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Introduction Multiple Myeloma (MM) remains an incurable disease and is associated with high rates of venous thromboembolism (VTE), the biological basis for which is not fully understood. Critically, VTE is associated with increased mortality in MM. This highlights the clinical importance of understanding cancer-coagulation crosstalk in MM. Accumulating evidence demonstrates that many solid tumours trigger endothelial cell (EC) activation with resultant von Willebrand Factor (VWF) secretion proposed to contribute to both risk of VTE and cancer metastasis. However, the interplay between VWF and MM disease biology remains poorly defined. Methods/Results 100 patients with plasma cell disorders were recruited to this study. Significantly elevated plasma VWF antigen (VWF:Ag) levels were observed in patients with newly diagnosed MM (NDMM) compared to those with monoclonal gammopathy of undetermined significance (MGUS) or smouldering MM (SMM) (median 292.7 IU/dL vs 133.1 IU/dL; P We also observed increased VWF collagen binding activity in NDMM/RRMM compared with MGUS/SMM (median 455.7 IU/dL vs 189.7 IU/dL; P Next we measured VWF:Ag levels in bone marrow (BM) samples from 10 patients and found that VWF is released locally within the BM niche (median 190.2 IU/dL). Co-culture of primary human ECs with supernatant from freshly isolated primary MM cells or several Human Myeloma Cell Lines (HMCLs) demonstrated that MM cells stimulate release of VWF from ECs in a rapid manner, suggestive of Weibel-Palade body exocytosis (median 34.9ng/ml vs 9.2ng/ml in untreated EC; P Using flow cytometry, we assessed the direct interaction of MM cells and VWF in vitro. Both primary MM cells and HMCLs bound significantly to human recombinant VWF in a dose-dependent manner. Binding was reduced by 50% following treatment with LMWH (P Conclusion These data suggest that MM is not only associated with a marked quantitative increase in plasma VWF:Ag, but also impacts VWF functional activity. Our novel data help define the biological mechanisms underpinning elevated VWF levels in MM, with a key contribution of VEGF-A secreted directly from MM cells in the BM microenvironment. Collectively, our findings provide insights into cancer-coagulation crosstalk in MM and may help identify novel therapeutic targets to reduce VTE risk and disease progression. Disclosures Glavey: Celgene and BMS company: Research Funding; Janssen: Honoraria, Research Funding; Abbvie: Research Funding; Amgen: Honoraria, Research Funding. Quinn: Takeda: Honoraria. O'Sullivan: Leo Pharma: Research Funding.

Multiple Myeloma (MM) is a haematological malignancy characterised by clonal proliferation of plasma cells within the bone marrow (Landgren and Weiss, 2009). Unfortunately, despite the major improvements to the treatment of MM within the last decade, it remains an incurable disease. Therefore, novel innovative combinations of less toxic therapies are warranted, especially for elderly patients with relapsed/refractory disease. The anti-apoptotic BCL-2 family of proteins (BCL-2, BCL-XL and MCL-1) are critical regulators of the intrinsic apoptotic pathway and determine the survival of human MM cells (Letai et al., 2004, Del Gaizo Moore et al., 2008). Recently, Venetoclax, a selective BCL-2 inhibitor, was FDA approved for the treatment of chronic lymphocytic leukaemia (CLL) and acute mylogenous leukemia (AML), in combination with demethylating agents (Roberts et al., 2016, DiNardo et al., 2018, DiNardo et al., 2019) It is known that some MM patients with t(11;14) have a good response to combination treatment with venetoclax, however certain patients who do not have t(11;14) also respond to venetoclax. Therefore, a biomarker for response is urgently required in MM, as it has heterogeneous anti-apoptotic dependencies. In AML, venetoclax is combined with the epigenetic modifier 5-azacytidine. Highlighting, that screening for epigenetic modifier's, maybe a useful approach to identify synergistic combination of treatments with venetoclax in MM. Methods: To assess anti-apoptotic protein dependence in MM cell lines (JJN3, RPMI-8226, KMS18, MM1S, U266) and primary patient samples, BH3 profiling was used. Briefly, cells are exposed to a series of BH3-only peptides (20-23 mer in length) following gentle permeabilisation of cell membrane with low concentrations of digitonin. The loss of mitochondrial potential (JC-1) or the release of cytochrome c (cytochrome-c-FITC antibody) was assessed by plate reader or by flow cytometry. Cell death was assessed by Annexin V/ propidium iodide staining by flow cytometry. Using primary patient samples, CD138 + cells were isolated using the Miltenyi MAC sorter. For the epigenetic screen cell viability was assessed by CellTiter-Glo® and death was then confirmed by Annexin V/Pi staining. Results BH3 profiling was used to assess anti-apoptotic dependence in a panel of five MM cell lines. It is a functional assay that interrogates BCL-2 protein interactions using synthetic BH3 peptides to measure the loss of mitochondrial membrane potential. The BH3 profiling was correlated to the response of the cell lines to a series of BH3 mimetics : venetoclax (selective BCL-2 inhibitor), ABT-263 (BCL-2, BCL-XL and BCL-W inhibitor), WEHI-539 (BCL-XL inhibitor) and AMG-176 (MCL-1 inhibitor). This data highlighted that BH3 profiling is a powerful tool for identifying anti-apoptotic dependnece in MM. It also showed and that there is a diverse anti-apoptotic dependence in MM cell lines and primary patient samples. Remarkably, one patient with plasma cell leukemia showed BCL-2 dependence by BH3 profiling, a t(11:14) translocation and a sustained in-vivo single agent response to venetoclax (Glavey et al., 2020).. Next, we performed an unbiased epigenetic modifier screen in two MM cell lines JJN3 (MCL-1 dependent cell lines) and KMS-18 (mixed anti-apoptotic dependence) to induce BCL-2 dependence and sensitivity to venetoclax. The screen included the following classes of epigenetic modifiers: histone deacetylase inhibitors, histone methyltransferase inhibitors, DNA methyltransferase inhibitors and histone acetylase inhibitors. Interestingly, two classes of epigenetic drugs were synergistic with venetoclax in three different MM cell lines (CI Conclusion. BH3 profiling is a powerful tool to identify the anti-apoptotic dependence in MM cell lines and MM patient samples, which we can exploit pharmacologically to kill MM cells in a personalised medicine approach. Combining epigenetic modifiers with venetoclax induces BCL-2 dependence in MM and enhances response to treatment. Figure 1 Figure 1. Disclosures Flanagan: AbbVie: Research Funding. O'Dwyer: Bristol Myers Squibb: Research Funding; ONK Therapeutics: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy. Quinn: Takeda: Honoraria. Glavey: Janssen: Honoraria, Research Funding; Celgene and BMS company: Research Funding; Abbvie: Research Funding; Amgen: Honoraria, Research Funding. Ni Chonghaile: AbbVie: Research Funding.

