1.06). 36% of centers consistently (in at least 18/20 cases) reported number of schistocytes higher than median (5.1±4.1% for all cases), 36% consistently lower than median (0.9±1.3% for all cases), and 28% of centers reported results around median (2.3±2.5% for all cases). The difference might be in part due to inclusion of microspherocytes in the overall count. Centers that classified microspherocytes as schistocytes reported significantly higher values (mean for all cases 6,1±2,6% vs 2,8±2,4%, p=0.035). No significant differences were observed for the other morphological forms. In 31% of the evaluations on TAM cases the reported proportion of schistocytes was below 2%, while in 21% of control cases the proportion was reported to be higher than 2%.Conclusion: The survey identified the need for the standardization of TAM morphological diagnosis and clear criteria to distinguish TAM from other post-transplant complications. Several different methodologies for morphological diagnosis were observed. The existing variability in practices of schistocyte assessment among centers might be an obstacle to reliable multicenter interventional studies in TAM. DisclosuresGreinix:Novartis: Consultancy, Speakers Bureau; Bristol Myers Squibb: Consultancy, Speakers Bureau; Sanofi: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau; Mallinckrodt: Consultancy, Speakers Bureau. Stoelzel:medac: Other: Travel support.

Mortality after Allogeneic Stem Cell Transplantation Associates with Gene Polymorphisms in CD40L and Thrombomodulin in the Absence of Statins

Purpose:Endothelial vulnerability is a novel concept to understand complications after allogeneic stem cell transplantation (alloSCT). The concept is based on genetic polymorphisms in the recipients' thrombomodulin gene (THBD) and endothelial related serum markers prior to conditioning therapy. These parameters predict outcome of alloSCT. CD40 ligand (CD40L) is a key orchestrator of immune responses. Its expression on endothelial cells led us to study single nucleotide polymorphisms (SNPs) in the recipients' CD40L gene on outcome after alloSCT.Patients and methods:Three CD40L gene SNPs (rs3092920, rs30929252, rs3092936) were correlated with outcome endpoints in 342 alloSCT recipients. The SNPs had at least 10% minor allele frequency and tagged additional 21 polymorphisms encompassing 30 kb region of gene locus. The chosen three polymorphisms are in linkage disequilibrium with CD40LG haplotype (TGGC) of rs975379, rs3092952, rs3092933 and rs3092929 polymorphisms that was associated with increased circulating soluble CD40 ligand in inflammatory disorders.Overall survival (OS), non-relapse mortality (NRM), acute GVHD-related mortality, and transplant-associated microangiopathy (TAM) were analyzed. The genotype relevant to outcome was subsequently tested in an independent cohort (n=364) and merged into a genetic risk score with established THBD polymorphisms (rs1962, rs1042579 and rs1042580 (Rachakonda, et al., JCO 2014)). Validation of this risk score was attempted in the independent cohort. Finally, the score was evaluated in 375 independent, non-randomized patients taking statin-based endothelial prophylaxis.Results:While rs3092920 and rs30929252 had no impact on any endpoint, rs3092936 CC/CT genotype was associated with an increased risk of TAM (HR 4.83, p=0.001, 95%CI, 1.89-12.37), NRM (HR 2.24, p=0.019, 95%CI, 1.15-4.40) and acute GVHD-related mortality (HR 3.02, p=0.005, 95%CI, 1.39-6.56) (Figure 1). The combined genetic high risk score (CD40L and THBD) predicted OS and NRM in uni- and multivariable analyses (Multivariable analysis, training cohort, OS: HR 1.50, 95% CI 1.07-2.01, p=0.018; NRM: HR 2.52, 95% CI 1.54-4.13, p=0.0003; validation cohort, OS: HR 1.51, 95% CI 1.05-2.17, p=0.025; NRM: HR 2.17, 95% CI 1.25-3.78, p=0.006). In order to confirm and validate the prognostic impact of the genetic risk score on NRM in patients without statin therapy, the cause-specific Cox model was fitted to the validation cohort with an offset equal to the effect of the genetic risk score in the training cohort. The effect of THBD+CD40L score in the validation cohort was not significantly different from the effect in the training cohort.The predictive impact of the genetic risk score was completely lost in patients taking statins.Conclusion:The rs3092936C allele in the recipients' CD40L gene independently associates with NRM and risk of TMA. A combined genetic score based on THBD and CD40L polymorphisms strongly predicted outcome, but only in the absence of a statin based endothelial protection. Our results support the hypothesis that endothelial vulnerability can be defined prior to allogeneic stem cell transplantation by genetic markers in the recipient's genome. The normalization of mortality risk in patients treated with statins suggests a way of overcoming the negative impact of high risk genotypes and warrants further clinical validation. [Display omitted] DisclosuresLuft:Alexion: Consultancy; Neovii: Research Funding. Dreger:AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; Riemser: Consultancy, Research Funding; Riemser: Consultancy, Research Funding; Riemser: Consultancy, Research Funding; Jansen: Consultancy; Gilead: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding; Riemser: Consultancy, Research Funding; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; Riemser: Consultancy, Research Funding; Riemser: Consultancy, Research Funding; Riemser: Consultancy, Research Funding; Jansen: Consultancy; Riemser: Consultancy, Research Funding; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; Riemser: Consultancy, Research Funding; Jansen: Consultancy; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; Riemser: Consultancy, Research Funding; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; Jansen: Consultancy; Jansen: Consultancy; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; Jansen: Consultancy; Gilead: Consultancy, Speakers Bureau; AbbVie: Consultancy, Other: Travel grants, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Jansen: Consultancy; Riemser: Consultancy, Research Funding; Gilead: Consultancy, Speakers Bureau; Jansen: Consultancy; Jansen: Consultancy; medac: Other: Travel grants; medac: Other: Travel grants; medac: Other; medac: Other; medac: Other; Gilead: Consultancy, Speakers Bureau; Jansen: Consultancy; Gilead: Consultancy, Speakers Bureau; Jansen: Consultancy; Gilead: Consultancy, Speakers Bureau; medac: Other: Travel grants; Jansen: Consultancy; Gilead: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; Gilead: Consultancy, Speakers Bureau; medac: Other: Travel grants; Gilead: Consultancy, Speakers Bureau; medac: Other: Travel grants; medac: Other: Travel grants; medac: Other.

