ALBERT

Description: Survival of CLL cells requires sustained activation of the anti-apoptotic PI-3-kinase/Akt pathway, and many therapies for CLL cause leukemia cell death by triggering apoptosis. Blood lipoprotein particles are either pro- or anti-apoptotic. High density lipoprotein (HDL) particles are anti-apoptotic through sphingosine-1-phosphate receptor 3 (S1P3)-mediated activation of the PI-3-K/Akt pathway. We have noted that apoE4-very low density lipoprotein (VLDL) (but not apoE2- or apoE3-VLDL) particles increase apoptosis of endothelial cells by recruiting the phosphoinositol phosphatase SHIP-2 to the plasma membrane, thereby directly inhibiting the anti-apoptotic activity of HDL (DeKroon R, et al., Circ Res99:829–836, 2006). Since apoE4-VLDL increases apoptosis of certain cells, and since increased leukemia cell apoptosis favors longer survival in CLL, we hypothesized that APOE4 genotype would beneficially influence the clinical course of CLL. Of the 193 CLL patients (50 women and 133 men) studied, 29% had an APOE4 genotype. In the entire group, survival of men and women was not statistically different. However, women (but not men) with an APOE4 genotype had markedly longer survival than non-APOE4 patients (median 〉25 yr vs. 14.0 yr; p = 0.02) (Figure). Figure Figure Men and women had the same time-to-treatment (treatment-free survival) irrespective of APOE genotype. VLDL is metabolized to LDL by the actions of LPL. Patients had shorter survival and time-to-treatment if their CLL cell lipoprotein lipase (LPL) mRNA levels were high (p = 0.002). In analyzing APOE genotype and LPL levels in the same patients, we demonstrated that APOE4 was a more important determinant of survival than was the LPL level (p = 0.0007). The beneficial effect of APOE4 in CLL survival is likely mediated through allele-specific influences of APOE4 on serum lipoproteins increasing leukemia cell apoptosis. The frequency of the APOE alleles in the CLL patient population was not significantly different than that of a control population (16 and 13%, respectively). APOE genotype therefore does not appear to affect susceptibility to CLL, but influences the clinical course of disease, particularly after therapy is initiated. In contrast, APOE genotype does influence susceptibility to other diseases, most notably Alzheimer’s disease in which APOE4 markedly increases risk. The beneficial impact of APOE4 in CLL and its deleterious impact on Alzheimer’s disease expression may relate to a common mechanism of APOE4 in enhancing apoptotic cell death. APOE genotyping of patients with CLL may provide important clinical prognostic information, particularly in women. Most importantly, the allele-specific influence of APOE on disease progression may provide important new insights into the mechanisms of disease and response to therapy, and lead to new agents for treatment.

Description: Background and Significance : Chronic lymphocytic leukemia (CLL) is the most heritable hematologic malignancy; however, no common CLL predisposition genes are known. Monoclonal B lymphocytosis (MBL) is a hematologic syndrome characterized by small accumulations of B lymphocytes in the peripheral blood. MBL has a CLL-like immunophenotype, may progress to overt CLL, and is over represented in CLL families. Therefore, MBL observed in the context of familial CLL may be a marker of inherited risk for development of CLL. Detailed characterization of family-associated MBL may also provide mechanistic insights into the pathogenesis of familial CLL. Our strategy was to detail the biologic characteristics of CLL in family-associated MBL. Methods : Persons with MBL were identified by flow cytometric screening of peripheral blood from unaffected members of CLL kindreds ascertained by Genetic Epidemiology of CLL Consortium (GEC) sites. Flow cytometry was used to determine the surface immunophenotype including CD38 and intracellular ZAP-70. We defined MBL as populations of CD19+, CD5+, CD20lo, CD23+ B cells that comprised at least 2% of the CD19+ peripheral B cell compartment and did not exceed 5.0 × 109 MBL cells/L. RNA and