Background and aims: Acute myeloid leukaemia (AML) is a relatively rare haematological malignancy which is the most common acute leukaemia in adults. Patients with AML often have a substantial comorbidity burden. Consequently, different scores are used in clinical practice to predict outcomes in patients with multiple comorbidities. The Charlson Comorbidity Index (CCI), calculated based on 19 different medical conditions, weighs the comorbidities to measure a patient's burden of disease. Previous publications have suggested that the CCI may be useful in determining survival in AML patients. However, the CCI is not in routine use in Ireland for assessing patients with AML. In this study we examined the usefulness of the CCI to predict early mortality in AML patients, drawing on data from the Extended Blood Cancer Registration (EBCR) in Ireland. Methods: The EBCR was undertaken by National Cancer Registry Ireland registrars trained by consultant haematologists and deployed in national centres. Data collection began in 2017 and continued to 2019; 141 AML patients underwent extended data registration. Comorbidities were identified by ICD-9 codes and chart review. Kaplan Meier curves and Cox regression analyses were used to determine the usefulness of the CCI to predict early mortality in AML patients. Results: Of the 141 AML patients, 82% were between 50 and 70 years of age and 84 had died by 31/12/2019 (median survival time = 289.0 days). The median survival time for patients in the lowest tertile of the CCI was 498.5 days, compared to 246.0 and 116.5 days for subjects in tertiles 2 and 3, respectively (Figure 1. Log rank P-value Conclusions: Although results demonstrate a strong relationship between the CCI and early mortality in AML patients, our findings suggest that the CCI provides little or no additional prognostic information beyond that which is obtained from age at AML diagnosis alone. This study highlights the importance of validating risk assessment tools in order to determine their potential usefulness in a clinical setting and emphasise the importance of weighing in the treatment decision making paradigm. The Blood Cancer Network Ireland (BCNI) thank the Science Foundation of Ireland (SFI) and the Irish Cancer Society (ICS) for funding (2015-2021). We also thank our colleagues in the National Cancer Registry Ireland for assistance, advice and guidance. Figure 1 Figure 1. Disclosures Quinn: Takeda: Honoraria. O'Dwyer: Bristol Myers Squibb: Research Funding; Janssen: Consultancy; ONK Therapeutics: Current Employment, Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Szegezdi: ONK Therapeutics: Research Funding.

Red Blood Cells from COVID-19 Patients Show Evidence of Increased Oxidative Stress and Increased Lactate Influx Corona Disease 19 (COVID-19) is caused by SARS-CoV-2, a novel, highly infectious, single stranded RNA virus. In severe cases, excess oxidative stress produced by a 'cytokine storm' may generate excess reactive oxygen species (ROS) and lead to tissue damage in the lungs and elsewhere. As the potential role of RBCs in the pathophysiology of COVID-19 remains controversial (1), we investigated for evidence of increased oxidative stress and increased thrombotic tendency in RBCs from patients with COVID-19 infection. Following ethical approval and written informed consent, we used flow cytometry (BD FACSCanto II) to measure baseline RBC ROS following incubation with 2'-7'-dichlorofluorescein diacetate (DCF). RBC ROS were also measured following pre-incubation with hydrogen peroxide (H2O2) (2mM) +/- antioxidant N-acetyl cysteine (NAC) (0.6mM). We also measured RBC surface expression of adhesion molecules CD44, CD47 and CD242, as well as CD147. Results were expressed as mean +/- standard deviation (SD). RBC ROS were measured in 22 COVID-19 positive patients and in 10 age matched healthy controls. One patient died from respiratory failure, whilst only 3 others required ITU admission for continuous positive airway pressure (CPAP) or intubation. There was no statistical difference in mean basal RBC DCF mean fluorescence intensity (MFI) levels between COVID-19 positive patients and controls. However, mean increase in RBC DCF MFI following H2O2 incubation was significantly higher in the COVID-19 positive group (1105.7+/-336.3) compared to the control group (843.4+/-256.7)( p= 0.042). The increase in RBC DCF MFI in the COVID-19 positive group correlated with CRP (p=0.014) but not with D-dimer, serum ferritin or any complete blood count (CBC) parameters. Incubation of RBC with 0.6 mM NAC for 30 minutes prior to H2O2 exposure caused a mean reduction in DCF MFI of 26.7% in the COVID-19 positive group. RBC expression of CD44, CD47, CD242 and CD147 were measured In a separate cohort of COVID-19 positive patients (n=32), and in 22 age matched controls. There were no statistically significant differences in mean expression levels of CD44, CD47 and CD242 between the 2 groups. However, mean RBC CD147 MFI expression was higher in the COVID-19 group (1319.64+/-374.76) compared to controls (1061.59+/-253.33) (p=0.018). There was no significant correlation between RBC CD147 MFI and D-dimer, CRP, serum ferritin or any CBC parameters in the COVID-19 positive group. However, 21 of the 32 COVID-19 positive patients had blood lactate levels measured and there was a positive correlation between CD147 MFI expression and blood lactate (R=0.56, p=0.0077). Induction of oxidative stress by H2O2 resulted in a greater increase in ROS in RBCs from COVID-19 patients compared to controls and with correlation to CRP, despite the fact that there were very few patients with severe disease in the study. This suggests a role for oxidative stress in disease pathogenesis. Pre-incubation with NAC attenuated this increase in ROS, suggesting a possible role for antioxidants in therapy. Increased RBC cell surface expression of adhesion molecules CD44, CD47 and CD242 can facilitate RBC interaction with platelets and/or endothelial cells, potentially contributing to thrombosis. We found no increase in their expression in COVID-19 patients compared to controls although RBCs may contribute to thrombosis in COVID-19 infection by other means (1). CD147 is tightly associated with and enables proper expression of monocarboxylate transporter 1, the lactate transporter for RBCs. We found increased surface expression of CD147 on RBCs of COVID-19 patients, whilst CD147 expression showed a moderate correlation with serum lactate levels, suggesting that RBCs in COVID-19 infection may be acting as a lactate sink to protect against lactic acidosis. In summary, our study suggests that COVID-19 infection causes increased oxidative stress and increased lactate influx in RBCs. Further studies are warranted into the role of RBCs in COVID-19 infection. Reference: (1) Murphy P, Glavey S, Quinn J. Anemia and red blood cell abnormalities in COVID-19. Leuk Lymphoma 2021;62:1539 Disclosures Quinn: Takeda: Honoraria. Glavey: Abbvie: Research Funding; Celgene and BMS company: Research Funding; Janssen: Honoraria, Research Funding; Amgen: Honoraria, Research Funding.

