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Abstract Background: Platelet transfusions are important for supporting patients with hematologic disorders. Refractoriness to platelet transfusions may lead to serious complications and pose a challenge to clinical management. A variety of laboratory strategies to optimize transfusion support in this population are being used; however, data on clinical correlation and success of these interventions is limited. We report the laboratory testing, transfusion yield, and clinical correlation in a cohort of patients receiving cross-matched platelet units. Methods: All consecutive adult patients refractory to platelet transfusions (failure to increment platelet count by 10 x 10(9) times two) with platelet crossmatch performed between June 2014 and April 2016 at our institution were included. Detailed clinical information, laboratory data of the crossmatch results, and Single Antigen Bead (SAB; Luminex) for each platelet unit cross-matched was retrospectively collected. Mean fluorescence intensity (MFI) of antibodies directed towards donor platelet HLA antigens identified through SAB were grouped into zones according to previously validated laboratory data: green zone (<4,000 MFI), yellow zone (4000-10000) and red zone (>10,000). Adequate transfusion yield was defined as an absolute increase of at least 10 x 10((9)/L platelets on a post-transfusion (i.e., within 1 hour) sample. Patients with major bleeding per International Society on Thrombosis and Haemostasis (ISTH) criteria, palpable splenomegaly, fever during transfusion, DIC, active sepsis, or antibodies directed against human platelet antigens were excluded from the final analysis. Importantly, the Hematologist and Pathologist were blinded to the other's data until collection was completed. Data analysis correlating adequate transfusion yield and laboratory parameters was performed. Results: 22 patients (72% female) met our study criteria. All patients had a hematologic malignancy with prolonged pancytopenia after chemotherapy, 4 (18%) had undergone allogeneic bone marrow transplantation. A total of 422 platelet cross-matches were performed, with 17 patients ultimately receiving 46 cross-matched units. The indication for transfusion was: prophylactic 35 (76%), bleeding 4 (9%) and peri-procedural 7 (15%). Ten (22%) transfusion events were excluded: splenomegaly 3, fever 4 and active severe bleeding 2. In one case a post transfusion platelet count was not performed. The overall success rate of transfusion was 64% (23/36). All transfusions leading to an adequate yield had a negative crossmatch. Of the 13 ineffective transfusions, 2 had a positive crossmatch. Based on single antigen MFI assignment, 26 (74%) donor units were classified as green zone, 8 (23%) yellow and 1 (3%) red. The success rates according to the single MFI zone assignment are presented in Table 1. These MFI-defined assignments were predictive of clinically successful transfusions. Conclusion: Selection of appropriate donor platelet units in refractory patients is a challenge that is managed in a variety of ways. While crossmatching is sometimes necessary, a strategy of antigen-avoidance can dramatically increase the identification of potentially effective platelet units for many patients. Understanding of how to navigate HLA antibody data is essential for identifying which HLA antigens should be avoided. Based on these data, in general, our practice is to avoid transfusing a platelet when there is a donor specific antibody of 8,000 MFI or greater. Furthermore, in our dataset there were two patients with both successful and unsuccessful transfusions after receiving crossmatch-negative units with green zone assignment. This finding highlights the limitations of laboratory testing and emphasizes the importance of post-transfusion platelet counts for continuously improving the platelet support of each immune-refractory patient. Disclosures No relevant conflicts of interest to declare.

