Drug Resistance Alters CD38 Expression and in Vitro Response to Daratumumab in Waldenstrom Macroglobulinemia Cells

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 3018-3018 ◽  
Author(s):  
Aneel Paulus ◽  
Sharoon Akhtar ◽  
Yamima Bashir ◽  
Shumail M. Paulus ◽  
Hassan Yousaf ◽  
...  

Abstract Introduction: With approval of Daratumumab (Dara), targeting CD38 has become an attractive therapeutic option for various B cell cancers including WM. Using preclinical models of WM we investigated CD38 expression patterns, the impact of drug-resistance and the anti-WM effects of Dara, in vitro. An important aspect of our evaluation was the identification of optimal CD38 expression that correlates with maximal cytotoxic effects of Dara; such an approach has not been attempted previously in WM. Methods: WM cell lines (BCWM.1, MWCL.1 and RPCI.WM1) with isogenic proteasome inhibitor-resistant (CR, resistant to carfilzomib, bortezomib and ixazomib) and ibrutinib-resistant subclones (IR) were used. CD38 expression was measured by flow cytometry and a grading system was developed based on increasing CD38 MFI values with 1+= <50,000, 2+ = >50,000 and 3+ = >100,000. Daratumumab-induced specific lysis due to antibody dependent cell cytotoxicity (ADCC) or complement dependent cytotoxicity (CDC) was measured using the Calcein AM assay at an effector to target ratio (E:T) of 100:1. Peripheral blood mononuclear cells (PBMCs) and complement-containing serum were obtained from healthy human donors. Daratumumab, carfilzomib and ibrutinib were obtained from commercial sources. Results: Expression of CD38 (MFI) was highest in RPCI-WM1 (91295.6) > BCWM.1 (13865.3) > MWCL-1 (9804.19) (Figure 1A.). Intriguingly we observed an interesting change in CD38 expression with induction of drug resistance; all CR clones showed a decrease in MFI (RPCI-WM1/CR; øMFI 55960.5 > MWCL-1/CR; øMFI 3890.0 > BCWM.1/CR; øMFI 1381), while decreased expression was noted in all IR clones except one (MWCL-1/IR; øMFI 6272.96, BCWM.1/IR; øMFI 3076 vs. RPCI-WM1/IR; _MFI 461784.6) (Figure 1B). When we applied our CD38 expression grading system, RPCI-WM1/IR cells classified as Grade 3+, RPCI-WM1 and its CR clones as Grade 2+, while all other WM cells were Grade 1+. We noted that utilization of this grading system was helpful in correlating the extent of cytotoxicity to the level of CD38 expression (Table 1). We next treated WM cells with Dara and observed direct lysis in only RPCI-WM1/CR (43%) > BCWM.1/CR (19%) and RPCI-WM1 (11%) cells. However, when Dara-treated WM cells were cocultured with PBMCs, significantly increased ADCC was noted in RPCI-WM1 (90.3%), RPCI-WM1/IR (88.3%) and RPCI-WM1/CR (68.0%) cells (Figure 1C). Although CDC has been reported as a mechanism of mAb-mediated cell death in WM our evaluation of CDC as a potential effector mechanism in daratumumab-treated WM was negative as expected, highlighting ADCC rather than CDC as the primary cytotoxic mechanism. Conclusion: Our analysis of CD38 in WM preclinical models highlights several important findings: 1.) Expression of CD38 changes as WM tumor clones evolve with induction of drug-resistance; an effect that may also be cell-type specific as evidenced by increased CD38 expression in RPCI-WM1/IR cells, 2.) Daratumumab can exert a direct lethal effect in WM cells but this effect is variable and cell line dependent, 3.) Expression of CD38 is an important factor directing cytotoxicity of Dara however antigen density appears to be an important factor and a grading system can be beneficial for future preclinical and/or clinical studies, 4.) ADCC and not CDC appear to be the prominent mechanism of action and 5.) ADCC-mediated cytolytic activity of Dara is contingent on CD38 expression as evidenced by the most specific lysis being noted in CD38 Grade 2+ and 3+ expressing WM cells (Table 1.). These observations can help direct optimal design of clinical studies with Dara in WM where drug resistance and CD38 expression should be further explored as factors contributing to the clinical efficacy of this new agent. Disclosures Ailawadhi: Pharmacyclics: Consultancy; Novartis: Consultancy; Amgen Inc: Consultancy; Takeda Oncology: Consultancy. Ansell:BMS, Seattle Genetics, Merck, Celldex and Affimed: Research Funding.