genomic DNA from single MBL cells isolated by flow cytometric sorting were analyzed using PCR to determine immunoglobulin heavy and light chain sequences. MBL cells were sorted in bulk for FISH for loci associated with clinical CLL. Results : Twenty-two out of 190 (12%) unaffected family members were found to have MBL. We observed significant variability in the size of the MBL clone as a percentage of the CD19+ B cell compartment (mean 32%; range 2%–97%). Nonetheless, the absolute size of the MBL clone was small, 15 of 17 individuals had 〈 200 × 106 MBL cells/L. CD38 expression (defined as CD38 surface expression in ≥30% of MBL cells) was observed in 8 of 18 subjects tested. ZAP-70 (defined as intracellular expression in ≥ 20% of MBL cells) was expressed in 4 of 12 participants. Among 12 subjects tested, 5 MBL expressed both surface IgD and IgM, 3 expressed IgD only, 2 expressed IgM only, and 2 did not express IgD or IgM. Analysis of immunoglobulin heavy and light chains has been completed in 8 individuals. Both immunoglobulin heavy chain variable (IgVH) region mutated (n = 12) and unmutated (n = 4) sequences were observed. Four of 8 individuals had 2 or more unrelated MBL clones (range 2–5), including one individual with both unmutated and mutated clones. Among the 16 MBL clones identified in these 8 subjects, VH3 or VH4 rearrangements were observed in all MBL clones. The most commonly rearranged IgVH genes were 3–07 (3 MBL clones), 3–15 (3), and 4–34 (3). No VH1 family gene rearrangements were observed. In one individual, a VH3–07 MBL clone showed intraclonal diversification suggestive of antigen driven immunoglobulin sequence changes. Twenty productive light chain rearrangements were identified among the 16 MBL clones, with 11 Vλ and 9 Vκ genes used. We observed 6 productive rearrangements of Vλ1–51. MBL cells were bulk sorted for FISH from 9 subjects. Mono or biallelic deletion of 13q14.3 was observed in 5 subjects, the other 4 were normal. Conclusions : Our findings confirm that MBL is commonly observed among the unaffected family members from CLL kindreds. We found that some MBL clones express ZAP-70, CD38 or have unmutated IgVH genes and thus are similar to clinical CLL. The clinical outcome of these MBL clones in relation to our baseline prognostic characterization will be of interest. Small MBL clones are commonly oligoclonal. Importantly, although the immunoglobulin heavy and light chain genes rearranged in these MBL clones are all commonly used in CLL, the absence of VH1 and abundance of Vλ1–51 rearrangements do suggests differences in BCR usage between CLL and MBL. Further investigation of family associated MBL may clarify the genetics and immunobiology of familial CLL.

Description: Abstract 4190 Background and Significance: Myeloid Cell Leukemia-1 (Mcl-1) is an anti-apoptotic protein that is elevated in fludarabine-resistant CLL patients. Expression levels of Mcl-1 correlate with time to first treatment and overall survival in CLL patients. Furthermore, elevated levels of Mcl-1 have also been reported in B-cell lymphomas. The regulation of Mcl-1 stability occurs through phosphorylation of several serine and threonine residues catalyzed by constitutively activated kinases. The tumor suppressor protein phosphatase 2A (PP2A) is important in deactivation of several kinases: Akt, the mitogen activated protein kinases (MAPK) p38, JNK, ERK, and NFkB (through IkK). We have discovered novel peptides that antagonize the SET oncoprotein, a potent physiological inhibitor of PP2A, and increase cellular PP2A activity. Importantly, we note that SET is overexpressed in CLL and B-cell lymphoma cells and that treatment of these cells with SET antagonist peptides is cytotoxic for the malignant cells both in vitro and in vivo. We show here that activation of PP2A by antagonism of SET results in reduced Mcl-1 levels and induction of apoptosis in CLL and B-cell lymphoma cells. Methods: Patients were from the Duke University and V.A. Medical Centers, and normal controls were from the community. Blood CLL cells and control normal B-cells were purified using negative