He, Rong

Abstract Introduction: The revised international prognostic scoring system (IPSS-R) for myelodysplastic syndrome (MDS) is widely accepted and has been validated in multiple studies. Patients with adverse cytogenetics do poorly and that is reflected in this scoring system by having the highest score for cytogenetics; 2 for intermediate, 3 for poor and 4 for very poor. Little is known about the effect of marrow blasts in adverse cytogenetic in the high-grade MDS defined by IPSS-R intermediate (>3), high (>4.5) and very high (>5). The goal is to examine the effect of marrow blast percentage on outcome in patients with adverse cytogenetics that is present in the high-grade MDS. Methods: We performed data collection from the Mayo clinic records for patients with confirmed MDS after obtaining appropriate IRB approval. Patients were divided based on their total IPSS-R score and we extracted high-grade MDS cases with intermediate, high and very-high IPSS-R only. Cytogenetics and baseline CBC were available for analysis. We calculated the survival difference in patients with blasts <5% and patient with blasts of 5% to 19% for every group. Survival estimates were calculated by Kaplan-Meier method and compared by log-rank testing using JMP v.13. Results: Our database had 1300 patients with confirmed MDS, 41% (N=536) are high-grade MDS. From those, the median age was 70 and 70% were males. Median bone marrow blast was 6% (0-19). Baseline hemoglobin is 9.2 g/dL, WBC 2.7, ANC 1.05, and platelets 69. Their cytogenetics were 1% very good, 31% good, 23% intermediate, 16% poor and 29% very poor. The total IPSS-R groups were 39%,31%, and 30% for the intermediate, high, and very-high groups respectively. The overall survival (OS) for the high-grade MDS with marrow blast <5% was 12.3 months and for patients with marrow blasts ≥5% 11.4 months (P=.4). At each high-grade MDS; intermediate, high and very high, there were no statistically significant differences for patients with marrow blasts below or above 5%. In term of risk of progression to AML, patients with blasts ≥5% were at higher risk of progression compared with <5% (25% vs 10% , P<.001), with no statistically significant difference in term of time-to-AML progression. Conclusion: The percentages of bone marrow blasts had no impact on overall survival among patients with high grade MDS. However, patients with ≥5% marrow blasts are at a higher risk for progression to AML. Disclosures Al-Kali: Novartis: Research Funding.

Abstract Background: Acute myeloid leukemia (AML) is an aggressive blood cancer with a wide range of response and relapse rates using standard chemotherapy combining anthracycline plus cytarabine (7+3). The stem cell receptor tyrosine kinase KIT is expressed on more than 10% of blasts in 95% of relapsed AML cases and mediates leukemic proliferation and has anti-apoptotic effects (Domen and Weissman 2000). AML with high KIT expression is associated with poorer outcome (Del Poeta, Venditti et al 2003). Goals: To study the efficacy and safety of combination 7+3 and nilotinib in patients (pts) with AML and KIT expression. Primary goal is to determine the complete response (CR) rate; while secondary goals include 2-year overall survival (OS) and disease free survival (DFS) in addition to safety. Methods: A single arm, Phase II study, enrolled pts at Mayo Clinic (MN and AZ). Appropriate IRB was obtained and study was registered (NCT 01806571). Pts were enrolled if they were newly diagnosed with AML with KIT (CD117) expression of ≥ 20% on myeloblasts by flow cytometry. KIT mutations were allowed. Nilotinib 300 mg twice daily was given on days 4-14 of induction and consolidation; and continuous daily maintenance therapy for up to 2 years. Cytarabine 100 mg/m2/day continuous IV x7 days plus daunorubicin 60 mg/m2 IV daily x3 days were used for induction, while consolidation used standard cytarabine 3 gm/m2 twice daily days 1, 3, 5 for a total of 4 cycles. This is a Simon 1-stage design with a safety analysis after enrolling 12 pts, and an interim analysis after enrolling 18 out of 43 pts (Al-Kali, ASH 2015) recommended to continue study accrual. Results: i)- Demographics: Thirty four pts were enrolled from July 2013 to June 2017. Median age was 59 years (range 24-69) with 71% being male. Median laboratory findings include hemoglobin of 8.8 gm/dL, platelets of 56 x109/L, white blood count of 3.3 x109/L (0.4-125), and peripheral blood blasts 17 %(0-94%). Cytogenetics were normal in 43% of the pts and favorable cytogenetics were seen in 6%(inv 16). FLT3 gene testing was done on 26 pts and was positive in 13%. KIT gene sequencing (exon 8, 9, 10, 11, 17) revealed pathogenic mutation in 1/28 cases (4%). ii)- Clinical outcome Out of all 34 pts enrolled on the study, 18 (53%) achieved CR (or CR with incomplete platelet recovery) with a median CR duration of 21.8 months. Of 26 evaluable pts, the overall CR rate was 69%. 4 of the 18 pts (22%) who achieved remission needed a second induction. One pt died due to liver failure (had only one dose of nilotinib and toxicity was attributed to daunorubicin). 13 (38%) pts proceeded to allogeneic stem cell transplant (HSCT), 12 of whom are alive and none were able to initiate nilotinib maintenance. Only 6 (1 had HSCT) out of 34 (18%) pts relapsed after achieving CR. Median DFS was 45.8 months, while median OS was 42.4 months. 