2021 ◽  
Author(s):  
Michael S. Breen ◽  
Tom Rusielewicz ◽  
Heather N. Bader ◽  
Carina Seah ◽  
Changxin Xu ◽  
...  

ABSTRACTPost-traumatic stress disorder (PTSD) results from severe trauma exposure, but the extent to which genetic and epigenetic risk factors impact individual clinical outcomes is unknown. We assessed the impact of genomic differences following glucocorticoid administration by examining the transcriptional profile of human induced pluripotent stem cell (hiPSC)-derived glutamatergic neurons and live cultured peripheral blood mononuclear cells from combat veterans with PTSD (n=5) and without PTSD (n=5). This parallel examination in baseline and glucocorticoid-treated conditions resolves cell-type specific and diagnosis-dependent elements of stress response, and permits discrimination of gene expression signals associated with PTSD risk from those induced by stress. Computational analyses revealed neuron-specific glucocorticoid-response expression patterns that were enriched for transcriptomic patterns observed in clinical PTSD samples. PTSD-specific signatures, albeit underpowered, accurately stratify veterans with PTSD relative to combat-exposed controls. Overall, in vitro PTSD and glucocorticoid response signatures in blood and brain cells represent exciting new platforms with which to test the genetic and epigenetic mechanisms underlying PTSD, identify biomarkers of PTSD risk and onset, and conduct drug-screening to identify novel therapeutics to prevent or ameliorate clinical phenotypes.


2021 ◽  
Author(s):  
Michael Breen ◽  
Michael Breen ◽  
Tom Rusielewicz ◽  
Heather Bader ◽  
Carina Seah ◽  
...  

Abstract Post-traumatic stress disorder (PTSD) results from severe trauma exposure, but the extent to which genetic and epigenetic risk factors impact individual clinical outcomes is unknown. We assessed the impact of genomic differences following glucocorticoid administration by examining the transcriptional profile of human induced pluripotent stem cell (hiPSC)-derived glutamatergic neurons and live cultured peripheral blood mononuclear cells from combat veterans with PTSD (n=5) and without PTSD (n=5). This parallel examination in baseline and glucocorticoid-treated conditions resolves cell-type specific and diagnosis-dependent elements of stress response, and permits discrimination of gene expression signals associated with PTSD risk from those induced by stress. Computational analyses revealed neuron-specific glucocorticoid-response expression patterns that were enriched for transcriptomic patterns observed in clinical PTSD samples. PTSD-specific signatures, albeit underpowered, accurately stratify veterans with PTSD relative to combat-exposed controls. Overall, in vitro PTSD and glucocorticoid response signatures in blood and brain cells represent exciting new platforms with which to test the genetic and epigenetic mechanisms underlying PTSD, identify biomarkers of PTSD risk and onset, and conduct drug-screening to identify novel therapeutics to prevent or ameliorate clinical phenotypes.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 1568-1568
Author(s):  
Niels Van Nieuwenhuijzen ◽  
Marta Cuenca ◽  
Leonie Abbink ◽  
Eline Lammers ◽  
Margot Jak ◽  
...  