Selective T-cell depletion targeting CD45RA as a novel approach for HLA-mismatched hematopoietic stem cell transplantation in pediatric nonmalignant hematological diseases.

Severe aplastic anemia and congenital amegakaryocytic thrombocytopenia are rare bone marrow failure syndromes. Treatment for aplastic anemia consists of hematopoietic stem cell transplantation (HSCT) from a matched sibling donor or immunosuppressant drugs if there is no donor available. Congenital amegakaryocytic thrombocytopenia is a rare autosomal recessive disease that causes bone marrow failure and has limited treatment options, except for transfusion support and HSCT. In the absence of a suitable matched sibling donor, matched-unrelated, haploidentical, or mismatched donors may be considered. A 2-step partial T-cell-depletion strategy can remove CD45RA+ naïve T cells responsible for graft-versus-host disease (GvHD) while preserving memory T cells. Five patients underwent transplantation using this strategy with rapid neutrophil and platelet recovery. Acute and chronic GvHD ≥ grade 2 appeared in two and one patient, respectively. No severe infections were observed before day + 100. A high (60%) incidence of transplant-associated microangiopathy was observed. Three patients (60%) remain alive, with a median follow-up of 881 (range 323-1248) days. CD45RA-depleted HSCT is a novel approach for patients lacking a suitable matched donor; however, further improvements are needed.

Early bilirubinemia after allogeneic stem cell transplantation\u2014an endothelial complication

Hyperbilirubinemia occurs frequently after allogeneic stem cell transplantation. Causes include primary liver damage and endothelial complications as major contributors. Here, we have investigated the impact of early bilirubinemia (EB) on posttransplant outcomes. Maximum total bilirubin levels (days 0–28) were categorized using maximally selected log rank statistics to identify a cut off for the endpoint non-relapse mortality (NRM) in a training cohort of 873 patients. EB above this cut off was correlated with NRM and overall survival (OS) and with pre- and posttransplant Angiopoietin-2, interleukin (IL)18, CXCL8 and suppressor of tumorigenicity-2 (ST2) serum levels, and the endothelial activation and stress index (EASIX). Clinical correlations were validated in a sample of 388 patients transplanted in an independent institution. The EB cut off was determined at 3.6 mg/dL (61.6 µM). EB predicted OS (HR 1.60, 95% CI 1.21–2.12, p < 0.001), and NRM (CSHR 2.14; 1.28–3.56, p = 0.004), also independent of typical endothelial complications such as veno-occlusive disease, refractory acute graft-versus-host disease, or transplant-associated microangiopathy. However, EB correlated with high Angiopoietin-2, EASIX-pre and EASIX-day 0, as well as increased levels of posttransplant CXCL8, IL18, and ST2. In summary, EB indicates a poor prognosis. The association of EB with endothelial biomarkers suggests an endothelial pathomechanism also for this posttransplant complication.

Transplantation-Associated Microangiopathy (TAM) in Recipients of HLA-Haploidentical Hematopoietic Stem Cell Transplants Using Ptcy, CNI and MMF for GvHD Prophylaxis

