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PURPOSE Immunopeptidome divergence between mismatched HLA-DP is a determinant of T-cell alloreactivity and clinical tolerability after fully HLA-A, -B, -C, -DRB1, -DQB1 matched unrelated donor hematopoietic cell transplantation (UD-HCT). Here, we tested this concept in HLA-A, -B, and -C disparities after single class I HLA-mismatched UD-HCT. PATIENTS AND METHODS We studied 2,391 single class I HLA-mismatched and 14,426 fully HLA-matched UD-HCT performed between 2008 and 2018 for acute leukemia or myelodysplastic syndromes. Hierarchical clustering of experimentally determined peptide-binding motifs (PBM) was used as a proxy for immunopeptidome divergence of HLA-A, -B, or -C disparities, allowing us to classify 1,629/2,391 (68.1%) of the HLA-mismatched UD-HCT as PBM-matched or PBM-mismatched. Risks associated with PBM-matching status were assessed by Cox proportional hazards models, with overall survival (OS) as the primary end point. RESULTS Relative to full matches, bidirectional or unidirectional PBM mismatches in graft-versus-host (GVH) direction (PBM-GVH mismatches, 60.7%) were associated with significantly lower OS (hazard ratio [HR], 1.48; P < .0001), while unidirectional PBM mismatches in host-versus-graft direction or PBM matches (PBM-GVH matches, 39.3%) were not (HR, 1.13; P = .1017). PBM-GVH mismatches also had significantly lower OS than PBM-GVH matches in direct comparison (HR, 1.32; P = .0036). The hazards for transplant-related mortality and acute and chronic graft-versus-host disease but not relapse increased stepwise from full HLA matches to single PBM-GVH matches, and single PBM-GVH mismatches. A webtool for PBM-matching of single class I HLA-mismatched donor-recipient pairs was developed. CONCLUSION PBM-GVH mismatches inform mortality risks after single class I HLA-mismatched UD-HCT, suggesting that prospective consideration of directional PBM-matching status might improve outcome. These findings highlight immunopeptidome divergence between mismatched HLA as a driver of clinical tolerability in UD-HCT.

when using post-transplant cyclophosphamide (PTCy) graft-versus-host-disease (GVHD) prophylaxis for lymphoma patients, it is currently unknown whether a matched unrelated donor (MUD) or a haploidentical related donor is preferable if both are available.In this study we wanted to test if using a haploidentical donor has the same results of a MUD.a total of 2140 adults (34% CIBMTR, 66% EBMT registry) aged ≥18 years who received their first haploidentical hematopoietic cell transplant (haplo-HCT) or MUD-HCT (8/8 match at HLA-loci A, B, C, and DRB1) for lymphoma using PTCy-based GVHD prophylaxis from 2010-2019 were retrospectively analyzed.The majority of both MUD and haploidentical HCTs received reduced intensity/non-myeloablative conditioning (74% and 77%, respectively), used a peripheral blood stem cell graft (91% and 60%, respectively) and a three-drug GVHD prophylaxis (PTCy + calcineurin inhibitor + MMF in 54% and 90%, respectively). Haploidentical HCT has less favorable results versus MUD cohort in terms of overall mortality (HR=1.69, 95%CI=1.30-2.27, p0.001), progression-free survival (HR=1.39, 95%CI=1.10 - 1.79, p=0.008), non-relapse mortality (HR=1.93, 95% CI=1.21 - 3.07, p=0.006), platelets engraftment (HR=0.69, 95%CI=0.59 - 0.80, p0.001), acute grade 2-4 GVHD incidence (HR=1.65, 95%CI=1.28 - 2.14, p0.001) and chronic GVHD (HR=1.79, 95%CI=1.30 - 2.48, p0.001). No significant differences were observed in terms of relapse and neutrophil engraftment. Adjusting for propensity score yielded similar results.whenever MUD is available in a timely manner, it should be preferred over a haploidentical donor when using PTCy-based GVHD prophylaxis for patients with lymphoma.