selection with antibodies. The human Ramos and Raji B-cell lymphoma cell lines were from ATCC. We determined cytotoxicity using the MTS colorimetric assay. SET antagonist peptides were prepared by chemical synthesis. Western blotting and immunoprecipitation were performed with antibodies to SET, Mcl-1, PP2Ac, c-Myc, Axin, Pin-1, GSK3beta, Bcl-2, Bcl-XL and beta-actin. Apoptosis assays were performed with the annexin-V/propidium iodide staining method. Results: We previously demonstrated SET overexpression in CLL cells and that SET antagonist peptides activate PP2A and are cytotoxic for malignant B-cells. Using freshly-isolated CLL cells and Raji and Ramos cell lines, cytotoxicity of the SET antagonist peptide COG449 was evaluated. We found the concentrations for 50% cytotoxicity (ED50) to be 77 nM for CLL cells, 125 nM for Ramos cells, 250 nM for Raji cells, and 〉10,000 nM for normal B-cells. Annexin-V staining indicated that apoptosis was induced at concentrations comparable to the ED50s for cytotoxicity of the compounds tested. COG449 treatment of NOD/SCID mice bearing tumors after xenografting with Ramos cells resulted in reduced tumor growth. After treatment for 8 days, there was a 61% reduction in final tumor mass at harvest on day 19 (p

Description: Abstract 1785 Background: Chronic lymphocytic leukemia (CLL), the most common hematopoietic malignancies in adults, remains incurable, and new approaches to treatment are needed. Previous research has defined certain molecular characteristics of CLL (e.g., cytogenetic abnormalities, dysregulated signaling pathways, and alterations of apoptotic proteins) that improve our understanding of this disease and provide prognostic information. In addition to these molecular signatures, it is now clear from multiple settings that changes in cellular metabolism can impact the survival and promote the growth and proliferation of malignant cells. Unlike many cancers, however, CLL cells can have a very low rate of proliferation. Because targeting cancer metabolism may attack a fundamental feature of cancer biology, we sought to characterize the metabolic program of CLL in hopes of establishing new prognostic markers and identifying novel treatment targets. We evaluated the glycolytic and lipid metabolism profiles of B-CLL cells from low- and high-risk CLL patients. Methods: We collected blood from CLL patients seen at the Duke Center for CLL and enrolled in IRB-approved protocols at the Duke University and Durham VA Medical Centers. CLL lymphocytes were isolated using negative selection yielding greater than 95% purity of CLL lymphocytes. Standard prognostic testing was done as we have described before. Glut1 expression was detected by immunoblot. Glycolytic rate and lipid oxidation rate was measured by using 3H-labled glucose or palmitic acid respectively as described in the literature. Cell viability was measured by propidium iodide exclusion assay. Results: CLL cells exhibited higher expression of the major glucose transporter Glut1 compared to naïve B cells purified from healthy donors (n=20 for CLL and n=3 for normal). CLL cells from a subset of high-risk patients (unmutated IGVH; total n=6) had higher glycolytic rate compared to those from low-risk (mutated IGVH; total n=11) patients. In contrast, no significant change in lipid oxidation was observed between high-risk (IGVH unmutated; n=2) to low-risk (IGVH mutated; n=4) patients. CLL cells were also sensitive to glycolysis inhibitor 2-deoxyglucose (2-DOG), with 2-DOG (5uM) mediating cytotoxicity in vitro. Conclusion: We establish for the first time that purified, malignant CLL cells overexpress the glucose transporter Glut1, and that the glycolysis inhibitor 2-DOG is cytotoxic for CLL cells in vitro. In addition, our results demonstrate that cells from high-risk CLL patients have enhanced glucose metabolism relative to leukemia cells from low-risk patients. Therefore, glucose metabolism in these malignant B cells may represent a novel prognostic marker and a novel therapeutic target in this incurable disease. Disclosures: No relevant conflicts of interest to declare.

