About 10% of patients with severe hemophilia exhibit a milder clinical phenotype with less frequent bleeds. Among many other factors, coinheritance of prothrombotic mutations have been proposed to act as modulators of clinical severity in severe hemophilia. We conducted a study to evaluate the impact of 3 prothrombotic mutations (factor V Leiden, factor II, and methylenetetrahydrofolate reductase mutations) on clinical phenotype of patients with severe hemophilia in our institution. For this purpose we compared the average annual factor concentrate consumption between carriers and noncarriers of prothrombotic mutations. A total of 38 hemophilia A and B patients with factor levels less than 1 were recruited between October 2006 and October 2007. Prothrombotic mutations were detected in venous blood using polymerase chain reaction amplification technique. Eighteen patients (47%) carried no prothrombotic mutations. The remaining 20 patients (53%) were found to be carriers of either 1 or 2 mutations. Median age in both carrier and the non-carrier groups was 27 years. None of the patients in either group gave a history of thromboembolic event. Median annual factor concentrate consumptions in carriers and noncarriers were 610 +/- 530 units/kg and 770 +/- 670 units/kg, respectively (P = .203). Our results demonstrated no significant difference in annual factor concentrate consumption between carriers and noncarriers of prothrombotic mutations. Considering that average annual factor consumption is a surrogate indicator of clinical phenotype, we concluded that coinheritance of prothrombotic mutations was not associated with occurrence of different clinical phenotypes in severe hemophilia.

The Janus kinase 2(V617F) (JAK2 (V617F)) mutation is an acquired genetic defect that is considered to enhance thrombosis in Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). Thrombosis is also a well-defined component of Behcet syndrome (BS). The aim of this study was to determine the frequency of JAK2 ( V617F ) mutation in BS-associated thrombosis. A total of 152 patients with BS (62 with thrombosis and 90 without thrombosis) were enrolled. An additional 186 patients with MPNs and 107 healthy blood donors were included to serve as diseased and healthy controls, respectively. None of the patients with BS and healthy controls carried the JAK2 (V617F) mutation, whereas 67% of patients with MPNs were positive for JAK2 ( V617F ). The frequency of thrombosis in patients with MPNs was not statistically different between carriers and non-carriers of JAK2 ( V617F ) mutation. Our data suggest that JAK2 (V617F) is not directly related to thrombosis in MPNs and in other thrombotic entities, such as BS.

According to our findings, MF regresses with imatinib therapy over time, and the MF grades at diagnosis do not have a negative impact on the responses to imatinib treatment. Therefore, the adverse prognostic impact of the MF among patients with CML seems to disappear in the era of the TKIs.

The second most common fragile site in the human genome is the FRA16D region where the WWOX gene is localized which codes for a 414 amino acid protein. WWOX is a member of the WW-domain containing protein family consisting of 2000 members. It is a partner of several transcription factors and therefore functions in multiple physiological and pathological processes such as cell growth, differentiation and tumor suppression. Genomic alterations within the WWOX gene and its differential expression have been found in a variety of human tumors. Although some transcription factor partners of the WWOX protein have been identified its exact mechanism of action is not known. A recent study indicated that WWOX inhibits the Wnt/β-catenin pathway by preventing the nuclear import of the Dishvelled (Dvl) proteins. Dvl proteins are the main down-stream target of Wnt receptors (Frizzled- FRZ). Following binding of Wnt to its receptor alterations of β-catenin degradation lead to β-catenin accumulation in the cytoplasm. Accumulated β-catenin translocates into the nucleus and activates expression of target genes. Therefore dysregulation of the Wnt signaling pathway is a key oncogenic mechanism in many different cancers. Although Wnt and its receptor FRZ have been analyzed in head and neck squamous cell carcinoma (HNSCC) the intracellular components of the pathway have not been investigated. This is the first study in the literature reporting a role for β-catenin and Dvl mRNA level alterations in HNSCC. In our previous study we have identified that the WWOX gene is inactivated in HNSCC as a result of genetic and epigenetic alterations. To identify the mechanism of action of WWOX in HNSCC in this study we investigated its expression in association with Dvl-1, Dvl-2, Dvl-3 and β-catenin expression in 98 HNSCC samples. We observed down-regulation of the WWOX mRNA in 73.5% of the HNSCC tumor samples compared to their non-cancerous counterparts. Up-regulation of the Dvl-1, Dvl-2, Dvl-3 and β-catenin mRNAs were detected in 32.7%, 36%, 38.8% and 24.5% of the same tumor samples, respectively. We also detected a statistically significant correlation between the WWOX gene expression and mRNA levels of the intracellular components of the Wnt pathway genes. Our results indicate that WWOX acts as a tumor suppressor in the HNSCC development and progression by inhibiting the expression of the Dvl proteins. Citation Format: Ayse Nur Buyru, Asuman Celebi, Betul Seyhan. The role of WWOX in HNSCC through Wnt/beta-catenin pathway [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr B33.