Patients with severe aplastic anemia (SAA) can have an unrecognized inherited bone marrow failure syndrome (IBMFS) because of phenotypic heterogeneity. We curated germline genetic variants in 104 IBMFS-associated genes from exome sequencing performed on 732 patients who underwent hematopoietic cell transplant (HCT) between 1989 and 2015 for acquired SAA. Patients with pathogenic or likely pathogenic (P/LP) variants fitting known disease zygosity patterns were deemed unrecognized IBMFS. Carriers were defined as patients with a single P/LP variant in an autosomal recessive gene or females with an X-linked recessive P/LP variant. Cox proportional hazard models were used for survival analysis with follow-up until 2017. We identified 113 P/LP single-nucleotide variants or small insertions/deletions and 10 copy number variants across 42 genes in 121 patients. Ninety-one patients had 105 in silico predicted deleterious variants of uncertain significance (dVUS). Forty-eight patients (6.6%) had an unrecognized IBMFS (33% adults), and 73 (10%) were carriers. No survival difference between dVUS and acquired SAA was noted. Compared with acquired SAA (no P/LP variants), patients with unrecognized IBMFS, but not carriers, had worse survival after HCT (IBMFS hazard ratio [HR], 2.13; 95% confidence interval[CI], 1.40-3.24; P = .0004; carriers HR, 0.96; 95% CI, 0.62-1.50; P = .86). Results were similar in analyses restricted to patients receiving reduced-intensity conditioning (n = 448; HR IBMFS = 2.39; P = .01). The excess mortality risk in unrecognized IBMFS attributed to death from organ failure (HR = 4.88; P < .0001). Genetic testing should be part of the diagnostic evaluation for all patients with SAA to tailor therapeutic regimens. Carriers of a pathogenic variant in an IBMFS gene can follow HCT regimens for acquired SAA.

The number of haploidentical hematopoietic stem cell transplantations (haplo-HSCT) performed has increased substantially in recent years. Previous single-center studies using in silico algorithms to quantitively measure HLA disparity have shown an association of the number of HLA molecular mismatches with relapse protection and/or increased risk of acute graft-versus-host disease (GVHD) in haplo-HSCT. However, inconsistent results from small studies have made it difficult to understand the full clinical impact of molecular mismatch in haplo-HSCT. In this study, we investigated the potential of the HLA class I and II mismatched eplet (ME) score measured by HLA-Matchmaker, as well as ME load at a specific locus to predict outcomes in a registry-based cohort of haplo-HSCT recipients. We analyzed data from 1287 patients who underwent their first haplo-HSCT for acute lymphoblastic leukemia, acute myelogenous leukemia, or myelodysplastic syndrome between 2013 and 2017, as entered in the Center for International Blood and Marrow Transplant Research database. ME load at each HLA locus and total class I and II were scored using the HLA-Matchmaker module incorporated in HLA Fusion software v4.3, which identifies predicted eplets based on the crystalized HLA molecule models and identifies ME by comparing donor and recipient eplets. In the study cohort, ME scores derived from total HLA class I or class II loci or individual HLA loci were not associated with overall survival, disease-free survival, nonrelapse mortality, relapse, acute GVHD, or chronic GVHD (P < .01). An unexpected strong association was identified between total class II ME load in the GVH direction and slower neutrophil engraftment (hazard ratio [HR], 0.82; 95% confidence interval [CI], 0.75 to 0.91; P < .0001) and platelet engraftment (HR, 0.80; 95% CI, 0.72 to 0.88; P < .0001). This was likely attributable to ME load at the HLA-DRB1 locus, which was similarly associated with slower neutrophil engraftment (HR, 0.82; 95% CI, 0.73 to 0.92; P = .001) and slower platelet engraftment (HR, 0.76; 95% CI, 0.70 to 0.84; P < .0001). Additional analyses suggested that this effect is attributable to a match versus a mismatch in the graft-versus-host direction and not to ME load, as a dose effect was not identified. These findings contradict those of previous relatively small studies reporting an association between ME load, as quantified by HLA-Matchmaker, and haplo-HSCT outcomes. This study failed to demonstrate the predictive value of ME from HLA molecules for major clinical outcomes, and other molecular mismatch algorithms in haplo-HSCT settings should be tested.