Abstract Background Myelofibrosis (MF), polycythemia vera (PV), and essential thrombocythemia (ET) are myeloproliferative neoplasms (MPNs) whose associated disease burden includes a range of debilitating symptoms, thrombosis, hemorrhage, and shortened survival. To enhance patient care, it is important to understand the impact of MPNs in patients' lives; however, little is known regarding how these conditions affect patients' quality of life (QOL), activities of daily living, productivity, and emotional well-being. The US LANDMARK survey (Mesa et al. BMC Cancer 2016) captured data for US patients. Here, we present an interim analysis of results of another MPN LANDMARK survey conducted in the rest of the world. Methodology MPN LANDMARK survey is a cross-sectional survey of MPN patients across 6 countries (Australia, Canada, Germany, Japan, Italy, and UK). Patients completed an online questionnaire to measure MPN related symptoms experienced over the past 12 months and the impact of their condition on their QOL and ability to work. Additional questions related to employment productivity and activity impairment (including absenteeism and loss of productivity over the past 7 days). Patients included in this interim analysis had completed the survey by July 18, 2016, with enrollment continuing in all countries. Results Patients: Overall, 437 patients had completed the survey (98 MF, 121 PV, 218 ET). For MF and PV, the male to female gender split was relatively even (54% male for each), whereas an expected greater proportion of ET patients was female (70%). Patients with MF were significantly older than PV and ET patients (mean ages, 62, 59, and 55 years, respectively) and more had been diagnosed within 2 years of experiencing their symptoms (83% MF, 67% PV, 71% ET). MPN Symptoms (Table): Most patients (94%) experienced MPN-related symptoms in the past 12 months. The most commonly reported symptom among all subtypes was fatigue (69% MF, 62% PV, 73% ET), incidence of other common symptoms varied depending on disease subtype (MF: shortness of breath [38%], bruising [36%], night sweats [35%], early satiety [33%]; PV: night sweats [36%], trouble concentrating [36%], trouble sleeping [34%], dizziness [34%]; ET: trouble sleeping [37%], dizziness [37%], bruising [35%], night sweats [35%]). When asked which symptom patients would most like to have resolved, most patients preferred to have feeling of fatigue/tiredness improved across all disease subtypes (31% MF, 30% PV, 33% ET). Patients experienced an average of 6.4 symptoms at diagnosis but this progressed to an average of 7.6 symptoms since diagnosis after a median time of 6 years. QOL: A majority of patients indicated that they experienced a reduction in QOL due to MPN symptoms (87% MF, 71% PV, 73% ET) with 33% and 26% of MF and ET patients expressing that their condition has caused emotional hardship, and one-third of patients with PV reporting that they have felt worried or anxious about their disease (39%). MPN Impact on Activity/Employment: Patients reported a high impact on their ability to work, 12% reported voluntarily leaving their job, 10% had taken early retirement, 10% had moved onto disability living allowance, 8% moved to a lower paid job, and 2% experienced involuntary loss of work (Table). Of the patients who were in full-time or part-time employment at the time of the survey (MF [n=17]), PV [n=41], ET [n=98]), approximately, 40% had been absent from work within the past 7 days; this was the highest in MF patients (41% MF, 38% PV, 33% ET). On an average, over the past 7 days, MF patients had missed 3.1 hours from work, PV patients 2.3 hours and ET patients 2 hours. Across all subgroups, a substantial proportion of patients reported impairment in work (mean: 34% MF, 33% PV, 31% ET) and overall activity (mean: 46% MF, 42% PV, 39% ET). Conclusions This interim analysis from the MPN LANDMARK survey indicates that MPN patients experience a high burden of disease, including a high prevalence of symptoms, an increase in the number of symptoms from diagnosis and reduction of their emotional well-being, QOL, and ability to work. These results are consistent with those from the previous US LANDMARK survey with the addition of novel data on how MPNs impact work. When treating MPN patients, care should be taken in trying to manage a patient's disease burden, so as to minimize the impact on a patient's daily life. Further results from additional survey responses will be presented at the congress. Disclosures Harrison: Baxaltra: Consultancy, Honoraria, Speakers Bureau; Novartis: Consultancy, Honoraria, Other: travel, accommodations, expenses, Research Funding, Speakers Bureau; Gilead: Honoraria, Speakers Bureau; Incyte Corporation: Honoraria, Speakers Bureau; Shire: Honoraria, Speakers Bureau. Koschmieder:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Foltz:Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Koehler:Novartis Inc. (Germany): Consultancy, Other: Training. Komatsu:Shire: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Boothroyd:Novartis: Employment, Equity Ownership. Spierer:Novartis: Employment. Ronco:Novartis: Employment. Taylor-Stokes:Adelphi Real World: Employment. Waller:Adelphi Real World: Employment. Mesa:Celgene: Research Funding; Galena: Consultancy; Novartis: Consultancy; CTI: Research Funding; Ariad: Consultancy; Incyte: Research Funding; Gilead: Research Funding; Promedior: Research Funding.