Abstract Background Since its approval in 2015, daratumumab has become incorporated in standard-of-care regimens of antimyeloma therapy. However, response to daratumumab in patients with relapsed/refractory multiple myeloma (RRMM) is heterogeneous, and a reliable biomarker of response is lacking. Expression of CD38 was shown to be associated with response to daratumumab, but failed to predict responses consistently and is therefore not used in clinical practice. Aim of our study was to develop an in vitro method that accurately identifies patients with RRMM that will respond to daratumumab treatment. Methods We obtained CD38 mean fluorescent intensity (MFI) of plasma cells from patients with RRMM just before starting daratumumab therapy, as well as best clinical response to treatment and duration of response to daratumumab in weeks. When possible, extra material was obtained at the bone marrow biopsy performed before the start of daratumumab treatment and frozen in liquid nitrogen in our local biobank facility. All included patients provided written informed consent. Bone marrow mononuclear cells from patients with RRMM were thawed and cultured for a week in a hydrogel-based culture system, supplemented with pro-survival cytokines IL-6 and APRIL. To examine the in vitro response to daratumumab, we added 0.1 μg/ml daratumumab or 0.1 μg/ml IgG1κ isotype to the culture wells. We measured complement-dependent cytotoxicity (CDC) by adding 10% pooled human serum and antibody-dependent cellular cytotoxicity (ADCC) by adding healthy-donor peripheral blood mononuclear cells (PBMC) in a 10:1 effector-to-target ratio. After overnight incubation, hydrogel cultures were broken down mechanically and specific lysis was determined with flow cytometry, using CD138 and CD38 multi-epitope antibodies to select plasma cells, and using ToPro3 live/dead stain and Flow-Count Fluorospheres to obtain absolute numbers of surviving plasma cells. Results First, we analyzed CD38 MFI of plasma cells from 35 patients with RRMM just before starting daratumumab treatment, both as monotherapy or as part of a regimen. As was previously reported by others 1,2, we found a significant association between expression of CD38 and response (p = 0.01) (Figure 1A). However, we also observed considerable overlap between CD38 MFI values of responders and non-responders, with AUC ROC = 0.75. Therefore the discriminatory value of CD38 expression to predict response is weak. Next, we tested daratumumab in vitro on plasma cells obtained from 10 patients with RRMM. Daratumumab ADCC was associated with clinical response by the corresponding patients (p = 0.008), with a median specific lysis of 54.3% for patients who obtained a PR and 26.0% for patients who did not obtain a PR (Figure 1B). Median CDC for patients who did not obtain a PR was 3.16% versus 45.3% for patients who did obtain a PR, without a significant difference between the two groups (p = 0.18). Further evaluation of these results revealed AUC ROC of 1.00 and 0.81 for ADCC and CDC, respectively, outperforming CD38 expression. For ADCC, a threshold value of 39.6% lysis translated to a diagnostic accuracy of 100%, while for CDC a threshold value of 29.4% resulted in a diagnostic accuracy of 87.5%. Ultimately, we compared these results to CD38 expression. With an optimal CD38 MFI threshold value of 10989, diagnostic accuracy of CD38 expression was 71.4%. In addition, we examined ability of the test methods to predict the clinically experienced duration of response to daratumumab treatment. We observed no difference in duration of response when using the optimal threshold values of CD38 MFI (p = 0.13) and CDC lysis (p = 0.12), but duration of response was significantly different for patients with an ADCC lysis above and below the threshold value of 39.6% (p = 0.002) (Figure 1C). Conclusion In summary, we developed an straightforward and consistent in vitro method to predict response to daratumumab treatment in vivo. Measuring ADCC in patient-derived plasma cells using healthy-donor PBMC within our hydrogel-based culture system corresponds with the overall clinical response and duration of response to daratumumab. Our results support further clinical validation of the in vitro use of primary plasma cells to identify patients most likely to benefit from treatment. References 1. Nijhof IS, et al. Blood. 2016;128(7):959-970. 2. Kitadate A, et al. Haematologica. 2019;105(1):e37-e40. Figure 1 Figure 1. Disclosures Peperzak: Philips Healthcare: Research Funding. Minnema: Celgene: Other: Travel expenses; Alnylam: Consultancy; Janssen: Consultancy; Cilag: Consultancy; Kite/Gilead: Consultancy; BMS: Consultancy.


