Abstract: Chronic active Epstein-Barr virus (EBV) disease (CAEBV) is characterized by high levels of EBV predominantly in T and/or natural killer cells with lymphoproliferation, organ failure due to infiltration of tissues with virus-infected cells, hemophagocytic lymphohistiocytosis, and/or lymphoma. The disease is more common in Asia than in the United States and Europe. Although allogeneic hematopoietic stem cell transplantation (HSCT) is considered the only curative therapy for CAEBV, its efficacy and the best treatment modality to reduce disease severity prior to HSCT is unknown. Here, we retrospectively assessed an international cohort of 57 patients outside of Asia. Treatment of the disease varied widely, although most patients ultimately proceeded to HSCT. Though patients undergoing HSCT had better survival than those who did not (55% vs 25%, P & lt; .01), there was still a high rate of death in both groups. Mortality was largely not affected by age, ethnicity, cell-type involvement, or disease complications, but development of lymphoma showed a trend with increased mortality (56% vs 35%, P = .1). The overwhelming majority (75%) of patients who died after HSCT succumbed to relapsed disease. CAEBV remains challenging to treat when advanced disease is present. Outcomes would likely improve with better disease control strategies, earlier referral for HSCT, and close follow-up after HSCT including aggressive management of rising EBV DNA levels in the blood.

Abstract: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening inflammatory syndrome that may complicate hematologic malignancies (HMs). The appropriateness of current criteria for diagnosing HLH in the context of HMs is unknown because they were developed for children with familial HLH (HLH-2004) or derived from adult patient cohorts in which HMs were underrepresented (HScore). Moreover, many features of these criteria may directly reflect the underlying HM rather than an abnormal inflammatory state. To improve and potentially simplify HLH diagnosis in patients with HMs, we studied an international cohort of 225 adult patients with various HMs both with and without HLH and for whom HLH-2004 criteria were available. Classification and regression tree and receiver-operating curve analyses were used to identify the most useful diagnostic and prognostic parameters and to optimize laboratory cutoff values. Combined elevation of soluble CD25 ( & gt;3900 U/mL) and ferritin ( & gt;1000 ng/mL) best identified HLH-2004–defining features (sensitivity, 84%; specificity, 81%). Moreover, this combination, which we term the optimized HLH inflammatory (OHI) index, was highly predictive of mortality (hazard ratio, 4.3; 95% confidence interval, 3.0-6.2) across diverse HMs. Furthermore, the OHI index identified a large group of patients with high mortality risk who were not defined as having HLH according to HLH-2004/HScore. Finally, the OHI index shows diagnostic and prognostic value when used for routine surveillance of patients with newly diagnosed HMs as well as those with clinically suspected HLH. Thus, we conclude that the OHI index identifies patients with HM and an inflammatory state associated with a high mortality risk and warrants further prospective validation.