R-CHOP chemoimmunotherapy is first line therapy for diffuse large B cell non Hodgkin lymphoma (DLBCL), although R-CHOP may be suboptimal treatment for some subtypes of DLBCL, in particular double-hit (DH) or triple-hit (TH) lymphoma. For assessment of response to chemoimmunotherapy, it has been proposed that PET-CT scan may be superior to CT scan and, in particular, demonstration of metabolic complete response (CR) by PET-CT scan at end of treatment (EOT) may be an important indicator of long term survival. However, the usefulness of follow up scans in asymptomatic patients remains debatable. We wished to assess the role of an interim CT or PET-CT scan (after 3-4 courses of chemoimmunotherapy) in predicting overall survival in patients at our centre with stage II- IV DLCBCL (Lugano Modification of Ann Arbor Classification) who received chemoimmunotherapy with curative intent. We also recorded results of scans at EOT and any further follow up scans. Between 1/7/15 and 1/7/19, 43 consecutive patients receiving R-CHOP had an interim CT or PET-CT scan. 3 of 4 patients with DH lymphoma by FISH testing changed to dose adjusted R-EPOCH after one course of R-CHOP. 39 patients had no evidence of DH, with 37 showing either partial response (PR) (N = 11) or CR (N=26) on interim CT or PET-CT scan. Of these 37 cases, one patient died of neutropenic sepsis, whilst 36 remain alive with 35 in complete remission. 30 of these 37 patients had CT scan and/or PET-CT scan at EOT: 27 were in CR, 2 were in stable PR and 1 patient (in CR on interim PET -CT scan) showed relapse on PET-CT scan. 16 patients in CR at EOT had 55 follow up surveillance scans (median 2, range 1-8) -two further relapses were detected on PET-CT scan, both 4 months after EOT. Two of the relapsed cases are in CR following further chemoimmunotherapy and allogeneic stem cell transplant whilst the other relapsed case is currently responding to further chemoimmunotherapy. 2 patients without evidence of DH showed disease progression on interim scan and were refractory to further chemotherapy, dying within 3 months and 18 months of diagnosis. All 4 patients with DH lymphoma had PR or CR at interim scan but relapsed within 5 to 8 months after diagnosis and proved chemotherapy refractory with death in 3. One patient with DH lymphoma remains in CR following local radiation and maintenance therapy with rituximab, lenalidomide and metformin. In our experience, patients with DLBCL, without DH or TH, who have evidence of response to R-CHOP at interim scan have an excellent prognosis. In this patient cohort, 85 EOT and follow up scans detected 3 relapses, suggesting that the detection rate of follow up scans in asymptomatic patients in this good prognosis group is low and of questionable usefulness. The 3 relapsed patients were readily salvageable by further chemoimmunotherapy with or without allogeneic stem cell transplant. In contrast, patients with DH lymphoma or evidence of disease progression on interim scan have very poor prognosis and urgently require alternative therapy approaches. Disclosures No relevant conflicts of interest to declare.

Introduction: The microenvironment plays a major role in the survival of Chronic Lymphocytic Leukaemia (CLL) cells by promoting CLL cell growth and drug resistance. The traffic of CLL cells that involve migration from the blood and adhesion to the high endothelial venules (HEVs) facilitates the homing of lymphocytes in the lymph nodes to protect CLL cells and offer them the necessary survival signals. L- Selectin mediates adhesion of CLL cells to LN-microenvironment through a multistep process that entails rolling, sticking, and crawling. Acitretin is a retinoid that used in the treatment of severe psoriasis and less frequently in the control of squamous skin cancer. Acitretin activates nuclear retinoic acid receptors (RAR), resulting in induction of cell differentiation, inhibition of cell proliferation, and inhibition of tissue infiltration by inflammatory cells. It is reported that retinoids induce apoptosis in CLL and improve the sensitivity of CLL cells to fludarabine. Method: We used MEC-1 "CLL like" cell line and CLL cells from known CLL patients to investigate the effect of acitretin on the expression of the major markers that control CLL cells traffic including L-selectin (CD62L), CD49d and CXCR4 (CD184) . We treated CLL cells with increasing doses of acitretin (10 nM up to 10 mM). After treatment for 48 to 72 hours, L-selectin, CD49d and CXCR4 expression was measured using flowcytometry. Dimethyl sulfoxide (DMSO) treated cells were used as a negative control. A Leukocyte adhesion assay was done using CytoSelect Leukocyte-endothelium adhesion assay according to the protocol provided. To assess the mechanism through which L-Selectin reduces the adhesion of CLL cells to the endothelium, we used western blot to measure the effect of acitretin on PI3k-p85. Results: Acitretin in a dose as low as 10 nM significantly reduced the expression of L-selectin in primary CLL cells after treatment for 48 hours (P= 0.0475) and 72 hours (P= 0.0048). On the contrary, acitretin did not change the expression of CD49d or CXCR4. Similar significant reduction in L-selectin expression was recognized when MEC-1 cells were treated with 10 nM of acitretin for 48 hours (P= 0.0179) and 72 hours (P= 0.0159). To test the effect of acitretin on the adhesion of MEC-1 cells to the endothelium; we used CytoSelect adhesion assay that showed significant reduction in the adhesion of MEC-1 cells to human umbilical vein endothelial cells (HUVEC) after treatment with acitretin 10 mM for 48 hours (P= 0.0048). Ibrutinib treatment has also significantly reduced the adhesion of MEC-1 cells to HUVEC cells (P= 0.0045) and when combined with acitretin the reduction in adhesion was more pronounced (P= 0.0003). Finally, to understand the mechanism through which acitretin down regulates the expression of L-selectin and reduces the adhesion of MEC-1 cells, we tested the effect of acitretin on the PI3K pathway using western blot. PI3K is required for the cytoskeleton changes during neutrophil rolling on E‐selectin and we investigated if similar interaction takes place between PI3K and L-selectin in CLL cells. Treatment of MEC-1 cells with acitretin 10 mM for 48 hours resulted in significant down regulation of the PI3K-p85 (P= 0.0007). Treatment with Ibrutinib alone or combined with acitretin did not result in significant change in PI3K- p85. This may explain the mechanism through which acitretin reduces the expression of L-selectin and compromises CLL adhesion to the endothelium. Conclusion: We showed that the retinoid acitretin significantly reduced the expression of L-selectin in CLL cells and MEC-1 "CLL like" cells in vitro. The reduction in L-selectin resulted in reduced adhesion of CLL cells to the endothelium hampering homing of CLL cells to lymph nodes. The mechanism through which acitretin exerts this effect can be explained by down regulation of PI3K-p85. The use of acitretin as an adjunct treatment in CLL can be beneficial, however further research including in vivo studies is required. Disclosures Quinn: Janssen: Honoraria.

