Diverse macrophage populations contribute to distinct manifestations of human cutaneous graft-versus-host disease.

BACKGROUND: Graft-versus-host disease (GvHD) is a major life-threatening complication of allogeneic haematopoietic stem cell transplantation (HSCT), limiting the broad application of HSCT for haematological malignancies. Cutaneous GvHD is described as a post-transplant inflammatory reaction by skin-infiltrating donor T cells and remaining recipient tissue-resident memory T cells. Despite the major influence of lymphocytes on GvHD pathogenesis, the complex role of mononuclear phagocytes (MNPs) in tissues affected by GvHD is increasingly appreciated. OBJECTIVES: To characterize the identity, origin and functions of MNPs in patients with acute cutaneous GvHD. METHODS: Using single-cell RNA sequencing and multiplex tissue immunofluorescence, we identified an increased abundance of MNPs in skin and blood from 36 patients with acute cutaneous GvHD. In cases of sex-mismatched transplantation, we used expression of X-linked genes to detect rapid tissue adaptation of newly recruited donor MNPs resulting in similar transcriptional states of host- and donor-derived macrophages within GvHD skin lesions. RESULTS: We showed that cutaneous GvHD lesions harbour expanded CD163+ tissue-resident macrophage populations with anti-inflammatory and tissue-remodelling properties including interleukin-10 cytokine production. Cell-cell interaction analyses revealed putative signalling to strengthen regulatory T-cell responses. Notably, macrophage polarization in chronic cutaneous GvHD types was proinflammatory and drastically differed from acute GvHD, supporting the notion of distinct cellular players in different clinical GvHD subtypes. CONCLUSIONS: Overall, our data reveal a surprisingly dynamic role of MNPs after HSCT. Specific and time-resolved targeting to repolarize this cell subset may present a promising therapeutic strategy in combatting GvHD skin inflammation.

Emergency Department Utilization Following Allogeneic Hematopoietic Stem Cell Transplantation: A Single-Center Retrospective Longitudinal Analysis of 557 Patients.

Allogeneic hematopoietic stem cell transplantation (HSCT) recipients are at risk of various complications during post-transplantation follow-up. Some patients may refer to an emergency department (ED) for medical attention, but data on ED visits by HSCT recipients are lacking. In the present study, we aimed to assess ED utilization in HSCT recipients and associated risk factors during post-transplantation follow-up, identify subgroups of HSCT recipients presenting to the ED, analyze outcomes and prognostic factors for hospitalization and 30-day mortality after ED visits, and assess mortality hazard following an ED presentation. The study involved a retrospective single-center longitudinal analysis including 557 consecutive recipients of allogeneic HSCT at the Medical University of Vienna, Austria, between January 2010 and January 2020. Descriptive statistics, event estimates accounting for censored data with competing risks, latent class analysis, and multivariate regression models were used for data analysis. Out of 557 patients (median age at HSCT, 49 years [interquartile range (IQR), 39 to 58 years]; 233 females and 324 males), 137 (25%) presented to our center's ED at least once during post-HSCT follow-up (median individual follow-up, 2.66 years; IQR, .72 to 5.59 years). Cumulative incidence estimates of a first ED visit in the overall cohort were 19% at 2 years post-HSCT, 25% at 5 years post-HSCT, and 28% at 10 years post-HSCT. These estimates were increased to 34%, 41%, and 43%, respectively, in patients residing in Vienna. Chronic graft-versus-host disease (GVHD) was the sole risk factor showing a statistically significant association with ED presentation in multivariate analysis (hazard ratio [HR], 2.34; 95% confidence interval [CI], 1.63 to 3.35). Patients presented to the ED with various and often multiple symptoms. We identified 3 latent patient groups in the ED, characterized mainly by the time from HSCT, chronic GVHD, and documented pulmonary infection. Hospitalization was required in 132 of all 216 analyzed ED visits (61%); in-hospital mortality and 30-day mortality rates were 13% and 7%, respectively. Active acute GVHD, systemic steroids, documented infection, pulmonary infiltrates, and oxygen supplementation were statistically significant predictors of hospitalization; shorter time from HSCT, pulmonary infiltrates, and hemodynamic instability were independent risk factors for 30-day mortality. ED presentation during the last 30 days increased the mortality hazard in the overall cohort (HR, 4.56; 95% CI, 2.68 to 7.76) after adjustment for relevant confounders. One-quarter of the patients visited the ED for medical attention at least once during post-HSCT follow-up. Depending on the presence of identified risk factors, a significant proportion of patients may require hospitalization and be at risk for adverse outcomes. Screening for these risk factors and specialist consultation should be part of managing most HSCT recipients presenting to the ED.

