Sinusoidal obstruction syndrome or veno-occlusive disease (SOS/VOD) is a potentially life-threatening complication of hematopoietic SCT (HSCT). This review aims to highlight, on behalf of the European Society for Blood and Marrow Transplantation, the current knowledge on SOS/VOD pathophysiology, risk factors, diagnosis and treatments. Our perspectives on SOS/VOD are (i) to accurately identify its risk factors; (ii) to define new criteria for its diagnosis; (iii) to search for SOS/VOD biomarkers and (iv) to propose prospective studies evaluating SOS/VOD prevention and treatment in adults and children.

Background: The use of post-transplant cyclophosphamide (PTCy) is highly effective in preventing graft-versus-host disease (GVHD) in the haploidentical (Haplo) transplant setting and is being increasingly used in matched sibling (MSD) and matched unrelated (MUD) transplants. There is no information on the impact of donor types using homogeneous prophylaxis with PTCy. Methods: We retrospectively compared outcomes of adult patients with acute myeloid leukemia (AML) in first complete remission (CR1) who received a first allogeneic stem cell transplantation (SCT) with PTCy as GVHD prophylaxis from MSD (n = 215), MUD (n = 235), and Haplo (n = 789) donors registered in the EBMT database between 2010 and 2017. Results: The median follow-up was 2 years. Haplo-SCT carried a significantly increased risk of acute grade II-IV GVHD (HR 1.6; 95% CI 1.1-2.4) and NRM (HR 2.6; 95% CI 1.5-4.5) but a lower risk of relapse (HR 0.7; 95% CI 0.5-0.9) that translated to no differences in LFS (HR 1.1; 95% CI 0.8-1.4) or GVHD/relapse-free survival (HR 1; 95% CI 0.8-1.3). Interestingly, the use of peripheral blood was associated with an increased risk of acute (HR 1.9; 95% CI 1.4-2.6) and chronic GVHD (HR 1.7; 95% CI 1.2-2.4) but a lower risk of relapse (HR 0.7; 95% CI 0.5-0.9).

onor lymphocyte infusion has been used in the management of relapsed hematologic malignancies after allogeneic hematopoietic cell transplantation. It can eradicate minimal residual disease or be used to rescue a hematologic relapse, being able to induce durable remissions in a subset of patients. With the increased use of haploidentical ABSTRACT B. Dholaria et al.

Allogeneic hematopoietic SCT remains the only treatment that can correct the hematological manifestations in patients with thalassemia major. Improving the clinical outcomes of high-risk, heavily transfused patients with liver fibrosis and inadequate iron chelation remains a challenge. Because of the relatively high probability of graft rejection and regimen-related toxicity in many patients receiving SCT for advanced thalassemia major, further development of new treatment regimens is warranted. This review addresses the reported clinical studies in patients with advanced thalassemia major and we have summarized our suggested conditioning approach to improve the outcome after SCT.