Introduction Myelodysplastic Syndrome (MDS) is classically a disease of older people, with median age at presentation of 70-75 years. The incidence of MDS is estimated at 5-13/100,000/year, but rises to >20/100,000/year in older populations. An increase in diagnosis over the last decades is in part due to improved recognition of MDS, but likely also to an increase in the ageing population. There is very little data on the clinical course, management and outcomes for very old patients (≥85 years of age) with MDS. Patients and Methods: This was a retrospective, multicentre analysis of 84 patients with MDS or Chronic Myelomonocytic Leukemia (CMML) aged ≥85 years at diagnosis from 6 centres in Ireland. Results: We identified 84 patients aged ≥85 years at time of diagnosis of MDS (n= 70) or CMML (n=14), including 47 men (56%) and 37 women (44%). Median age at diagnosis was 87 years (range 85-98). Most patients (93%) were anemic at presentation, including 45/47 men (96%) and 33/37 women (89%). Median hemoglobin (Hb) was 9.5 g/dl (range 5.9 -13.8). Median neutrophil count was 2.4 x109/L (range 0-72). Forty-four patients had thrombocytopenia (median platelet count 144 x 109/L (range 18-624)). Data regarding co-morbidities were available for 75 patients: 69% had hypertension, 36% ischemic heart disease, 39% atrial fibrillation, 31% heart failure, 19% diabetes and 39% renal dysfunction. Ferritin was elevated in 18 (32%) of 57 patients tested. 2006 WHO subgroups were reported for 81 patients: RCMD (32; 40%), CMML (14; 17%), RA (10; 12%), RAEB-1 (10; 12%), RAEB-2 (7; 9%), RARS (2; 3%), t-MDS (2; 3%), Hypoplastic MDS (1; 1%) and 5q- Syndrome (1; 1%). Cytogenetic analysis was performed in 49 patients (58%); results were available for 39 (46%). No patient had molecular studies for MDS-associated mutations or p53 deletions/mutations. Karyotype was normal in 23 patients (59% of those with results available), deletion Y in 5 (13%), Trisomy 8 in 5 (13%), complex in 3 (7.7%), 5q- in 2 (5.2%), and monosomy 7 in 1 (2.5%). Risk stratification by IPSS-R was available for only 37/84 patients, primarily due to lack of cytogenetic testing. Data were available regarding treatment strategies for 81 patients. Thirty-five (43%) received supportive care only. Forty-five patients (57%) were transfused; 29 (34%) became transfusion-dependent during the course of their disease. Of these, only 14 (48%) received erythropoietin (EPO). Of 50 patients with significant anemia likely to cause symptoms (Hb < 10g/dl), only 21 (42%) received EPO. Five patients (6%) received azacitidine (1-18 cycles; median 5), 7 (8%) received G-CSF; none received lenalidomide or iron chelation. Median survival for all patients was 17 months (range 0-147), 16 months for men (range 0-70), and 27 months for women (range 1-147). In 35 patients who had IPSS-R data available, median survival was 49 months for Very Good, 30 months for Good and 13 months for Intermediate category patients. For 4 patients in the Poor and Very Poor categories median survival was 1, 5, 7 and 28 months. Median survival for patients with RA was 28 months (n=10), RCMD 25 months (n=29), CMML 13 months (n= 14), RAEB-1 10 months (n=10) and RAEB-2 19 months (n=7). Six patients (including 3 with RAEB-1, 1 with CMML and 1 with t-MDS) developed Acute Myeloid Leukaemia (7%) at a median of 4.5 months from diagnosis. Median survival for these patients was 9.5 months. Of 84 patients, 60 have died. The main causes of death included marrow failure, sepsis, cardiac events, other malignancies and gastrointestinal bleeding. Conclusions Anemia is the commonest presenting feature of MDS in the very old, and may be the sole cytopenia. Unexplained anemia in the very old should trigger suspicion of underlying MDS, especially if associated with a high MCV. In many patients over 85 years cytogenetic analysis is not performed, precluding accurate prognostic evaluation. MDS in these very old patients is not often actively managed with pharmacological intervention or chemotherapy. Up to 50% of transfusion-dependent patients do not receive erythropoeitin. Azacitidine and lenalidomide are infrequently used. Co-morbidities (especially cardiac and renal disorders) are very common. Survival can be prolonged, especially in patients with low-risk disease. With an ageing population, management of very elderly patients with MDS is becoming more challenging and a more proactive approach should be considered. Figure. Figure. Disclosures Quinn: Janssen: Honoraria.

Introduction- The mainstream therapy for AML is cytarabine (AraC) and anthracycline-based intensive chemotherapy. Between 10-40% of patients however have a refractory disease. It is becoming increasingly accepted that the risk for refractory disease could be reduced by finding better ways of selecting the induction therapy. While multiple in vitro and in vivo experimental models exist for pre-clinical drug efficacy testing, they are either labour intensive, too time consuming or generate variable results, making them unsuitable for clinical application. Furthermore, very few, if any of these methods have been shown to replicate the clinical response of patients. The aim of this study was to develop a functional drug testing system that can rapidly and faithfully predict the clinical response of the patient and therefore be utilized to help the identification of patients suitable for AraC+daunorubicin (DnR) therapy. Methods- Primary samples were obtained through Blood Cancer Biobank Ireland. All patients were consented and the research project was approved by the local Research Ethics Committee of NUI, Galway. Mononuclear AML blasts were isolated from bone marrow (BM) aspirates of newly diagnosed patients by ficoll-paque gradient separation. HS-5 human bone marrow mesenchymal stromal cells (BMSC), healthy donor (HD)-derived BMSCs immortalised with hTERT (iMSC) and primary BMSCs (non-immortalised, pBMSC) from HDs and AML patients were used as feeder layers. Cytokine and chemokine secretion by BMSCs was determined using antibody arrays (R&D systems). Extracellular matrix (ECM) scaffold formation was determined by immunocytochemical detection of collagen I, III, IV, V, VI, laminin and fibronectin. AML blasts were cultured in direct contact on established BMSC feeder layer. BMSCs were identifiable by either GFP expression or green cell tracker labelling (CFSE) and the percentage of dying AML cells (negative for GFP/CFSE and positive for the viability dye, ToPro-3) was determined with FACS. Results- In order to choose the most suitable BMSC feeder layer, three main characteristics were studied: cytokine/chemokine secretion, formation of ECM-BMSC proteocellular scaffold and ability to support ex vivo AML blast survival were determined. HS-5 cells, iMSCs and primary, HD pBMSC secreted 66, 59 and 51 paracrine factors, respectively including angiopoietin 1, fibroblast growth factor, interleukin-6 (IL-6), interleukin-8 (IL-8), granulocyte colony stimulating factor (G-CSF), C-X-C motif chemokine 12 (CXCL12), CXCL10 and vascular endothelial growth factor. 51% of cytokines/chemokines were common between iMSCs and HD pBMSC, while the HS-5 secretome shared 43% commonality with HD pBMSC. iMSCs also showed an equal ability to establish an ECM-BMSC scaffold with HD pBMSC and they had a superior ability to support the ex vivo survival of AML blasts over HS-5 cells. To determine how closely iMSCs can replicate the effects of BMSCs of AML patients, AML blasts were cultured on matching BMSCs (BMSCs isolated from the same patient). When these AML-BMSC co-cultures were exposed to the BH3 mimetics ABT-199 and ABT-737 or AraC+DnR, iMSCs closely replicated the protective effect of the patients' own BMSCs. Using this optimized ex vivo co-culture model, we tested 16 AML patient samples by exposing iMSC-AML blast co-cultures to a clinically-relevant dosage of AraC+DnR. To quantify drug efficacy, the area under the curve (AUC) for each treatment timepoint (24 h and 48 h) was calculated. By applying a cut-off value of 35% efficacy, we found that the ex vivo test could predict the clinical response of the patient in 81.2% of cases (p-value= 0.002, Figure). Conclusions- The developed drug efficacy test can recapitulate the key features of the BM microenvironment and could predict the clinical response of patients with high accuracy. The advantages of this model over more complex pre-clinical AML models is its suitability to be developed into a laboratory diagnostic tool which could greatly advance the clinical decision on treatment choice. Figure. Figure. Disclosures Quinn: Janssen: Honoraria.