Description: Background: Chronic lymphocytic leukemia (CLL) is an incurable cancer of mature B-lymphocytes that infil­trate the bone marrow, secondary lymphoid organs, and blood. Much progress has been made during the past decade in understanding the pathogenesis and prognosis in CLL. Patients with unmutated immunoglobulin gene heavy chain variable region (IGHV) genes have inferior clinical outcomes when compared to patients with mutated IGHV. While there is robust data regarding clinical outcomes in patients with single IGHV rear­range­ments in CLL, there is limited data regarding double IGHV rearrangements. Thus, we investigated the preva­lence of double IGHV rearrangements in our institutional cohort to determine molecular features and the prog­nos­tic significance of CLL cases with double IGHV rearrangements. Methods: Patients with CLL receiving care at Duke University and Durham Veterans Affairs (VA) Medical Centers were enrolled into a longitudinal cohort study between 1999 and 2014. IGHV mutation analysis was performed on DNA from all study patients. Patients were followed clinically for disease progression, need for treatment, and overall survival. The primary end points were time to treatment (TTT) or overall survival (OS). Survival curves were estimated using Kaplan-Meier method. Statistical differences were tested using propor­tional hazards tests for a clinical significance of p 〈 0.05. CLL cell isolation and IGHV mutational analysis were done as we have previously described (BLOOD 109:1559-1567, 2007). Statistical analysis was performed using SAS enterprise guide 5.1 and JMP Pro 11. Results: A total of 489 CLL patients were studied. Of these, 420 had one IGVH gene rearrangement (single IGHV; 86%). In 69 patients (14%), we amplified two IGHV rearrangements, indicating likely biallelic IGHV. The median TTT for the single IGHV group was 5.4 years, and the median OS for the single IGHV group was 15.3 years. For the double IGHV group, the mean TTT was 6.5 years (p = 0.44), and the median OS was 15.8 years (p = 0.73). Patients with single mutated IGHV (m) had better survival (median OS = 20.1 years) than those with single unmutated IGHV (u) (median OS = 11.3 yrs; p

Description: B-cell chronic lymphocytic leukemia (CLL), an incurable leukemia, is characterized by defective apoptosis. We found that the SET oncoprotein, a potent inhibitor of the protein phosphatase 2A (PP2A) tumor suppressor, is overexpressed in primary CLL cells and B-cell non-Hodgkin lymphoma (NHL) cell line cells. In CLL, increased levels of SET correlated significantly with disease severity (shorter time to treatment and overall survival). We developed SET antagonist peptides that bound SET, increased cellular PP2A activity, decreased Mcl-1 expression, and displayed selective cytotoxicity for CLL and NHL cells in vitro. In addition, shRNA for SET was cytotoxic for NHL cells in vitro. The SET antagonist peptide COG449 inhibited growth of NHL tumor xenografts in mice. These data demonstrate that SET is a new treatment target in B-cell malignancies and that SET antagonists represent novel agents for treatment of CLL and NHL.

Description: Abstract 4576 Background: Chronic lymphocytic leukemia (CLL) has a highly variable clinical course. Some patients require treatment early while others can be monitored without therapy. CD38 expression has been shown in multiple cohorts to have prognostic significance. An elevated percentage of CD38 positive CLL lymphocytes at the time of diagnosis is correlated with a more rapid need for therapy and a shorter overall survival. The extent to which CD38 varies during the course of CLL, including after therapy, has only been evaluated in a limited fashion. Methods: From a cohort of over 500 CLL patients at the Duke University and Durham VA Medical Centers, we selected 136 patients in whom we had measured CD38 expression by flow cytometry on two or more occasions. We determined the first, maximum, minimum, and range (maximum – minimum) CD38 values. We compared these values to other molecular prognostic markers using Wilcoxon tests and assessed the prognostic significance of these values using Cox proportional hazard models and Kaplan-Meier analyses. Results: Of the 136 patients, 70% were male and 88% Caucasian, with a median age of 60. The majority had low clinical stage at diagnosis—either Rai stage 0 (68%) or 1 (19%). Molecular prognostic markers were also generally favorable. Eighty-two (67%) patients had mutated IGHV status, 69 (51%) were ZAP70 negative, and 76 (63%) had either 13q deletion or normal cytogenetics, determined by fluorescent in situ hybridization. CD38 expression was measured a median of 5.5 times (2 – 19). The median time between the first and last CD38 measurements was 1206 days (81 – 4109). The median values were 6% (0.6 – 99) for maximum CD38, 1.5% (0 to 84.5) for minimum CD38, and 4.9% (0.2 to 95.3) for CD38 range. Maximum, minimum, and CD38 range were significantly lower in patients with mutated compared to unmutated