Abstract: Polymerization of sickle cell hemoglobin S (HbS) is recognized as a key event in the pathophysiology of sickle cell disease (SCD). Repeated HbS polymerization promotes an altered red blood cell (RBC) membrane, hemolysis, and microparticle (MP) formation, which have been shown to play significant roles in the interaction of RBCs with vascular endothelium and progression of vaso-occlusive events. Circulating RBC-derived MPs are elevated in SCD patients and they release a significant portion of their contents including oxidized HbS and heme to the cells of the vasculature. We have recently reported that free HbS oxidizes faster, remains locked in a highly oxidizing form (ferryl) longer, and loses heme faster than normal HbA (Kassa et al., J Biol Chem 290: 27939, 2015). The contributions of HbS higher oxidation states (ferric and ferryl heme) to MP formation, membrane alterations, and heme loss are poorly defined in SCD. RBC-derived MPs (ranging in size between 100-300 nm in diameter) generated by sheer stress or isolated by ultracentrifugation from the plasma (circulating) of SCD patients (N=6), ethnically matched control subjects (N=5), humanized transgenic sickle mice (Townes-SS, N=4), and control wild-type mice (Townes-AA, N=4) were identified by flow cytometry using CD235a glycophorin antibody and annexin V for externalized phosphatidylserine (PS). Time courses of Hb oxidation, obtained during 30 hour incubations of mouse or human MPs were biphasic. The initial levels of oxidized (ferric) Hb (30 to 45%) were slightly reduced within the first ~10 hours, likely due to the presence of RBC residual reductive enzymes within MPs. This was followed by a second phase in which Hb oxidation (ferric Hb) increased linearly and uncontrollably to 65 to 75% of total Hb. SCD MP's contained highly reactive ferryl Hb intermediates, carbonylated membrane proteins, and phosphorylated band 3 proteins. Quantitative proteomic analysis indicated a higher level of protein oxidation in MPs derived from SCD mice and patients. Five-fold higher levels of irreversibly oxidized βCys93 oxidation were found in untreated versus hydroxyurea-treated SCD patients. Intriguingly, HbS β subunits from SCD MPs were ubiquitinated and MPs isolated from untreated SCD patients had 25-fold higher ubiquitination levels than hydroxyurea-treated SCD patients that were comparable to normal controls. MP ubiquitination levels were correlated with HbS and an overall increase in MP oxidative stress, and inversely correlated with HbF. Compared to respective control MPs, incubation of either mice or human SCD MPs with human endothelial cells (HUVEC) activated apoptotic pathways and impacted cellular bioenergetic parameters by lowering mitochondrial oxygen consumption rates to a greater degree in a manner that was correlated with the redox state of Hb iron within MPs. Human endothelial cells incubated with SCD MPs showed greater intracellular reactive oxygen species production and heme oxygenase-1 induction. In summary, Hb transformation to higher oxidation forms is markedly increased in MPs generated from SCD mice and patients, which when incubated with endothelial cells, lead to mitochondrial dysfunction and apoptotic cell death. These mechanistic analyses of RBC-derived SCD microparticles suggest potential anti-oxidative reducing modalities that may interrupt MP heme-mediated pathophysiology in patients with SCD. Disclosures Belcher: Cydan/Imara: Research Funding; CSL-Behring: Research Funding. Vercellotti:CSL-Behring: Research Funding; Imara: Research Funding.

Abstract: Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyper-inflammatory syndrome which may occur in adults with hematologic malignancies (HM). The diagnosis of HLH in this context (HM-HLH) is hindered by a number of factors. First, the currently used HLH 2004 diagnostic criteria are derived from pediatric patients commonly with HLH-associated genetic lesions, a very different population than adults with cancer. Second, most parameters used for diagnosis of HLH are directly impacted by the underlying HM and may reflect the presence of the malignant clone itself rather than an inflammatory process. Finally, appropriate diagnostic cutoff values for laboratory abnormalities in HM-HLH have not been defined. In this study we determine the diagnostic value of the laboratory components of the HLH 2004 diagnostic criteria and establish optimal cutoffs for the diagnosis of HM-HLH in HM patients. Methods: This is a multicenter, retrospective study of adult patients with a hematologic malignancy in whom sCD25 was measured because of clinically suspected HM-HLH or as part of routine screening of patients with a newly diagnosed hematologic malignancy, between January 2012 and March 2020. We considered patients fulfilling the five of eight of the HLH 2004 diagnostic criteria to have HM-HLH. Patients fulfilling fewer than five criteria were assigned to the HM group. These cohorts were well balanced in terms of disease distribution. We established the optimal