Transplant-associated microangiopathy (TAM) is a life-threatening complication after allogeneic transplantation, related to endothelial toxicity caused by chemoradiotherapy, infections, immunosuppressive drugs and GvHD. Clinical manifestations include severe thrombocytopenia, microangiopathic hemolysis and organ dysfunction (e.g. renal, neurological) in the absence of disseminated intravascular coagulation. The reported incidence of TAM after allogeneic hematopoietic stem cell transplantation (HSCT) varies between 0,5 to 70%. Data for TAM occurrence and outcome in the context of HLA-haploidentical transplantation (haplo-HSCT) are rare. Here, we report our experience on TAM incidence, disease manifestation, treatment and outcome in T-cell-replete haplo-HSCT using PTCY as GvHD prophylaxis. We retrospectively analyzed the treatment course of 148 adult patients undergoing haplo-HSCT with regard to the incidence of TAM at our center from January 2012 to April 2019. The diagnosis of TAM required the fulfillment of the criteria as defined by Ruutu et al., Haematologica 2007. Median age of the entire cohort was 54 years (23-74). The majority of patients was transplanted for myeloid disease (60%). Postgrafting immunosuppression consisted of PTCY, CNI and MMF in all patients. Median follow-up time upon survivors was 3 years (4 months - 7 years). Twenty of 148 patients developed TAM, with a cumulative incidence of 10% at day 100. Median interval from haplo-HSCT to TAM onset was 63 days (23-295 days), with seven patients showing TAM after day +100. Median platelet count at diagnosis was 20 x 109/L (range: 6-116), predominantly de novo or worsening thrombocytopenia. Median LDH level was 437 IU/L (305-1445 IU/L). Serum haptoglobin levels were decreased in 85% of the TAM patients. 12/20 patients had active infection at the time of TAM diagnosis, most commonly viral (10/12). All but three patients presented with concurrent active acute GvHD requiring systemic steroid treatment in 16 patients Renal function abnormalities were diagnosed in 55% of the patients affected by TAM, with 4 patients requiring hemodialysis. Nine patients developed grade III hypertension and three patients showed neurologic dysfunction. Upon diagnosis of TAM, CNI dose was reduced (7 patients) or temporarily discontinued (7 patients). No switch to another CNI was performed. FFPs were transfused in nine patients, three patients underwent plasma exchange therapy without any effect. In four patients rituximab was applied. With a CI of 18% vs 2% (p0.002) using a PBSC graft was a risk factor for TAM development when compared to BM. Neither origin of disease (myeloid/lymphoid) nor sex of patient/donor or conditioning intensity (RIC/MAC) influenced the incidence significantly. Estimated one-year and three-year overall survival did not differ between the TAM and the non-TAM cohort (61% vs 61% and 46% vs 47%, p=0.9). Only one patient died because of TAM. With an incidence of 10% at day +100 at our center TAM is a serious but not rare complication after haplo-HSCT using PTCY, CNI and MMF for GvHD prophylaxis. However, in our cohort disease course was moderate with low TAM-associated mortality. The use of a PBSC graft was the only factor influencing TAM incidence. Disclosures Hiddemann: F. Hoffmann-La Roche: Research Funding.

Macrophage-mediated complications after stem cell transplantation.

Complications after hematopoietic stem cell transplantation (HSCT) especially graft versus host disease (GVHD) are serious events and the keys to success of HSCT. Pathological diagnosis of complications is critical but sometimes not definite in GVHD diagnosis. In this review, we focus on the role of macrophages in HSCT complications. In the early period after HSCT, residual recipient macrophages have important roles for engraftment and rejection. Hemophagocytosis is the main feature of activated recipient macrophages. Skin lesions after HSCT are usually skin GVHD but mimicking histology of interface dermatitis is hardly differentiated. Macrophages and lymphocytes of these lesions were studied and increased numbers of macrophages were significantly associated with overall survival of HSCT. It could be suggested macrophages were good predictive markers for skin GVHD-like lesions. Intestinal type transplantation-associated microangiopathy (i-TAM) is an independent pathogenesis from GVHD with serious prognosis. Activated macrophages in these lesions are important and key to the pathogenesis of i-TAM. These activated macrophages are predominantly residual recipient tissue-resident macrophages. Cryptogenic organizing pneumonitis is a lung complication around day 100 after HSCT caused by activated alveolar macrophages. They are donor-derived tissue-resident macrophages. Residual recipient and donor-derived macrophages work in different ways in HSCT complications.

EASIX and mortality after allogeneic stem cell transplantation.

Allogeneic stem cell transplantation (alloSCT) is an effective immunotherapy in patients with hematological malignancies. Endothelial dysfunction was linked to major complications after alloSCT. We asked the question if the "Endothelial Activation and Stress Index" (EASIX; [(creatinine × LDH) ÷ thrombocytes]) can predict mortality after alloSCT. We performed a retrospective cohort analysis in five alloSCT centers in the USA and Germany. EASIX was assessed prior to conditioning (EASIX-pre) and correlated with mortality in 755 patients of a training cohort in multivariable models. The predictive model established in the training cohort was validated in 1267 adult allo-recipients. Increasing EASIX-pre predicted lower overall survival (OS) after alloSCT, and successful model validation was achieved for the validation cohort. We found that EASIX-pre predicts OS irrespective of established scores. Moreover, EASIX-pre was also a significant prognostic factor for transplant-associated microangiopathy. Finally, EASIX-pre correlated with biomarkers of endothelial homeostasis such as CXCL8, interleukin-18, and insulin-like-growth-factor-1 serum levels. This study establishes EASIX-pre based on a standard laboratory biomarker panel as a predictor of individual risk of mortality after alloSCT independently from established clinical criteria.