Introduction Multiple Myeloma (MM) patients are at an approximately 9-fold increased risk of developing venous thromboembolism (VTE), with risk being highest in the first year following diagnosis1. VTE is associated with significant morbidity and negatively influences survival in MM2. Although the Khorana score has been shown to predict rate of thrombosis in solid tumors, the validity of this score in haematological malignancies has yet to be assessed. Given the elevated rates of VTE in these conditions, in particular MM, clinically relevant risk prediction scores are essential. Additionally, data from the MRC-XI trial indicates that standard thromboprophylaxis may not prevent VTEs in MM3. Therefore identification of risk factors for MM-VTE are required to improve our understanding of the pathophysiology of thrombosis and to develop risk-adapted clinical practice guidelines. Through interrogation of an extensive clinical database we sought to identify factors predictive for VTE in our MM population. Methods We performed a retrospective cohort study of all newly diagnosed MM patients at our centre from 2001-2017. Patient medical records were reviewed for clinical and laboratory data including FBC parameters, beta-2-microglobulin, paraprotein and serum free light chain on the day of diagnosis, to minimize steroid effect. All VTE events were recorded, along with MM treatment regimen and thromboprophylaxis at time of event. History of thrombosis was defined as occurring within 6 month prior to, or following a diagnosis of MM. Patients with MGUS or smoldering MM were excluded. Statistical analysis including logistic regression and cox proportional hazard modelling was performed using SPSS (IBM Analytics, USA). A comparison of mortality was also performed between age matched cases with VTE and controls without VTE. Results Over a period of 17 years, 266 patients were diagnosed with myeloma, of which 34 (12.7%) developed VTE following MM diagnosis or within the preceding six months. The mean age of the VTE cohort at MM diagnosis was younger than the mean age of the non-VTE cohort (62.5 years vs. 68.6 years). Pulmonary embolisms and deep vein thromboses were equally represented (44% and 56% respectively) and additional risk factors for thrombosis were present in 46% of patients, not related to MM therapy. Of the patients on immunomodulatory drugs or corticosteroids at time of VTE, all were receiving thromboprophylaxis with either low molecular weight heparin (LMWH) or aspirin at time of VTE. The mortality odds ratio was 3.3 (95% CI 2.4-4.5) in patients who developed VTE in comparison to age matched controls with MM. Younger age at MM diagnosis ( Conclusions Our data confirms that VTE is associated with an increased mortality in MM patients and estimates the risk of death to be 3.3 fold higher in these patients. As recently reported in a large cohort of MM patients, younger age is associated with an increased risk of VTE development4, our data support this finding and excludes longer duration of MM, and follow-up time, as confounding variables. Importantly, our data confirms, in unselected "real world" patients the signal that is now apparent from analysis of VTE in the MRC-XI trial3, that thromboprophylaxis with LMWH or aspirin is suboptimal for VTE prevention. This may point to alternative thrombotic mechanisms in MM-VTE and further data in larger MM cohorts is needed to develop risk adapted strategies for prevention strategies for these patients. References Kristinsson SY et el, Blood. 2008 Nov 1;112(9):3582-6. Schoen MW et al. J Clin Oncol 36, 2018 (suppl; abstr 8051). Bradbury CA et al, Blood 2017 130:553. Sanfilippo KM et al. Blood 2016;128:4726. Disclosures Quinn: Janssen: Honoraria. Lavin:Shire: Honoraria, Research Funding, Speakers Bureau. O'Donnell:Baxter: Research Funding, Speakers Bureau; Octapharma: Speakers Bureau; CSL Behring: Consultancy; Daiichi Sankyo: Consultancy; Pfizer: Consultancy, Research Funding; Novo Nordisk: Research Funding, Speakers Bureau; Bayer: Research Funding, Speakers Bureau; Shire: Research Funding, Speakers Bureau; Leo Pharma: Speakers Bureau.