2020 ◽  
Vol 21 (7) ◽  
pp. 722-734
Author(s):  
Adele Soltani ◽  
Arefeh Jafarian ◽  
Abdolamir Allameh

micro (mi)-RNAs are vital regulators of multiple processes including insulin signaling pathways and glucose metabolism. Pancreatic &#946;-cells function is dependent on some miRNAs and their target mRNA, which together form a complex regulative network. Several miRNAs are known to be directly involved in &#946;-cells functions such as insulin expression and secretion. These small RNAs may also play significant roles in the fate of &#946;-cells such as proliferation, differentiation, survival and apoptosis. Among the miRNAs, miR-7, miR-9, miR-375, miR-130 and miR-124 are of particular interest due to being highly expressed in these cells. Under diabetic conditions, although no specific miRNA profile has been noticed, the expression of some miRNAs and their target mRNAs are altered by posttranscriptional mechanisms, exerting diverse signs in the pathobiology of various diabetic complications. The aim of this review article is to discuss miRNAs involved in the process of stem cells differentiation into &#946;-cells, resulting in enhanced &#946;-cell functions with respect to diabetic disorders. This paper will also look into the impact of miRNA expression patterns on in vitro proliferation and differentiation of &#946;-cells. The efficacy of the computational genomics and biochemical analysis to link the changes in miRNA expression profiles of stem cell-derived &#946;-cells to therapeutically relevant outputs will be discussed as well.


2018 ◽  
Vol 38 (10) ◽  
Author(s):  
Susana Beceiro ◽  
Attila Pap ◽  
Zsolt Czimmerer ◽  
Tamer Sallam ◽  
Jose A. Guillén ◽  
...  

ABSTRACTThe liver X receptors (LXRs) are ligand-activated nuclear receptors with established roles in the maintenance of lipid homeostasis in multiple tissues. LXRs exert additional biological functions as negative regulators of inflammation, particularly in macrophages. However, the transcriptional responses controlled by LXRs in other myeloid cells, such as dendritic cells (DCs), are still poorly understood. Here we used gain- and loss-of-function models to characterize the impact of LXR deficiency on DC activation programs. Our results identified an LXR-dependent pathway that is important for DC chemotaxis. LXR-deficient mature DCs are defective in stimulus-induced migrationin vitroandin vivo. Mechanistically, we show that LXRs facilitate DC chemotactic signaling by regulating the expression of CD38, an ectoenzyme important for leukocyte trafficking. Pharmacological or genetic inactivation of CD38 activity abolished the LXR-dependent induction of DC chemotaxis. Using the low-density lipoprotein receptor-deficient (LDLR−/−) LDLR−/−mouse model of atherosclerosis, we also demonstrated that hematopoietic CD38 expression is important for the accumulation of lipid-laden myeloid cells in lesions, suggesting that CD38 is a key factor in leukocyte migration during atherogenesis. Collectively, our results demonstrate that LXRs are required for the efficient emigration of DCs in response to chemotactic signals during inflammation.


Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2898-2898
Author(s):  
Michael R McKeown ◽  
Christopher Fiore ◽  
Emily Lee ◽  
Matthew L Eaton ◽  
Christian C. Fritz