Epigenetic regulation of T cell lineages in skin and blood following hematopoietic stem cell transplantation.

Allogeneic hematopoietic stem-cell transplantation (HSCT) seeks to reconstitute the host's immune system from donor stem cells. The success of HSCT is threatened by complications including leukemia relapse or graft-versus-host-disease (GvHD). To investigate the underlying regulatory processes in central and peripheral T cell recovery, we performed sequential multi-omics analysis of T cells of the skin and blood during HSCT. We detected rapid effector T cell reconstitution, while emergence of regulatory T cells was delayed. Epigenetic and gene-regulatory programs were associated with recovering T cells and diverged greatly between skin and blood T cells. The BRG1/BRM-associated factor chromatin remodeling complex and histone deacetylases (HDACs) were epigenetic regulators involved in restoration of T cell homeostasis after transplantation. In isolated T cells of patients after HSCT, we observed class I HDAC-inhibitors to modulate their dysbalance. The present study highlights the importance of epigenetic regulation in the recovery of T cells following HSCT.

Cytokine Release Syndrome during Antithymocyte Globulin/Anti-T Lymphocyte Globulin Serotherapy for Graft-versus-Host Disease Prophylaxis before Allogeneic Hematopoietic Stem Cell Transplantation: Incidence and Early Clinical Impact According to American Society of Transplantation and Cellular Therapy Grading Criteria.

Antithymocyte globulin (ATG)/anti-T lymphocyte globulin (ATLG) aids graft-versus-host disease (GVHD) prophylaxis in HLA-matched related and unrelated donor hematopoietic stem cell transplantation (HSCT). Its use is frequently accompanied by systemic infusion reactions attributable to cytokine release syndrome (CRS). However, detailed data on ATG/ATLG-induced CRS and its correlation with clinical outcome parameters are lacking. This study aimed to analyze the incidence, characteristics, risk factors, and early clinical impact of CRS during ATG/ATLG administration before allogeneic HSCT according to the American Society of Transplantation and Cellular Therapy (ASTCT) CRS grading criteria. This retrospective single-center analysis included consecutive recipients of allogeneic HSCT treated with ATG/ATLG as GVHD prophylaxis at the Medical University of Vienna between January 1, 2014, and August 15, 2021. Multivariate regression models were used to explore risk factors for CRS and its association with clinical outcomes (acute GVHD grade II-IV, clinically significant cytomegalovirus infection, nonrelapse mortality, and overall survival) at 6 months after HSCT. A total of 284 patients (median age, 54 years; interquartile range [IQR], 45 to 61 years; 120 females, 164 males) were included in the study. ATLG was used in 222 patients (78%); ATG, in 62 (22%). One hundred sixty-six patients (58%) developed CRS grade ≥1 during ATG/ATLG administration. CRS was mostly mild, with 92% of the cases CRS grade 1-2. Thirteen patients (5%) developed CRS grade 3, and 1 patient had CRS grade 4. No CRS-related death (grade 5) occurred. Patients with CRS showed a pronounced systemic inflammatory response as measured by inflammatory markers C-reactive protein, IL-6, and procalcitonin. In multivariate analysis, lymphoma as the underlying disease, high ATLG dose of 60 mg/kg, and body weight were significantly associated with CRS. Patients with CRS grade ≥1 had a higher 6-month incidence of acute GVHD II-IV compared with patients without CRS (24% versus 14%; P = .04). This effect remained statistically significant only for CRS grade 3-4 (subdistribution hazard ratio, 3.70; 95% confidence interval, 1.58 to 8.68; P < .01) after adjusting for relevant confounders. Other clinical outcome parameters were not affected by the occurrence of CRS. In our cohort, CRS defined by ASTCT grading was a frequent but mostly mild complication following ATG/ATLG administration for GVHD prophylaxis. Our data suggest a possible interaction of (higher-grade) CRS with an increased risk for developing acute GVHD. Further studies to corroborate this finding are warranted, as it could inform the investigation of additional prophylactic interventions, such as IL-6 blockade, in this setting.