IGHV status (p 〈 0.005 for all parameters, Wilcoxon rank sum test). Elevated maximum and CD38 range were significantly associated with a more rapid time to therapy (TTT) and shorter overall survival (OS) in a univariate Cox proportional hazards model (p 〈 0.03 for all, Wald test). In a multivariate Cox proportional hazards model including first CD38 and maximum CD38 values, only maximum CD38 remained statistically significant. We found that patients with high CD38 variation (CD38 range greater than the median) had significantly shorter TTT and OS than patients with low CD38 variation (p = 0.002 for both, log rank test). Using receiver operator characteristic analyses, we determined that the best cut-off for dichotomizing the first CD38 according to TTT and OS in the entire Duke/Durham VA CLL cohort was 11%. Using this cut-off, 15 patients (11%) converted from CD38 negative to CD38 positive. Using the standard 30% cut-off, 14 patients (10%) converted from CD38 negative to CD38 positive. Patients with a first CD38 measurement less than 11% and subsequent measurements above 11% had a favorable OS, similar to patients with low CD38 for all measurements (p = 0.002, log rank test). However, patients with a first CD38 measurement less than 30% who had subsequent measurements above 30% had an inferior OS, similar to patients with high CD38 for all measurements (p = 0.006, log rank test). Lastly, among 24 patients with CD38 measurements before and after first therapy, the percentage of CD38 positive cells increased in 19 patients (79%), with a median value of 3.2% before to 6.9% after therapy (p = 0.005, Wilcoxon signed rank test). Conclusions: CD38 values vary as patients transition across the disease trajectory. This variation appears to have prognostic significance, with high variation associated with faster time to first therapy and shorter overall survival. Additionally, in our cohort, a patient's maximum CD38 value had more prognostic significance than a single initial measurement. Thus, longitudinally measuring CD38 throughout the clinical course of CLL could aid in the management of CLL patients, refining the initial prognostic assessment, and improving patient counseling and decision making. Disclosures: No relevant conflicts of interest to declare.

Description: B cell chronic lymphocytic leukemia (CLL), the most common subtype of leukemia in the United States of America and in Europe, is treatable but incurable. New drugs are needed for its management. Phosphodiesterase inhibitors (PDEi) block catabolism of cyclic nucleotides resulting in accumulation of cellular cAMP and cGMP. These PDEi also decrease production of inflammatory cytokines such as tumor necrosis factor. Furthermore, they inhibit expression of inducible nitric oxide synthase (NOS2) mRNA and NO production. Researchers have previously noted that nonspecific PDE inhibitors such as theophylline as well as a relatively specific PDE4 inhibitor (rolipram) cause CLL cell death in vitro, while relatively sparing normal peripheral blood mononuclear cells (PBMC). The purpose of this study was to evaluate the effectiveness of CD160130 in the killing of freshly isolated CLL cells in vitro. CD160130 is a novel, orally available heterocyclic pyrimido-indole derivative that is relatively PDE4-specific. Patients were from the V.A. and Duke University Medical Centers, and normal controls were from the community. Control normal PBMC were isolated by ficoll-Hypaque centrifugation, and CLL cells were purified using negative selection with antibodies. We determined cytotoxicity using the MTS colorimetric assay. Samples from 10 CLL patients (6 male and 4 female) and 10 normal controls were examined. Nine of 10 patients were stage 0 at presentation, and 1 was stage 2. They had been followed 6.1 yr (median; range 0.7–19.1 yr). One of 10 was CD38 positive, and 6 of 10 were Zap-70 positive. Of nine analyzed, one had unmutated IgVH gene, and 9 were mutated. Six patients had not been treated, and 4 had been treated with chlorambucil, fludarabine, and/or rituximab. Four had normal cytogenetics by FISH analysis; one had trisomy 12; three had 13q14 del; and one had 17p del. Of seven determined, two had elevated CLL cell lipoprotein lipase mRNA elevated. CD160130 induced cell death in a dose-dependent fashion in all patients’ samples, with a mean cytotoxicity of 96% at 12.5 uM. The mean ED50 for killing was 233 nM in media with FBS and 314 nM in serum-free medium, while that for PBMC was higher at 7500 nM with FBS and 5210 nM with serum-free medium. The agent was 32.2 fold more potent for killing of CLL cells compared to PBMC in medium with FBS and 16.6 fold more potent for CLL cells in serum-free medium. In summary, the PDE4 inhibitor CD160130 potently kills freshly isolated CLL cells in vitro in the presence or absence of serum. The killing is relatively selective for CLL cells compared to normal PBMC. In vivo trials of CD160130 in patients with CLL should help determine the toxicity and efficacy in patients.