2-year DFS and OS were 58% and 72%, respectively. iii)- Safety Thirty four pts were evaluated for adverse events (AE). Fourteen pts had G4 non-hematological AEs, including fourteen G4 AEs related to infection, 2 with electrolyte imbalances, 1 heart failure, 1 elevated bilirubin, 1 elevated lipase, and 1 jejunal hemorrhage. One patient had G5 liver failure. Most common (>20%) G3 non-hematological AEs were febrile neutropenia (56%), hypophosphatemia (21%), elevated ALT (21%) and hypertension (21%). Conclusion: Combination daunorubicin and cytarabine with nilotinib (DATA) appears to be safe and effective. Final results show an acceptable safety profile with most common AE being infection. Thirty day mortality was low (3%). DATA regimen has comparable CR rates of 53% (intent to treat) and 69% in evaluable pts. Relapse rates were very low at 18% with durable responses and encouraging survival rates. Figure. Figure. Disclosures Al-Kali: Novartis: Research Funding. Tibes:Novartis: Research Funding. Palmer:Novartis: Research Funding.

Abstract Background : Pre-treatment determinants of survival in adult acute myeloid leukemia (AML) include performance status, age, karyotype, the distinction between primary and non-primary AML and FLT3-ITD/NPM1 mutational status. Current literature on AML natural history and risk factors is often based on information derived from stringent protocol studies. In the current series of 1,123 adult patients seen at the Mayo Clinic between 2004 and 2017, we examined long-term survival specified by a number of primarily established risk factors. Methods: Diagnosis of AML and its sub-classification was according to World Health Organization criteria. Study subjects were recruited from the Mayo Clinic AML database. Conventional response criteria were used for CR and CRi assignment; the latter met all criteria for CR with the exception of platelet count <100 x 109/l or absolute neutrophil cunt <1 x 109/l. Standard statistical methods were used for analysis of overall survival, calculated from the initial diagnosis of AML to date of death or last follow-up; analyses were performed both in the absence and in the presence of censoring of survival at time of allogenic stem cell transplant (ASCT). The JMP® Pro 13.0.0 software from SAS Institute, Cary, NC, USA, was used for all calculations. Results: 1,123 adult patients (median age 65 years, range 18-94; 61% males) with non-APL AML were considered; 61% were age >60 years. 351 (31%) patients were seen between 2004 and 2009 and 772 (69%) between 2010 and 2017. AML subcategories were primary (56%), post-myelodysplastic syndromes (post-MDS; 24%), therapy-related (10%), post-myeloproliferative neoplasm (post-MPN; 8%) and post-MDS/MPN (3%). Cytogenetic risk distribution, according to the European LeukemiaNet classification, was favorable in 47 (4%), intermediate in 650 (58%) and adverse risk in 426 (38%) patients. FLT3, NPM1 and CEBPA mutation information was available in 462 (24% mutated), 393 (27% mutated) and 228 (11% mutated) patients, respectively. Treatment included intensive chemotherapy (IC) in 766 (68%) patients, less aggressive chemotherapy, including the use of hypomethylating agents in 144 (13%) and supportive care alone in 213 (19%) patients. ASCT was utilized in 258 (23%) cases, almost all performed after achieving CR/CRi. Complete remission (CR) and CR with incomplete count recovery (CRi) were listed in 333 (30%) and 248 (22%) patients, respectively; the corresponding rates in IC-treated patients were 43% and 32%. Almost all cases of CR/CRi occurred in IC-treated patients; 2 (1.4%) CRs were listed for less aggressive chemotherapy. After a median follow-up of 11 months, 798 (71%) deaths were recorded. Median survival for all 1,123 patients was 14 months with 1-, 3- and 5-year survival rates of 54%, 29% and 23%, respectively; a slight but significant (p=0.01) improvement in survival was apparent in more recent years (Figure 1a). Figures 1b, 1c and 1d depict analysis stratified by AML subcategories, treatment received and response obtained, respectively. Similarly, figures 2a, 2b and 2c depict analysis stratified by karyotype, use of ASCT and age. Multivariable analysis of pre-treatment parameters evaluable in all 1,123 patients identified age >60 years (HR 2.2, 1.9-2.6), adverse karyotype (HR 2.9, 1.9-4.9), intermediate-risk karyotype (HR 1.6, 1.02-2.6), post-MPN AML (HR 1.9, 1.5-2.4) and other secondary AML (HR 1.3 (1.1-1.6), as risk factors for shortened survival; the inclusion in the model of FLT3/NPM1 mutational status in 392 informative cases confirmed the adverse prognostic effect of age >60 years (HR 1.8, 1.4-2.5), adverse karyotype (HR 3.7, 1.4-15.3), post-MPN AML (HR 2.8, 1.6-4.6), other secondary AML (HR 1.4, 1.0-1.9) and FLT3+NPM1- (HR 2.8, 1.6-4.9) and FLT3-NPM1- (HR 1.7, 1.2-2.7) profile. Results were unchanged when survival was censored at time of ASCT. Additional prognostic interaction with treatment strategy and ASCT is further elaborated in an accompanying abstract to be presented. Conclusions: The current study, the largest coming from a single institution, provides practically useful information that should assist with patient consultation on AML prognosis and treatment. The study confirms the primary prognostic importance of age, karyotype and FLT3/NPM1 mutational status, in real-life practice. Novel observations included comparable value of CRi vs CR and the particularly worse prognosis associated with post-MPN AML. Disclosures Al-Kali: Novartis: Research Funding.