Long-term skin-resident memory T cells proliferate in situ and are involved in human graft-versus-host disease.

The skin contains a population of tissue-resident memory T cells (Trm) that is thought to contribute to local tissue homeostasis and protection against environmental injuries. Although information about the regulation, survival program, and pathophysiological roles of Trm has been obtained from murine studies, little is known about the biology of human cutaneous Trm Here, we showed that host-derived CD69+ αß memory T cell clones in the epidermis and dermis remain stable and functionally competent for at least 10 years in patients with allogeneic hematopoietic stem cell transplantation. Single-cell RNA sequencing revealed low expression of genes encoding tissue egress molecules by long-term persisting Trm in the skin, whereas tissue retention molecules and stem cell markers were displayed by Trm The transcription factor RUNX3 and the surface molecule galectin-3 were preferentially expressed by host T cells at the RNA and protein levels, suggesting two new markers for human skin Trm Furthermore, skin lesions from patients developing graft-versus-host disease (GVHD) showed a large number of cytokine-producing host-derived Trm, suggesting a contribution of these cells to the pathogenesis of GVHD. Together, our studies highlighted the relationship between the local human skin environment and long-term persisting Trm, which differs from murine skin. Our results also indicated that local tissue inflammation occurs through host-derived Trm after allogeneic hematopoietic stem cell transplantation.

Anti-Apoptotic Molecule BCL2 Is a Therapeutic Target in Steroid-Refractory Graft-Versus-Host Disease.

Graft-versus-host disease (GVHD) is the leading cause of mortality after hematopoietic stem cell transplantation and primarily affects barrier organs such as the skin. One-third of cases are refractory to steroid treatment resulting in poor outcomes and the need for novel therapies. Longitudinal analysis of T-cell transcriptomes in patients before the appearance of GVHD symptoms revealed the upregulation of anti-apoptotic regulator B-cell lymphoma 2 (BCL2) at GVHD initiation. To determine the potential of BCL2 inhibition in active GVHD, we analyzed tissues of 88 patients with acute or chronic GVHD. BCL2 RNA was elevated in multiple organs affected by GVHD and expression correlated with transplant-related mortality and steroid-refractory GVHD. BCL2-expressing lymphocytes were present in skin lesions and peripheral blood of patients with acute and chronic GVHD. Inhibition of BCL2 increased the CD4 to CD8 ratio in allogeneic T cells in vitro and induced apoptosis of T cells from patients with steroid-pretreated chronic GVHD ex vivo. In addition, the higher ratio of regulatory to nonregulatory T cells upon blockage of BCL2 could add to the anti-inflammatory effect of BCL2 blockage. Collectively, our results highlight BCL2 as an important factor for GVHD development and introduce BCL2 inhibition as previously unreported and urgently needed targeted therapy in the treatment of steroid-refractory GVHD.

Extracorporeal photopheresis as second-line therapy for patients with acute graft-versus-host disease: does the number of cells treated matter?