The Optimal Dosage of Methotrexate for Graft-Versus-Host Disease Prophylaxis in Umbilical Cord Blood Transplantation

Introduction The combination of methotrexate (MTX) and a calcineurin inhibitor is widely used for GVHD prophylaxis in umbilical cord blood transplantation (UCBT). However, the optimal MTX dosage for GVHD prophylaxis in UCBT remains unclear. Methods We investigated the impact of the MTX dosage on clinical outcomes of UCBT. We retrospectively analyzed a cohort of 70 patients who received first UCBT between October 2002 and December 2017 in our hospital. Of the 70 recipients, 37 received MTX at doses of 10 mg/m2 on day 1, and 7 mg/m2 on days 3 and 6 (low-dose MTX: LD-MTX), and 33 received MTX at doses of 15 mg/m2 on day 1, and 10 mg/m2 on days 3 and 6 (standard-dose MTX: SD-MTX), in combination with tacrolimus (TAC).The following conditions within day 180 were considered to be transplant-related complications with endothelial cell damage: sinusoidal occlusive syndrome, systemic transplant-associated microangiopathy (TAM), intestinal TAM, capillary leak syndrome, idiopathic pneumonia syndrome, and diffuse alveolar hemorrhage. We defined grade 3-4 acute GVHD and/or transplant-related complications with endothelial cell damage as severe transplant-related complications in this study. Results The characteristics of patients and transplantation procedures were comparable between the two groups. T-cell depletion was not used as GVHD prophylaxis in our study. The median follow-up period for surviving patients was 1504 days (range, 302-3864). The cumulative incidence of neutrophil engraftment by day 42 was 97.3% (95% CI, 71.5%-99.8%) for the LD-MTX group and 93.9% (95% CI, 73.1%-99.8%) for the SD-MTX group (P = 0.36). The cumulative incidence of platelet engraftment by day 60 was 78.4% (95% CI, 60.6%-88.8%) for the LD-MTX group and 87.9% (95% CI, 69.0%-95.6%) for the SD-MTX group (P = 0.40). Univariate analysis findings revealed that the risk of grade 3-4 acute GVHD was significantly lower in the SD-MTX group than in the LD-MTX group (P = 0.013). Multivariate analysis findings revealed that SD-MTX was significantly associated with a lower incidence of severe transplant-related complications (HR = 0.25; 95% CI, 0.07-0.87; P = 0.029). Non-relapse death was not observed in patients with standard-risk disease in the SD-MTX group (n = 22). There was no significant difference between the two groups in the 2-year incidence of relapse: 27.0% (95% CI, 13.9%-42.0%) for the LD-MTX group and 15.3% (95% CI, 5.4%-29.7%) for the SD-MTX group (P = 0.55). Conclusion Our study demonstrated that the GVHD prophylaxis consisting of SD-MTX and TAC led to a significantly lower incidence of severe acute GVHD and/or TRC-EC than the combination of LD-MTX and TAC without increasing the risk of graft failure and relapse. Thus, while our findings need to be further verified by multicenter studies with larger cohorts of patients, for now SD-MTX is optimal in combination with TAC for GVHD prophylaxis in UCBT.

Central Nervous System Complications after Allogeneic Hematopoietic Stem Cell Transplantation: The Role of Calcineurin Inhibitors