Although thyroid cancer (TC) is a rare cancer with a rate of 2.1%, it is the most common cancer type among endocrine tumors. The molecular mechanisms of thyroid cancer, which develops as a result of environmental and genetic factors, are still unclear. SOX family genes are transcription factors that are expressed in a tissue-specific manner and play a role in the developmental processes. SRY-box transcription factor 15 (SOX15) is an important member of the SOX family and is involved in carcinogenesis. Its downregulation has been associated with the development and progression of different human malignancies. Some SOX family members have been reported to control cell proliferation by acting as negative regulators of the Wnt/β-catenin signaling pathway. MYC, CCND1 and CTNNB1 genes are important components of the Wnt signaling pathway. Recently, we have shown that epigenetic silencing of the SOX15 gene is associated with the pathogenesis of papillary thyroid carcinoma,In the present study, to further the understanding of the molecular mechanisms of SOX15 in papillary thyroid carcinoma (PTC) we investigated SOX15 expression in association with the transcriptional targets of the Wnt/β-catenin pathway.Primary thyroid tumors and adjacent nonmalignant tissue samples were collected from 52 patients, prior to any treatment. Total RNA was isolated from tissue samples and reverse transcription was performed. Expression levels of the SOX15, CTNNB1, c-MYC and CCND1 genes were analyzed by qRT-PCR using the SYBR green and Light-Cycler 480 system (Roche Diagnostics, Germany). β2M was used as the reference to normalize the mRNA levels. Statistical analysis was performed using the SPSS 21.0 (IBM® SPSS® Statistics, IBM Corporation Somers, NY, USA) program.SOX15 gene expression was significantly downregulated in 64.6% of PTC tissues compared to their normal counterparts. In contrast, CCND1, CTNNB1 and c-MYC gene expressions were significantly upregulated in 70.2%, 60% and 57.8% of the patients. Among the group of patients with downregulated SOX15 expression CCND1, CTNNB1 and c-MYC expression were upregulated in 46.8%, 40% and 40% of the subjects, respectively. Our data suggest that SOX15 downregulation may contribute to activation of Wnt signaling and provides further evidence indicating involvement of SOX15 in modulating the Wnt/β-catenin pathway in thyroid carcinogenesis. Citation Format: Ayse Nur Buyru, Ayşegul Soysal, Ahmet Ozaydın, Betul Seyhan, Soykan Arıkan, Nejat Dalay. Expression of SOX15 and Wnt pathway genes in papillary thyroid carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 776.