BACKGROUND: Extracorporeal photopheresis (ECP) has demonstrated efficacy as second-line treatment for steroid-refractory (SR) acute graft-versus-host disease (aGVHD). The aim of our study was to analyze whether the amount of ECP-treated cells in patients with SR, aGVHD has an impact on response at 1 month. STUDY DESIGN AND METHODS: Data on white blood cells, lymphocytes, monocytes, mononuclear cells, and neutrophils, including absolute counts and counts per kilogram of body weight in ECP products from patients with aGVHD, were collected. For each cell population, the median dose per single ECP and the cumulative doses collected during the first week and the first month of treatment were compared with the response to ECP. RESULTS: In total, 99 patients underwent 1215 ECP procedures. Overall response was defined as a complete response if all signs of aGVHD resolved or a partial response if greater than 50% resolution was reached without other, additional immunosuppression. An overall response was obtained by 75% of patients, including 53% complete responses. Univariate analysis showed a correlation of lymphocytes and mononuclear cells/kg body weight for a single procedure and overall response. In logistic regression analysis, no tested variable had an influence on response. In receiver operating characteristic curve analysis, cutoffs of 8.4 × 106 /kg body weight lymphocytes and 13.9 × 106 /kg body weight mononuclear cells were associated with an overall response to ECP at 1 month with 75% sensitivity. CONCLUSION: Our results in patients with steroid-refractory aGVHD confirm that response rates to ECP are high and that certain cutoff values for lymphocytes and mononuclear cells/kg body weight in each individual procedure can predict an overall response to ECP at 1 month.

Complete neurologic and cognitive recovery after plasmapheresis in a patient with chronic inflammatory demyelinating polyneuropathy after allogeneic hematopoietic stem cell transplantation.

UNLABELLED: Neurologic complications after allogeneic hematopoietic stem cell transplantation (HSCT) are rare but poorly understood. We present a case report of a 57-year-old-male patient who was diagnosed in 2009 with acute myeloid leukemia (AML). He received two standard induction chemotherapies, as well as a following consolidation. Six months later, an allogeneic HSCT was performed. Shortly after HSCT the patient developed progressive polyneuropathy of the lower legs and hypoesthesia. Five months later a severe dementia followed. All images of the brain and spine showed no specific pathologies. High dose corticosteroids and immunoglobulins did not improve the neurologic symptoms. Due to severe worsening of the neuropsychiatric status and the clinical presentation, chronic inflammatory demyelinating polyneuropathy (CIDP) was suspected. Therefore, the patient received ten cycles of plasmapheresis. The patient showed a significant improvement of the neuropsychiatric symptoms and cognitive status. CONCLUSIONS: Immune mediated neuropathies after allogeneic HSCT, such as CIDP, have great variability in symptoms and presentation and are challenging to diagnose and treat. Plasmapheresis is a safe and efficient treatment for patients with unclear persisting autoimmune neuropathy after HSCT.

Umbilical Cord Blood Transplantation Is a Feasible Rescue Therapeutic Option for Patients Suffering from Graft Failure after Previous Hematopoietic Stem Cell Transplantation.

OBJECTIVE: Umbilical cord blood (UCB) is an important graft source for hematopoietic stem cell transplantation (SCT). Due to less stringent human leukocyte antigen (HLA) matching criteria compared to bone marrow or peripheral blood stem cells, UCB enables patients lacking an HLA-matched donor to receive potentially curative SCT. METHODS: We retrospectively analyzed the efficacy and safety of UCB transplantation (UCBT) at our center. RESULTS: Between June 2009 and June 2015, 27 UCBT were performed in 25 patients. Reasons for the use of UCB were lack of adequate related or unrelated stem cell donor (n = 20) and graft failure after previous SCT (n = 7). Median time to neutrophil engraftment was 22 days. Four patients experienced primary graft failure. Thirteen patients developed acute graft-versus-host disease (GVHD), whereupon 6 subsequently also developed chronic GVHD. After a median follow-up time of 19 months, 9 patients relapsed and 12 patients died. Cause of death was relapse in 8 and transplant-related events in 4 patients. Median overall survival and progression-free survival have not been reached yet. CONCLUSION: In our experience, UCBT is an alternative graft source for patients lacking a suitable related or unrelated donor and a feasible treatment option for patients experiencing graft failure after previous SCT.