SUMMARY Exquisite regulation of energy homeostasis protects from nutrient deprivation but causes metabolic dysfunction upon nutrient excess. In human and murine adipose tissue, the accumulation of ligands of the receptor for advanced glycation end products (RAGE) accompanies obesity, implicating this receptor in energy metabolism. Here, we demonstrate that mice bearing global- or adipocyte-specific deletion of Ager, the gene encoding RAGE, display superior metabolic recovery after fasting, a cold challenge, or high-fat feeding. The RAGE-dependent mechanisms were traced to suppression of protein kinase A (PKA)-mediated phosphorylation of its key targets, hormone-sensitive lipase and p38 mitogen-activated protein kinase, upon β-adrenergic receptor stimulation—processes that dampen the expression and activity of uncoupling protein 1 (UCP1) and thermogenic programs. This work identifies the innate role of RAGE as a key node in the immunometabolic networks that control responses to nutrient supply and cold challenges, and it unveils opportunities to harness energy expenditure in environmental and metabolic stress., Graphical Abstract, In Brief Hurtado del Pozo et al. show that the deletion of adipocyte RAGE, whose ligands accumulate in metabolic stress, protects from obesity and cold challenges through the modulation of protein kinase A activities. This work adds RAGE to the immunometabolic networks that regulate energy expenditure in environmental and metabolic stress.

Background The receptor for advanced glycation end products (RAGE) is linked to cellular stress and inflammation during Alzheimer's disease (AD). RAGE signals through Diaphanous-1 (DIAPH1); however, the expression of DIAPH1 in the healthy and AD human brain has yet to be methodically addressed. Objective To delineate the cell- and disease-state specific expression of DIAPH1 in the human medial temporal cortex during healthy aging and AD. Methods We used semi-quantitative immunohistochemistry in the human medial temporal cortex paired with widefield and confocal microscopy and automated analyses to determine colocalization and relative expression of DIAPH1 with key cell markers and molecules in the brains of subjects with AD versus age-matched controls. Results We report robust colocalization of DIAPH1 with myeloid cells and increased expression during AD, which strongly correlated to increased neutral lipids and morphology of inflamed myeloid cells. DIAPH1 moderately colocalized with markers of endothelial cells, astrocytes, neurons, and oligodendrocytes. Discussion Our findings localize DIAPH1 particularly to myeloid cells in the CNS, especially in AD in the locations of lipid droplet accumulation, thereby implicating RAGE-DIAPH1 signaling in dysregulated lipid metabolism and morphological changes of inflamed myeloid cells in this disorder.

Islet amyloidosis is characterized by the aberrant accumulation of islet amyloid polypeptide (IAPP) in pancreatic islets, resulting in β cell toxicity, which exacerbates type 2 diabetes and islet transplant failure. It is not fully clear how IAPP induces cellular stress or how IAPP-induced toxicity can be prevented or treated. We recently defined the properties of toxic IAPP species. Here, we have identified a receptor-mediated mechanism of islet amyloidosis–induced proteotoxicity. In human diabetic pancreas and in cellular and mouse models of islet amyloidosis, increased expression of the receptor for advanced glycation endproducts (RAGE) correlated with human IAPP–induced (h-IAPP–induced) β cell and islet inflammation, toxicity, and apoptosis. RAGE selectively bound toxic intermediates, but not nontoxic forms of h-IAPP, including amyloid fibrils. The isolated extracellular ligand–binding domains of soluble RAGE (sRAGE) blocked both h-IAPP toxicity and amyloid formation. Inhibition of the interaction between h-IAPP and RAGE by sRAGE, RAGE-blocking antibodies, or genetic RAGE deletion protected pancreatic islets, β cells, and smooth muscle cells from h-IAPP–induced inflammation and metabolic dysfunction. sRAGE-treated h-IAPP Tg mice were protected from amyloid deposition, loss of β cell area, β cell inflammation, stress, apoptosis, and glucose intolerance. These findings establish RAGE as a mediator of IAPP-induced toxicity and suggest that targeting the IAPP/RAGE axis is a potential strategy to mitigate this source of β cell dysfunction in metabolic disease.

