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Abstract Abstract 4804 Background: Chronic myeloid leukemia (CML) is one of the classic myeloproliferative neoplasms characterized by a reciprocal translocation of BCR and ABL t(9;22)(q34;q11). Tyrosine kinase inhibitors (TKI) have revolutionized the management of CML in inducing rapid and prolonged responses. However; clonal evolution (CE) is considered a poor prognostic factor and a criterion for accelerated phase (AP) CML by the World Health Organization (WHO). Deletion of chromosome Y (−Y) is frequently considered an age-related abnormality and the exact prognostic value has not yet been determined. Aim: To determine if –Y carries an impact on the clinical outcome of male pts with CML. Methods: All male patients diagnosed with chronic phase CML in our institution between 1993 and 2011 were screened for -Y. Data were collected in a retrospective manner and compared (using t-test) to male patients with sole BCR-ABL translocation after excluding patients with advanced stages (accelerated phase, blast phase). Demographics, laboratory tests, cytogenetic analysis, molecular testing and survival data were abstracted. Kaplan-Meier estimates of overall survival were used via JMP software v9.0. Institutional Review Board (IRB) approval was obtained for this study in accordance with the Helsinki Declaration. Results: 20 of 162 (12%) males with CML were found to have –Y abnormality (group 1). CML male patients with sole Philadelphia chromosome abnormality were the control cohort (group 2). In group1; the median age was 57 years, BMI 27.7, hemoglobin 12.2 g/dL, white blood cell count (WBC) 32.8 x109/L, platelet 270 x109/L, and peripheral blood blasts 1%. Sokal risk was low in 30%, intermediate in 65% and high in 5% of pts. Nine pts (45%) were treated with interferon (IFN) prior to TKI. In group 2; the median age was 54 years, hemoglobin 12 g/dL, WBC 57 x109/L, and platelet 282 x109/L. Sokal risk was low in 37%, intermediate in 47%, and high in 16%. 46 of 142 patients (32%) had received previous interferon therapy. All patients in both groups had chronic phase CML at the time of diagnosis, with a median bone marrow cellularity of 95%. In group 1, 14 of 20 pts (70%) received imatinib, all of whom achieved a complete hematological response (CHR), 7 of 14 pts (50%) had partial cytogenetic response, 2 of 14 pts (14%) achieved a complete cytogenic response (CCyR);1 (7%) pt achieved CCyR within 12 months and an additional 1 (7%) by 18 months). Two pts of 12 (16%) achieved at least a major molecular response (MMR); one of whom (8%) achieved a complete molecular response (CMR). In comparison, 107of 142 pts (75%) in group 2 received imatinib, all of whom achieved CHR. Twenty-one pts (20%) achieved partial cytogenetic remission. CCyR was more frequently achieved than group 1 (48/107 pts (45%), p 0.026); 24 pts (22%) achieved CCyR within 12 months of therapy and an additional 10 pts by 18-months. MMR and/or CMR was higher in group 2 compared to group 1 (34 /101 (34%), p 0.18); 16 (16%) of which were CMR. In group 1; 6 (30%) pts had disease progression; 4 of 20 pts (20%) progressed to blast phase (BP) and 2 pts (10%) progressed to AP, compared to 32 (22%) pts in group 2 (p 0.17); 22 (15%) of whom progressed to BP and 10 (7%) patients progressed to AP. Median overall survival was 110 months in group 1 compared to 155 months in group 2 (log rank p=0.48). On multivariate analysis, CCyR was an independent factor for a better OS (p 0.03), but not –Y (p 0.7). Conclusion: Loss of the Y chromosome in chronic myelogenous leukemia is an infrequent phenomenon (12%). Although patients with –Y had a statistically significant less chance to achieve CCyR, loss of the Y chromosome did not affect the progression rate or overall survival. Larger scale studies are needed to confirm our observations Disclosures: No relevant conflicts of interest to declare.

Increased plasma homocysteinemia is considered a risk factor of dementia, including Alzheimer’s disease (AD) and vascular dementia. However, the reason elevated plasma homocysteinemia increases the risk of dementia remains unknown. A pathological hallmark of AD is neurofibrillary tangles (NFTs) that consist of pathologically phosphorylated tau proteins. The effect of homocysteine (Hcy) on tau aggregation was explored using human neuroblastoma M1C cells that constitutively express human wild-type tau (4R0N) under the control of a tetracycline off system, primary mouse cultured neurons, and by inducing hyperhomocysteinemia in a mouse model of tauopathy (HHCy mice). A wide range of Hcy concentrations (10–1000 µM) increased total tau and phosphorylated tau protein levels. Hcy activated glycogen synthase kinase 3, and cyclin dependent kinase 5, major tau phosphokinases, and inactivated protein phosphatase 2A, a main tau phosphatase. Hcy exhibited cytotoxic effects associated with enhanced activation of caspase. Truncation of tau in the C-terminus, the cleavage site of caspase 3 (i.e., D421, detected by the TauC3 antibody) was also increased. Total tau, phosphorylated tau, as well as C-terminal cleaved tau were increased in the sarkosyl insoluble tau fraction. Hcy also increased the level of tau oligomers, as indicated by the tau oligomer complex 1 (TOC1) antibody that specifically identifies oligomeric tau species, in the tris insoluble, sarkosyl soluble fraction. The levels of TOC1-positive oligomeric tau were increased in brain lysates from HHCy mice, and treating HHCy mice with S-adenosylmethionine, an intermediate of Hcy, reduced the levels of oligomeric tau to control levels. These observations suggest that Hcy increases the levels of phosphorylated tau as well as truncated tau species via caspase 3 activation, and enhanced tau oligomerization and aggregation.