Introduction Patients with inherited and acquired platelet disorders (PD) frequently present with thrombocytopenia and/or mucocutaneous bleeding. Diagnosis of PDs relies on both clinical and laboratory investigation, which encompasses both routine and esoteric platelet testing. The former includes platelet indices, light transmission aggregation (LTA) and platelet function analyzer (PFA-100). The latter includes platelet glycoprotein (GP) assessment by flow cytometry and platelet transmission electron microscopy (PTEM). Several recent studies have demonstrated limited sensitivities of routine platelet testing. It is uncertain if a combination of both routine and esoteric testing can vastly improve the sensitivity. Our goal is to assess the value of platelet esoteric testing and the ultimate sensitivity of laboratory platelet testing in diagnosing PDs. Methods Patients (between year 2012 and 2015) with a known or suspected inherited or acquired platelet disorders were recruited for platelet routine and esoteric testing. Patients' clinical features including ISTH bleeding assessment tool (BAT) scores, platelet count, LTA, PFA-100 ADP (CADP) and epinephrine (CEPI) cartridge closure times, GP expression by flow cytometry and PTEM were performed. All clinical and laboratory variables were collected and statistically analyzed. Results A total of 69 patients (51 females; median age 40 years; range: 8 months to 76 years) were enrolled to this cohort study. By retrospective chart review, 34 patients (49%) had a positive ISTH-BAT score (range 0 to 16). The most common bleeding manifestations (on any degree of severity) were cutaneous bleeding present in 53% of patients (n=37), menorrhagia in 47% of females (n=24), epistaxis in 36% (n=25) and postoperative bleeding in 35% (n=24). Joint, muscle and CNS hemorrhage were the least frequent with 7%, 6% and 1% of patients reporting bleeding in these sites. A total of 22 patients (32%) had thrombocytopenia at the time of their evaluation. Fifty-eight patients (84%) had platelet aggregation studies and of those 15 (26%) had an abnormal study. PFA-100 was performed in 57 patients (83%) of whom 42% (n=24) had prolonged closure times with either ADP or epinephrine. PTEM was performed on all samples. Twenty-seven patients (39%) had abnormal platelet structure including 17 patients who had dense granule deficiency. GP by flow cytometry was performed in 41 patients (59%) and abnormal glycoprotein expression was detected in 6 patients (15%). Of the 55 patients who had all tests performed, 22 patients (40%) had completely normal results. Of the routine tests, only PFA-CEPI or -CADP prolongation is associated with the likelihood of a PTEM abnormality (P<0.005). With the assistance of molecular testing, there were 2 cases of MYH-9 mutation-related platelet disorders, one of RUNX1 mutation-associated thrombocytopenia, one of York platelet syndrome, two of Bernard Soulier variants, one of Quebec syndrome and three of gray platelet syndrome or variants. Bleeding scores showed no statistically significant association with severity of any laboratory abnormalities. Conclusion In this cohort, the sensitivity of routine platelet testing in clinically suspected PDs is about 30-40%. Addition of platelet esoteric testing improves the sensitivity to 60%. However, the degree of platelet laboratory abnormalities do not predict severity of bleeding. The findings of this cohort underscore the importance of clinical assessment and both platelet routine and esoteric testing in investigation of patients with suspected PDs. Disclosures No relevant conflicts of interest to declare.