Abstract SY-1425, a potent and selective agonist of the retinoic acid receptor RARα, is being investigated in a Ph2 trial in a novel genomically-defined subset of non-APL AML and MDS patients (clinicaltrials.gov NCT02807558). RARa is a nuclear hormone receptor and transcription factor that regulates genes involved in cell differentiation and proliferation. We identified a super-enhancer (SE) at the RARA locus, the gene encoding RARa, in a subset of primary non-APL AML blasts. Preclinical models demonstrated a correlation between the presence of a RARA SE and sensitivity to SY-1425, providing the rationale for clinical investigation. Further research has investigated pharmacodynamics (PD) markers and combinations of drugs to support clinical development of SY-1425. In this study we identified DHRS3mRNA induction as a measure of RARα target engagement with SY-1425. We also demonstrated synergy in preclinical models with SY-1425 and hypomethylating agents. Since RARα is a transcription factor that regulates target genes when bound by a retinoid, we characterized the dynamic expression changes of a panel of RARA enhancer- high and - low non-APL AML cell lines (hereafter referred to as RARA-high and -low) in response to SY-1425 treatment. DHRS3 showed the largest expression increase following treatment in 3 RARA-high cell lines, with a range of 29 to 115 fold. In contrast, there was a much lower DHRS3 induction in 3 RARA-low cell lines (range of 1.6 to 6.1 fold). Induction was found to be both time- and dose-dependent with maximal induction at approximately 6 hours and half maximal induction near the EC50 for the anti-proliferative effect in RARA-high cell lines. DHRS3 encodes dehydrogenase/reductase (SDR family) member 3, a metabolic enzyme involved in maintaining cellular retinol homeostasis and had previously been shown to be induced by retinoids. Thus, DHRS3induction in tumor cells represents a potentially useful PD marker for clinical studies of SY-1425. To better understand the mechanism of induction of DHRS3 by SY-1425 we examined the chromosomal localization of RARα as well as the epigenomic state of the DHRS3 locus by ChIP-seq for RARα and H3K27 acetylation, the latter being an indicator of active enhancers and promoters. In the untreated state, OCI-AML3 (a typical RARA-high AML cell line) was found to have multiple RARα binding sites both within and distal to the DHRS3 gene but minimal H3K27 acetylation. Following treatment with SY-1425, the level of H3K27 acetylation at DHRS3 increased, resulting in the formation of a SE. Moreover, the SE encompassed the RARα binding sites, consistent with the model in which SY-1425 converts RARα into an activator of DHRS3expression. Similar results were seen for the CD38 locus in which SY-1425 treatment increased expression, H3K27 acetylation, and RARα binding. CD38 is a cell surface antigen and marker of myeloid maturation readily analyzed by FACS analysis, suggesting it could be an additional PD marker to be used in clinical studies. Indeed, it was found that SY-1425 induced CD38 cell surface expression at similar levels in RARA-high AML cell lines and the NB-4 APL cell line, but not in RARA-low cell lines. We also investigated combinations of SY-1425 with approved or investigational AML and MDS agents in in vitro and in vivo models to inform future clinical studies and to further explore potential PD markers unique to the combined action of the drugs. Several standard of care agents and drugs in current development were found to have synergistic interactions with SY-1425 in RARA-high but not RARA-low cell lines. In particular, azacitidine and decitabine each showed strong in vitro synergy with SY-1425. Evaluation of SY-1425 plus azacitidine in a RARA-high PDX model of non-APL AML demonstrated a better response compared to either agent alone. Additional genome-wide ChIP-seq and expression studies of RARA-high cells treated with various combinations are being investigated to identify optimal PD markers for these combinations. These studies support the use of DHRS3 mRNA induction in tumor cells as a PD marker in the recently initiated Ph2 study of SY-1425 in genomically-defined non-APL AML and MDS patients (clinicaltrials.gov NCT02807558) and further exploration as a PD marker for future combination studies. Disclosures McKeown: Syros Pharmaceuticals: Employment, Equity Ownership. Fiore:Syros Pharmaceuticals: Employment, Equity Ownership. Lee:Syros Pharmaceuticals: Employment, Equity Ownership. Eaton:Syros Pharmaceuticals: Employment, Equity Ownership. Fritz:Syros Pharmaceuticals: Employment, Equity Ownership.


Blood ◽  
1998 ◽  
Vol 91 (5) ◽  
pp. 1556-1561 ◽  
Author(s):  
Vincent C. Dodelet ◽  
Neil R. Cashman