Abstract Background:Recurrent mutations in ATM, JAK1/3 and STAT5B genes have been identified in T-cell prolymphocytic leukemia (T-PLL), a mature T cell leukemia with poor survival. However, much remains to be understood regarding the dysregulated pathways involved in the pathogenesis of this aggressive disease. Here, we integrated the analyses of whole exome sequencing (WES) and transcriptomes of a cohort of 12 T-PLL samples to gain further insights into molecular mechanisms of this malignancy. Methods: Leukemic cells were isolated from peripheral blood or bone marrow samples of T-PLL patients. Tumor DNA and RNA, and germline DNA were extracted from purified leukemic T cells and bone marrow derived stromal cells, respectively. WES (n=12) and transcriptome analysis (n=10) were performed and data analyzed with published standard methods (Robinson et al. 2010 and DePristo et al. 2011) Results: 7 paired tumor and germline DNA and 5 tumor-only DNA samples were used for WES analysis. Mutations in ATM and TET2 were detected in 4 (33%) and 1 (8%) patients, respectively. JAK3 (p.M511I, p.Q501H and p.Q503H) or STAT5B (2 p.T628S and 1 p.N642H) mutations each occurred in 3 (25%) cases and were mutually exclusive, consistent with prior reports. Importantly, we found several novel mutations in genes with regulatory roles in the NOTCH signaling pathway. Specifically, 2 somatic mutations p.A3V and p.A3S in NOTCH2 and 2 other mutations (p.S244L and p.A1414V) in NOTCH4 were identified in 4 (33%) patients. One mutation was in the EGF- like and another one in the NODP domain critical for NOTCH-mediated cellular differentiation. Two (16.7%) novel missense mutations (p.G174D and p.V836I) were found in MAML2. Three missense mutations (2 p.S583N and 1 p.R190H) occurred in MAML1. Both MAML2 and MAML1 are essential cofactors of the NOTCH signaling pathway. In addition, a somatic mutation in the NOTCH signal regulator DTX2 (p.G268D) was detected. Altogether 7 (58.3%) patients harbored mutations in genes with a regulatory role in the NOTCH pathway. Among the epigenetic modifiers, we found deletions and point mutations in KDM6B and KDM6A in 4 (30%) patients including 2 codon deletions in KDM6B (p.X751Val) and 1 missense mutation each in KDM6B (p.R1016Q) and KDM6A (p.V510G). KDM6A and KDM6B are histone H3 lysine 27 demethylases known to be involved in regulation of DNA repair and play an important role in embryonic differentiation. Transcriptome analyses of 10 T-PLL cases versus normal CD3+ T cells from 5 healthy donors revealed 706 up-regulated and 655 down-regulated genes. Consistent with prior data, TCL1A and TCL1B were significantly overexpressed (23.7 and 13.1 fold, respectively). Using Ingenuity Pathway Analysis, we found PTEN Signaling, glutamate receptor, and axonal guidance signaling to be among the top 3 upregulated pathways. The top upstream regulators implicated for the up-regulated signals were FGF, Wnt/β-catenin and TNF. The top 3 down-regulated pathways were granulocyte adhesion and diapedesis, IL-17A in psoriasis and IL-10 signaling. The top regulators for the down-regulated pathways were LPS, TNF and IFNg. Wnt/β-catenin and Human embryonic stem cell pluripotency signaling were among the top 20 up-regulated pathways. Many genes involved in the regulation of Wnt signal pathway were included in the above pathways, including Wnt ligands (Wnt9A, Wnt4), transmembrane receptors (CDH1, LRP5, FZD6, FZD7, SMO), cytoplasmic factor (AXIN2), and nuclear factors (MYC, SOX12, SOX8, SOX18, CCND1). Summary: Our study identified recurrent mutations in the NOTCH signaling pathway as well as dysregulated embryonic developmental pathway, e.g. Wnt/NOTCH as newly implicated molecular mechanisms in T-PLL pathogenesis for further functional studies. Additionally, novel (KDM6A and KDM6B) and known mutations (ATM, TET2) in chromatin regulatory genes underscore the importance of epigenetic dysregulation in the tumorigenesis of T-PLL. Disclosures Parikh: Pharmacyclics: Honoraria, Research Funding. Mustjoki:Ariad: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Novartis: Honoraria, Research Funding. Ding:Merck: Research Funding.