Abstract BACKGROUND: Complement-mediated thrombotic microangiopathies (TMAs) are a subset of TMAs in which the thrombocytopenia, microangiopathic hemolytic anemia, and end organ damage are caused by mutations in genes encoding the alternative complement pathway. Numerous complement genes have been implicated in complement-mediated TMAs including complement factor H (CFH), CD46 (MCP), complement factor I (CFI), complement component 3 (C3), complement factor B (CFB), factor H related 5 (CFHR5), and thrombomodulin (THBD) among others. Genetic analysis typically yields a mutation in 60% of patients whose TMA is presumed to be mediated by complement dysregulation. However, the description of novel disease-associated variants may increase this proportion. METHODS: A retrospective study of patients with TMAs diagnosed between 2000 and 2014 was performed. TMA diagnosis was made based on thrombocytopenia and evidence of microangiopathic hemolytic anemia. Analysis was performed with Alamut¨ software with additional in silico prediction tools (SIFT, MutationTaster, and Polyphen) for classification of gene variants. Variants of unknown significance (VUS) and likely pathogenic variants were further assessed using several mutation databases, including HGMD, ClinVar, and Factor H database RESULTS: Of patients diagnosed with a TMA, genetic analysis was performed in only a 10% of patients. Of the 29 patients with genetic studies performed, mutations were identified in 18 patients (62%). The majority of the mutations had been described previously in the literature, but four novel variants were identified: three missense and one splice-site. The table below summarizes these variants as well as laboratory findings on presentation. These were two variants of CFH, one variant of CFHR5, and one variant of CFI. In silico modeling of these variants revealed two polymorphisms likely to be pathogenic, one polymorphism likely benign given the lack of predicted splicing changes, and one VUS. Table 1. Protein Mutation Classification Age Sex Hemoglobin (g/dL) Platelets (thousands) Creatinine (mg/dL) CFH c.245-10_245-9dup Likely benign 61 F 11.6 51 6.7 CFH c.476G>A, p.Ser159Asn Likely pathogenic 43 F 9.1 101 9.1 CFHR5 c.1412G>A p.Gly471Glu Likely pathogenic 30 F 9.8 129 4.9 CFI c.1190T>A p.Val397Glu Unknown significance 51 M 9.4 125 6.1 DISCUSSION: With therapy available to target the alternative complement pathway, genetic analysis to identify genetic variants capable of causing complement mediated TMAs is an essential part of the evaluation. This genetic data must be interpreted and correlated with functional analysis and clinical phenotype. The reporting of novel variants in clinical databases, with inclusion of relevant clinical findings, is necessary to accurately classify and verify variants as pathologic mutations or benign polymorphisms. The full understanding of this diverse disease requires a more complete understanding of its genetics. While complement pathway-directed therapies are available, their rational use requires thorough interpretation of laboratory data, including genetic analysis. Disclosures Murray: Mayo Clinic: Patents & Royalties: Patent Application Filed.

Abstract Next-generation sequencing (NGS) has revealed new insight into the complexity of clonal and subclonal architecture of multiple myeloma (MM). The introduction of targeted studies allows the detection of mutations with very low allele frequencies at affordable price. However, there is few information about the prognostic impact of this mutational profile in series of homogeneously treated MM patients. In this study, we analyzed the most frequently mutated genes in MM from patients included in a randomized clinical trial applying the highest read depth to date. We performed a correlation study between our results and cytogenetics aberrations and clinical outcomes. We used Ampliseq Library Kit 2.0 to target 77 genes (M3Pv2.0 panel) related to critical pathophysiological pathways, associated to drug resistance or targetable with molecular drugs in MM. We sequenced DNA (15ng) from CD138+ purified plasma cells from 80 MM patients at diagnosis included in GEM2010MAS65 clinical trial. We sequenced at an average read depth of 1500X and using Ion Proton sequencer (Thermo Fisher, USA, PaloAlto, CA). We used Ion Reporter software applying in-house modifications in call variants process. We also sequenced DNA from CD138 negative population in 30% of patients in order to filter out potential artifacts and stablish conditions for excluding germline variants. We first fitted a cox-proportional hazard model to predict survival and a second approach using a penalized regression LASSO. We identified 137 gene mutations in the 80 patients analyzed, 54 mutations were predicted pathogenic by Shif and Poliphen and 65 have been described in COSMIC database. 