Introduction Unrelated donor (UD)-recipient disparity for human leukocyte antigen (HLA) class I adversely affects outcome of hematopoietic cell transplantation (UD-HCT). HLA polymorphisms in the peptide antigen binding groove can affect the repertoire of presented peptides. We have recently shown that the degree of peptide divergence between mismatched HLA-DP allotypes is related to T-cell alloreactivity and clinical permissiveness after UD-HCT (Meurer et al Blood 2021). Here, we hypothesized that the clinical tolerability also of HLA class I mismatches in UD-HCT might depend on the divergence of their respective peptide repertoires. Methods We studied 2,562 patients after 9/10 HLA-A, -B, -C, -DRB1, -DQB1-matched UD-HCT for acute myeloid or lymphocytic leukemia, or myelodysplastic syndrome, between 2008 and 2018, and 14,426 10/10 HLA-matched UD-HCT with similar characteristics. Peptide divergence of the mismatched HLA allotypes was predicted based on hierarchical clustering of experimentally determined peptide binding motifs (PBM) (Bassani-Sternberg et al Front Immunol 2018), with 21 different PBM groups identified in 122 HLA class I allotypes (44, 63 and 18 for HLA-A, -B and -C, respectively). The mismatched cohort was stratified into PBM-matches or PBM-mismatches, and within the latter into host-versus-graft (HvG), graft-versus-host (GvH) or bidirectional PBM-mismatches (Figure 1A). The primary study endpoint was overall survival (OS); secondary endpoints included treatment-related mortality (TRM), GVHD and relapse. P-value Results The available PBM data allowed us to classify 1,629/2,562 (63.6%) of our pairs. Of these, 386 (23.7%) were PBM-matched and 1,243 (76.3%) were PBM-mismatched, and in the latter, 254 (20.5%), 238 (19.1%) and 751 (60.4%) had HvG, GvH or bidirectional PBM-mismatches, respectively. Transplants were performed mainly with peripheral blood stem cells (78%), myeloablative conditioning (65%) and tacrolimus-based graft-versus-host disease (GvHD) prophylaxis (74%). About half of the 9/10 HLA-matched HCT were performed using in vivo T-cell depletion by anti-thymocyte globulin or Campath, and none used post-transplant cyclophosphamide. Multivariable analyses showed that 10/10 HLA-matched transplants had significantly higher OS, lower TRM and aGvHD 3-4 compared to 9/10 HLA-matched transplants but relapse was similar (Figure 1B,C). There were no significant differences between the PBM-matched and aggregate PBM-mismatched group (Figure 1B). In further analysis, pairs with a bidirectional or only GvH PBM-mismatch had significantly worse OS, compared to pairs in the PBM-matched group or with only a unidirectional HvG (hazards ratio [HR] 0.76, 95% confidence interval [CI] 0.63-0.92, P = 0.0036; Figure 1C). The hazards of TRM and aGvHD 3-4 were lower for the HvG or PBM-matched group compared to the reference (HR 0.78, 95% CI 0.65-0.95, P = 0.0135 and HR 0.79, 95% CI 0.65-0.95, P = 0.0126, respectively), although these were not statistically significant (Figure 1C). Conclusion We show that single HLA class I PBM-mismatches with high peptide divergence in the unidirectional or bidirectional GvH directions are significantly associated with worse survival after 9/10 HLA-matched UD-HCT compared to PBM-matched or unidirectional mismatching in the HvG direction. These data suggest that the mechanistic role of peptide-diversity for T-cell alloreactivity we previously observed for HLA-DPB1 disparity (Meurer et al., Blood 2021), is also a relevant to class I mismatches, providing a new rationale for selecting permissive donors in the setting of 9/10 HLA-matched UD-HCT. Avoiding class I PBM mismatches in the GvH direction is associated with better survival. Figure 1 Figure 1. Disclosures Paczesny: Medical University of South Carolina: Patents & Royalties: inventor on the ST2 bispecific antibody patent application. Lee: Amgen: Research Funding; AstraZeneca: Research Funding; Incyte: Research Funding; Janssen: Other; Kadmon: Research Funding; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Syndax: Research Funding; Takeda: Research Funding.

