There is preliminary evidence that the local renin-angiotensin system (RAS) could affect neoplastic hematopoiesis. The aim of this study is to search messenger RNA (mRNA) expressions of the essential RAS elements in myeloid and lymphoid hematological neoplastic disorders. Forty-six patients with newly diagnosed myeloid (AML, biphenotypic leukemia, CML) or lymphoid (CLL, NHL, B-ALL, T-ALL) hematological disorders were included in the study. In the lymphoid group, the median expression values of RENIN, ACE1, ACE2 and ANGIOTENSINOGEN (ANGTS) mRNAs were 1.96%, 0.42%, 0.00% and 0.00%, respectively; in the myeloid group, 0.73%, 1.55%, 0.04% and 0.006%, respectively. In the lymphoid group, RENIN levels were significantly higher (p = 0.001), whereas ACE1 and ACE2 levels were significantly higher in the myeloid group (p values were 0.013 and 0.010, respectively). ANGTS levels were similar in both groups. In patients with non-ALL lymphoid malignancies, RENIN expressions were significantly higher when compared to ALL patients (p = 0.004). All patients with active disease had significantly higher RENIN mRNA expression levels than patients without active disease (2.03% vs 0.30%) (p = 0.034). The result of our present study indicates that the activities of local RAS may differ in distinct disease states such as leukemia and lymphomas.

Objective: The prominent functions of the local renin-angiotensin system (RAS) in primitive hematopoiesis further support the hypothesis that local autocrine bone marrow RAS could also be active in neoplastic hematopoiesis. The aim of this study is to examine critical RAS elements in normal CD34+ hematopoietic stem cells and multiple myeloma (MM)-related progenitor cells.Materials and Methods: The study group comprised the total bone marrow cells (CBM) of 10 hematologically normal people, the CD34+ stem cell samples (CD34+CBM) of 9 healthy donors for allogeneic peripheral stem cell transplantation, and the CD34+ stem cell samples (CD34+MM) of 9 MM patients undergoing autologous peripheral stem cell transplantation. We searched for the gene expression of the major RAS components in healthy hematopoietic cells and myeloma cells by quantitative real-time polymerase chain reaction analysis.Results: RENIN, angiotensinogen (ANGTS), and angiotensin converting enzyme-I (ACE I) mRNA expression levels of CBM were significantly higher than those in myeloma patients (p=0.03, p=0.002, and p=0.0008, respectively). Moreover, RENIN and ANGTS mRNA expression levels were significantly higher in CD34+ stem cell samples of healthy allogeneic donors compared to those in myeloma patients (p=0.001 and p=0.01). However, ACE I expression levels were similar in CD34+CBM and CD34+MM hematopoietic cells (p=0.89).Conclusion: Although found to be lower than in the CBM and CD34+CBM hematopoietic cells, the local RAS components were also expressed in CD34+MM hematopoietic cells. This point should be kept in mind while focusing on the immunobiology of MM and the processing of autologous cells during the formation of transplantation treatment protocols.

1692 Background: There has been a remarkable improvement in the management of chronic myeloid leukemia (CML) after imatinib mesylate (IM) became available in the market, but there is still a group of patients who are resistant to imatinib. Although point mutations in the BCR-ABL kinase domain is the most common mechanism for resistance in patients with CML receiving tyrosine kinase inhibitor (TKI) therapy, there are several mechanisms that can play a role in the resistance to TKIs. Multi drug resistance gene (MDR1) [ABCB1 (ATP-binding cassette, sub-family B (MDR/TAP), member 1) ] product is an ATP-driven efflux pump contributing to the pharmacokinetics of drugs that are P-glycoprotein (P-gp) substrates and to the multidrug resistance of cancer cells. More than 50 single nucleotide polymorphisms (SNPs) have been identified concerning the MDR1 gene, and SNP polymorphisms may affect the expression and function of the P-gp. The SNPs T1236C, G2677T/A, and C3435T are the most common variants in the coding region of ABCB1. Imatinib is a substrate of P-gp-mediated efflux, and P-gp mediated drug efflux can play a role in IM resistance. So identifying these SNPs may allow to predict the drug disposition and responses to IM in CML patients. The aim of the study was to identify the C3435T SNP variants, and the associations between MDR1 C3435T polymorphism and IM efficacy in our CML patients. Methods: Between December 2010 and March 2011, 110 chronic phase (CP) CML patients who consecutively visited our outpatient clinic were enrolled in this study. Hematologic, cytogenetic and molecular response patterns to IM as well as the association between MDR1 C3435T polymorphism and responses to imatinib were evaluated in our patient cohort. MDR1 C3435T polymorphisms were detected by real-time polymerase chain reaction (RT-PCR). We could assess complete cytogenetic response (CCyR) and major molecular response (MMR) in one hundred and six patients (96%) among these 110 patients. The differences in genotype frequencies in all patients taking imatinib treatment was determined by using the chi-square test. All tests were two-sided, and p <0.05 was considered as statistical significant. This study was approved by the local research ethics committee, and written informed consent was obtained from the patients. Results: 59 patients were male (54%), and fifty-one were female (46%). Median age was 50.5 years (range, 19–84 years). 