Background Haematopoietic stem-cell transplantation (HSCT) recipients are considered at high risk of poor outcomes after COVID-19 on the basis of their immunosuppressed status, but data from large studies in HSCT recipients are lacking. This study describes the characteristics and outcomes of HSCT recipients after developing COVID-19. MethodsIn response to the pandemic, the Center for International Blood and Marrow Transplant Research (CIBMTR) implemented a special form for COVID-19-related data capture on March 27, 2020. All patients-irrespective of age, diagnosis, donor type, graft source, or conditioning regimens-were included in the analysis with data cutoff of Aug 12, 2020. The main outcome was overall survival 30 days after a COVID-19 diagnosis. Overall survival probabilities were calculated using Kaplan-Meier estimator. Factors associated with mortality after COVID-19 diagnosis were examined using Cox proportional hazard models. Findings 318 HSCT recipients diagnosed with COVID-19 were reported to the CIBMTR. The median time from HSCT to COVID-19 diagnosis was 17 months (IQR 8-46) for allogeneic HSCT recipients and 23 months (8-51) for autologous HSCT recipients. The median follow-up of survivors was 21 days (IQR 8-41) for allogeneic HSCT recipients and 25 days (12-35) for autologous HSCT recipients. 34 (18%) of 184 allogeneic HSCT recipients were receiving immunosuppression within 6 months of COVID-19 diagnosis. Disease severity was mild in 155 (49%) of 318 patients, while severe disease requiring mechanical ventilation occurred in 45 (14%) of 318 patients-ie, 28 (15%) of 184 allogeneic HSCT recipients and 17 (13%) of 134 autologous HSCT recipients. At 30 days after the diagnosis of COVID-19, overall survival was 68% (95% CI 58-77) for recipients of allogeneic HSCT and 67% (55-78) for recipients of autologous HSCT. Age 50 years or older (hazard ratio 2•53, 95% CI 1•16-5•52; p=0•020); male sex (3•53; 1•44-8•67; p=0•006), and development of COVID-19 within 12 months of transplantation (2•67, 1•33-5•36; p=0•005) were associated with a higher risk of mortality among allogeneic HSCT recipients, and a disease indication of lymphoma was associated with a higher risk of mortality compared with plasma cell disorder or myeloma (2•41, [1•08-5•38]; p=0•033) in autologous HSCT recipients. Interpretation Recipients of autologous and allogeneic HSCT who develop COVID-19 have poor overall survival. These data emphasise the need for stringent surveillance and aggressive treatment measures in HSCT recipients who develop COVID-19.