IntroductionDespite its curative potential, the outcome after allogeneic hematopoietic stem cell transplantation (SCT) strongly depends on transplant-related mortality. Neurological complications, especially those affecting the central nervous system (CNS), are often associated with a significant rate of morbidity. Commonly used immunosuppressive drugs are calcineurin inhibitors (CNI) such as cyclosporinA (CsA) and tacrolimus (TAC) which are associated with an increased risk of neurotoxicity. So far no direct comparison between CsA and TAC has been performed to identify the better option in terms of “neurologic tolerability” in the setting of SCT.Patients and MethodsWe performed a retrospective analysis of consecutive patients (pts) who underwent SCT for different hematological malignancies and developed one or more CNS complications between 1999 and 2018 at the University Hospital of Ulm (Germany) and received CsA or TAC as Graft versus Host Disease (GvHD) prophylaxis/therapy. During post transplant follow up, in case of neurological manifestations, neurological evaluation, brain imaging (CT-scan or MRI), electroencephalography and, if necessary, a lumbar puncture (including microbiological analysis) were performed.ResultsWe identified 60 out of 1256 pts who experienced a total of 79 CNS complications. Pts' characteristics are listed in Table 1. Seventy-four of 79 (94%) complications occurred in pts receiving CNI (n=58/60 pts): 51/74 (69%) were detected during or after TAC administration, while in 23/74 cases (31%) CsA was used. No statistically significant differences were observed in the two subgroups with regard to conditioning regimen (myeloablative vs reduced intensity), donor type (matched related vs matched unrelated vs mismatched related), and incidence of severe GvHD (both acute and chronic). In both cohorts early complications (within 1 month after SCT) were mostly represented by vascular events and metabolic encephalopathy (sepsis or chemotherapy-related). As intermediate complications (2-6 months after SCT) we observed a trend towards increased infections of herpes encephalitis in the TAC cohort (p=0.08), CNI-neurotoxicity and CNS symptoms due to severe transplant-associated microangiopathy (TMA). As late effects (>1 year (y) after SCT) we detected secondary CNS neoplasms, CNS relapse or neurologic effects of chronic GvHD. Comparing the time of onset of all complications, we observed a median time of 6 months after SCT in the TAC-cohort (range: day -1 - 13y) and of 11 months in the CsA-cohort (range: day 0 - 4y). The frequency of the different types of CNS complications was similar in the two cohorts with exception for the occurrence of neurological manifestations related to TMA (Figure 1), which was statistically significant higher (p=0.01) in pts receiving TAC. These changes were reversible in 33% of cases (4/12) after discontinuation of TAC (which, at the time of TMA onset, was within or below the therapeutic ranges in 91% of cases) or after specific treatment (e.g. Eculizumab, plasma exchange).ConclusionsOur data suggest a possible increment of neurologic complications in pts undergoing GvHD prophylaxis/therapy with TAC, especially related to the development of severe TMA, which is known to promote mental status changes. Although these findings need to be further explored and validated in larger prospective cohorts, they could have clinical relevance, such as avoiding TAC in pts at high risk of developing TMA as well as a stricter TMA monitoring in pts undergoing GvHD prophylaxis with TAC to minimize the development of severe TMA forms with neurological involvement. DisclosuresDöhner:Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Pfizer: Research Funding; Agios: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Celator: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Jazz: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; AbbVie: Consultancy, Honoraria; AROG Pharmaceuticals: Research Funding; Astellas: Consultancy, Honoraria; Sunesis: Consultancy, Honoraria, Research Funding; Celator: Consultancy, Honoraria; Astex Pharmaceuticals: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; AROG Pharmaceuticals: Research Funding; Astellas: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Amgen: Consultancy, Honoraria; Bristol Myers Squibb: Research Funding; Seattle Genetics: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Pfizer: Research Funding.

Human Umbilical Cord Derived Mesenchymal Stromal Cells to Treat Steroid-Refractory Acute GvHD III/IV or Overlap Syndrome: Interim Analysis of a Multicenter Phase I/II Study

BackgroundTreatment of patients developing steroid-refractory acute GvHD (SR-aGvHD) after allogeneic hematopoietic cell transplantation (HCT) remains an unmet clinical need and a major therapeutic challenge. Mesenchymal stromal cells (MSC) induce immunosuppression and reduce the inflammatory status initiated by aGvHD. We performed an interim analysis of a multicenter, prospective, non-randomized, phase I/II study, planned to test the safety and activity of human umbilical cord (UC), third-party MSC given sequentially after Pentatostatin for the treatment of SR-aGvHD grade III-IV as well as the overlap syndrome (EUDRACT n. 2012-000582-21), NCT02032446).Patients and MethodsThird-party UC MSC were produced under GMP conditions as previously described (Capelli C et al Cytotherapy, 2011, 13, 786-801). The treatment schedule was based on the sequential administration of Pentostatin, given iv at dose of 1 mg/m^2 for 3 consecutive days, followed by 3 MSC infusions given at weekly intervals. Between October 2013 and May 2018 (range 4.6 years) we enrolled 27 allogeneic HCT adult recipients (22 male) with SR-aGvHD (n 25) or overlap syndrome (n 2), median age 47 years (range 19-62) transplanted from HLA-identical sibling donors (6; 22%), haploidentical donors (2; 7%), unrelated donors (18; 67%) or cord blood (1; 4%). Target organ involvement included skin in 11 cases (44%), gastrointestinal tract (GI) in 23 (92%) and liver in 12 (48%). Nine patients had grade III (33%), 16 patients grade IV (60%) and 2 patients had severe overlap syndrome (7%). Most of patients exhibited multiple organ involvement (n 16, 64%). Patients started MSC therapy at median of 22 days (10-2101) after the onset of aGvHD or overlap syndrome.ResultsThe infusions of UC MSC-infusion were always well tolerated without any immediate or late toxic event. Response to MSC therapy, by day 30 after the final MSC dose, was evaluable in 16 of 27 patients: 7 achieved CR (26%), 6 PR (22%) and 3 NR (11%). Ten patients died before reaching the evaluation time of response: 8 patients for aGvHD and 2 for haematological disease. One patient was lost to follow up after 9 days from the last UC-MSC infusion. Remarkably, the subgroup of patients with single organ involvement (8 GI, 1 liver) were all evaluable showing 6 patients in overall response (67%, 4 RC and 2 PR). No response was observed in 2 cases of severe overlap syndrome. Patients achieving CR had improved longer term OS vs patients in PR/NR (80% vs 50% at 1 year). For patients with grade III and IV SR-aGvHD, CR rates at day 30 were 67% and 31% respectively. During tapering of steroid therapy 4 out of 7 patients that obtained CR had aGvHD recurrence, at median time of 87 days. We observed relapse of underlying malignancy in 5 patients and all died with active disease. At last follow-up 8 out of 27 patients were alive with no GVHD in 5 of them; 14 patients died from TRM: aGvHD or overlap syndrome itself (n=10), infections (n= 2), cGvHD (n= 2). Two patients with uncontrolled GvHD had clinical signs of Transplant Associated Microangiopathy (TAM). A total of 17 reported AE and 12 SAE were registered. In 23 out of 27 patients infectious complications were observed, in most cases virus related (n.25; CMV followed by BK virus and EBV), and fungal infections (3 aspergillus pneumoniae). Blood-stream documented infections (5) and pneumoniae (5) were also observed.ConclusionsThe infusion of cord blood derived MSC proved safe in all cases. As expected in patients with steroid refractory aGvHD, a high rate of infectious complications were observed. When considering that most patients (60 %) had grade IV aGvHD, the response rate and the OS are promising and this warrants not only the completion of this Phase I/II study but also planning a future pivotal trial. DisclosuresNo relevant conflicts of interest to declare.