Introduction: Permissive HLA-DPB1 mismatches defined by the T-cell epitope (TCE) model are an established selection criterion for unrelated donors in allogeneic hematopoietic cell transplantation (alloHCT) (Dehn et al. Blood 2019). Based on biological evidence, the TCE model has classified HLA-DPB1 alleles into at least three functional groups, one of which (TCE group 3; TCE3) houses a large number of alleles with different structural and functional characteristics. We have recently shown that structurally close HLA-DP allotypes have similar peptide-binding motifs and share a significant proportion of their immunopeptidomes, the latter being fundamental for permissiveness (Meurer & Crivello et al. Blood 2021). Hence, we hypothesized that HLA-DPB1 mismatches involving alleles that encode structurally distant allotypes within TCE3 could be less permissive than those involving alleles that encode structurally closer allotypes, and thus have a differential impact on clinical outcomes. Methods: Multidimensional scaling techniques were used to compare 28 polymorphic positions (amino acids 8-215) among 51 alleles present in a cohort of 5,140 10/10 matched patient-donor pairs who received a first alloHCT for AML, ALL, or MDS between 2008-2017. Based on these analyses, TCE3-permissive mismatches (N=2,216) were further stratified into those involving structurally close or more distant combinations and compared with HLA-DPB1-matched (N=785) and non-permissively mismatched (N=2,023) pairs. These models were tested in parallel to the "classical" TCE model considering permissive mismatches (N=2,332) as a whole, to determine their association with overall survival (OS), disease-free survival (DFS), treatment-related mortality (TRM), primary disease relapse, and acute (a) and chronic (c)GVHD. Kaplan-Meier analysis and log-rank testing were used to compare the median OS and DFS. The incidences of GVHD, relapse and TRM were compared using competing risks and Gray's test. The effect of HLA-DPB1 mismatch on time-to-event outcomes was modelled by Cox regression after adjusting for confounders and testing for the proportional hazards assumption. Results: Within TCE3, we identified a subgroup of 4 frequent and structurally as well as functionally closely related alleles (i.e. DPB1*02:01, 04:01, 04:02, 23:01) that form a separate cluster (Figure 1A). These "core" alleles have similar bound-peptide motifs (van Balen et al. J Immunol 2020) and can be distinguished from other alleles in TCE3 in terms of the strength of in vitro alloreactive responses elicited from permissive responders (Meurer et al. Front Immunol 2018). Moreover, principal component analysis identified the HLA-DP 84-87 DEAV/GGMP motif as a major factor driving structural variability among TCE3 alleles (not shown). We used these observations to stratify TCE3 permissive mismatches in the allo-HCT cohort into "core" (N=930) and "non-core" (N=1,286) or into DEAV/GGPM-matched (N=1,209) and mismatched (N=1,007) pairs (Figure 1B). Multivariable analysis confirmed the association of aGVHD2-4 for the classical TCE model of non-permissive mismatching (p Conclusion: Our results suggest that structural differences within TCE3 that reflect functional divergence and differential immunogenicity of alleles in this group associate with the risks of aGVHD and TRM after alloHCT. Hence, within the population of 10/10 matched donors, selection of "core" TCE3-permissive donors might reduce patient morbidity after transplantation. Figure 1 Figure 1. Disclosures Paczesny: Medical University of South Carolina: Patents & Royalties: inventor on the ST2 bispecific antibody patent application. Lee: AstraZeneca: Research Funding; Incyte: Research Funding; Janssen: Other; Kadmon: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Research Funding; Syndax: Research Funding; Takeda: Research Funding; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding.