85% of patients harbored at least 1 mutation. The most frequently mutated genes were KRAS (16%), DIS3 (15%), NRAS (13%), BRAF (6%), and TP53 (5%), accounting for the 54% of the total number of mutations. The most frequently mutated pathways were RAS and NFKB in 34% and 28% of patients respectively. Mutational allele frequency for KRAS, BRAF and TP53 was, in all cases, lower than 50% while DIS3 showed mutations in a broad range (from 2 to 85%). Only one patient presented one mutation in NRAS at 73 % of allele frequency. For patients with more than one mutation, two different scenarios have been found. Some patients showed several genes mutated in a similar allele frequency values. On the contrary, a complex subclonal structure was confirmed in 3 patients, with mutations at very different clonal frequency. CD138 negative fraction was sequenced to confirm that these mutations were exclusive of plasma cells. The first of them had two mutations in DIS3 at 8 and 53% of allele frequency, second in KRAS and DIS3 at 13 and 63% respectively and the third in NRAS and IFNGR2 at 5 and 37% respectively. We found no differences in the survival based on pathway, mutational allele frequency or number of mutations. We also investigated pairwise associations between events and we not found significant correlations (Figure 1). Cox-proportional hazard model only showed a negative impact in survival of patients with TP53 mutations. This ultra-deep targeted sequencing strategy is able to detect mutations in most of patients, at very low allele frequency and using a minimal amount of DNA. Despite of its huge capacity to detect mutations, we have not identified new prognostic factors in MM patients treated with highly efficient therapies. However, this study again confirms the complexity of the genomic landscape of MM and the great heterogeneity between patients. The role of theses mutations at relapse as well as in the subsequent treatment effectiveness remains unknown and should be preferably investigated in larger cohorts of homogeneously treated MM patients. Figure 1 Figure 1. Disclosures Martínez-López: Novartis: Honoraria, Speakers Bureau. Oriol:Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Stewart:celgene: Consultancy.

Abstract Background Congenital/hereditary qualitative platelet disorders (CQPD) can be classified by platelet count (eg, normal or decreased) and platelet size as well as by functional defect. Based on mean platelet volume (MPV), congenital thrombocytopenias (CT) are classified as macro-thrombocytopenias (eg, Bernard-Soulier syndrome [BSS], MYH-9 [myosin heavy chain 9, non-muscle]-associated thrombocytopenias, gray platelet syndrome [GPS], etc.); microthrombocytopenias (eg, Wiskott-Aldrich syndrome and variants); and those with normal platelet size. CQPDs with normal platelet count include Glanzmann thrombasthenia (GT), dense granule storage pool disorders (DG-SPD) including Hermansky-Pudlak syndrome (HPS), platelet secretion disorders and many others. Diagnosis has relied on platelet counting and sizing, blood smear light microscopy, platelet aggregation (agg) and platelet function analyzer (PFA-100) studies. Platelet transmission electron microscopy (PTEM) and flow cytometry can provide supplementary information and molecular analysis is also evolving. The objective of this study was to determine the roles of platelet transmission electron microscopy (PTEM) and flow cytometry in the diagnosis of CQPD and CT. Methods In this retrospective cohort study, after IRB approval, the electronic medical record system was queried for patients (pt) with a confirmed CQPD or CT seen at Mayo Clinic between 2000 and 2015. A detailed chart review was undertaken. Results 54 pt (64% female) met our study criteria; median age was 32 years (range 1 day to 81 years). 18/54 (33%) pt had macrothrombocytopenia: BSS 4 (7%); MYH-9 10 (19%); gray platelet syndrome 4 (7%). 36/54 (66%) had normal MPV: Glanzmann thrombasthenia 6 (11%); storage pool disorders including DG-SPD 10 (19%) and HPS 2 (3%), mild alpha granule deficiency 3 (6%) and York platelet syndrome 4 (7%); platelet secretion disorders 4 (7%); ANKRD26 mutation 3 (6%); congenital amegakaryocytic thrombocytopenia 1 (2%); GATA-1 mutation 1 (2%); RUNX-1 mutation 1 (2%); and Jacobsen syndrome 1 (2%). 