Summary Background The risks after unrelated-donor haemopoietic-cell transplantation with matched HLA-A, HLA-B, HLA-C, HLA-DRB1, HLA-DQB1 alleles between donor and recipient (10/10 matched) can be decreased by selection of unrelated donors who also match for HLA-DPB1; however, such donors are difficult to find. Classification of HLA-DPB1 mismatches based on T-cell-epitope groups could identify mismatches that might be tolerated (permissive) and those that would increase risks (non-permissive) after transplantation. We did a retrospective study to compare outcomes between permissive and non-permissive HLA-DPB1 mismatches in unrelated-donor haemopoietic-cell transplantation. Methods HLA and clinical data for unrelated-donor transplantations submitted to the International Histocompatibility Working Group in haemopoietic-cell transplantation were analysed retrospectively. HLA-DPB1 T-cell-epitope groups were assigned according to a functional algorithm based on alloreactive T-cell crossreactivity patterns. Recipients and unrelated donors matching status were classified as HLA-DPB1 match, non-permissive HLA-DPB1 mismatch (those with mismatched T-cell-epitope groups), or permissive HLA-DPB1 mismatch (those with matched T-cell-epitope groups). The clinical outcomes assessed were overall mortality, non-relapse mortality, relapse, and severe (grade 3–4) acute graft-versus-host disease (aGvHD). Findings Of 8539 transplantations, 5428 (64%) were matched for ten of ten HLA alleles (HLA 10/10 matched) and 3111 (36%) for nine of ten alleles (HLA 9/10 matched). Of the group overall, 1719 (20%) were HLA-DPB1 matches, 2670 (31%) non-permissive HLA-DPB1 mismatches, and 4150 (49%) permissive HLA-DPB1 mismatches. In HLA 10/10-matched transplantations, non-permissive mismatches were associated with a significantly increased risk of overall mortality (hazard ratio [HR] 1·15, 95% CI 1·05–1·25; p=0·002), non-relapse mortality (1·28, 1·14–1·42; p<0·0001), and severe aGvHD (odds ratio [OR] 1·31, 95% CI 1·11–1·54; p=0·001), but not relapse (HR 0·89, 95% CI 0·77–1·02; p=0·10), compared with permissive mismatches. There were significant differences between permissive HLA-DPB1 mismatches and HLA-DPB1 matches in terms of non-relapse mortality (0·86, 0·75–0·98; p=0·03) and relapse (1·34, 1·17–1·54; p<0·0001), but not for overall mortality (0·96, 0·87–1·06; p=0·40) or aGvHD (OR 0·84, 95% CI 0·69–1·03; p=0·09). In the HLA 9/10 matched population, non-permissive HLA-DPB1 mismatches also increased the risk of overall mortality (HR 1·10, 95% CI 1·00–1·22; p=0·06), non-relapse mortality (1·19, 1·05–1·36; p=0·007), and severe aGvHD (OR 1·37, 95% CI 1·13–1·66; p=0·002) compared with permissive mismatches, but the risk of relapse was the same in both groups (HR 0·93, 95% CI 0·78–1·11; p=0·44). Outcomes for HLA 10/10-matched transplantations with non-permissive HLA-DPB1 mismatches did not differ substantially from those for HLA 9/10-matched transplantations with permissive HLA-DPB1 mismatches or HLA-DPB1 matches. Interpretation T-cell-epitope matching de...

SummaryA joint working group established by the Haemato-oncology subgroup of the British Committee for Standards in Haematology (BCSH) and the British Society for Bone Marrow Transplantation (BSBMT) has reviewed the available literature and made recommendations for the diagnosis and management of acute graft-versus-host disease. This guideline includes recommendations for the diagnosis and grading of acute graft-versus-host disease as well as primary treatment and options for patients with steroid-refractory disease. The goal of treatment should be effective control of graft-versushost disease while minimizing risk of toxicity and relapse.

Key Points High-resolution matching for HLA-A, -B, -C, and -DRB1 is required for optimal survival in myeloablative-unrelated donor transplantation. HLA-DPB1 nonpermissive mismatches should be avoided in otherwise matched transplants to minimize overall mortality.

Several international recommendations address the assessment of graft-versus-host disease (GvHD) after hematopoietic cell transplantation (HCT). This position statement by GvHD experts from the European Society for Blood and Marrow Transplantation (EBMT), the National Institutes of Health (NIH) and the Center for International Blood and Marrow Transplant Research (CIBMTR) reviews the existing guidelines for both acute and chronic GvHD, addresses potential confusions that arise in daily practice and proposes consensus definitions for many key terms. We provide a historical perspective on the currently available guidelines and recommend the Mount Sinai Acute GvHD International Consortium (MAGIC) criteria for acute GvHD and the NIH 2014 criteria for chronic GvHD as the most comprehensive and detailed criteria available. This statement also offers practical guidance for the implementation of these recommendations and a set of consensus definitions for commonly used GvHD terms in order to facilitate future clinical and translational research. To assist the dissemination of these recommendations, a web-application based on this position statement is available ( https://www.uzleuven.be/egvhd ). We believe that adherence to a common set of GvHD assessment criteria is vitally important to improve the quality of data, compare results of retrospective studies and prospective clinical trials, and make therapeutic recommendations based on quality evidence.

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This Special Report, this month’s CME article, details evidence-based guidelines for the selection of optimal unrelated donors and cord blood units for allogeneic hematopoietic cell transplantation.

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