Incidence and characteristics of invasive fungal diseases in allogeneic hematopoietic stem cell transplant recipients: a retrospective cohort study.

BACKGROUND: Allogeneic hematopoietic stem cell transplant (HSCT) recipients experience an increased risk for invasive fungal diseases (IFDs). METHODS: This retrospective cohort study at the Medical University of Vienna aspired to assess the incidence, characteristics and the outcome of IFDs as well as the associated risk factors in a setting where only 43 % of patients were given systemic antifungal prophylaxis during aplasia. IFDs were classified as probable or proven according to the EORTC/MSG consensus group. All adult patients (n = 242) receiving an allogeneic HSCT at the University Hospital of Vienna from January 2009 to December 2013 were enrolled. RESULTS: The primary outcome of this study was the one-year incidence for IFDs after HSCT, which was 10.3 % (25/242). Overall 28 patients experienced an IFD - 20 probable and 8 proven - with invasive aspergillosis being the predominant IFD (n = 18), followed by invasive candidiasis (n = 7) and pneumocystis pneumonia (n = 3). Patients with an IFD were more likely to be admitted to an intensive care unit (64 % versus 12 %, p < 0.0001) and had a significantly higher mortality in the first year after HSCT (48 % versus 25 %, p = 0.02). Multivariate regression analysis revealed that intensified immunosuppressive therapy (high-dose cortisone and basiliximab or etanercept) because of severe graft-versus-host disease (adjusted odds ratio (AOR) 3.6, p = 0.01) and transplant-associated microangiopathy (AOR 3.7, p = 0.04) were associated with an increased risk for IFD, while antifungal prophylaxis given during aplasia and post-engraftment was associated with a decreased risk (AOR 0.3, p = 0.02). CONCLUSIONS: We documented a one-year incidence for IFDs of 10.3 % and no selection of rare pathogens at a centre with moderate use of antifungal prophylaxis. Intensified immunosuppressive therapy and transplant-associated microangiopathy were significant risk factors for IFDs.

CD19+CD21low B cells and CD4+CD45RA+CD31+ T cells correlate with first diagnosis of chronic graft-versus-host disease.

Chronic graft-versus-host disease (cGVHD) is a serious and frequent complication of allogeneic hematopoietic stem cell transplantation (HCT). Currently, no biomarkers for prediction and diagnosis of cGVHD are available. We performed a large prospective study focusing on noninvasive biomarkers for National Institutes of Health-defined cGVHD patients (n = 163) in comparison to time-matched HCT recipients who never experienced cGVHD (n = 64), analyzed from day 100 after HCT. In logistic regression analysis, CD19(+)CD21(low) B cells (P = .002; hazard ratio [HR], 3.31; 95% confidence interval [CI], 1.53 to 7.17) and CD4(+)CD45RA(+)CD31(+) T cells (P < .001; HR, 3.88; 95% CI, 1.88 to 7.99) assessed on day 100 after HCT were significantly associated with subsequent development of cGVHD, independent of clinical parameters. A significant association with diagnosis of cGVHD was only observed for CD19(+)CD21(low) B cells (P = .008; HR, 3.00; 95% CI, 1.33 to 6.75) and CD4(+)CD45RA(+)CD31(+) T cells (P = .017; HR, 2.80; 95% CI, 1.19 to 6.55). CD19(+)CD21(low) B cells were found to have the highest discriminatory value with an area under the receiver operating curve of .77 (95% CI, .64 to .90). Our results demonstrate that CD19(+)CD21(low) B cells and CD4(+)CD45RA(+)CD31(+) T cells are significantly elevated in patients with newly diagnosed cGVHD.