44 pt (81%) had a positive bleeding history: epistaxis 52%, cutaneous bleeding 57%, gastrointestinal bleeding 21% and menorrhagia 54%; 10 pt (19%) had a negative bleeding history. Results of standard and esoteric platelet testing are summarized in Table 1. Diagnosis in the 10 pt with glycoprotein deficiency (BSS or GT) was established by agg; flow cytometry was confirmatory but not necessary. Of the 23 pt with SPD, 5 had a negative bleeding history; 4 pt had normal agg and PFA-100 and were diagnosed exclusively by PTEM. In this group, the abnormalities on platelet aggregation and PFA were variable and PTEM allowed for a better definition of the specific abnormalities. For MYH-9 patients, PTEM confirmed leukocyte inclusions that had already been identified on light microscopy. PTEM was the only diagnostic modality able to identify the abnormality in York platelet syndrome. In 5/54 (9%) genetic testing was necessary for diagnosis (GATA-1, ANKRD26 and RUNX-1) Conclusion In this cohort, standard platelet assays established the diagnosis in the large majority of CQPD and CT. PTEM was essential for confirmation in DG-SPD, mild alpha granule deficiency and York platelet syndrome and useful in combination with molecular testing to establish a diagnosis in selected cases. Guidance on selection of patients for such specialized testing requires further study. Table 1. Results of standard and esoteric platelet testing for 54 patients with congenital qualitative platelet disorders and/or thrombocytopenia Disorder n (%) Platelet aggregation PFA PTEM Flow cytometry Confirmation by genetics Done Abnormal Done Abnormal Done Abnormal Done Abnormal Glanzmann thrombasthenia 6 (11) 6 6 5 5 1 0 3 3 0 Bernard-Soulier syndrome & variants 4 (7) 4 4 4 4 3 0 4 4 0 MYH-9 related disorders 10 (19) 7 2 8 3 5 5 4 2 5 Dense granule deficiency and HPS 12 (22) 12 8 12 8 12 12 4 0 0 Alpha granule deficiency* 7 (13) 7 4 7 6 7 7 4 4 1 York platelet syndrome 4 (7) 1 0 1 1 4 4 1 1 0 TXA2 or PG synthesis/receptor defect 4 (7) 4 4 4 3 3 0 3 0 0 CATM 1 (2) 0 - 0 - 0 - 0 - 1 ANKRD26 3 (6) 3 3 3 2 3 3 3 3 3 GATA-1 1 (2) 0 - 1 1 1 1 1 1 1 RUNX-1 1 (2) 1 0 1 1 0 - 0 - 1 Jacobsen syndrome 1 (2) 1 0 1 1 1 1 1 0 1 MYH-9: myosin heavy chain 9, non-muscle (MHY-9) associated thrombocytopenia, HPS: Hermansky-Pudlak Syndrome, TXA2: thromboxane A2, PG: prostaglandin CATM: congenital amegakaryocytic thrombocytopenia. * Includes gray platelet syndrome Disclosures Pardanani: Stemline: Research Funding.

Abstract Background: While Factor V Leiden is associated with an increased risk of thrombosis, the magnitude of that risk among homozygous carriers is uncertain. Methods: In a cross-sectional study of Mayo Clinic patients referred to the Special Coagulation Laboratory for a thrombophilia profile (n=379) over the 18-year period, 1996-2013, the prevalence of venous and arterial thrombosis was estimated for patients found to be Factor V Leiden carriers based on leukocyte genomic DNA genotyping. T tests and chi-square tests were used for continuous and categorical variables, respectively. Results: Among homozygous (n=111) and heterozygous (n=268) carriers, the mean age at testing (50.3 and 50.5 years, respectively; p=0.9) and the proportion of females (50% and 54%, respectively; p=0.5) did not differ significantly. Of 29 asymptomatic carriers at the time of testing, 14 were homozygotes. Of the remaining 350 carriers, the mean age at first venous or arterial thrombosis (42 vs 43.8 years; p=0.5) among homozygous and heterozygous carriers, respectively, did not differ significantly. Thirty-five (33%) and 83 (31%) homozygous and heterozygous carriers, respectively, had at least one recurrent venous or arterial thrombosis (p=0.72). The prevalence of deep venous thrombosis (DVT) was 61% and 46% in homozygous and heterozygous carriers, respectively (p=0.008); the prevalence of pulmonary embolism was 18% and 20%, respectively (p=0.69). The prevalence of arterial thrombosis (mainly stroke and/or TIA) was higher in heterozygous (23%) compared to homozygous carriers (8%). Conclusion: In the largest sample of homozygous Factor V Leiden carriers reported to date, thrombosis penetrance and phenotype did not appear to differ among homozygous vs. heterozygous carriers with the exception of a higher prevalence of DVT among homozygous carriers. These data should be interpreted with caution due to the potential for referral bias. Disclosures No relevant conflicts of interest to declare.