Recently published clinical trials have confirmed the effectiveness of anti-CD38 monoclonal antibody therapy in myeloma. Furthermore, in vitro studies of chronic lymphocytic leukaemia (CLL) cells suggest that CD38 expression can be enhanced by treatment with retinoid derivatives and thus may enhance the cytotoxic effects of anti-CD38 therapy. However, retinoids have been shown to have diverse effects on cellular function and we have previously shown that the retinoid drug acitretin upregulates CD38 expression while also reducing cell homing to the chemokine CXCL12 in primary CLL cells. To investigate possible key mechanisms for these effects, we purified CD20+ B cells from the peripheral blood of 20 CLL patients (9 previously treated, 11 untreated) and, using flow cytometry, measured percentage cell surface expression of CD38 and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4, CD152). We also measured gene expression levels of the key retinoid receptor, stimulated by retinoic acid 6 (STRA6) and it's agonist, retinol-binding protein 4 (RBP4), as well as CTLA-4, cyclin D1 (CCND1) and the transcription factors, lymphoid enhancer factor 1 (LEF1) and signal transducer and activator of transcription 3 (STAT3) using RT-PCR. GAPDH was used as a reference gene. Mean percentage surface expression of CD38 and CTLA-4 was 21.96% and 45.25% respectively. Mean ∆CT gene expression levels of CCND1, CTLA-4, LEF1 and STAT3 were 12.03, 5.57 , 5.99 and 8.98 respectively. RBP4 and STRA6 gene expression levels were undetectable in all 20 patients. Gene expression of LEF1 showed significant correlations with CTLA-4 (rs=0.572, p=0.008), CCND1 (rs=0.61, p=0.004) and STAT3 (rs=0.587, p=0.006). There was also a significant correlation between gene expression of CCND1 and of STAT3 (r =0.499, p=0.025). No significant correlations were found between percentage surface expression of CTLA-4 and gene expression levels of either CTLA-4 or of LEF1. A weak negative correlation between percentage surface expression of CTLA-4 and of CD38 was not statistically significant. Comparing untreated and previously treated patients, there was no significant difference in gene expression levels of CTLA-4 and of LEF1 or in surface expression of CTLA-4. The failure to detect RBP4 and STRA6 gene expression in unstimulated peripheral blood CLL cells is evidence against an autocrine retinoid effect in CLL, although upregulation of STRA6 gene expression following stimulation by retinoids might be anticipated. The Wnt signalling pathway has been shown to be active in CLL, including aggressive disease subtypes, highlighting the potential benefits in targeting this pathway. Intriguingly, CTLA-4 expression, although found to be the most highly induced gene following treatment with recombinant Wnt-3a in melanoma cell lines, is associated with a favourable outcome in CLL, possibly by inhibiting cell proliferation and survival. In contrast, expression of LEF1, which is a direct target of the Wnt signalling pathway, is associated with disease progression in CLL. Our finding that CTLA-4 and LEF1 gene expression levels are strongly correlated suggests that further investigation of the relationship between CTLA-4 and the Wnt/β-Catenin pathway in CLL is required and that targeting of the Wnt/β-catenin pathway may have unwanted consequences on CTLA-4 expression and function. Disclosures Quinn: Celgene: Honoraria; Janssen Cilag: Honoraria.

Background: MGRS is a heterogeneous group of pathologic renal conditions attributed to a clonal plasma cell disorder, without classical features of myeloma. However, there is a need to distinguish MGRS from MGUS and unrelated renal abnormality as the clonal protein in MGRS plays a direct role in kidney damage and requires treatment of the underlying clone. Outcomes in patients with diagnosis of cast nephropathy and renal amyloidosis have been previously reported. But long-term outcomes of MGRS patients with other renal histologies remain unclear. Also data on whether the level of tumour burden in the marrow and type of treatment for MGRS influence long-term outcomes is lacking. This analysis was conducted to study long term outcomes in renal biopsy proven (non cast nephropathy & AL Amyloid) MGRS patients. Aims: This multi-centre retrospective study was set up to analyse clinical outcomes in renal biopsy proven MGRS patients. Long-term haematological and renal outcomes were analysed. Correlation between tumour burden, type of treatment applied and level of response obtained was also analysed. Methods: Thirty-seven MGRS patients were retrospectively audited across 3 centres in the United Kingdom and 1 centre in the Republic of Ireland between 2004 and 2016. Patients were eligible for inclusion if they had a confirmed diagnosis of MGRS by renal biopsy. Patients with cast nephropathy and renal AL Amyloidosis were excluded. Renal survival was defined as the time until renal replacement therapy was required or failure to come off the renal replacement therapy commenced at diagnosis. Overall survival (OS) was calculated from the time of MGRS diagnosis until death from any cause. Results: Median age at diagnosis was 68 years and median follow-up was 33.5 months (range, 0.7-141.7 months). There were 29 male patients and 8 female patients. 20/25 patients had hypertension at the time of diagnosis (records unavailable for 12 patients). Majority of patients were kappa light chain restricted 85% vs 15% lambda LC restricted. Renal histology showed: 65% Light Chain Deposition Disease, 8% Mixed Heavy and Light Chain Deposition Disease, 1 % Proliferative Glomerulonephritis with monoclonal IgG, 11% Light Chain Tubulopathy, 6% Cryoglobulunemia, 3% Immunotactoid Glomerulonephritis. Renal survival for the whole cohort was 74% and overall survival was 84%. At the time of renal biopsy, 43% of patients had >10% plasma cells versus 46% of patients with 10% plasma cells versus 70 % in 10% plasma cells, not statistically significant (P = 0.14). Chemotherapy treatment was administered in 24 patients (65%) for their MGRS versus 13 patients (35%) who had no treatment for their PC clone. Of the 24 patients who had treatment: 20 had Bortezomib-based therapy (VEL), 6 had Thalidomide-based therapy, 4 had Lenalidomide and 4 had stem cell transplant. Patients who received VEL treatment for PC clone had a renal survival of 84 % versus 63% in patients who did not have VEL treatment (P = 0.45). OS in patients who received VEL was 95 % versus 72 % in patients who did not receive VEL treatment (P= 0.1). Good haematological response (≥VGPR) in 11/37 patients achieved and renal survival in these patients was significantly better at 90 % versus 61 % in patients who had Conclusion: We report long-term outcomes in a large cohort of MGRS patients: 74% renal survival and 84% overall survival at a median of 33 months follow up. For the first time, we show treatment for the PC clone shows better outcomes; with patients treated with VEL therapy significantly improved renal survival. Patients with higher tumour burden have a non-significant reduction in overall survival. Overall, the results of this study show better OS in MGRS patients when compared with outcomes previously reported in cast nephropathy and renal AL amyloid. Figure 1 Figure 1. Disclosures Ramasamy: Celgene: Honoraria, Research Funding.