4429 Background Imatinib mesylate (IM) is considered the mainstay of chronic myeloid leukemia (CML) treatment for almost a decade. The primary goal of the study is to share data of a substantial number of CML patients followed at one center. Methods We analyzed data from 177 CML patients who were treated in our institution and received IM for at least 24 months. They were stratified into low, intermediate and high risk groups based on Sokal score. Early chronic phase (ECP) (within one year from diagnosis to IM start), late chronic phase (LCP) (≥ 12 months from diagnosis), and accelerated phase (AP) CML patients were included in the study. Patients were evaluated for hematologic, cytogenetic and molecular responses, event-free survival (EFS) and overall survival (OS), frequency of adverse events. Results The median age was 51.2 years (range, 22–86 years), with 77 females and 100 males. Patients were followed for a median of 60 months (range, 24–116 months). IM was started at a dose of 400 mg daily. 97.7% were in chronic phase, and 2.3% were in accelerated phase.75.1% of chronic phase CML patients were in early and 24.9% in late chronic phase. 42% of patients were low Sokal risk, 44% intermediate and 14% were high risk patients. 12% of the patients did not receive any prior therapy, 1% had received prior therapy with interferon (IFN), 73% were treated with hydroxyurea (HU) (mostly short course) and 14% with both HU and IFN. Complete hematologic response (CHR) was achieved in 90% of patients at 3 months (median time, 2.02 months). Cumulative rates of cytogenetic and molecular responses at 6, 12, 18 and 24 months are summarized in Table 1. Complete cytogenetic response (CCyR) was achieved in a significantly higher proportion of patients within the low and intermediate Sokal risk group (79.4%, 85.2%) compared with the high risk patients (14.3%, p=0.001). There was a significant difference in the complete molecular response (CMR) ratio achieved by low, intermediate and high Sokal risk patients (70.4%, 63.8% and 33.3%, p<0.05). 5-year OS rates were 100% and 84% among low-intermediate and high Sokal risk patients (p=0.0001) (Figure 1). The EFS at 5 years was 77%, 81%, and 63% in low, intermediate and high Sokal risk patients (p=0.001) (Figure 2). ECP CML patients achieved higher CCyR rates (87%) compared with LCP CML patients (48.6%, p=0.001). CMR rates were 67.7% and 46.9% in ECP and LCP CML patients (p<0.05). 62.2% of the patients remained on 400 mg/day IM treatment and in 3.4% the dose was increased to 600 mg/day. Second-generation tyrosine kinase inhibitors (TKIs) were initiated in 21% of the study population. Hematological and non-hematological toxicities were experienced in 23.7% and 56.7% of our patients. In 6.2% a dose reduction and in 3.4% a switch to a second generation TKI was necessary due to toxicity. 5-year OS and EFS rates of the entire cohort were calculated as 97% and 77%. EFS rates at 5 years were significantly higher among patients achieving CCyR compared with those without a CCyR (92%, 64%, p=0.0001) (Figure 3A). 5-year EFS rates were significantly higher in patients achieving CMR compared with those who did not (95%, 58%, p=0.0001) (Figure 3B). Conclusion In the current report, we described the outcome of unselected CML patients, treated outside of clinical trials. Grouping patients according to their Sokal prognostic score predicted IM response in this cohort. A longer interval from diagnosis to the start of IM and high Sokal risk score were adverse prognostic factors. 'Real life' data of our study are in accordance with the previous data reflecting the prognostic impact of cytogenetic and molecular responses on survival. Close follow-up of the responses and timely initiation of second-generation tyrosine kinase inhibitors were associated with high survival rates. Disclosures: No relevant conflicts of interest to declare.

Objective: A single-nucleotide polymorphism of the growth hormone 1 gene, GH1 IVS4+90A>T (rs2665802), associated with short stature and a polymorphism of the growth hormone receptor gene, exon 3 deleted variant, associated with increased responsiveness to growth hormone have been reported previously. We aimed to investigate the frequency of both polymorphisms and their correlation to height in Turkish short children. Also, we aimed to evaluate the effect of exon 3 deleted variant on response to 1-year growth hormone therapy. Materials and Methods: Children with idiopathic isolated growth hormone deficiency (n = 39) and with idiopathic short stature (n = 10) and 50 control subjects were evaluated for anthropometric parameters, annual growth velocity, and annual height gain. Growth hormone receptor gene polymorphisms were analyzed via multiplex polymerase chain reaction; growth hormone 1 gene polymorphism was analyzed via polymerase chain reaction and single-strand conformation polymorphism techniques. Results: The frequency of genotypes carrying the “A” allele was not significantly higher in the idiopathic isolated growth hormone deficiency group than in the idiopathic short stature and control groups ( P = .03 for each). The exon 3 deleted variant genotype was significantly lower in the idiopathic short stature group compared to the control group ( P = .01). There was no effect of exon 3 deleted variant, on response to the first-year growth hormone therapy. Conclusion: In Turkish population, no correlation was found between the “A” allele of GH1 IVS4+90A>T polymorphism and idiopathic isolated growth hormone deficiency and short stature, and a significant negative correlation was found between exon 3 deleted variant and idiopathic short stature and short stature. Exon 3 deleted variant has no effect on response to growth hormone treatment.