Abstract Background Waldenström macroglobulinemia (WM) is a rare, indolent immunoglobulin M- associated lymphoplasmacytic lymphoma characterized by the alternation in the MYD88 locus in 90-95% of the cases. MYD88L265P is the most common alteration in WM patients and is considered a key molecular signature with a pathophysiological role in WM. Because of extremely low prevalence of WM with MYD88 wild type (WT) genotype there is a paucity of clinical and outcome data in this unique patient population. A recent study (Treon et al, Blood May, 2014), in an analysis based on the patients' MYD88 status, reported on the clinical features including older age at presentation and an unexpectedly higher mortality (38%) in the MYD88WTcohort compared to MYD88L265P patients (mortality 6%, P < .0001). However, the sample size of the MYD88WT WM cohort was small (n=15), with a few events during the short follow-up (median 4.84 years). Herein, we report on larger cohort of WM patients with this rare genotype. Methods This study included patients evaluated at Mayo Clinic, Rochester in whom the diagnosis of WM was established based on their clinicopathologic features and the MYD88 mutation status was determined through AS-PCR (assay sensitivity 1% mutant allele) performed on archived bone marrow samples obtained between 2007-2014. Patients with MYD88WT status were the focus of this study. Clinical data were collected from the patients' medical records. The Kaplan-Meir method was utilized for the survival analysis calculated from the time of diagnosis of WM. Outcomes of MYD88WT patients were compared with those harboring the MYD88L265Pmutation. Results Our cohort of 171 patients with an established diagnosis of WM and known MYD88 mutation status was found to be enriched for MYD88WT (n=40) patients. All patients required therapy. At diagnosis, the median age of the patients with MYD88 WT was 63 years (range 37.5-83.5 years; comparable to that of the MYD88L265P cohort, median 65 years, range: 32-92 years, p=0.16). Familial WM was identified in 10% of patients. Sixty four percent of patients presented with constitutional symptoms at diagnosis. These symptoms included fatigue (45%), weight loss (17%), night sweats (8%) dizziness (10%), dyspnea (23%), bleeding (10%), headache (10%) and hyper viscosity syndrome (5%). Splenomegaly and lymphadenopathy was observed in 20% and 27% of patients, respectively. Thirteen percent of patients had concomitant AL amyloidosis. Additional baseline characteristics are reported in Table 1. Transformation to a higher grade lymphoma was noted in 9 (23%) of patients, four of whom had received a purine analog and /or chlorambucil previously. The estimated median follow of MYD88WT patients was 8.1years (95% CI: 6.4-8.9) and their median overall survival (OS) was 8.5 years (95% CI: 6.4-29.4). No OS difference was evident between this cohort and the remainder of the patients with the MYD88L265Pmutation (n=131, median OS 11.7 years, 95% CI: 10-18, p=0.7; median follow-up 7.7 years 95% CI: 6.4-9.1, Figure 1). Conclusion In this relatively large cohort of WM MYD88WT patients with a prolonged follow-up, the MYD88mutation status was not found to be a determinant of patients' outcomes. Our findings contradict the results of a seminal previous study and require external validation, preferably through prospective studies. Disclosures Kapoor: Amgen: Research Funding; Takeda: Research Funding; Celgene: Research Funding. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding. Kumar:Sanofi: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Glycomimetics: Consultancy; Onyx: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Array BioPharma: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Consultancy; Millennium: Consultancy, Research Funding; AbbVie: Research Funding; Kesios: Consultancy.