cutoffs for laboratory parameters used for the diagnosis of HM-HLH using receiver operating curves (ROC) in a discovery cohort and tested their performance in a validation cohort. In order to improve the results obtained using the individual ROC, we then created a combined ROC using parameters demonstrating the highest individual performance (highest area under the curve (AUC)), in order to develop a diagnostic index. Finally, we examined the performance of each parameter in each cohort by using a contingency table and Chi-square and Fisher's exact test to determine the positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity and likelihood ratio (LR) of disease for each parameter. Results: 212 adults with HM with or without HLH in whom testing for HLH was performed were included in the study. HMs were: B cell lymphoma (41%), T cell lymphoma (26%), Hodgkin lymphoma (9%), acute myeloid leukemia (8%), myelodysplastic syndrome (8%), myeloproliferative neoplasms (5%) and chronic lymphocytic leukemia (4%). 99 (47%) patients had HM-HLH. Despite considerable overlap in laboratory values between the patient groups, all parameters apart from fibrinogen were able to distinguish HM-HLH from HM alone, with ferritin and sCD25 having the greatest discriminatory power. ROC analysis revealed an optimal cutoff value of & gt;5,600 U/mL for sCD25 (sensitivity/specificity 76%/78%, AUC=0.83) and & gt;1,300 ng/ml for ferritin (sensitivity/specificity 76%/76%, AUC=0.83). Combining the two markers to create a novel inflammatory index (HM-INFL) yielded superior diagnostic ability (AUC =0.86). Using HLH 2004 cutoff levels the HM-INFL index had a sensitivity of 94% and NPV of 94% and when using the optimal cutoff levels, it had a specificity of 92% and PPV of 90% (Table 1). Conclusions: HM-INFL is an index comprising only ferritin and sCD25. Using the original HLH 2004 cutoffs the index is an effective screening tool. Using our newly defined cutoff levels obtained by ROC analysis it is highly specific and can be used as a confirmatory test for the diagnosis of HLH in HM patients. These findings also support the hypothesis that HLH in the context of HM is an inflammatory condition associated with immune dysregulation. Disclosures Miller: Foundation Medicines, Inc.: Consultancy. Daver:Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Bristol-Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; Servier: Research Funding; Genentech: Research Funding; AbbVie: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novimmune: Research Funding; Gilead: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Trovagene: Research Funding; Fate Therapeutics: Research Funding; ImmunoGen: Research Funding; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Membership on an entity's Board of Directors or advisory committees; Trillium: Consultancy, Membership on an entity's Board of Directors or advisory committees; Syndax: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; KITE: Consultancy, Membership on an entity's Board of Directors or advisory committees; Agios: Consultancy, Membership on an entity's Board of Directors or advisory committees. Jordan:Sobi: Consultancy.

Abstract: Wiskott-Aldrich syndrome (WAS) is an X-linked disease caused by mutations in the WAS gene, leading to thrombocytopenia, eczema, recurrent infections, autoimmune disease, and malignancy. Hematopoietic cell transplantation (HCT) is the primary curative approach, with the goal of correcting the underlying immunodeficiency and thrombocytopenia. HCT outcomes have improved over time, particularly for patients with HLA-matched sibling and unrelated donors. We report the outcomes of 129 patients with WAS who underwent HCT at 29 Primary Immune Deficiency Treatment Consortium centers from 2005 through 2015. Median age at HCT was 1.2 years. Most patients (65%) received myeloablative busulfan-based conditioning. With a median follow-up of 4.5 years, the 5-year overall survival (OS) was 91%. Superior 5-year OS was observed in patients & lt;5 vs ≥5 years of age at the time of HCT (94% vs 66%; overall P = .0008). OS was excellent regardless of donor type, even in cord blood recipients (90%). Conditioning intensity did not affect OS, but was associated with donor T-cell and myeloid engraftment after HCT. Specifically, patients who received fludarabine/melphalan-based reduced-intensity regimens were more likely to have donor myeloid chimerism & lt;50% early after HCT. In addition, higher platelet counts were observed among recipients who achieved full ( & gt;95%) vs low-level (5%-49%) donor myeloid engraftment. In summary, HCT outcomes for WAS have improved since 2005, compared with prior reports. HCT at a younger age continues to be associated with superior outcomes supporting the recommendation for early HCT. High-level donor myeloid engraftment is important for platelet reconstitution after either myeloablative or busulfan-containing reduced intensity conditioning. (This trial was registered at www.clinicaltrials.gov as #NCT02064933.)