Introduction: Lenalidomide, bortezomib and dexamethasone (RVD) is considered a new standard of care regimen for patients with newly diagnosed multiple myeloma. A previous phase I/II study of RVD in front-line myeloma enrolled 66 patients and achieved a partial response rate or better of 100%, overall and a CR/nCR rate of 52% in the phase 2 portion of the study with encouraging tolerability, but high rates of peripheral neuropathy (PN), albeit mainly mild to moderate grade (Richardson et al, Blood 2010). Subcutaneous (SQ) administration of single agent bortezomib has been shown to be non-inferior to IV bortezomib and led to lower rates of PN, a common treatment-related toxicity (Moreau et al, Lancet Oncol 2011). Herein we present preliminary results of the RsqVD Study, a multi-center, open-label single arm phase II trial, incorporating SQ bortezomib with lenalidomide and dexamethasone and including patients who were considered either transplant eligible or ineligible. All patients subsequently received maintenance therapy with lenalidomide until progression, plus the addition of subcutaneous bortezomib twice monthly in high risk patients (ISS stage II or III and/or high risk cytogenetics features, t(4;14, t(14;16) and del17p). The primary endpoint was overall response rate (ORR) after 4 cycles of induction therapy (PR or better). Secondary endpoints include: rate and severity of PN, safety, time to progression, progression-free survival, duration of response and overall survival. Methods: Planned treatment was 4 cycles of lenalidomide 25 mg/day on days 1-14 and dexamethasone 20/mg/day on days 1, 2, 4, 5, 8, 9, 11 and 12 plus bortezomib 1.3 mg/m2as SQ injection on days 1, 4, 8 and 11 of a 21-day cycle. Thromboprophylaxis with aspirin 75 mg/day or higher was mandatory and HSV prophylaxis was as per institutional standard. Following 4 cycles, patients were planned to proceed with stem cell mobilization and autologous stem cell transplant (ASCT) or further induction therapy up to a total of 8 cycles. Following completion of ASCT or induction therapy, all patients were scheduled to receive lenalidomide maintenance in 28 - day cycle until progression, unacceptable toxicity or withdrawal of consent. Patients with high-risk features received SQ bortezomib on days 1 and 15 during maintenance phase. Response was investigator-assessed as per IMWG criteria. Sample size (n=42) was determined to provide 80% power to test an acceptable ORR of >70% versus an unacceptable ORR of Results: Between November 2014 and February 2016, 42 patients were enrolled across 8 sites in Ireland. Baseline demographic factors include: 64% males, 36% females; median age of 64 years (45-79 years); 41% ISS stage I, 59% ISS stage II/III. FISH analysis detected t(4;14) in 18% of patients (7/40), t(14;16) in 3% of patients (1/36) and del17p in 10% of patients (4/40). 64% (27/42) patients proceeded to stem cell mobilization and 60% (25/42) to ASCT. The median number of induction cycles completed was 4 (1 to 8 cycles). 40 of a total of 42 patients were considered evaluable for the primary endpoint of ORR. A preliminary analysis of ORR following 4 cycles of induction therapy indicates that 98% (39/40) of patients achieved partial response or better. PN of any grade has been reported by sites in 43% (18/42) of patients to date. Conclusion: RsqVD is a highly effective regimen in newly diagnosed multiple myeloma producing a very high ORR following initial induction therapy, with a lower overall rate of PN described by sites than expected. Full analyses of response and safety data for induction treatment and follow up will be presented, as well as preliminary evaluation of response to subsequent therapy. Disclosures O'Gorman: Janssen Cilag: Research Funding; Celgene: Research Funding. O'Dwyer:Celgene: Consultancy, Honoraria, Research Funding; Glycomimetics: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding. Quinn:Celgene: Honoraria; Janssen Cilag: Honoraria. Murphy:Celgene: Honoraria; Janssen Cilag: Honoraria. Crotty:BMS, Takeda, Novartis, Janssen, Roche: Honoraria. Hayden:Celgene: Honoraria; Janssen Cilag: Honoraria; Amgen: Honoraria. Richardson:Jazz Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Background: CD38 is a cell surface receptor and ectoenzyme expressed in a variety of haematological malignancies. In CLL, CD38 expression is a marker of poor prognostic disease and is now attracting growing interest as a target molecule for anti CLL therapy. Retinoids modulate CD38 expression due to the presence of the Retinoic Acid Response Element (RARE) DNA sequence in the promotor region of the CD38 gene. In this study we demonstrate that the retinoic acid derivative, acitretin, upregulates the expression of CD38 on the MEC-1 cell line and on primary CLL cells from CD38 positive patients. We propose that, by doing so, Acitretin may render these cells more susceptible to the actions of anti CD38 monoclonal antibody drugs and thus have a potential role as an adjunct to such therapies. Methods: Primary CLL cells were freshly isolated from whole blood of CLL patients using the FICOLL density centrifugation technique. The CLL like cell line MEC-1 was obtained from DSMZ, Germany. MEC-1 cells and cells from three CD38 negative and five CD38 positive patients were treated with 10micM acitretin for 24, 48 and 72hrs. CD38 expression was measured by FACS analysis at baseline and at the different time points. Results are expressed as fold increase in Mean Fluorescence Intensity (MFI). Migration assays were performed using 2x10^6 cells per well incubated with 10microM acitretin overnight in 1%FBS. Cells were subsequently transferred to chamber inserts overlying 10%FBS media containing 200ng/ml CXCL12 in all wells, except negative controls. Cells were then allowed to migrate for 4hrs. Migration was calculated as percentage of cells in lower chamber to upper chamber. Results: Acitretin increased the expression of CD38 on MEC-1 cells by a mean of 7.4 fold and on cells from CD38 positive patients by a mean of 3.4 folds (n=5). Acitretin, however, did not modulate CD38 expression levels on primary CLL cells from CD38 negative patients (n=3). Migration of primary CLL cells from 11/14 patients toward the CXCL12 chemokine was reduced in response to Acitretin treatment as compared to untreated controls. Mean migration of treated cells was 12.3% versus 27.3% mean migration in untreated controls. Conclusion: Our findings re-affirm the potent effect of retinoid drugs as upregulators of CD38 expression and suggest that their use in CLL therapeutics in conjunction with anti CD38 monoclonal antibodies should be explored. We also propose that acitretin appears to exert a favourable blocking effect on CLL cell migration towards micro-environmental chemokines such as CXCL12, warranting further evaluation. Disclosures Murphy: Celgene: Honoraria.

A proliferation-inducing ligand (APRIL) promotes survival and drug resistance in multiple myeloma (MM) cell lines. We studied the effect of APRIL on cell-cycle behavior in primary MM cells and correlated our findings with D-type cyclin expression by immunohistochemistry and/or Western blotting. In MM cases, expressing cyclin D2 APRIL significantly increased the percentage of CD138+ cells in S + G2/M phase (from 8.4% ± 1.9% to 14.3% ± 2.6%, n = 15, P < .01), whereas a lesser effect was seen in cases expressing cyclin D1 (n = 18). Cell-cycle response to APRIL was most marked for cyclin D2-expressing cases with IgH translocations (P < .01) and was accompanied by increased expression of cyclin D2, CDK4, CDK6, and phospho-retinoblastoma protein. Cell-cycle proteins in cyclin D1+ cells were not modulated by APRIL. Surface expression of B-cell maturation antigen and transmembrane activator and calcium-modulating cyclophilin ligand interactor was not significantly different between cyclin D1+ and D2+ MM cells. We observed activation of nuclear factor-κB and PI3-kinase pathways in response to APRIL in both cyclin D1+ and D2+ MM cells. In conclusion, APRIL stimulates G1/S progression in cyclin D2+ MM cells bearing IgH translocations but has minimal effect on cyclin D1+ cells, suggesting MM cells from different cyclin D/translocation classes rely on different mechanisms for cell-cycle re-entry.

