High-throughput screening (HTS) identified benzothiazole analogue 3 as a potent fatty acid amide hydrolase (FAAH) inhibitor. Structure-activity relationship (SAR) studies indicated that the sulfonyl group, the piperidine ring and benzothiazole were the key components to their activity, with 16j being the most potent analogue in this series. Time-dependent preincubation study of compound 3 was consistent with it being a reversible inhibitor. Activity-based protein-profiling (ABPP) evaluation of 3 in rat tissues revealed that it had exceptional selectivity and no off-target activity with respect to other serine hydrolases. Molecular shape overlay of 3 with a known FAAH inhibitor indicated that these compounds might act as transition-state analogues, forming putative hydrogen bonds with catalytic residues and mimicking the charge distribution of the tetrahedral transition state. The modeling study also indicated that hydrophobic interactions of the benzothiazole ring with the enzyme contributed to its extraordinary potency. These compounds may provide useful tools for the study of FAAH and the endocannabinoid system.

Background. Serum free light chains (sFLC), the most commonly detected paraprotein in CLL, were recently proposed as useful tools for the prognostication of CLL patients. Objective. To investigate the prognostic implication of sFLC and the summated FLC-kappa plus FLC-lambda in a CLL patients' series. Patients and Methods. We studied 143 CLL patients of which 18 were symptomatic and needed treatment, while 37 became symptomatic during follow-up. Seventy-two percent, 18%, and 10% were in Binet stage A, B and C, respectively. Median patients' followup was 32 months (range 4–228). Results. Increased involved (restricted) sFLC (iFLC) was found in 42% of patients, while the summated FLC-kappa plus FLC-lambda was above 60 mg/dL in 14%. Increased sFLC values as well as those of summated FLC above 60 were related to shorter time to treatment (P = 0.0005 and P = 0.000003, resp.) and overall survival (P = 0.05 and P = 0.003, resp.). They also correlated with β2-microglobulin (P = 0.009 and P = 0.03, resp.), serum albumin (P = 0.009 for summated sFLC), hemoglobin (P < 0.001), abnormal LDH (P = 0.037 and P = 0.001, resp.), Binet stage (P < 0.05) and with the presence of beta symptoms (P = 0.004 for summated sFLC). Conclusion. We confirmed the prognostic significance of sFLC in CLL regarding both time to treatment and survival and showed their relationship with other parameters.

BLyS is involved in CLL biology and its low soluble serum levels related to a shorter time to first treatment (TFT). TACI is a BLyS receptor and can be shed from cells' surface and circulate in soluble form (sTACI). We investigated the impact of serum BLyS and sTACI levels at diagnosis in CLL patients and their relationship with disease parameters and patients' outcome. Serum BLyS was determined in 73 patients, while sTACI in 60. Frozen sera drawn at diagnosis were tested by ELISA. sTACI concentrations correlated with BLyS (P = −0.000021), b2-microglobulin (P = 0.005), anemia (P = −0.03), thrombocytopenia (P = 0.04), Binet stage (P = 0.02), and free light chains ratio (P = 0.0003). Soluble BLyS levels below median and sTACI values above median were related to shorter TFT (P = 0.0003 and 0.007). During a ten-year followup, sTACI levels, but not BLyS, correlated with survival (P = 0.048). In conclusion, we confirmed the prognostic significance of soluble BLyS levels with regard to TFT in CLL patients, and, more importantly, we showed for the first time that sTACI is a powerful prognostic marker, related to parameters of disease activity and staging and, more importantly, to TFT and OS.