Assessment of Calcineurin Inhibitor-Associated Neurotoxicity in Patients with Sickle Cell Disease Receiving a Matched Sibling Donor or T-Cell Depleted Haploidentical Hematopoietic Stem Cell Transplantation

Introduction: Sickle cell disease (SCD) is one of the most prevalent monogenic hematological disorders leading to progressive multi-organ damage and reduced life expectancy despite a significant improvement of conventional and supportive care. Allogeneic hematopoietic stem cell transplantation (HSCT) with a matched sibling donor (MSD) represents currently the only curative treatment option, limited by a donor availability <20%. In a pilot study, we compared α/β/CD19 and CD3/CD19, respectively T-cell depleted haploidentical HSCT (T-haplo-HSCT) with MSD HSCT in patients (pts) with advanced stage SCD, using almost identical HSCT regimens for both donor groups.Neurotoxicity (NT) contributes significantly to HSCT-associated morbidity and mortality. Calcineurin inhibitor (CNI) related NT after HSCT is mostly caused by cyclosporine A (CsA) and tacrolimus (FK506) with an overall frequency between 4.2% - 28.8%, and severe NT in 4% - 11%, such as posterior reversible encephalopathy syndrome (PRES), seizures, visual disturbance, cortical blindness, aphasia or ataxia.Particularly in hemoglobinopathies (thalassemia, SCD) the reported incidence is around 30%, possibly also due to impaired hepatic metabolization of CsA and FK506 based on iron overload. However, also infusion modalities might impact on NT, since it was more frequently reported after 4-hours bolus injections (10.3%) than continuous infusion (3.3%). However, the excessive NT observed in SCD might be also related to the systemic vasculopathy, increasing with age and pro-inflammatory triggers after allo-HSCT.Methods: A total of 30 pts aged 3 to 31 years with homozygous SCD or HbS 0/+ ß-Thal were treated between 2012 and 2018. Nine pts received a MSD bone marrow (BM) graft, 21 pts received T-haplo-HSCT from a relative (1 second T-haplo-HSCT due to graft rejection) with a α/β CD19 or CD3/CD19 depleted graft. Post-HSCT immunosuppression consisted of either CsA in 6 MSD and 16 T-haplo-HSCT pts or FK506 in 3 MSD and 6 T-haplo-HSCT pts, both mostly in combination with mycophenolate mofetil (MMF). FK506 was administered as a 20-hours continuous infusion, while CsA was given as 4-hours bolus injections. Dosage was adjusted according to usual target levels (CsA: 120ng/ml; FK506: 7ng/ml). Duration of immunosuppression was >6 months in T-haplo-SCT and <6 months in MSD, depending on chimerism. All pts developing neurological symptoms indicative for severe CNI-related NT underwent neuroradiological imaging (MRI/CT) with consecutive symptomatic treatment as indicated.Results: Overall CNI-related NT was observed in 32.3% of our HSCT pts. Severe NT such as PRES and visual disturbance combined with aphasia was present in 16.1% (Table 1). Overall, NT was more prevalent in MSD (n=5, 55.5%) than in T-haplo-HSCT pts (n=5, 22.7%). The majority of NT events was observed under CsA prophylaxis (8/10; 80%) and in only 22% (2/9) pts with FK506. All 5 cases of severe NT, particularly all PRES, occurred on CsA. Complete recovery of neurologic symptoms was achieved in all pts spontaneously or after switching CsA to FK506 or everolimus (Table 1). Moreover, 60% of pts with NT was >18 years, and 90% >12 years suggesting an increasing risk with age while a third of patients with pre-existing NT experienced no post-HSCT NT. Of note, 4 of 5 pts with severe NT also experienced a mild acute GvHD (Table 1). The overall (OS) and disease-free survival (DFS) with a median follow-up of 17 months in T-haplo-HSCT pts and 22 months in 9 MSD HSCT pts was 90% vs. 100%, respectively.Conclusions: Our data confirm an elevated risk for NT in SCD pts following allo-HSCT. Importantly, the incidence of NT events seems to be related to age (90% of pts with NT were >12years), donor source (MSD vs. T-Haplo; 55.5% vs 22.7%) and CsA rather than FK506 (CSA 80% vs. FK506 20%). All severe NT (particularly all PRES) were observed in pts with CsA prophylaxis, while the continuous infusion of FK506 might have levelled concentration peaks. Nevertheless, the NT observed with CsA post-HSCT could be the consequence of predominantly CsA-related vascular complications inflicting systemically pre-damaged vessels of SCD pts. The mechanism of action could be similar to other systemic endotheliopathies such as sinusoidal obstruction syndrome (VOD/SOS), transplant-associated microangiopathy (TAM) and acute GvHD which was observed in 4/5 pts with severe NT, compared to an overall GvHD rate of 29%. [Display omitted] DisclosuresCorbacioglu:Gentium: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria.