Multiple myeloma (MM) may be classified according to D-type cyclin dysregulation. Amongst nonhyperdiploid cases, those with IgH translocations t(4;14) or t(14;16) express high levels of cyclin D2, and those with t(11;14) express elevated cyclin D1. Although translocation-based subgroups may behave differently, cyclin D2 dysregulated disease tends to progress with more proliferative disease and poorer outcomes compared to cyclin D1. The importance of methylation status has been described in MM, with the transition from MGUS to symptomatic MM characterised by global hypomethylation, and gene-specific hypermethylation differences between cytogenetic subtypes. To investigate the utility of methylation profiling between D1 and D2-dysregulated MM, we carried out a pilot study of global methylation changes between these groups. Primary bone marrow samples were collected from eight cyclin D1 patients with t(11;14), and eight D2 patients (four t(4;14) and four t(14;16)), and CD138+ cells purified by magnet-assisted selection. Following bisulfite conversion, samples were processed on llumina Infinium human methylation27 arrays. Methylation was classified with a beta score between 0 (unmethylated) and 1 (methylated). Initial analysis was performed using Illumina GenomeStudio, and subsequently with the Limma package in R. Differentially methylated probes were corrected for false discovery rate (FDR), with a threshold of 0.01 considered significant. Survival analyses were calculated from the date of sampling. Unsupervised clustering split the samples into two groups (group 1 and group2), which did not match with D-cyclin status, but did show clear differences in clinical course. Survival analysis between groups 1 and 2 showed trends toward differences in median overall survival (61.7 vs 11.9 months, p=0.06) and progression free survival (24.4 vs 7.2 months, p=0.34). Although not significant at the p We then went on to perform supervised clustering between the samples, splitting them into two groups (D1 and D2) based on their cyclin D status. This analysis did not reveal any MVPs even at a less stringent FDR-adjusted threshold of 0.05. However, we did observe that of the top 20 differentially methylated probes three were for the CCND1 gene, which in all cases showed relative hypomethylation in the cyclin D1 dysregulated samples. Other genes of potential interest with relative hypomethylation in the cyclin D1 group were DAB2 which has previously been reported to be hypermethylated in the t(4;14) OPM2 cell line, and AK3L1 – a kinase which interestingly, has been reported as showing vulnerability to targeted RNAi inhibition in two cyclin D2 dysregulated cell lines (KMS11 and JJN3). In this small cohort, although cyclin D1 vs cyclin D2 classification does not appear to be sufficient to define distinct methylation profiles, a group of genes with hypermethylation appears to be associated with poorer prognosis. The hypomethylation of CCND1 in cyclin D1 dyregulated samples, although below the significance threshold in this dataset, is consistent with previously described findings of CCND1 hypomethylation in t(11;14) cell lines, but our results in the D2 MM samples differ from previous reports of hypomethylation in all nonhyperdiploid primary samples. We intend to investigate this further and extend this analysis by prospective sampling and methylation analysis on a larger cohort of patients treated on a standard protocol. Disclosures No relevant conflicts of interest to declare.

In myeloma, the use of autologous stem cell transplantation in younger patients as well as the introduction of thalidomide, lenalidomide and bortezomib has resulted in improvement in long-term survival of both younger and older patients. Bortezomid and high dose dexamethasone is currently recommended to treat newly diagnosed myeloma patients presenting with renal impairment and may lead to varying degrees of improvement in renal function. We have assessed not only survival trends for all patients diagnosed at our centre over the past 18 years but also the survival of the subset of patients with severe renal impairment who required dialysis at diagnosis. All patients diagnosed with myeloma at our centre between January 1995 and December 2012 were included. We constructed Kaplan-Meier curves and used the Breslow generalised Wilcoxon test to evaluate overall survival (OS) patterns (diagnosed in three calendar periods: 1995-2000; 2001-2006; 2007-2012) for our total patient population as well as the subset of patients who required dialysis within 4 weeks of diagnostic bone marrow test. 262 patients (60.3% males) were diagnosed between 1995 and 2012. For all patients, median OS significantly increased from 13.2 months in period 1995-2000 to 27 months in period 2001-2006 with median OS not yet reached in period 2007-2012 (p=0.0001). In patients 70 years old or less, median OS significantly increased from 25.4 months in period 1995-2000 to 46.7 months in period 2001-2006 with median OS not yet reached in period 2007-2012 (p=0.0482). Improved median OS was also seen in patients > 70 years old: 4.4 months in period 1995-2000, 17.4 months in period 2001-2006 and 25.1 months in period 2007-2012 (p In our overall myeloma patient population, median OS has continued to increase over the time periods 1995-2000, 2001-2006 and 2007-2012, both for younger patients 70 years old or less and older patients >70 years old. Patients requiring dialysis at diagnosis, however, continue to have much poorer median OS, despite the use of bortezomib and dexamethasone containing regimens in recent years. The possible benefit of improved supportive measures and the early use of other emerging novel agents in this poor prognostic subgroup should be explored in the clinical trial setting. Disclosures: No relevant conflicts of interest to declare.

Abstract 124 Introduction: Understanding how multiple myeloma (MM) cells proliferate and self-renew is crucial to treating resistant disease and preventing relapse. The TNF family members APRIL (A proliferation-inducing ligand) and BAFF (B-cell activating factor) are secreted in the MM bone marrow microenvironment and share two common receptors, TACI and BCMA. APRIL and BAFF and have been shown to exert a mainly anti-apoptotic effect in human myeloma cell lines (HMCLs). Little is known, however, about the proliferative effect of APRIL and BAFF on primary MM cells. Aims: We aimed to determine the effect of APRIL and BAFF on cell cycle progression in primary MM cells and on the modulation of D-type cyclins and other cell cycle proteins. Patients and Methods: We studied the effects of APRIL and BAFF on purified MM cells from 26 patients by flow-cytometry using surface CD138 / Ki67 / propidium iodide staining. A culture system was optimised in which a mean (±SEM) of 73.3±10.9% (n=23) of primary CD138+ MM cells survived for up to 3 days in vitro. D-type cyclin expression was assessed by immuno-histochemistry (IHC) ± western blotting and correlated with FISH for IgH translocations. Fourteen patients expressed cyclin D1, 4 in association with t(11;14); while 12 patients expressed cyclin D2, 1 with t(4;14) and 4 with t(14;16). TACI and BCMA expression were determined by flow cytometry. Western blotting was used to determine expression and modulation of cell cycle proteins and activation of signalling pathways in vitro. Membrane-bound APRIL was detected by IHC in MM trephine biopsies. Results: In-vitro culture with APRIL for 72 hours increased the overall percentage of CD138+ cells in S+G2/M phases (S/G2M) from a mean (±SEM) of 5.5 ± 1.1% to 8.1 ± 1.5% (p Disclosures: No relevant conflicts of interest to declare.