Abstract: Children with acute myeloid leukemia (AML) have a dismal prognosis due to a high relapse rate; however, the molecular basis leading to relapsed pediatric AML has not yet been fully characterized. To define the spectrum of alterations common at relapse, we performed integrated profiling of 136 relapsed pediatric AML cases with RNA sequencing (RNA-seq), whole-genome sequencing, and target-capture sequencing. In addition to well-characterized fusion oncoproteins, such as those involving KMT2A (n=36, 26.5%) or NUP98 (n=18, 13.2%), we also identified somatic mutations in UBTF (upstream binding transcription factor) in 12 of 136 cases (8.8%) of this relapsed cohort. Somatic alterations of the UBTF gene, which encodes a nucleolar protein that is a component of the RNA Pol I pre-initiation complex to ribosomal DNA promoters, have rarely been observed in AML. In our cohort, all alterations can be described as heterozygous in-frame exon 13 tandem duplications (UBTF-TD), either at the 3' end of exon 13 of UBTF or of the entire exon 13 (Fig. A). As we noticed limited detection in our pipeline as a result of complex secondary indels alongside the duplications, we established a soft-clipped read-based screening method to detect UBTF-TD more efficiently. Applying the screening to RNA-seq data of 417 additional pediatric AMLs from previous studies and our clinical service, we identified 15 additional UBTF-TDs, many of which have not been previously reported. At the amino acid level, UBTF-TDs caused amino acid insertions of variable sizes (15-181 amino acids), duplicating a portion of high mobility group domain 4 (HMG4), which includes short leucine-rich sequences. UBTF-TD AMLs commonly occurred in early adolescence (median age: 12.6, range: 2.4-19.6), and 19 of the total 27 cases had either normal karyotype (n=12) or trisomy 8 (n=7). UBTF-TD is mutually exclusive from other recurrent fusion oncoproteins, such as NUP98 and KMT2A rearrangements (Fig. B), but frequently occurred with FLT3-ITD (44.4%) or WT1 mutations (40.7%). The median variant allele fraction (VAF) of the UBTF-TD was 48.0% (range: 9.7-66.7%). In four cases with data at multiple disease time points, the identical UBTF-TDs were present at high allele fractions at all time points, suggesting that UBTF-TD is a clonal alteration. tSNE analysis of the transcriptome dataset showed that UBTF-TD AMLs share a similar expression pattern with NPM1 mutant and NUP98-NSD1 AML subtypes, including NKX2-3 and HOXB cluster genes (Fig. C) . Altogether, these findings suggest that UBTF-TD is a unique subtype of pediatric AML. To address the impact of UBTF-TD expression in primary hematopoietic cells, we introduced UBTF-TD and UBTF wildtype expression vectors into cord blood CD34+ cells via lentiviral transduction. UBTF-TD expression promotes colony-forming activity and cell growth, yielding cells with a persistent blast-like morphology (Fig. D). Further, transcriptional profiling of these cells demonstrated expression of HOXB genes and NKX2-3, similar to UBTF-TD AMLs in patients, indicating that UBTF-TD is sufficient to induce the leukemic phenotype. To investigate the prevalence of UBTF-TDs in larger de novo AML cohorts, we applied the above UBTF-TD screening method to the available de novo AML cohorts of TCGA (n=151, adult), BeatAML (n=220, pediatric and adult), and AAML1031 (n=1035, pediatric). We identified UBTF-TDs in 4.3% (45/1035) of the pediatric AAML1031 cohort, while the alteration is less common (0.9%: 3/329, p=0.002) in the adult AML cohorts (Fig. E). In the AAML1031 cohort, UBTF-TDs remain mutually exclusive with known molecular subtypes of AML and commonly occur with FLT3-ITD (66.7%) and WT1 (40.0%) mutations and either normal karyotype or trisomy 8. The presence of UBTF-TDs in the AAML1031 cohort is associated with a poor outcome (Fig. F, median overall survival, 2.3 years) and MRD positivity; multivariate analysis revealed that UBTF-TD and WT1 are independent risk factors for overall survival within FLT3-ITD+ AMLs. In conclusion, we demonstrate UBTF-TD defines a unique subtype of AMLs that previously lacked a clear oncogenic driver. While independent of subtype-defining oncogenic fusions, UBTF-TD AMLs are associated with FLT3-ITD and WT1 mutations, adolescent age, and poor outcomes. These alterations have been under-recognized by standard bioinformatic approaches yet will be critical for future risk-stratification of pediatric AML. Figure 1 Figure 1. Disclosures Iacobucci: Amgen: Honoraria; Mission Bio: Honoraria. Miller: Johnson & Johnson's Janssen: Current Employment. Mullighan: Pfizer: Research Funding; Illumina: Membership on an entity's Board of Directors or advisory committees; AbbVie: Research Funding; Amgen: Current equity holder in publicly-traded company.