Description: Introduction: Chronic Lymphocytic Leukemia (CLL) is a malignancy characterized by B-lymphocytes with aberrant expression of CD5. In normal T-lymphocytes, CD5 is an important regulator of T-cell receptor signaling. In CLL, CD5 acts as a repressor of B-cell receptor (BCR) signaling, whereby phosphorylated CD5 anchors SHP-1 at the cell membrane, resulting in inhibition of BCR-mediated second messenger signaling. The significance of CD5 on outcomes of CLL patients has not been evaluated. Because BCR signaling is an oncogenic stimulus in CLL, we hypothesized that higher levels of CD5 may be associated with superior clinical outcomes. Methods: Median fluorescence intensity (MFI) of CD5 on CLL cells was determined by flow cytometry. CLL samples and clinical data were obtained from patients enrolled in IRB-approved protocols at the Duke University and Durham VA Medical Centers. Molecular prognostic markers were measured as described previously. Descriptive and time to event (Cox proportional hazard and Kaplan-Meier) statistical analyses were performed in the statistical environment, R. Results: Between March 2011 and April 2015, 961 CLL samples were evaluated from 352 unique CLL patients. One to 10 samples were evaluated per CLL patient. The mean CD5 MFI was calculated for each unique patient, with a median of 206.59 (range 0.50 - 768.31) and median standard deviation of 33.02 (range 0.09 - 315.46) for CLL patients with multiple samples collected. 150 patients received therapy (44%), and there was no significant difference in CD5 MFI mean or standard deviation between patients who received and did not receive therapy. CD5 MFI values did not significantly differ among CLL demographic or prognostic groups. Cox proportional hazard ratio analyses showed that higher CD5 MFI is associated with longer time to therapy (TTT, p = 0.037), but not overall survival. Based on the distribution of CD5 MFI, we divided the CLL cohort into thirds, with low CD5 defined as MFI 〈 137, high CD5 defined as MFI 〉 283.5, and medium CD5 with MFI between these values. Kaplan-Meier analyses demonstrated a significant difference in TTT between these three groups (p = 0.004), with higher CD5 MFI associated with longer TTT. Moreover, CD5 MFI added to established molecular prognostic markers to risk stratify CLL patients (p 〈 0.0001 for CD38 and IGHV, p = 0.0003 for FISH, and p = 0.004 for ZAP70). Importantly, for those with good prognostic markers such as IGHV mutation or low CD38 expression, lower CD5 identified patients with shorter TTT (p = 0.01 for IGHV mutated; p = 0.0009 for CD38 negative). However, TTT was not significantly different in unmutated IGHV CLL patients or CD38 positive CLL patients with varying degrees of CD5 expression. Conclusions: Surface CD5 expression varies among CLL patients. For most individual patients, there appears to be a low level of variability in CD5 expression, regardless of CLL-directed therapy. Higher CD5 expression is associated with superior clinical outcomes in CLL, consistent with prior in vitro determination of CD5 as a negative regulator of BCR signaling. The relevance of CD5 in risk-stratifying IGHV mutated and CD38 negative CLL patients is of particular relevance, since these subgroups of CLL are particularly dependent on BCR-signaling as an oncogenic process. These findings are important both for prognostication and for development of therapies for this group of CLL patients. Disclosures No relevant conflicts of interest to declare.