Abstract Background: High risk CLL patients treated with novel targeted therapies continue to experience disease progression (PD), and more than 50% of these PD patients evolve into Richter's syndrome (RS), (Maddocks, Jama Oncol 2015). Standard chemotherapy for large cell lymphoma has limited efficacy (median overall survival <12 months) in RS. Novel immunotherapy using a PD-1 antibody to block immune checkpoint signals to activate the cytotoxic T -cell has significant efficacy in relapsed Hodgkin lymphoma (Ansell, NEJM 2015). We conducted a phase 2 trial to test the safety and clinical efficacy of the anti-PD-1 antibody pembrolizumab in patients with relapsed/refractory CLL and relapsed low grade B non-Hodgkin lymphoma (B-NHL) (MC1485 trial). Methods: MC1485includes two arms: patients with relapsed/refractory CLL (including RS) and patients with relapsed B-NHL. The main end points of this study are safety and overall response rate. The first 6 patients enrolled in either arm were included in a designed safety interim analysis. Here we report the initial interim analysis from the CLL arm. Relapsed/refractory CLL including RS who had ECOG performance 0-2 and normal organ function were included. Patients with active autoimmune disease or interstitial lung disease were excluded. Pembrolizumab 200 mg was administered intravenously every 3 weeks until progression, excessive toxicity, or completion of 2 years of therapy. Soluble plasma PD-L1 levels were measured in these 6 patients using an established ELISA assay (Frigola, Clin Cancer Res, 2011). CD8+ T cell subsets were assessed for their functional status using an established analysis (Liu, Oncoimmunology. 2013) at baseline and after 2 cycles of therapies. Results: As of July 27th, 2015, 16 relapsed/refractory CLL patients including 5 RS patients were enrolled. The median age was 71 years (58-81). The median number of prior therapies was 3 (1-6). All CLL patients had received chemoimmunotherapy (FCR/PCR). 4 out of 5 RS patients had received anthracycline-containing chemotherapy. 5 out of 8 patients who had received prior ibrutinib therapy progressed on ibrutinib. 8 patients had 17p-/TP53 mutation. Herein, we report preliminary results from the interim analysis of CLL arm including 4 RS and 2 CLL as well as the 5th RS who had response evaluation by PET. The median cycles of therapy administered was 4 (3-7). One patient experienced grade 2 cytokine release syndrome with transient febrile neutropenia, grade 3 headache and skin rashes. These symptoms resolved with steroid therapy. One patient experienced grade 3 myalgia and was also treated with steroids. The other patients in this safety cohort tolerated pembrolizumab well. The most common drug-related adverse events were grade 1 dyspnea (33%, 2/6) and grade 1 anemia (33%, 2/6). Based on investigator assessment using the Cheson 2007 International Working Group Criteria, 4 out of 5 RS patients had responded to therapy. One patient had a complete remission after 2 cycles and remains in remission. One patient had almost complete PET response after two cycles and is classified as PR as her bone marrow have not been re-evaluated yet. Two patients had notable responses with nodal and skin lymphoma improvements before they showed potential evidence of progressive diseases. The remaining 1 RS and 2 CLL had stable disease and continued on therapy at the last follow-up. Soluble PD-L1 levels (sPD-L1, n=6) were measured at baseline and after 2 cycles of therapies. 3 RS patients who had responded to therapy had decreased or stable sPD-L1 levels. The 4th RS and two CLL had increased sPD-L1 levels and had not demonstrated clinical response. CD8 T-cell subset analyses performed blindly (n=4) showed increased CD8 T cell function in one of the 4 patients tested. This patient who demonstrated CD8 T cell functional enhancement is the only patient in the 4 tested patients who had notable response to pembrolizumab. Conclusion: Pembrolizumab is tolerated in relapsed CLL and RS patients. Early efficacy observed in heavily pretreated RS patients including patients progressed on both anthracycline-based treatment and ibrutinib indicate PD-1 inhibition is a promising novel approach in patients with RS. Our CD8 T cell subset analysis may be used as a biomarker assay to predict clinical response in the era of novel immunotherapy. This trial and further correlative analysis is ongoing and will be presented at the ASH meeting. Disclosures Ding: Merek: Research Funding. Shanafelt:Cephalon: Research Funding; Pharmactckucs: Research Funding; Janssen: Research Funding; Hospira: Research Funding; Polyphenon E Int'l: Research Funding; Celgene: Research Funding; Glaxo-Smith_Kline: Research Funding; Genentech: Research Funding. Kay:Tolero Pharma: Research Funding; Hospira: Research Funding; Pharmacyclics: Research Funding; Genentech: Research Funding; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity's Board of Directors or advisory committees, Research Funding. Ansell:Bristol-Myers Squibb: Research Funding; Celldex: Research Funding.