Abstract Acute lymphoblastic leukemia (ALL) in adolescents and young adults (AYA) is characterized by distinct presenting features and inferior prognosis compared to pediatric ALL. Age, as a continuous variable, is negatively correlated with prognosis, in spite of risk-adapted combination chemotherapy. To better understand the etiology of ALL in this age group, we performed the first genome-wide association study (GWAS) to comprehensively examine germline single nucleotide polymorphisms (SNPs) for their association with susceptibility to B-ALL in AYAs. In the discovery GWAS, we compared genotype frequency at 635,297 SNPs between 308 AYA ALL cases (age 16-39 years, treated on the Children’s Oncology Group [COG], the Alliance-Cancer and Leukemia Group B, Eastern Cooperative Oncology Group, MD Anderson Cancer Center, and St. Jude Children’s Research Hospital trials) vs. 6,661 non-ALL controls. The association between genotypes at each SNP and ALL susceptibility was tested by using a logistic regression model after adjusting for genetic ancestries to control for population stratification. SNPs that reached P≤ 5×10-8 in the discovery GWAS were tested in an independent cohort of 82 AYA ALL cases from the COG protocols and 5,755 non-ALL controls. We identified a single genome-wide significant susceptibility locus on 10p14 signified by two SNPs within the GATA3 gene: rs3824662, P=2.8x10-10, odds ratio (OR)=1.77; rs3781093, P=3.2x10-9, OR=1.73, both of which were validated in the replication cohort (P=1.9x10-8 and P=4.3x10-5, respectively). We also examined the association signals in AYAs for susceptibility loci previously identified in pediatric ALL: ARID5B, IKZF1 and PIP4K2A variants were nominally significant in AYAs in the discovery GWAS and/or in the replication analysis, whereas CEBPE or CDKN2A/CDKN2B were not significant. These results imply both similarities and differences in genetic predisposition to ALL between children and AYAs. At the GATA3 locus, rs3824662 risk variant was over-represented in Philadelphia chromosome (Ph)-like ALL in AYAs (P=0.02), confirming our previous report of Ph-like ALL susceptibility variants in GATA3 (Nat Genet 45:1494). Importantly, even after excluding Ph-like cases, rs3824662 remained associated with the risk of developing ALL in AYAs, suggesting that the influence of the GATA3risk variant on ALL susceptibility in AYAs extends beyond the predisposition to Ph-like subtype. We next examined the relationship between GATA3 risk allele frequency and age at diagnosis in a cohort of unselected childhood and adolescent ALL cases enrolled in the COG P9900 protocols (N=1,827). Dividing patients into four consecutives age groups (<5, 5-10, 10-15 and >15 years), we observed a clear progressive increase in the risk allele frequency at rs3824662 (P=6.29×10-11) with increasing allelic odds ratio (i.e. relative risk of ALL conferred by each copy of the risk allele). This correlation between genotype and age was evident regardless of genetic ancestry, although the risk variant was more common among individuals with higher Native American ancestry. In contrast, the frequency of ALL susceptibility variant in ARID5B decreased progressively with increasing age at diagnosis (P=0.006), whereas PIP4K2A, CDKN2A/CDKN2B, IKZF1 and CEBPE variants were not related to age. Finally, we compared rs3824662 risk variant frequency by age in the COG P9900 protocols after stratifying the ALL cases into TCF3-PBX1, ETV6-RUNX1, hyperdiploid, MLL-rearranged and B-other. There was a trend that the risk allele was more frequent in cases older than 16 years compared to those below 16 in the five subtypes examined. In conclusion, we have identified inherited GATA3 genetic variants that strongly influence ALL susceptibility in adolescent and young adults, indicating potential age-related differences in ALL biology. Disclosures No relevant conflicts of interest to declare.