Abstract: The PD-1/PD-L1 pathway plays an important role in regulation of alloimmune responses and in induction and maintenance of peripheral tolerance. Because GVHD is driven by donor T cells and PD-L1 expression can be markedly elevated on T cells during activation, we investigated the functional significance of PD-L1 expressed by donor T cells in regulating murine models of acute GVHD. PD-L1 expression was up-regulated on donor CD4 and CD8 T cells during GVHD. We considered the possibility that PD-L1 expression on activated donor T cells might inhibit GVHD by down regulating donor anti-host T cell responses, consistent with PD-L1 co-inhibitory activity when expressed on host parenchymal cells during GVHD. Surprisingly, T cell mediated GVHD lethality was markedly reduced in recipients of PD-L1-/- compared to WT donor T cells in both B6 to BALB/c model of GVHD(P 〈 0.0001; Fig 1A) and in B6 to B10.BR model (P=0.0047; Fig 1B), suggesting that PD-L1 expression on donor T cells is involved in interactions that enhance T cell mediated effector function. Survival data confirmed that PD-L1-/- Teffs and not Tregs were responsible for reduced lethality in recipients of PD-L1-/- donor T cells (Fig 1C). During GVHD, PD-L1-/- donor CD4 and CD8 T cells had reduced expression of gut homing receptors (Fig 1D), and recipients of PD-L1-/- donor T cells had reduced T cell infiltration into lymphoid organs and gut, retained intestinal epithelial integrity, and had lower inflammatory cytokine production. PD-L1-/- donor CD4 and CD8 T cells had increased expression of multiple inhibitory receptors (Fig 1E, 1F), reduced T cell proliferation, and increased T cell apoptosis by transcriptional profiling and cell surface marker expression. Four pathways, including proteasome activity showed decreased expression in PD-L1-/- donor T cells. In vitro T cell activation in the presence of single (PD-L1:B7-1) vs. dual (PD-L1:B7-1 and PD-L1:PD-1) pathway blocking anti-PD-L1 mAb confirmed that T-T interaction between PD-1 and PD-L1 is important for proliferation and survival, whereas sensitive in vitro assays with supported lipid bilayers found no evidence for a functionally relevant cis interaction of PD-L1 and PD-1 on T cells. We found a significant increase in glucose transporter (GLUT1) expression in proliferating WT vs. PD-L1-/- donor CD4 and CD8 T cells, along with increased glycolysis, OXPHOS, glutamine consumption and glutamate production. We also observed increased fatty acid (FA) uptake and FA oxidation, and enhanced pharmacologic inhibition of FA oxidation in WT donor T cells, suggesting that PD-1:PD-L1 interactions are important for FA metabolism, which may further support T cell survival. Studies using stable isotope carbon tracers highlighted the divergent roles for glutamine and glucose in energy generation and biosynthetic pathways. Given the importance