Long-term follow-up after allogeneic stem cell transplantation in patients with myelodysplastic syndromes or secondary acute myeloid leukemia: a single center experience.

OBJECTIVE AND METHODS: We performed a single center analysis of 60 adult patients (33 males and 27 females) with myelodysplastic syndromes (MDS) or secondary acute myeloid leukemia (AML) who underwent allogeneic hematopoietic stem cell transplantation (HCT) at our institution. RESULTS: Allogeneic stem cell in patients were transplanted between 1988 and 2010, 28 had an human leukocyte antigen (HLA)-identical sibling donor, 23 had an HLA-identical unrelated donor, and 9 had an 1 allele mismatched donor. The median age at time of HCT was 44 (range: 18-68) years. Conditioning therapy was myeloablative in 36 patients and consisted of a reduced-intensity conditioning (RIC) regimen in 24 patients. Graft-versus-host disease (GvHD) prophylaxis was performed with a combination of methotrexate and cyclosporine A in 36 patients, and cyclosporine A plus mycophenolate mofetil in 24 patients. The 10-year probability of overall survival was 46 %. CONCLUSION: In a multivariate analysis, we identified pretransplantation serum ferritin as the only independent adverse prognostic variable predicting survival in our patients.

Fatal skin and pulmonary infection caused by Hormographiella aspergillata in a leukaemic patient: case report and literature overview.

Invasive systemic fungal infections are a major cause of morbidity and mortality in patients after hematopoietic stem cell transplantation. We report the case of a fatal infection with Hormographiella aspergillata in a patient undergoing allogenic peripheral blood stem cell transplantation for acute myeloid leukaemia.

Lung transplantation for bronchiolitis obliterans after allogeneic hematopoietic stem cell transplantation: a single-center experience.

BACKGROUND: Bronchiolitis obliterans (BO) is a detrimental late pulmonary complication after allogeneic hematopoietic stem cell transplantation (HCT) associated with chronic graft-versus-host disease (cGvHD). When systemic immunosuppressive treatment fails to improve, severe BO patients should be considered for lung transplantation (LuTX). We present seven patients undergoing LuTX for severe refractory BO after HCT. METHODS: Seven patients with hematologic malignancies developed severe cGvHD with lung involvement presenting as BO after allogeneic HCT. Evaluation for LuTX was initiated after failure of a median of 4 immunosuppressive regimens. RESULTS: Between 1996 and 2012, seven patients with severe refractory BO were evaluated for LuTX. The median time from HCT to diagnosis of chronic lung GvHD was 8.2 months (range, 3.7-16.6). At a median time of 18.1 months (range, 6-120) after diagnosis of BO, six patients received a bilateral sequential LuTX, and one patient received a single LuTX. Six postoperative courses were uneventful; the patient with single LuTX died from septic multiorgan failure. Three LuTX recipients had a mild acute rejection after one to three months after LuTX, and one patient experienced fatal chronic rejection and hemolytic uremic syndrome. At present, three (43%) LuTX recipients remain alive at a median observation time of 26 months (range, 1 month-16 years) after LuTX. The median overall survival from LuTX was 24 months (95% CI, 0.5-78); the median overall survival time after allogeneic HCT is 98 months (95% CI, 46-198). CONCLUSION: This case series illustrates that LuTX is a possible therapeutic option for selected patients with severe treatment-refractory BO.

CD19(+)CD21(low) B cells and patients at risk for NIH-defined chronic graft-versus-host disease with bronchiolitis obliterans syndrome.