4976 Background and Aims: TGF-beta1 normally down-regulates B-cell proliferation. Resistance to its effects is reported in malignant cells of B-lineage such as chronic lymphocytic leukemia (CLL) and multiple myeloma (MM) cells. There are however very few studies on serum TGF-beta1 levels in patients with B-cell lymphoproliferative diseases and their eventual correlations with parameters of disease activity and survival. The purpose of our study was to assess any eventual relationship between serum TGF-beta1 levels and disease parameters, as well as time to first treatment (TFT) and overall survival (OS) in a series of MM, Waldenstrom's macroglobulinemia (WM) and CLL patients at diagnosis. Patients and Methods: 92 MM, 64 WM and 110 CLL patients were studied. In the MM group, paraprotein was IgG in 64, IgA in 18, LC in 8 and IgD in 2 patients while 32, 25 and 43% of patients were in ISS stage 1, 2 and 3 respectively. MM patients' median follow-up was 51 months. All patients required treatment a some point, 55% immediately. In the WM group, 44, 27 and 29% of patients were in WM – IPSS stage 1, 2 and 3 respectively. WM patients' median follow-up was 49 months; 75% of them required treatment during follow – up. In the CLL group, 54% and 74%, 25% and 20%, 14% και 6%, were in stage 0 and A, 1 and β, 2 and C according to Rai and Binet respectively. Median follow up was 43 months; 14 patients needed immediate treatment, 30 more required treatment during follow up while the others are still just followed. Patients' frozen sera, drawn at diagnosis, were retrospectively analyzed while sera from 20 healthy individuals (HI) were tested as controls. Serum TGF-beta1 measurements were done by ELISA according to the manufacturer's instructions. Statistical analysis was performed by SPSS software, version 15. 0. Results: Median serum TGF-beta1 levels were 36330 pg/ml (range 4. 6 – 77976) in MM patients, 33965 pg/ml (range 1665–615000 pg/ml) in WM, 12207 pg/ml in CLL (range 0 – 42970) and 32902 pg/ml in HI (range 1941 – 58123). CLL patients presented significantly lower TGF-beta1 levels than those with MM and WM (p<0. 00001). Patients with TGF-beta1 levels above median presented a longer TFT than the others in MM and CLL (p=0. 0003, and p=0. 002 respectively) while in addition a longer OS was observed in MM and WM patients with increased serum TGF-beta1 median (p=0. 001, and 0. 02 respectively). Furthermore, serum TGF-beta1 levels stongly correlated with clinical and laboratory parameters of adverse prognosis such as staging, anemia, beta-2 microglobulin levels, serum LDH and serum free light chain concentrations. Conclusions: Our results of longer TFT in MM and CLL and improved OS in MM and WM patients with increased serum TGF-beta1 levels, suggest that a degree of sensitivity to the suppressive effect of TGF-beta1 may remain in neoplastic B-cells in the majority of B-cell lymphoproliferative disorders. Disclosures: No relevant conflicts of interest to declare.

4568 Background and Aim: Symptomatic CLL patients need treatment immediately. For these patients, molecular-genetic factors (mutated-unmutated, ZAP 70, ATM, p53) are important prognostic factors of response and survival. Nevertheless, 2/3 of newly diagnosed patients are asymptomatic and require only of follow up that can last for months or years. For these patients overall survival (OS) depends on the time to first treatment (TFT). The most frequent paraprotein produced in CLL is serum free light chain in 50% of the patients. It has recently been shown that serum free light chains (sFLC) and their sum above 60 (κ+λ above 60) are useful prognostic factors for TFT. We therefore studied the eventual prognostic implication of sFLC and the summated FLC-kappa plus FLC-lambda in a CLL patients' series. Patients and Methods: 143 CLL patients were studied of which 18 needed immediate treatment while 37 more needed treatment during their follow up. 64% and 72%, 28% and 18%, 7.5% and 10%, were in stage 0 and A, 1 and β, 2 and C according to Rai and Binet respectively. Median patients' follow up was 32 months (range 4–228). Light chain restriction was established by flow cytometry or bone marrow biopsy immunohistochemistry. Serum free light chain values were retrospectively determined by nephelometry (Freelite™, the Binding Site Birmingham, UK) in frozen sera drawn at diagnosis. Elevated sFLC values were defined using as cut-off values the 95th percentile range of healthy individuals. Statistical analysis was performed using SPSS v15.0. Hazard ratios and prognostic significance of abnormal sFLC, HLC and ratios were determined by univariate Cox regression analysis. Kaplan Meier method was used for pictorial representation of survival and time to treatment. Results: Increased sFLC were found in 45% of the patients while the summated FLC-kappa plus FLC-lambda was higher than 60 mg/dl in 14%. Increased sFLC values as well as values of FLC κ+λ>60 were related to shorter TFT (p=0,0005 and p=0,000003 respectively). In addition, high levels of sFLC and FLC κ+λ >60 correlated with β2-microglobulin (r=0.2, p=0.009 και r=0.2, p=0.03 respectively), serum albumin (r=0.2, p=0.009 only for FLC κ+λ > 60), negatively with hemoglobin (r=-0.3, p=0.000003 και r=-0.2, p=0.0002 respectively), increased LDH (p=0.037 και 0.001 respectively), Rai stage (p=0.03 και 0.003 respectively) and Binet stage (p=0.02 only for FLC κ+λ > 60) and with the presence of beta-symptoms (p=0.004 only for FLC κ+λ > 60). Finally, increased sFLC and FLC κ+λ>60 values correlated with shorter OS (p=0.05 and p=0.003 respectively). Conclusion: The results of our study confirmed the significance of sFLC in CLL with regard to TFT and their relationship with adverse prognostic clinical and laboratory parameters but also demonstrated for the first time their impact on OS. Disclosures: No relevant conflicts of interest to declare.