37.6% of the patients were low, 45% were intermediate, and 17.4% were high risk according to Sokal risk score. The CCyR rate was 71%, and MMR rate was 60%. The frequencies of MDR1 3435 CC, CT, and TT genotypes were 22.5%, 55%, and 22.5%, respectively. No statistically significant difference was observed between the frequencies of the genotypes according to gender. The CCyR rates in patients with CC, CT, and TT genotypes were 88%, 62%, and 75%, respectively (Figure 1). The patients with CC genotype had significantly higher CCyR rates when compared to patients having CT/TT and CT genotypes (p =0.04 and p =0.023, respectively) (Table 1). The patients with CC, CT, and TT genotypes did not differ significantly between each other regarding the MMR rates. There were no significant difference between the C3435T genotypes and second generation TKI usage regarding both CCyR and MMR. Conclusion: Before starting IM therapy, the individual patientÕs MDR1 gene polymorphism pattern can be important in determining the treatment strategy in patients with CML. Among our patient cohort, the patients with CC genotype had significantly higher CCyR rates than patients with CT/TT and CT genotypes. Up to now, there are a few studies in CML patients with different results regarding MDR1 gene polymorphisms, and since racial differences can be seen in the frequencies of MDR1 gene polymorphisms, further studies in larger series are needed to define the genetic polymorphisms with therapeutic relevance in patients on imatinib. Disclosure: This study was supported by Istanbul University Research Fund. Disclosures: No relevant conflicts of interest to declare.

Background and Aim BCR-ABL1 mutation testing is recommended for chronic myeloid leukemia (CML) patients who have suboptimal response and/or treatment failure with tyrosine kinase inhibitor (TKI) therapy. BCR-ABL1 mutations in the kinase domain (KD) of ABL1 account for at least 40-50% of all TKI resistant cases. Thus, detection of low-level mutations after development of resistance may offer critical information to guide subsequent therapy selection. The current gold standard for BCR-ABL1 mutation detection is Sanger sequencing (SS), which has an analytical sensitivity of approximately 10-20%. In this study, our aim was to detect low level BCR-ABL1 variants in follow up samples of CML patients with TKI resistance using next-generation sequencing (NGS) approach. Methods Eight patients with CML who were resistant to imatinib had been routinely sequenced with SS for BCR-ABL1 KD mutations between December 2009 and December 2012. We then retrospectively analyzed these samples with NGS. RT and long range PCR was performed to amplify BCR-ABL1 fusion transcripts and the PCR products sequenced bidirectional after library preparation. We performed a fusion transcript based BCR-ABL1 mutation assay using Roche 454 amplicon deep-sequencing technology that is suited for detecting low level variants in pooled amplicon samples. Sequencing data was analyzed with GS Amplicon Variant Analyzer (AVA) software, and the variant frequency cut-off was adjusted to 1%. Results Clinical features, sequencing results, and the outcomes of the patients were summarized in Table 1. Four patients were male, and the median age was 37 years (range, 20-60 years). The patients were all in chronic phase at the time of the diagnosis. After imatinib resistance, 4 patients had received dasatinib (DAS), and 2 were given nilotinib (NIL) as second line TKI treatment. The remaining two patients had both received DAS and NIL (Table 1). In a set of 20 clinical samples, at different time points, NGS not only identified all the mutations detected by SS, but additionally identified low level variants present between 1 – 28.12 %. T315I and E255K/V were the most common mutations, which were detected in four patients, both by SS and NGS at the same time points (Table 1). Two patients (patient #1 and #4) had T315I, and they both progressed to blastic phase and died. E255K was detected in patients #2 and #3, and patient #2 had achieved and maintained complete cytogenetic and major molecular responses with 100 mg daily DAS, whereas patient #3 had received both NIL and DAS, but she was deceased due to myeloid blastic crisis. Among 4 patients (patients #5, #6, #7, and #8), mutation analysis was performed at eleven different time points, and these patients were wild-type with SS. We also did not detect any clinically significant mutations in these patients by NGS. Most probably mechanisms other than KD mutations were responsible for the TKI resistance among these four patients. Conclusions Polyclonal mutations in BCR-ABL1 KD are commonly identified in TKI resistant patients. Thus, detection of low-level mutations after development of resistance offers critical information to guide subsequent therapy selection. An inappropriate kinase inhibitor selection could highly increase the risk of treatment failure with clonal expansion of the resistant mutant. In our imatinib resistant cohort, we detected low level variants accompany to known mutations which may constitute background genetic variations. Although we had expected to detect mutations earlier by NGS (i.e. before these mutations can be detected by SS), we did not observe such finding in our patients. The patients' samples may not show a stable mutation spectrum between time points. Hence, it is not always possible to spot a mutation before patients show resistance to therapy. Regular NGS analysis might detect these mutations in earlier phases, which might help clinicians to choose the most suitable individual treatment modality for the patients. Acknowledgment The authors would like to thank the Interlaboratory Robustness of Next-generation sequencing (IRON) Phase II study group members, especially to Simona Soverini and Alexander Kohlmann who designed BCR-ABL primers and plates. We also would like to thank the Research Fund of the Istanbul University (Project no. 24244) and Turkish Society of Hematology for supporting the study. Disclosures: Sayitoglu: Roche Diagnostics: Research Support Other.