of acetyl-CoA as a high energy thioester intermediate in the TCA cycle and a lipogenic precursor for T cells undergoing expansion, significantly enhanced production of acetyl-CoA from glucose by WT donor T cells support the notion that PD-L1 on T cells promotes clonal expansion of alloreactive T cells. In summary, these data are the first to show that PD-L1 expression on donor T cells can provide positive signals for T cell survival, activation, and metabolism. Greater understanding of the function of PD-L1 expression by activated donor T cells will provide new insight into the regulation of GVHD and suggest strategies to selectively inhibit PD-L1 on donor T cells that may be clinically useful to prevent GVHD. Figure 1. PD-L1-/- vs. WT donor T cells lessen GVHD lethality, independent of donor Treg function. (A) Survival of BALB/c mice with WT B6 or PD-L1-/- T cells. (B) Survival of B10.BR mice with WT B6 or PD-L1-/- T cells. (C) Survival of BALB/c mice with WT B6 or PD-L1-/- T cells, or with WT B6 or PD-L1-/- CD25 depleted T cells (recipients of WT T cells vs. WT CD25-depleted T cells, P = 0.0003; recipients of PD-L1-/- T cells vs. PD-L1-/- CD25-depleted T cells, P = 0.2306; recipients of WT vs. PD-L1-/- T cells, P 〈 0.0001). (D) BALB/c mice transplanted with WT B6 or PD-L1-/- T cells. Mice were killed on d7 post-BMT and splenocytes were analyzed for LPAM-1, CCR9, and CXCR3 expression (not shown) on donor T cells. (E-F) BALB/c mice were transplanted with B6 Ly5.2 T cells plus PD-L1-/- T cells. Mice were killed on d3 post-BMT and splenocytes were analyzed for CTLA-4 and Lag-3 expression on donor T cells. Figure 1. PD-L1-/- vs. WT donor T cells lessen GVHD lethality, independent of donor Treg function. (A) Survival of BALB/c mice with WT B6 or PD-L1-/- T cells. (B) Survival of B10.BR mice with WT B6 or PD-L1-/- T cells. (C) Survival of BALB/c mice with WT B6 or PD-L1-/- T cells, or with WT B6 or PD-L1-/- CD25 depleted T cells (recipients of WT T cells vs. WT CD25-depleted T cells, P = 0.0003; recipients of PD-L1-/- T cells vs. PD-L1-/- CD25-depleted T cells, P = 0.2306; recipients of WT vs. PD-L1-/- T cells, P 〈 0.0001). (D) BALB/c mice transplanted with WT B6 or PD-L1-/- T cells. Mice were killed on d7 post-BMT and splenocytes were analyzed for LPAM-1, CCR9, and CXCR3 expression (not shown) on donor T cells. (E-F) BALB/c mice were transplanted with B6 Ly5.2 T cells plus PD-L1-/- T cells. Mice were killed on d3 post-BMT and splenocytes were analyzed for CTLA-4 and Lag-3 expression on donor T cells. Disclosures Aoyama: CHUGAI PHAMACEUTICAL CO.,LTD: Honoraria; Mochida Pharmaceutical Co.,Ltd: Honoraria; Kyowa Hakko Kirin Company,Limited: Honoraria. Milone:Novartis: Patents & Royalties, Research Funding. Miller:Coronado: Speakers Bureau; BioSciences: Speakers Bureau; Celegene: Speakers Bureau. Sharpe:Costim Pharmaceuticals: Patents & Royalties.