ABSTRACT BACKGROUND The number of haploidentical hematopoietic stem cell transplantations (haplo-HSCT) being performed has substantially increased in recent years. Single-center studies have previously used in silico algorithms to quantitively measure HLA disparity and shown an association of the number of HLA molecular mismatches with relapse protection and/or increased risk of acute graft-versus-host disease (GVHD) in haplo-HSCT. However, inconsistent results from small studies have made it difficult to understand the full clinical impact of molecular mismatch in haplo-HSCT. OBJECTIVE In the current study, we investigated the potential of the HLA class I and II mismatched eplet (ME) score measured by HLAMatchmaker, as well as ME load at a specific locus to predict outcomes in a registry-based cohort of haplo-HSCT recipients. STUDY DESIGN We analyzed data from patients (n= 1,287) who underwent their first haplo-HSCT for acute lymphoblastic leukemia, acute myeloid leukemia, or myelodysplastic syndrome between 2013 and 2017, as reported to the Center for International Blood and Marrow Transplant Research database. ME load at each HLA locus and total Class-I and -II were scored using the HLAMatchmaker module incorporated in HLA Fusion software v4.3, which identifies predicted eplets based on the crystalized HLA molecule models and identifies ME by comparing donor and recipient eplets. RESULTS In the cohort studied, ME scores derived from total HLA Class I or Class II loci or individual HLA loci were not associated with overall survival, disease-free survival, non-relapse mortality, relapse, acute or chronic GVHD (P< .01). An unexpected strong association was identified between total class II ME load in the GVH direction and slower neutrophil engraftment (HR 0.82; 95% CI, 0.75 - 0.91; P < .0001) and platelet engraftment (HR 0.80; 95% CI, 0.72 - 0.88; P < .0001). This was likely attributable to ME load at the HLA-DRB1 locus, which was similarly associated with slower neutrophil engraftment (HR 0.82; 95% CI, 0.73 - 0.92; P = .001) and slower platelet engraftment (HR 0.76; 95% CI, 0.70 - 0.84; P < .0001). Additional analyses suggested that this effect is attributable to matched vs. mismatched in the GVH direction and not to ME load, as there was no dose effect identified. CONCLUSION These findings contradict those of prior relatively small studies reporting that ME load, as quantified by HLAMatchmaker, was associated with haplo-HSCT outcomes. As the study failed to demonstrate the predictive value of ME from HLA molecules for major clinical outcomes, other molecular mismatch algorithms in haplo-HSCT settings should be tested. Disclosures Lee: Pfizer: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Janssen: Other; Takeda: Research Funding; Syndax: Research Funding; AstraZeneca: Research Funding; Kadmon: Research Funding; Amgen: Research Funding.