Higher Peak Tacrolimus Concentrations after Allogeneic Hematopoietic Stem Cell Transplantation Increase the Risk of Endothelial Cell Damage Complications

Noninfectious transplantation-related complications (TRCs) such as graft-versus-host disease (GVHD) and endothelial cell damage (TRC-EC) are critical after allogeneic hematopoietic stem cell transplantation. Tacrolimus (TAC) is used to control GVHD. Hypertension and renal failure are common adverse events after TAC treatment. Higher blood concentrations of TAC would be expected to reduce the risk of GVHD but may increase TRC-EC. TRC-EC often develops in patients with GVHD; thus, it is difficult to clinically determine the proper intensity of immunosuppression. We therefore evaluated the impact of weekly mean/peak TAC blood concentrations (PTCs) on TRC-EC occurrence and prognosis. Patients (N = 295) who received TAC as a GVHD prophylaxis at our institute from 2009 to 2016 were eligible for this retrospective study. Forty-three patients were diagnosed with TRC-EC: 8 with sinusoidal obstructive syndrome, 28 with transplant-associated microangiopathy, and 7 with idiopathic pneumonia syndrome. The cumulative incidence of TRC-EC at 12 months was 13.8% (95% confidence interval [CI] 10.1% to 18.1%). After multivariate analysis high PTCs during days 22 to 28 (hazard ratio [HR] 2.47; 95% CI, 1.37 to 4.45; P < .01) and grades II to IV acute GVHD (HR, 5.61; 95% CI, 2.99 to 10.53; P < .01) were associated with TRC-EC occurrence. The probability of overall survival (OS) at 12 months was 67.7% (95% CI, 61.7% to 73.0%). After multivariate analysis TRC-EC diagnosis (HR, 2.47, 95% CI, 1.59 to 3.83; P < .01) and high-risk disease (HR, 1.75; 95% CI, 1.17 to 2.61; P < .01) were significantly associated with poor OS. In conclusion, higher PTC during days 22 to 28 increased the risk of TRC-EC. TRC-EC development was associated with poor OS.

Low Pre-Transplant Testosterone Levels in Male Patients Are Associated with Endothelial Vulnerability and Non-Relapse Mortality after Allogeneic Stem Cell Transplantation