Introduction: Imatinib mesylate (IM) is the first tyrosine kinase inhibitor (TKI) licensed for the treatment of chronic myeloid leukemia (CML). Severe bone marrow fibrosis (BMF) has been reported in excess of 40% of the patients with CML at diagnosis. Before TKIs became available, BMF which emerged at diagnosis and/or in the late periods of the disease was defined to be a poor prognostic factor, and it contributed significantly to morbidity and mortality from 10% to 30% in patients with CML. The relationship between BMF and both disease progression and prognosis has been the subject of re-evaluation after the introduction of IM therapy. In patients with CML, it has not been clearly demonstrated yet, whether IM improves the poor prognostic effect of fibrosis, and prevents the new BMF development or not. Aim: The purpose of this study was to evaluate the effects of IM therapy on BMF formation, and the prognostic significance of BMF in patients with CML. Material and Methods: One hundred and thirty-five CML patients were enrolled in the study. Patients' demographics, Sokal risk scores, molecular and cytogenetic responses and follow-up periods were noted from the patients' files retrospectively. All pre- and post-IM bone marrow biopsy samples, which were stained with hematoxylin and eosin, were re-evaluated for the current analysis. Grading of BMF was according to the European consensus decisions, graded as 0-III. The term "last bone marrow biopsy" (LBMB) is referred to a biopsy, which was performed at 18th months or later on during IM treatment. Results: The median age was 44 years (range, 18-92 years), and 78 patients (58%) were male. One hundred and twenty-eight patients (95%) were in chronic phase [CP], 4 patients (3%) were in accelerated phase [AP], and 3 patients (2%) were in blast crisis [BC] at the time of IM initiation. Out of 128 CML-CP patients, one hundred and twenty patients (93%) were in early CP, whereas 8 (7%) were in late CP. The percentage of low, intermediate, and high Sokal risk scores were 35%, 43%, and 22%, respectively. Before IM was initiated, thirty-one patients had received previous treatment modalities (hydroxyurea (HU) in twenty-one, and 10 patients had received interferon plus HU. he median duration of IM treatment was 45 months (range, 2-106 months). The rates of complete hematological response (CHR) at 3rd month, complete cytogenetic response (CCyR) at 12th month, and major molecular response (MMR) at 18th month were 92.4%, 71.6%, and 67.6%, respectively. BMF before the initiation of IM therapy was grade 0 in 52 patients (39%), grade I in 39 patients (29%), grade II in 28 patients (21%), and grade III in 16 patients (12%). There was a positive correlation between the Sokal risk scores and the grades of BMF at diagnosis (r:0.313, p <0.01), and as the Sokal risk scores increase, the grades of BMF also increase and the difference was significant (p =0.025). Also the spleen size significantly differ according to the grade of BMF, and the patients with a higher grade of BMF also had a larger spleen (p <0.001). The control bone marrow biopsies at the 12th month of IM were available in one hundred and four patients, and 70 (67%) of them have grade 0, 26 (25%) of them have grade I, 7 (7%) of them have grade II, and 1 (1%) of them has grade III BMF. After 12 months of IM treatment, the grades of BMF have significantly decreased when compared to the pre-treatment values (p =0.001), and BMF grades in LBMB has shown to be significantly decreased when compared to the pre-treatment values (p <0.001) (Table 1 and Figures 1&2). There was no significant difference regarding the grades of BMF, between the biopsy at 12th months and LBMB (p =0.703). The CCyR rates at 12th month did not differ according to the pre-imatinib BMF grades (p =0.127). There was no significant difference between patients with or without CCyR at 12 months of IM regarding grades of BMF (p =0.785). The MMR rates at 18 months did not differ according to pre-treatment grades of BMF (p =0.112). There was no significantly difference in overall survival rates between initial BMF mild (grade 0-I) and severe (grade II-III) groups (p =0.278). Conclusion: IM can reduce BMF after a long period of follow-up, independently from the molecular and cytogenetic responses. The BMF grades at diagnosis does not have a negative impact on the response to IM treatment. Therefore, the adverse prognostic impact of the marrow fibrosis among CML patients seems to disappear in the era of the TKIs. Disclosures No relevant conflicts of interest to declare.