Bronchiolitis obliterans syndrome (BOS), pathognomonic for chronic graft-versus-host disease (cGVHD) of the lung, is a progressive and often fatal complication after allogeneic hematopoietic cell transplantation (HCT). Biomarkers for the prediction and diagnosis of BOS are urgently needed to improve patients' prognosis. We prospectively evaluated B-cell subpopulations and B-cell activating factor (BAFF) in 136 patients (46 BOS, 41 no cGVHD, 49 cutaneous cGVHD) to define novel biomarkers for early diagnosis of National Institutes of Health-defined BOS diagnosed a median of 11 mo after HCT. Patients with newly diagnosed BOS had significantly higher percentages of CD19(+)CD21(low) B cells (25.5 versus 6.6%, P < .0001), BAFF (7.3 versus 3.5 ng/mL, P = .02), and BAFF/CD19(+) ratio (0.18 versus 0.02 ng/10(3) CD19(+) B cells, P 5 .007) compared with patients without cGVHD. The area under the receiver operating curve for CD19(+)CD21(low) B cells was 0.97 (95% confidence interval, 0.94-0.99) and a cutoff point >9% was optimal for diagnosing BOS in patients with first drop of pulmonary function tests with a sensitivity of 96% and a negative predictive value of 94%. Thus, elevated levels of CD19(+)CD21(low) B cells are a potential novel biomarker for HCT patients at risk for developing BOS at an early stage and could allow improvement of patient outcome.

Frequency and prognostic value of D alloantibodies after D-mismatched allogeneic hematopoietic stem cell transplantation after reduced-intensity conditioning.

BACKGROUND: Due to the fact that the ABO and D system is inherited independently from the HLA system, approximately 40% of allogeneic hematopoietic stem cell transplants (HSCT) are performed across the blood group barrier. Reports on the development of de novo anti-D in patients undergoing reduced-intensity conditioning (RIC) followed by D-mismatched allogeneic HSCT are rare. The objective of this study was to evaluate the frequency of anti-D alloimmunization after D-mismatched HSCT following RIC and its prognostic impact on transplant outcome. STUDY DESIGN AND METHODS: Forty patients with hematologic diseases who underwent D-mismatched HSCT were retrospectively analyzed: 19 D- patients with a D+ donor and 21 D+ patients with a D- donor. Routine serologic testing for blood group typing and antibody screening was performed by a column agglutination method every time when transfusion of red blood cell units was requested and in the posttransplantation course to demonstrate establishment of donor ABO type and to detect alloimmunization. RESULTS: After a median serologic follow-up of 21 (range, 0 to 73) months after HSCT, anti-D was identified in 2 of 21 (10%) D+ patients receiving a D- transplant, 23 and 34 months after HSCT. None of the 19 D- patients with a D+ donor developed an anti-D. CONCLUSION: We observed an infrequent de novo anti-D formation that is more likely in D+ recipients of D- grafts. However, the development of anti-D does not normally impair the transplant outcome and is not of clinical relevance in the posttransplant course.

Stable non-transforming minimal residual disease in Philadelphia chromosome positive acute lymphoblastic leukemia after autologous transplantation: origin from neoplastic yet 'pre-leukemic' stem cells?

In acute lymphoblastic leukemia (ALL), the Philadelphia chromosome (Ph) is associated with a poor prognosis. For these patients, hematopoietic stem cell transplantation (HSCT) and BCR/ABL tyrosine kinase inhibitors (TKIs) are considered standard of therapy. However, it remains unclear whether BCR/ABL TKIs should be administered lifelong as maintenance post-HSCT, and whether the presence of minimal residual disease (MRD) is invariably associated with relapse. We report on two patients with Ph+ ALL who were successfully treated with polychemotherapy and consecutive autologous HSCT. Both patients are in continuous hematologic remission after an observation period of 12 years and 18 years, respectively, despite measurable MRD and although no maintenance therapy was initiated. BCR/ABL transcript-levels ranged between 0.1 and 3% in patient 1, and 0.01 and 0.1% in patient 2 during the observation time. Collectively, these data suggest that not all Ph+ subclones even those that persist after HSCT in Ph+ ALL, may have the potential to cause a hematologic relapse. We hypothesize that these small-sized clones are derived from neoplastic stem cells that have not (yet) accumulated a sufficient number of pro-oncogenic hits required for full transformation to ALL-initiating (stem) cells and thus overt leukemia.