Introduction: Low testosterone has been demonstrated to be an independent determinant of endothelial (dys)function in men. Graft-versus-host disease (GVHD) is a major contributor to non-relapse mortality (NRM) after allogeneic stem cell transplantation (alloSCT). Vulnerability of the recipients' endothelial cell system is a novel concept to explain why a proportion of patients with acute GVHD fail to respond to escalating immunosuppressive therapy and ultimately succumb to GVHD and related complications. This retrospective study investigated the prognostic impact of pre-transplant testosterone levels on NRM after alloSCT in male patients.Patients and methods: Between 2002 and 2014, a total of 277 male patients undergoing alloSCT at Heidelberg University (median age 55 years) provided informed consent to participate in this observational study (training cohort). 71 patients (26%) received transplants from related donors (RD). Diagnoses were acute myeloid leukemia (AML) in 108 patients (48%), myelodysplastic syndrome (MDS) in 66 patients (29%), lymphoid malignancies (lymphoma, chronic and acute lymphoid leukemia) in 75 patients (33%), and multiple myeloma in 28 patients (12%). A total of 176 patients (78%) received statin treatment post alloSCT as per institutional standard policy. For validation, an independent patient cohort of 205 men allografted for AML and MDS (median age 57 years, 18% RD, no statin treatment) at Essen University was analysed.Pre-transplant serum samples for testosterone measurements were collected between 0 and 2 months before alloSCT and cryopreserved at -80°C. Testosterone concentrations were measured by radioimmunoassay. Pre-transplant levels of suppressor of tumorigenicity-2 (ST2) were determined by ELISA.Overall survival (OS), incidence of relapse and NRM and were calculated from date of alloSCT to the appropriate endpoint using Cox regression analysis with cause specific hazard models for NRM and relapse. As confounding prognostic factors we included testosterone levels, age, donor type, graft type, donor sex, conditioning intensity, and disease type and stage prior to alloSCT.Results: Median pre-transplant testosterone level in the training and validation cohort was 13.6 nmol/L (range 0.3-41.7 nmol/L) and 16.0 nmol/L (0.8-38.1 nmol/L), respectively. In the training cohort, lower pre-transplant testosterone as continuous variable was associated with shorter OS (p=0.009). Lower testosterone levels showed a trend towards higher NRM (p=0.09) and a significant association with NRM after onset of acute GVHD (p=0.02). Multivariate analysis confirmed that lower pre-transplant testosterone levels were a significant predictor of an increased NRM risk after GVHD onset (p=0.03). In the subgroup of patients not receiving statins post-transplant, lower testosterone levels were associated with increased incidence of transplant-associated microangiopathy (p=0.01). In addition, lower pre-transplant testosterone levels correlated with higher pre-transplant ST2 levels indicating endothelial vulnerability.In the validation cohort, similar results with regard to OS (p=0.02), NRM (p=0.04), NRM after acute GVHD onset (p=0.03) in univariate analysis, and to NRM after GVHD onset (p=0.02) in multivariable analysis could be observed. The association of pre-transplant testosterone levels (in quartiles) and incidence of NRM after GVHD onset in the training and validation cohort is depicted in Figure 1A and 1B, respectively.Conclusion: Our study suggests that low pre-transplant testosterone is associated with serological and clinical evidence for endothelial damage and is an independent risk factor for a fatal outcome of GVHD. Prospective studies in the alloSCT setting investigating testosterone and testosterone supplementation in deficient patients are highly warranted. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Alterations of Plasma Complement C3b, C5b and VWF, ADAMTS13 in Patients with Graft-Versus-Host Disease and Thrombotic Microangiopathy after Hematopoietic Stem-Cell Transplantation

Background: Transplant-associated microangiopathy (TMA) is an uncommon but devastating complication in patients undergoing hematopoietic stem-cell transplantation (HSCT). It may be confused with severe graft-versus-host disease (GVHD), infection, and other transplant related thrombotic diseases. Limited studies have shown the changes in plasma VWF/ADAMTS13 or complement activation markers in patients after HSCT. However, the role of VWF/ADAMTS13 and complement activation in patients with TMA and GVHD is not fully understood. Current study is to investigate the alterations of plasma levels of C3b, C5b and VWF/ADAMTS13 in patients with TMA and to explore their roles in the pathogenesis and early diagnosis of transplant-associated TMA.Methods: From 2011 to 2014, 14 patients with TMA were enrolled into the study in a single medical center. 71 other patients following HSCT were recruited as control subjects including 11 cases of hepatic vein occlusion disease (VOD), 20 cases of severe infections, 20 cases of severe II-IV° GVHD and 20 cases without complications. Blood sample was collected before transplantation and at the onset of transplantation related complication. Fluorescence resonance energy transfer substrate (FRETS)-VWF73 assay detected plasma ADAMTS13 activity. Collagen-binding assay and latex immunoassay determined VWF activity and VWF antigen, respectively. Plasma VWF multimer was determined by agarose gel electrophoresis and Western blot. Plasma levels of complement C3b and C5b were measured with ELISA.Results: Compared with the levels before transplantation, plasma ADAMTS13 activity and VWF antigen or activity in the patients with TMA did not differ from those who developed TMA, with infection or GVHD or without any complication (p> 0.05). However, plasma ADAMTS13 activity decreased and the ratio of VWF antigen/activity increased significantly in patients with VOD (p< 0.05). Plasma VWF multimer distribution was similar in patients with infection, GVHD or without complication, but ultralarge multimers of VWF was present in patients with TMA and VOD. Plasma levels of complement C3b was increased in patients after HSCT (198.46 ng/ml ±14.78 ng/ml) compared with healthy subjects (85.02 ng/ml±8.50ng/ml) (p< 0.05), but exhibited no difference in the other groups. Plasma C3b increased significantly in patients with TMA and GVHD (p<0.05). The plasma levels of C3b were higher in the TMA group (480.70 ng/ml±66.76ng/ml) than the GVHD group (298.50 ng/ml ±32.06 ng/) (p< 0.05). Also, plasma levels of C5b in patients with TMA were significantly increased (1059.49 ng/ml ±85.57 ng/ml) as compared with those before transplantation (653.19ng/ml ±44.91ng/ml) and other groups (p< 0.05).Conclusions: We conclude that plasma ADAMTS 13 activity and the ratio of VWF antigen/activity remained stable in the patients with transplant-associated TMA, but the levels of complement C3b and C5b, particularly the C5b, increased significantly, suggesting the critical role of complement pathway in the pathogenesis of TMA. C5b may be a specific biomarker for early diagnosis of TMA but C3b is a marker for both TMA and GVHD. DisclosuresNo relevant conflicts of interest to declare.