Abstract: More than 600 U.S. hemophilia patients have been genotyped as part of the pilot study for a prospective surveillance system for factor inhibitors conducted at 12 U.S. Hemophilia Treatment Centers. 80% of enrolled subjects had hemophilia A, 58% with severe disease, 24% moderate, and 18% mild. Age ranged from & lt;1 to 84 years. 83% were white, 8% black, and 4% Hispanic. In hemophilia A patients, all exons, all intron-exon junction regions, and the 3′ untranslated region of the factor VIII (F8) gene were resequenced in both directions by automated sequencer. The VariantSEQr™ protocol was used for resequencing on a 3730 DNA Analyzer from Applied Biosystems. The PCR primers and M13 sequencing primers are described at http://www.ncbi.nlm.nih.gov/sites/entrez?db=probe with a few modifications to the PCR primers to enhance throughput and reproducibility. Data were analyzed with SeqScape®. Inversions of intron 22 and intron 1 in the F8 gene were examined by PCR. Among 477 hemophilia A patients, missense mutations were found in 196 (41%), intron 22 inversions in 139 (29%), frameshifts in 50 (10%), nonsense mutations in 41 (9%), large deletions in 18 (4%), intron 1 inversions in 9 (2%), splice site changes in 5 (0.6%), and insertion in 1 (0.2%). Two mutations were identified in 4 (0.8%). No mutation was identified in 18 (4%). 124/139 of int22 inversions were reported to result in severe hemophilia, as well as 18/18 large deletions, 44/50 frameshifts, 37/41 nonsense mutations, and 8/9 int1 inversions. Of 196 missense mutations, 56 resulted in severe disease, 55 in moderate, and 80 in mild. History of inhibitor was reported in 79 patients, 22.4% of those with severe, 11.8% of those with moderate, and 2.4% of those with mild disease. Inhibitors occurred in 61% of those with large deletions, 26% of intron 22 inversions, 22% of nonsense mutations, 14% of frameshifts, 11% of intron 1 inversions, 6% of missense mutations, 20% of splice site changes, and 11% of those with no mutation identified. 173 distinct mutations were observed, 81 of which have not been reported previously in the Hemophilia A Mutation Database (HAMSTeRS). Among the patients enrolled in the study, black patients with hemophilia A were more likely to have a history of inhibitor than white patients (p=0.02). In hemophilia B patients, the promoter, coding regions, and intron-exon junctions of the factor IX (F9) gene were resequenced as above. Among 123 hemophilia B patients, 90 (73%) had missense mutations, 9 (7%) had frameshift mutations, 8 (7%) had nonsense mutations, and 3 (2%) had deletions. Two enrolled patients had history of FIX inhibitor, one with a large deletion and one a missense mutation. Centralized testing with high-throughput systems allows genotype to be used as a variable in ongoing studies of inhibitor risk. This project is supported by the CDC Foundation through a grant from Wyeth Pharmaceuticals, which had no role in data analysis or abstract preparation.

Abstract: Ex vivo fucosylation of cord blood cells improves their homing capacities, leading to faster neutrophil and platelet engraftments. This method is quick, safe, and does not require a GMP laboratory; therefore, it can be used widely.

Abstract: Umbilical cord blood (UCB) transplantation is potentially curative for acute leukemia. This analysis was performed to identify risk factors associated with leukemia relapse following myeloablative UCB transplantation. Acute leukemia patients (n = 177; 88 with acute lymphoblastic leukemia and 89 with acute myeloid leukemia) were treated at a single center. Patients received a UCB graft composed of either 1 (47%) or 2 (53%) partially human leukocyte antigen (HLA)–matched unit(s). Conditioning was with cyclophosphamide and total body irradiation with or without fludarabine. The incidence of relapse was 26% (95% confidence interval [CI], 19%-33%). In multivariate analysis, relapse was higher in advanced disease patients (≥ third complete remission [CR3] ; relative risk [RR], 3.6; P 〈 .01), with a trend toward less relapse in recipients of 2 UCB units (RR = 0.6; P = .07). However, relapse was lower for CR1-2 patients who received 2 UCB units (RR 0.5; P 〈 .03). Leukemia-free survival was 40% (95% CI, 30%-51%) and 51% (95% CI, 41%-62%) for single- and double-unit recipients, respectively (P = .35). Although it is known that transplantation in CR1 and CR2 is associated with less relapse risk, this analysis reveals an enhanced graft-versus-leukemia effect in acute leukemia patients after transplantation with 2 partially HLA-matched UCB units. This trial was registered at http://clinicaltrials.gov as NCT00309842.