Description: Introduction Although chronic lymphocytic leukemia (CLL) is a generally indolent malignancy, there is a spectrum of disease aggressiveness. Clinical and molecular prognostic markers are helpful for the clinician and for the patient, in terms of disease management and life planning. Additional prognostic markers can help with further risk stratification, especially for CLL patients with “low-risk” disease. The prognostic value of absolute monocyte count (AMC) has been evaluated in various malignancies, including CLL where elevated AMC at diagnosis was shown to be associated with rapid time to first therapy (TTT), and in one series, inferior overall survival (OS). The mechanism by which elevated AMC is associated with worse treatment free survival is not known. However, CD14, which is secreted by monocytes, improves in vitro CLL cell survival, and is found at high levels in the serum of CLL patients. We hypothesized that elevated AMC at the time of CLL diagnosis is associated with inferior survival and that elevated serum CD14 is associated with high AMC and worse survival. Methods CLL patients followed at the Duke University and Durham VA Medical Centers and enrolled in an IRB approved protocol to collect clinical data and blood samples were evaluated. We selected patients for whom AMC was measured between three months prior to diagnosis to three months after diagnosis. We evaluated the correlation between AMC and TTT and OS, with AMC as a continuous and as a dichotomized variable. We also assessed the prognostic capability of AMC in relation to other clinical and molecular prognostic markers, such as Rai stage, race, interphase cytogenetics by FISH, CD38 and ZAP70 expression, and IGHV mutation status. We measured serum CD14 levels using an ELISA assay, and evaluated the correlation between CD14 levels and clinical outcomes or AMC. Cox proportional hazard models were used to evaluate time to event outcomes, Wilcoxon rank sum test and Kruskal-Wallis rank sum test were used to compare AMC to other prognostic markers, and Pearson’s correlation test was used to compare continuous variables. Results From a cohort of over 600 CLL patients, we selected 222 patients with AMC measured ± three months from the date of diagnosis. AMC ranged from 0 to 7.63 cells/mL. With a median follow up of 5.2 years (range 0.1 – 18.2), 102 patients (46%) had been treated, and 59 patients (27%) died. This was not significantly different from the entire cohort. Higher AMC was significantly correlated with shorter TTT (p = 0.002, hazard ratio 1.37, 95% CI 1.12 – 1.68) and inferior OS (p = 0.017, hazard ratio 1.39, 95% CI 1.06 – 1.83). There was no significant difference in AMC in patients stratified by Rai stage, race, interphase cytogenetics, CD38 or ZAP70 expression, or IGHV mutation status. When combined with molecular prognostic markers (IGHV mutation status, CD38 and ZAP70 expression, and interphase cytogenetics) in multivariate models, AMC retained significant prognostic power for TTT and OS. The serum soluble CD14 levels were measured in CLL patients from this cohort, with a mean CD14 level of 2.3 ug/mL. The prognostic significance of serum CD14 and correlation with AMC will be presented. Conclusions Absolute monocyte count at the time of CLL diagnosis is associated with inferior clinical outcomes – both TTT and OS. These results confirm and extend other reports evaluating the prognostic significance of circulating monocytes in CLL. Our evaluation of serum CD14, a monocyte-derived secreted protein that promotes CLL cell viability, in concert with AMC may provide a possible explanation for the associations identified in this cohort of patients. As an easily measured clinical marker, AMC can be readily used and/or combined with other prognostic markers to improve risk stratification and patient counseling at the time of diagnosis. Disclosures: No relevant conflicts of interest to declare.