4603 Background Chronic lymphocytic leukemia (CLL) is the most frequent leukemia in the Western world with an annual incidence of 5/100,000. The clinical course of the disease is highly variable; while some CLL patients experience a stable clinical course that will never affect their morbidity or mortality, some of them will eventually progress and require chemotherapy. In addition to the traditional prognostic markers (e.g. Rai and Binet staging systems), more recently, mutational status of the variable regions of the immunoglobulin heavy chains (IgVH), chromosomal aberrations, CD38 expression and Zeta-chain-associated protein kinase 70 (ZAP-70) expression are used to better determine the prognosis in CLL patients. A novel CLL-specific gene, CLL Up-regulated gene 1 (CLLU1) that uniquely overexpressed in CLL patients, was recently demonstrated. It has been shown that CLLU1 mRNA expression levels in CLL patients predict time to initiation of therapy as well as overall survival (OS), and CLLU1 is highly up-regulated in poor-risk groups. The aim of this study is to investigate the relationship between CLLU1 levels and well known prognostic parameters and, to determine the importance of CLLU1 gene on prognosis and clinical course in our CLL patients. Methods 116 (46 female, 70 male) CLL patients who consecutively visited our outpatient clinic between May 2009 and March 2010 were enrolled in the study. Median age was 60 years (range, 30–87 years). Blood samples were drawn from the patients for CLLU1 determination, and CLLU1 levels were determined by RT-PCR method. CLLU1 expression level was counted both in CLL patients and healthy B cells as the difference between CLLU1 and abl (taken as an house keeping gene) gene. Then, they are transformed as folds which is the ratio between CLLU1 level in CLL patients and that in healthy B cells. Patients with CLLU1 expression exceeding the CLLU1 expression of normal (CD19+) B-cells were taken as positive. Each patient was followed for at least one year for survival data. For the statistical analysis, student’s t-test, Mann-Whitney U test and Pearson correlation were used. p<0.05 was considered as statistical significant. The study was approved by the local research ethics committee, and written informed consent was obtained from the patients. Results There was no relationship between CLLU1 levels and, sex, age, modified RAI and BINET stages, lymphocyte counts and LDH levels at the time of diagnosis. Patients with nodular bone marrow infiltration had lower CLLU1 levels than patients with non-nodular infiltration (57.6 vs 498). Patients with high β2 microglobulin levels had higher CLLU1 levels than the ones with low β2 microglobulin levels (356.7 vs 13.6, p<0.05). ZAP-70 positive patients had higher CLLU1 levels than ZAP-70 negative patients (217.2 vs 10.2, p=0.007) (Figure 1). Among the patients with CD38 levels studied (n=53) CLLU1 levels were higher in patients with CD38 levels above the median value than patients with CD38 levels below the median value (438.4 vs 42.2). CLLU1 levels were higher in cases who needed treatment than cases without treatment. Patients with a shorter time to treatment had higher CLLU1 levels than patients with a longer time to treatment (p=0.028) (Figure 2). Conclusion With a limited number of patients we could demonstrate that CLLU1 levels correlated with β2 microglobulin levels and ZAP-70. Although there were similar findings also with CD38 levels; the association was not statistically significant due to the limited number of cases. Time to treatment was shorter in patients with CLLU1 levels above the median value than patients with CLLU1 levels below the median value. CLLU1 is a promising and specific new prognostic parameter in patients with CLL, and further studies in larger series are needed to define the impact of CLLU1 in the prognosis and clinical course of CLL patients. Disclosure This study was supported by Istanbul University Research Fund. Disclosures: No relevant conflicts of interest to declare.