Abstract Abstract 2273 Background: Continuous flow left ventricular assist device (CF-LVAD) recipients have high tendency of post-surgical gastrointestinal (GI) bleeding. We previously described the loss of high molecular weight VWF multimers (HMWM), due to either an accelerated clearance or enhanced cleavage of the HMWM, in most CF-LVAD recipients (Ann Thorac Surg. 90:1263–9). However, besides the tedious plasma VWF multimer analysis, neither VWF ristocetin cofactor nor collagen binding activity assay provides sufficient sensitivity for detecting such an acquired VWF abnormality (AVWA). In this study, we examined a new automated latex particle-enhanced immunoturbidimetric VWF activity assay (VWF:Lx) for its ability of detecting CF-LVAD-AVWA. We also analyzed the VWF pro-peptide (VWF:pp) to explored the potential mechanism of CF-LVAD-AVWA. Design: As part of an on-going prospective multicenter study, pre- and post-CF-LVAD implantation (7, 30 days and 5–7 months) blood samples were collected from 15 LVAD recipients (median age 52 years; 10 male and 5 female; 2008∼2009). Plasma VWF antigen (VWF:Ag), VWF:Lx activity, VWF:pp/Ag ratios were measured; and plasma VWF multimer analyses were performed on all available plasma samples. Standard statistical analyses were employed. Result: Loss of VWF HMWM was observed in 3 patients prior to CF-LVAD implantation and virtually all patients after surgery. VWF:Ag, VWF:Lx or VWF:pp/Ag ratios of the pre- and post-implantation samples were not significantly different (P> 0.1). However, VWF:Lx/Ag ratios of the post-implantation samples were significantly decreased (P<0.05). At a cut off of 0.8, the VWF:Lx/Ag ratio has a 90% sensitivity and specificity for detecting AVWA. Conclusions: VWF:Lx/Ag ratio has excellent sensitivity and specificity in detecting CF-LVAD-AVWA, and its impact on predicting post-surgical bleeding tendency in CF-LVAD recipients is being investigated. The distinct CF-LVAD-AVWA is most likely caused by enhanced cleavage, rather than clearance, of the HMWM. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: The 2016 revision to the World Health Organization (WHO) classification of myeloid neoplasms has specifically categorized germline mutations that are associated with myeloid clonal evolution (Arber et al. Blood 2016). This group consists of myeloid neoplasms with an isolated germline predisposition (CEBPA, DDX41), myeloid neoplasms associated with congenital thrombocytopenia (ETV6, RUNX1, ANKRD26) and germline myeloid neoplasms with multi-organ dysfunction (GATA2, chromosomal breakage disorders, telomere biology disorders etc). We carried out this study to describe the clinical spectrum of germline disorders with predisposition to myeloid neoplasms as categorized by the 2016 WHO classification revision. Methods: After Institutional Review Board (IRB) approval, the adult and pediatric bone marrow failure syndrome database (1990-2016) and the electronic medical record were queried for germline disorders involving GATA2, CEBPA, DDX41, ETV6, RUNX1, ANKRD26, Down syndrome and Noonan syndrome. Chromosomal breakage assays (Diepoxybutane/Mitomycin-C), flow-fluorescent in-situ hybridization (FISH) for telomere length assessment, Fanconi anemia complementation assays and Sanger/Next Generation sequencing (NGS) for the aforementioned germline disorders with myeloid predisposition were carried out in Clinical Laboratory Improvement Amendments (CLIA)-certified laboratories. These disorders were then classified based on the 2016 WHO classification revision. Results : 54 individuals (37 families) were included in the study. Eleven (20%) patients belonging to 5 families were identified as having germline mutations with a preexisting platelet disorder: ETV6 (n=1), ANKRD26 (n=5), RUNX1 (n=5). Forty-three (79%) patients (32 families) had inherited syndromes with multi-organ dysfunction: GATA2 (n=11, 26%), bone marrow failure syndromes (n=14, 33%) and telomere biology disorder (n=14, 33%). There was one patient with neurofibromatosis with a germline PTPN11 mutation who developed juvenile myelomonocytic leukemia, while there were three patients with Down syndrome; 2 with transient abnormal myelopoiesis and one who developed acute megakaryocytic leukemia. The clinical phenotype, prevalence and characteristics of myeloid clonal evolution and outcomes are presented in Table 1. No patients with germline CEBPA or DDX41 mutations were identified. Patients with germline platelet disorders did not have any prominent non-hematological manifestations. Erythrocytosis (20%) with long-standing thrombocytopenia (100%) was a unique feature associated with ANKRD26 mutations. Non-hematologic clues such as human papillomavirus (HPV)-driven warts, primary lymphedema (Emberger syndrome) and frequent atypical infections with monocytopenia were seen in patients with germline GATA2 mutations, and preceded myeloid clonal evolution (morphologic, cytogenetic and molecular). Notably, the age at presentation and penetrance of myeloid transformation was variable, with individuals from the same family developing symptoms during the first decade of life and others remaining asymptomatic to date (fifth decade). Somatic ASXL1 mutations were detected in all 3 (100%) patients with GATA2 mutations and in one patient with ANKRD26 mutation that developed myeloid clonal evolution. In our study myeloid clonal evolution was seen in 40% with RUNX1 mutations, 27% with GATA2 mutations, and 20% with ANKRD26 mutations. We could not calculate the same for bone marrow failure syndromes as the total number of cases seen are still being assessed. Outcomes with allogeneic stem cell transplantation were favorable in appropriately selected patients (Table 1). Conclusion : The 2016 WHO revision to the classification of myeloid neoplasms highlights the importance of recognition and molecular characterization of germline mutations (syndromic and non-syndromic) with risk for myeloid clonal evolution. While some of these disorders (GATA2, Fanconi anemia, telomere biology disorders) may have important non-hematological clues, many present with isolated thrombocytopenia (RUNX1, ETV6). The age and frequency of myeloid evolution is highly variable. Acquisition of somatic ASXL1 mutations at the time of clonal myeloid transformation highlights the role of epigenetic dysregulation in disease evolution. Disclosures Kenderian: Novartis: Patents & Royalties, Research Funding.