Introduction: Post-transplant cyclophosphamide (PTCy) is a standard GVHD prophylactic approach for haploidentical hematopoietic cell transplantation (haploHCT). Retrospective studies in patients with lymphoma showed lower chronic GVHD in haploHCT with PTCy-based GVHD prophylaxis compared to matched unrelated donor (MUD) HCT with calcineurin-based GVHD prophylaxis (+/- ATG). Recent retrospective studies showed that using MUD donors was better than haplo donors when PTCy and reduced-intensity conditioning are used for ALL, AML or MDS. However, no studies to date have compared haploHCT and MUD HCT when PTCy is used in the setting of lymphomas. Methods: 2155 adults (730 CIBMTR, 1425 EBMT) aged =/>18 years who received their first haploHCT or MUD HCT (8/8 match at HLA-loci A, B, C and DRB1) using PTCy from 2010-2019 for lymphoma were included. The majority of both MUD (n=312; 14%) and haplo (n=1843; 86%) HCTs received reduced intensity/non-myeloablative conditioning (n=1655; 77%) using a peripheral blood stem cell graft (n=1379; 64%) and a three-drug GVHD prophylaxis (PTCy + calcineurin inhibitor + MMF, n=1805; 84%). Hodgkin's lymphoma was the most common indication (n=899; 42%) followed by diffuse large B-cell lymphoma (n=525; 24%), T-cell lymphomas (n=328; 15%), mantle cell lymphoma (n=234; 11%) and follicular lymphoma (n=169; 8%). Most had chemosensitive disease at transplant (n=1781; 83%). Some main characteristics of the two cohorts are shown in Figure 1. Median follow-up among survivors was longer for haplo-HCT (36 and 31 months for the CIBMTR and EBMT cohort, respectively) than MUD-HCT (24 and 17 months, respectively). Cox proportional hazards models were built using stepwise forward and backward selection with a selection/retention threshold of 0.05. Any clinical variables that did not meet the proportional hazard assumption were adjusted for by stratification, and regression models were built to compare outcomes between donor types. Center effect was adjusted in all the models. Results: Figures 2 and 3 show the multivariate analysis results. Overall survival was 73% (71-75%) at 1 year and 65% (63-67%) at 2 years. Relapse was 21% (20-23%) at 1 year and 26% (24-28%) at 2 years. All outcomes favored MUD over haplo donors with the use of PTCy-based GVHD prophylaxis for both. Conclusions: Patients with lymphoma receiving PTCy HCT from MUDs demonstrated better outcomes than those with haplo donors in this retrospective study of CIBMTR and EBMT data Future prospective studies are needed to confirm and clarify the reasons for these differences. Figure 1 Figure 1. Disclosures Mussetti: GILEAD: Other: Clinical trials participation, Research Funding; TAKEDA: Honoraria; NOVARTIS: Honoraria, Other: Clinical trials participation. Hamadani: Janssen, Incyte, ADC Therapeutics, Omeros, Morphosys, Kite: Consultancy; Sanofi, Genzyme, AstraZeneca, BeiGene: Speakers Bureau; Takeda, Spectrum Pharmaceuticals and Astellas Pharma: Research Funding. Glass: Novartis: Consultancy; Riemser: Research Funding; Helios Klinik Berlin-Buch: Current Employment; Kite: Consultancy; Roche: Consultancy, Research Funding, Speakers Bureau; BMS: Consultancy. Blaise: Jazz Pharmaceuticals: Honoraria. Paczesny: Medical University of South Carolina: Patents & Royalties: inventor on the ST2 bispecific antibody patent application. Dreger: Novartis: Consultancy, Speakers Bureau; Riemser: Consultancy, Research Funding, Speakers Bureau; BMS: Consultancy; Bluebird Bio: Consultancy; AstraZeneca: Consultancy, Speakers Bureau; Gilead Sciences: Consultancy, Speakers Bureau; Janssen: Consultancy; AbbVie: Consultancy, Speakers Bureau; Roche: Consultancy, Speakers Bureau. Lee: AstraZeneca: Research Funding; Incyte: Research Funding; Janssen: Other; Kadmon: Research Funding; National Marrow Donor Program: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding; Syndax: Research Funding; Pfizer: Research Funding; Takeda: Research Funding; Amgen: Research Funding. Sureda: BMS/Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Speakers Bureau; Bluebird: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Support for attending meetings and/or travel, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Kite, a Gilead Company: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Sanofi: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; MSD: Consultancy, Honoraria, Speakers Bureau; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Mundipharma: Consultancy; Roche: Other: Support for attending meetings and/or travel; GSK: Consultancy, Honoraria, Speakers Bureau.