Introduction: Total body irradiation (TBI) continues to be an important part of the conditioning regimen for allogeneic hematopoietic cell transplantation (allo-HCT) in acute lymphoblastic leukemia (ALL). Previous dose escalation studies showed that higher than 12-Gray (Gy) was toxic and did not provide any apparent survival benefit - at least in patients (pts) transplanted in first complete remission (CR1) - thus establishing 12-Gy as the standard TBI dosage. Whether 8-Gy instead of 12-Gy TBI is sufficient in ALL CR1, as has been prospectively demonstrated for AML CR1 (Lancet Oncol 2012; 13: 1035-1044), has not yet been studied. Methods : In this registry-based retrospective study of the Acute Leukemia Working Party of the European Society for Blood and Marrow Transplantation (ALWP-EBMT), we compared outcomes of ALL-CR1 pts who underwent a matched-sibling donor (MSD) or matched-unrelated donor (MUD) allo-HCT (94% peripheral blood stem cells) with TBI-based conditioning at a total dose of 12-Gy vs 8-Gy. Patients included in this analysis had received fludarabine (Flu) as the sole chemotherapy counterpart of TBI (12-Gy vs 8-Gy TBIFlu). Results: The median follow up for the whole cohort (n=639 pts) was 22.5 months (95% CI, 17.2-24.1) and did not differ between the 8-Gy (n=494) and 12-Gy (n= 145) TBIFlu treated pts. 25% pts had B-precursor ALL, 54% Philadelphia (Ph)-positive ALL and 21% T-ALL (p=0.008 between groups). Patients conditioned with 8-Gy TBIFlu were older than 12-Gy TBIFlu treated pts (median 55.7 vs 40.3 years, IQR 50.2-61.3 vs 27-50.2 years, <0.0001) and more frequently received in vivo T-cell depletion (71% vs 40%, <0.0001). All other characteristics were well balanced between 8-Gy vs 12-Gy groups including time from diagnosis to HCT (5.5 vs 5.8 months), Karnofksy <90% (34% vs 26%), minimal residual disease (MRD) positivity at HCT (37% vs 43%), MUD (72% vs 68%) and type of GvHD prevention. Engraftment failure was low and below 2% in both groups. Overall, 29% and 27% of 8-Gy vs 12-Gy treated patients died, with the main causes of death not differing between groups (relapse 41% vs 44%, infections 26% vs 24%, GVHD 12.6% vs 12.7%, respectively). Both in univariate and in the age-adjusted Cox proportional-hazards analysis, relapse (REL), non-relapse mortality (NRM), leukemia-free survival (LFS), overall survival (OS), and GVHD-free, relapse-free survival (GRFS) were not influenced by TBI dose (Figure 1, Table 1). These results were confirmed when we focused on pts aged <55 years (median age 47 years; 8-Gy 229 pts vs 12-Gy 131 pts). In the multivariate analysis, an incremental age of 10 years was associated with increased NRM risk (hazard ratio [HR] 1.66, 95% CI, 1.25-2.22) and reduced OS (HR 1.32, 1.09-1.59). Ph+ and T-ALL pts had significantly better survival outcomes than Ph- B-ALL pts, mainly due to significantly fewer relapses (Table 1). Conclusion: Although there were limitations to this study (TBI dose and age were correlated; missing data on TBI fractionation; missing MRD data for nearly one-third of the pts) this retrospective analysis was able to investigate the effect of TBI total dose independently from the chemotherapy counterpart (TBIFlu regimen only) and suggests that 12-Gy and 8-Gy results in similar outcomes in ALL patients transplanted in CR1. Whether this is also true for more advanced disease (>=CR2) and/or young adults) cannot be answered, as our study included only CR1 pts, few of whom were below 25 years of age. The reduced REL risk of Ph+ B-ALL pts is probably due to the increased use of tyrosine kinase inhibitors (TKIs) pre- and post-transplant. Clinically, these results suggest 8-Gy TBI as sufficient for ALL patients transplanted in CR1 with no additional benefit of augmenting the conditioning intensity to 12-Gy, a finding which should be validated in prospective trials. Figure 1 Figure 1. Disclosures Spyridonidis: Menarini: Current Employment. Labopin: Jazz Pharmaceuticals: Honoraria. Giebel: Janssen: Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria, Speakers Bureau. Peric: Therakos: Honoraria; servier: Honoraria; MSD: Honoraria; Astellas: Honoraria; NOVARTIS: Honoraria; Abbvie: Honoraria; Pfizer: Honoraria. Schönland: Janssen: Honoraria, Other: Travel grants, Research Funding; Pfizer: Honoraria; Prothena: Honoraria, Other: Travel grants; Takeda: Honoraria, Other: Travel grants; Sanofi: Research Funding. Kröger: Novartis: Research Funding; Riemser: Honoraria, Research Funding; Sanofi: Honoraria; Neovii: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Gilead/Kite: Honoraria; Celgene: Honoraria, Research Funding; AOP Pharma: Honoraria. Stelljes: Novartis: Consultancy, Speakers Bureau; Amgen: Consultancy, Speakers Bureau; Kite/Gilead: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau; Medac: Speakers Bureau; Celgene/BMS: Consultancy, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau. Schroeder: JAZZ: Honoraria, Research Funding. McDonald: BioCryst Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees. Ganser: Novartis: Honoraria; Jazz Pharmaceuticals: Honoraria; Celgene: Honoraria. Wulf: Novartis: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Clinigen: Consultancy, Honoraria. Bazarbachi: Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Hikma: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astra Zeneca: Membership on an entity's Board of Directors or advisory committees.