Abstract The cellular isoform of the prion protein (PrPC) is a small glycoprotein attached to the outer leaflet of the plasma membrane by a glycosylphosphatidylinositol anchor. This molecule is involved in the pathogenesis of prion diseases in both humans and animals. We have characterized the expression patterns of PrPC during human leukocyte maturation by flow cytometry with monoclonal antibodies to PrPC, the glycan moiety CD15, and the stem cell marker CD34. We observe that prion protein is present on CD34+bone marrow (BM) stem cells. Although lymphocytes and monocytes maintain PrPC expression throughout their differentiation, PrPC is downregulated upon differentiation along the granulocyte lineage. In vitro retinoic acid–induced differentiation of the premyeloid line HL-60 into granulocyte-like cells mimics the suppression of PrPC in granulocyte differentiation, as both PrPC mRNA and protein are downregulated. These data suggest that selected BM cells and peripheral mononuclear cells may support prion agent replication, because this process is dependent on availability of PrPC. Additionally, retinoic acid–induced extinction of PrPC expression in HL-60 cells provides a potential model to study PrP gene regulation and protein function. Finally, these data suggest the existence of cell-specific glycoforms of PrPC that may determine cellular susceptibility to infection by the prion agent.


Blood ◽  
1994 ◽  
Vol 84 (3) ◽  
pp. 841-846 ◽  
Author(s):  
MR Silva ◽  
R Hoffman ◽  
EF Srour ◽  
JL Ascensao

Abstract Human natural killer (NK) cells comprise 10% to 15% of peripheral blood mononuclear cells and have an important role in immune responses against tumors, viral infections, and graft rejection. NK cells originate in bone marrow (BM), but their progenitors and lineage development have not been completely characterized. We studied the generation of NK cells from purified CD34+HLADR- and CD34+HLADR+ BM progenitors and the influence of various cytokines on their production. We show that CD3-CD56+ cytotoxic NK cells can develop from both progenitors populations when interleukin-2 (IL-2) is present in an in vitro suspension culture system containing IL-1 alpha and stem cell factor. Up to 83.8% and 98.6% CD3-CD56+ cells were detected in CD34+HLADR- and CD34+DR+ cultures, respectively, after 5 weeks of culture; significant numbers of NK cells were first detected after 2 weeks. Cytotoxic activity paralleled NK cell numbers; up to 70% specific lysis at an effector:target ratio of 10:1 was observed at 5 weeks. IL-7 also triggered development of CD3-CD56+ cells from these immature progenitors (up to 24% and 55% appeared in CD34+HLADR- and CD34+HLADR+ cultures, respectively). Our data suggest that BM stromas are not necessary for NK cell development and that IL-2 remains essential for this lineage development and differentiation.


Parasitology ◽  
2020 ◽  
Vol 147 (13) ◽  
pp. 1488-1498
Author(s):  
Sujeevi S. K. Nawaratna ◽  
Donald P. McManus ◽  
Robin B. Gasser ◽  
Paul J. Brindley ◽  
Glen M. Boyle ◽  
...  

AbstractPraziquantel (PZQ) is the drug of choice for schistosomiasis. The potential drug resistance necessitates the search for adjunct or alternative therapies to PZQ. Previous functional genomics has shown that RNAi inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) gene in Schistosoma adult worms significantly improved the effectiveness of PZQ. Here we tested the in vitro efficacy of 15 selective and non-selective CaMK inhibitors against Schistosoma mansoni and showed that PZQ efficacy was improved against refractory juvenile parasites when combined with these CaMK inhibitors. By measuring CaMK activity and the mobility of adult S. mansoni, we identified two non-selective CaMK inhibitors, Staurosporine (STSP) and 1Naphthyl PP1 (1NAPP1), as promising candidates for further study. The impact of STSP and 1NAPP1 was investigated in mice infected with S. mansoni in the presence or absence of a sub-lethal dose of PZQ against 2- and 7-day-old schistosomula and adults. Treatment with STSP/PZQ induced a significant (47–68%) liver egg burden reduction compared with mice treated with PZQ alone. The findings indicate that the combination of STSP and PZQ dosages significantly improved anti-schistosomal activity compared to PZQ alone, demonstrating the potential of selective and non-selective CaMK/kinase inhibitors as a combination therapy with PZQ in treating schistosomiasis.


Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 46-46
Author(s):  
Loic Ysebaert ◽  
Mary Poupot ◽  
Yovan Sanchez-Ruiz ◽  
Camille Laurent ◽  
Guy Laurent ◽  
...  