INTRODUCTION: While esophagectomy is the standard treatment for submucosal (T1b) esophageal adenocarcinoma (EAC) and squamous cell cancer (SCC), many elderly patients -the age group that esophageal cancer tends to affect- are not candidates for surgery. Endoscopic submucosal dissection (ESD) is a minimally invasive procedure that allows for en-bloc resection of early esophageal cancer and allows for precise histopathologic staging of the tumor. ESD could be curative in submucosal cancer without lymph node metastasis, and it allows for precise histopathologic staging. To evaluate the long-term outcomes of ESD in patients with EUS-staged T1b esophageal cancer. METHODS: A retrospective multicenter study was performed at three academic hospitals in the U.S. Patients who underwent ESD with a pre-procedural or post-procedural histopathologic diagnosis of T1b N0 M0 EAC or SCC were included in the study. Data was collected on demographics, tumor and procedure characteristics, procedure pathology, and follow-up. Local recurrence was confirmed by endoscopic findings and pathological analysis. Metastasis was confirmed by cross-sectional imaging. The main outcome was a composite of rate of metastasis and local recurrence. Follow-up time was defined as months from initial procedure to recurrence or last follow-up visit if recurrence-free. A time-to-event analysis was performed to evaluate recurrence. RESULTS: Fifty-two patients underwent ESD (mean age 69.6 years +/-9; 35 males) (Table 1). Based on available comorbidity data, 42% patients were not fit for surgery, as determined by an age-adjusted Charlson Comorbidity Index > 6. Twenty tumors (62%) were found to be HGD or T1a on post-ESD specimen analysis, while one was staged as T2. Nineteen patients were staged as T1b after ESD. Immediately after ESD, 6 patients were referred for surgery, 3 underwent chemoradiation therapy, and 6 radiation alone (Table 2). Patients were followed for a median of 18 months, and the calculated 24-month recurrence rate was 13% (Figure 1). CONCLUSION: This multicenter trial showed that ESD for T1b esophageal cancer can be acceptable for patients who deemed not surgical candidates. However, close follow up is necessary. ESD can also serve as a staging procedure, as our data confirms inaccurate EUS-staging of T1b cancer, with 62% of tumors being down-staged to T1a, as has been previously reported.

INTRODUCTION: The difference in long-term outcomes of endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) for Barrett’s related superficial neoplasia remains unclear. We aimed to compare the rates of local and metachronous recurrence of ESD and EMR in patients with clinically staged BE-associated high-grade dysplasia (HGD) and T1a esophageal adenocarcinoma (EAC). METHODS: Multicenter study at six academic hospitals in the U.S. including patients who underwent ESD for BE-HGD or T1a EAC. Primary outcome was a composite of metastasis and local recurrence rate. A time-to-event analysis was performed to evaluate recurrence. A Kaplan-Meier plot was constructed, and a log-rank test was used to compare the groups. A Cox hazard ratio regression analysis was performed to identify predictors of recurrence. RESULTS: A total of 241 patients were included. 154 underwent EMR, while 84 underwent ESD (Table 1). ESD had higher en bloc (96% vs 33%, P < 0.0001), R0 (76% vs 54%, P = 0.0009) and curative resection rates (75% vs 32%, P < .0001) when compared to EMR. The 24-month local recurrence rate for EMR and ESD was 43% and 11%, respectively ( P = 0.0007) (Figure 1). Significantly more endoscopic resection procedures were required to treat recurrence after EMR compared to after ESD (Table 1). EMR, piecemeal resection, positive margins, and non-curative resection were identified as predictors of recurrence on univariate analysis. En bloc resection remained significant after multivariate analysis (Table 2). CONCLUSION: This multicenter study showed that ESD results in more definitive treatment of BE-associated early neoplasia than EMR, with significant lower recurrence rates and less need for repeat endoscopic therapeutic procedures than EMR.