Prophylactic red blood cell exchange for prevention of severe immune hemolysis in minor ABO-mismatched allogeneic peripheral blood progenitor cell transplantation after reduced-intensity conditioning.

BACKGROUND: Delayed severe immune hemolysis due to donor-derived passenger lymphocytes is observed in minor and/or bidirectional ABO-mismatched transplants, especially after reduced-intensity conditioning (RIC). The incidence is reported in up to 30 percent of patients and can result in multiorgan failure (MOF) and death. STUDY DESIGN AND METHODS: A first group of 32 patients (historical control) underwent RIC followed by allogeneic hematopoietic peripheral blood progenitor cell transplantation at our institution. In 5 of 10 patients with a minor and/or bidirectional ABO-mismatched graft, severe immune hemolysis was observed, leading to death in 3 of them. Therefore, we initiated a protocol with prophylactic red blood cell (RBC) exchange in minor and/or bidirectional ABO mismatch of a second group of patients (study group) and investigated the incidence of hemolysis, transplant-related mortality (TRM), and overall survival (OS) and compared these data with the historical control group. Twenty-two of 80 patients in the study group had a minor and/or bidirectional ABO-mismatched donor. RESULTS: In 20 patients, a prophylactic RBC exchange was performed. Three patients showed mild to moderate citrate reactions, and in 1 patient the procedure had to be stopped because of hypotension. Eighteen of 20 patients engrafted uneventfully, 1 patient rejected his graft, and another 1 showed signs of mild hemolysis. In the minor and/or bidirectional ABO-mismatched setting patients in the study group had a lower risk for TRM at 1 year compared to patients in the historical control group (16% vs. 53%, p < 0.05) and a better 1-year OS (65% vs. 40%, p < 0.05). CONCLUSION: RBC exchange is a safe procedure, reducing the incidence of delayed severe immune hemolysis and thus the risk of TRM in minor and/or bidirectional ABO-mismatched cases.

ABO-incompatible allogeneic hematopoietic stem cell transplantation following reduced-intensity conditioning: close association with transplant-associated microangiopathy.

Transplant-associated microangiopathy (TAM) is a severe complication following allogeneic hematopoietic stem cell transplantation (HSCT) even after reduced-intensity conditioning (RIC). Data on 112 patients following RIC were analyzed with respect to TAM according to the ASBMT and risk factors, response to well-defined therapy and outcome were determined. TAM occurred in 11 of 112 patients. Univariate analysis determined acute graft-versus-host disease and ABO-incompatibility as risk factors for TAM. Treatment consisted of withdrawal of calcineurin inhibitors and plasma exchange (PE). Response to PE was 64%. PE seems to be an effective therapeutic option that should be assessed in larger patient cohorts.

The effect of intensified extracorporeal photochemotherapy on long-term survival in patients with severe acute graft-versus-host disease.

Acute graft-versus-host disease (GVHD) is a major cause of mortality after allogeneic hematopoietic stem cell transplantation. We performed a phase II study on patients with acute steroid-refractory GVHD grades II to IV given extracorporeal photochemotherapy (ECP) weekly and analyzed response and long-term survival. Complete resolution of GVHD was achieved in 82% of patients with cutaneous involvement, 61% with liver involvement, and 61% with gut involvement. The probability of survival was 59% among patients who responded completely to ECP compared to 11% in patients not responding completely. We conclude that intensified ECP is highly effective in acute GVHD and that sustained responses are associated with over 50% long-term survival.