Abstract Introduction: The prevalence of venous thrombosis and pulmonary embolism (VTE) increases with age. Definitive VTE diagnosis or exclusion relies on imaging modalities, which are found to be negative in a high proportion of tested patients. Algorithms based on pretest clinical probability (low and intermediate) in conjunction with negative d-dimer test results have reliably excluded VTE sparing the need for additional imaging studies. Currently, the cutoff for a negative d-dimer is based on reference ranges regardless of age of the donor population. Since baseline d-dimer increases with aging, an age-adjusted d-dimer (AADD) cutoff for patients older than 50 years (age*10 ng/mL FEU) has been shown to improve specificity of diagnosis while still maintaining a high sensitivity (>97%) of detecting VTE/PE (Righini, et al. JAMA, 2014). Due to FDA restrictions, clinical laboratories cannot implement and report such AADD cutoffs. Major hurdles include: AADD cutoffs are assay-dependent, and there is a lack of feasible strategy for laboratories to verify the AADD cutoffs. We hypothesize that an adequate study of age-distribution of baseline d-dimer levels of healthy donors can assist the verification of AADD cutoffs and ultimately ensure patient safety in the VTE patient population. Objective: Establish an age dependent reference range for patients 50 years or older with the HemosIL HS 500 D-dimer reagent on the ACL TOP 700 (Instrumentation Laboratory, Bedford MA, USA); and compare this range with the manufacturer provided and literature recommended AADD cutoffs. Methods: D-dimer assay was performed on plasma samples from normal adult donors per the manufacturers' instructions. D-Dimer age, gender distribution and association were analyzed using non-parametric Wilcoxon rank sum, Kolmogorov-Smirnov tests, and quantile regression methods to estimate the 95th percentile to establish a reference range. Results: We studied 241 healthy donors, ranging from 21-91 years of age. Statistically significant differences between males and females (100 [42%] male) were detected (p-value <0.001; p-value =0.0009). Using CLSI guidelines, these statistical differences (median d-dimer for men = 200, while median d-dimer for women = 300) are not considered clinically significant, since only 6% of women would be outside an overall reference range (CLSI guideline states to partition if over 8% for either group would be outside the overall reference range). Using the quantile regression method, a significant association between d-dimer and age was found at the median (P<0.0001). We then established a reference range (95th percentile) for donors younger than age 50 at 635 ng/mL FEU for both men and women and AADD reference range for patients 50 and older (635 + (age - 50)*10 ng/mL) (Figure 1). This reference range was verified with our sample set, with only 6.2% of donors higher than the established reference limit. If we used the non-AADD cutoff provided by the manufacturer for donors younger than 50 (500 ng/mL FEU) and the literature recommended AADD cutoffs for older donors (age*10 ng/mL FEU), 13.3% of our normal donors were above the limits, resulting in not validating this literature reference range per CLSI guidelines in EP28-A3c. These data imply that if both manufacturer and literature recommended AADD cutoffs were adopted, HemosIL HS 500 D-dimer assay should have sufficient sensitivity and negative predictive value, although with slightly lower specificity than those reported by Righini, et al. for detecting VTE/PE. Conclusion: Our study verifies the association between d-dimer level and age and for the first time, to our knowledge, determined AADD normal range for the HemosIL HS 500 D-dimer assay. The manufacturer and literature recommended AADD cutoffs should provide sufficient sensitivity and negative predictive value for VTE/PE exclusion. Figure 1 Age distribution of D-Dimer values (n=241). Figure 1. Age distribution of D-Dimer values (n=241). Disclosures No relevant conflicts of interest to declare.