Abstract Abstract 46 Introduction: CLL cells interact with many accessory cells in an environment mimicking that of normal mature B cells. Role of antigen, cytokines, adhesion pathways are critical for many aspects in the disease course (proliferation/survival, migration or homing, drug resistance, and presumably relapse). Nurse-like cells (NLC) belong to a monocytic-derived, bystander population among CLL lymph node and spleen stromal cells. Aim: To investigate the nature, functions, and location of NLC within CLL microenvironment. Methods: Gene expression profiles (GEP) from in vitro expanded NLC from patients (n=10) were produced and compared to those from normal CD14+ monocytes, M1-polarized macrophages, M2-polarized macrophages and tumor-associated macrophages (produced in the lab or downloaded from GEO datasets). Principal Component Analysis was used to categorize these five populations of cells and in-house-built GSEA software was used for functional interpretation of their relevant gene lists. Protein expression patterns were validated with multi-analyte ELISArray kits, proteome profiler arrays, flow cytometry (FC) or immunohistochemistry (IHC). Results: New insights into the physiopathological role of NLC in CLL are suggested from five lines of evidence: 1/a Òmonocytic gene signatureÓ (i.e. a set of 549 genes) is shared by the NLC and the monocyte subtypes. The genes over-represented in NLC vs normal monocytes pinpointed positive modulation of apoptotic cell clearance (scavenger, mannose and complement receptors, LXRalpha), lipid metabolism (Apolipoprotein E, PPAR signaling), extracellular matrix-receptor interactions (integrins, SPARC, Matrix MetalloProteinases) and actin cytoskeleton remodeling. 2/unsupervised clustering show that NLC represent an M2-skewed, TAM-like cell population. They down-regulate mRNA and proteins for classic M1 inflammatory markers (e.g. IL-1, IL-6, IL-12, COX2) while increase secretion of TGFbeta, IL-10, CCL17 and CCL22 soluble factors. 3/these and previously published observations suggest that B-CLL-to-NLC interactions may orchestrate immunosuppression in this disease. PBMCs from Òwatch and waitÓ CLL patients (all stage A/Rai 0, mutated IgVH, low risk cytogenetics profile) or healthy donors were stimulated with anti-CD3/CD28 beads + IL-2, either in standard RPMI+10% FCS or in conditioned medium (CM, after 14d CLL-NLC co-culture in vitro) and their proliferation/phenotype were compared after 2 weeks. Significant expansion of T cells with Treg (CD4+CD25+FoxP3+) phenotype was observed only from CLL PBMCs grown in conditioned medium (mean % Treg: 2.85 vs 3.05 in CM for normal PBMCs, and 1.54 vs 15.9 in CM for CLL PBMCs, P< 0.05). 4/although NLC make immune synapses with live B-CLL, they do not phagocytose them. Over-expression of CD47 (ÒdonÕt eat meÓ signal) by B-CLL cells (mfi= 3490 vs 2581 on normal cells, P< 0.05, n=18) may provide them with a protective signal against NLC. 5/from our GEP, flow cytometric and IHC analyses, we propose CD163 (classic M2 marker) as a reliable tool to identify NLC in vivo. Although in vitro, CLL cells can pervert healthy donor monocytes into NLC, only CLL-derived NLC are truly CD14+ CD163+. In vivo, CD163 staining reveals putative NLC in CLL lymph nodes(LN)/spleen sections but not in bone marrow. In LN from all patients, NLC reside in the subcapsular areas and line vessel structures, suggesting a role in CLL cells trafficking. Most interestingly, NLC infiltrate pseudofollicles structures only in a subset of cases. We will present updated IHC and clinical presentation correlation studies. Conclusions: Our results suggest that the role of NLC in CLL might be broader than initially thought. Beside of nursing and conferring drug resistance, NLC may also be crucial in the setting of immunosuppression, of CLL cells recruitment, and should thus be considered as therapeutic targets. Disclosures: Off Label Use: GA101 is not currently approved for CLL treatment.


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