Abstract Background: Peripheral blood (PB) JAK2V617F testing is ordered in routine clinical practice in several different clinical scenarios. Interpretation of the mutation level/allele burden information is however challenging given lack of a standardized assay and lack of adequate information to permit data interpretation in a non-research setting. Objectives: To describe: (i) disease distribution in unselected JAK2V617F-positive patients seen in routine clinical practice: (ii) disease-specific dispersion of JAK2V617F allele burden in these patients; and (iii) correlation of JAK2V617F allele burden with patient clinical characteristics both between and within specific diseases. Methods: The current study was approved by the Mayo Clinic institutional review board. Myeloid neoplasms were classified as per World Health Organization criteria. Clinical, laboratory and pathology results were centrally reviewed to confirm the reported diagnoses. JAK2V617F testing was done as part of routine clinical care; testing included allele burden measurement by a quantitative allele-specific PCR assay (sensitivity 0.01%) that is in clinical use at our institution (http://www.mayomedicallaboratories.com/test-catalog/Overview/31155); reporting of allele-burden data started in January 2012. The current analysis was restricted to PB samples from adult patients seen at our institution who consented to use of their medical records for research use; results of consecutive samples tested from January 2012 to April 2015 were collected. The PCR assay calibrator is a mixture of DNA from a JAK2V617F-positive cell line (HEL) and a -negative cell line (HL60). The final result is reported as % JAK2 V617F of total JAK2 (ie, [mutated/(mutated + wild-type)] x 100%). Results: We studied 349 patients (166 female; median age 65 years, range 18-92) who met eligibility criteria. The disease distribution was: polycythemia vera (PV) 146 patients (42%), primary myelofibrosis (PMF) 63 (18%), essential thrombocythemia (ET) 55 (16%) , post-PV MF 34 (10%), post-ET MF 12 (3%), myeloproliferative neoplasm-unclassified (MPN-u) 10 (3%), refractory anemia with ringed sideroblasts and thrombocytosis (RARS-T) 8 (2%), post-MPN acute myeloid leukemia (AML) 6 (2%), MPN-myelodysplastic syndrome-unclassified (MPN/MDS-u) 4 (1%), no identified hematological disease 2 (0.5%), and 'other' 9 (2.5%). The median (range) %JAK2V617F was as follows: PV 10.5% (0.5-86%), PMF 8% (0.5-88%), ET 2% (0.5-21%), post-PV MF 24% (0.8-95%), post-ET MF 14.5% (1-88%), MPN-u 4% (0.7-11%), RARS-T 2.5% (0.5-9%), post-MPN AML 31.5% (9-92%), MPN/MDS-u 14.5% (7-74%), no hematological disease 0.7% (n/a), and other 0.9% (0.5-19%) (p<0.0001). Distribution of patients in the following 7 JAK2V617Fallele burden strata: <1%, 1-2% , 3-5%, 6-10%, 11-20%, 21-50%, and 51-100% was: 42 patients (12%), 44 (13%), 61 (17%), 61 (17%), 49 (14%), 50 (15%) and 42 (12%), respectively. PV patients were identified across the entire allele burden spectrum, namely 3%, 12%, 16%, 19%, 14%, 20% and 16% in the aforementioned strata, respectively. Disease distribution in the 42 patients with <1% allele burden was: ET 14 patients, PMF 12, PV and 'other' 5 each, RARS-T and no hematological disease 2 each, and post-PV MF and MPN-u 1 each. JAK2V617F allele burden in ET (peak 21%) was significantly lower than PMF or PV (peak 86-88%) (p<0.0001). Mutation levels in post-ET (p<0.0001) and post-PV (p=0.004) MF were significantly higher than in ET and PV, respectively. Levels in post-PV/post-ET MF were also significantly higher than in PMF (p<0.0001). In contrast, JAK2V617F levels in ET and RARS-T were comparable (p=0.8). Finally, levels in post-MPN AML were significantly higher than in ET (p=0.0001) and PMF (p=0.007), marginally higher relative to PV (p=0.05), but not significantly higher relative to post-ET/post-PV MF. Conclusions: The current study provides guidance for the interpretation of peripheral blood JAK2 V617F allele burden, in routine clinical practice: i) levels below 1% are not infrequently reported, even in phenotypically classic PV, and do not imply low likelihood of a myeloid neoplasm, ii) allele burden per se is not diagnostically specific, but a threshold of greater than 20% might be used to question a diagnosis of ET or RARS-T, and iii) the highest allele burdens are seen in fibrotic and/or leukemic transformation of chronic-phase myeloproliferative neoplasm. Disclosures Pardanani: Stemline: Research Funding.