Citations

AbstractHistological transformation in Waldenström macroglobulinemia (WM) is an uncommon complication, with limited data, particularly regarding the impact of MYD88 L265P mutation on transformation. We examined risk factors and outcomes associated with transformation in WM, highlighting the role of MYD88 L265P mutation. Patients with WM seen at Mayo Clinic, Rochester, USA and University Hospital of Reims, France, between 01/01/1996 and December 31, 2017 were included; 50 (4.3%) of 1147 patients transformed to a high‐grade lymphoma, with median time‐to‐transformation of 4.5 (range 0‐21) years in the transformed cohort. The MYD88 L265P mutation status was known in 435/1147 (38%) patients (406 with non‐transformed WM and 29 patients in transformed cohort). On multivariate analysis, MYD88 WT status alone was an independent predictor of transformation (odds ratio, 7[95%CI: 2.1‐23]; P = .003). Additionally, the MYD88 WT status was independently associated with shorter time‐to‐transformation (HR 7.9 [95%CI: 2.3‐27; P = .001]), with a 5‐year transformation rate of 16% for MYD88 WT vs 2.8% with MYD88 L265P mutated patients. Patients with transformation demonstrated a significant increase in risk of death compared to patients who did not transform (HR 5.075; 95%CI: 3.8‐6.8; P < .001). In conclusion, the MYD88 WT status is an independent predictor of transformation and associated with a shorter time‐to‐transformation. Additionally, transformation conferred an inferior overall survival in patients with WM.

Abstract Background: Waldenstršms macroglobulinemia (WM) is an indolent B-lymphoplasmacytic lymphoma, which is highly sensitive to 20S proteasome inhibitors such as bortezomib. However, clinical resistance to the drug can be observed early at onset of therapy (primary or inherent resistance) or develop over time, through repeated exposure to the drug (acquired resistance). Although prior investigations into the biological mechanisms associated with bortezomib resistance (BR) have identified aberrations at the genomic (PSMB5 mutation) and transcriptional level (loss of XPB-1), there is limited data on the epigenetic abnormalities that support resistance to 20S proteasome inhibition. With this in mind, we conducted a comprehensive methylation and mRNA expression analysis in WM cells focusing on the molecular patterns that characterize inherent BR (iBR) as well as acquired BR (aBR). Materials and Methods: Bortezomib sensitive (BS) human WM cell lines, BCWM.1 and MWCL-1, the iBR WM cell line RPCI-WM1 (developed from a bortezomib-refractory WM patient) as well as aBR subclones (BCWM.1/BR, MWCL-1/BR) were used in the study. Methylation status of WM cells was profiled by Illumina Infinium 450k methylation array. Methylation IDAT files were background subtracted using GenomeStudio v1.9. Beta mixture quantile dilation (BMIQ) method in R watermelon package was used to adjust type II probes into distribution characteristic of type I probes. For each gene, probes were partitioned into 6 regions using R IMA package and the ones belonging to the same region were averaged, including transcription start sites (TSS; both 200 bp and 1500 bp upstream), 5' untranslated region (UTR), and 3'UTR, the first exon, and genebody. Gene regions showing a significant adjusted p-value and a beta difference of >0.1 or <-0.1 were selected for differential hypermethylation and hypomethylation, respectively. Correlation with gene expression was conducted only on genes showing >1.5 fold change in expression. Overview of methodology is shown in Figure 1. Results: We first assessed the differential methylation pattern (TSS, 200bp upstream of gene body) of bortezomib-sensitive (BS, BCWM.1, IC50 6nM) and iBR cells, (RPCI-WM1). A total of 3,801 hypermethylated and 1,865 hypomethylated DNA regions were observed in iBR cells relative to BS cells (Figure 2A). In iBR cells, a negative correlation between hypermethylated DNA and corresponding gene expression was found in 1,039 genes (Spearman r = -0.12) (Figure 2B). In parallel, we compared the methylation pattern (TSS 200bp) of BS WM cells (BCWM.1 and MWCL-1) with their aBR derivatives, which display ~20 – 50 fold resistance to bortezomib. aBR subclones showed differential hypermethylation of 1,521 DNA regions and hypomethylation of 651 genomic regions relative to BS WM cells. These findings were not unexpected as aBR cell lines, being derivatives of BS WM cells, are clonally related to the former, whereas iBR cells are derived from a different clone. Meta-analysis of iBR and aBR followed by pathway enrichment (NextBio, Illumina Inc), revealed a significant clustering of commonly hypermethylated genes within the Validated Transcriptional Targets of TP63 isoforms Canonical Pathway (p<1.9-E5, Figure 2C) and the CEBPA binding site Geneset 2 (p<8.2-E9, Figure 2D); pathways whose genes are actively involved in suppression of cell growth and differentiation. Further validation and functional relevance of candidate gene targets from this analysis, which are relevant to WM pathobiology, are currently being investigated. Conclusion: This is the first study to examine and correlate the global methylation and gene expression profiles in WM tumor cells that are inherently wired to resist 20S proteasome inhibition as well as tumor cells, which have acquired resistance through continuous exposure to bortezomib. Although considerable differences were observed in the methylation profiles of WM cells displaying inherent vs. acquired resistance, a number of common genes emerged and pointed towards transcriptional repressors, whose inactivation through methylation has been linked to other cancers. Altogether, these findings uncover cellular systems in WM cells, which are affected by DNA methylation, subsequent mRNA suppression and which may be associated as a whole with both inherent and acquired forms of bortezomib resistance. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Deubiquitinating enzyme (DUB) inhibitors are an emerging class of compounds, which are increasingly being regarded for their anti-cancer activity and therapeutic potential. The 19S regulatory particle of the proteasome contains two DUBs, USP14 and UCHL5, which are critical for the proper unfolding and deubiquitination of proteins prior to their entry into the 20S proteasome β-catalytic core. In B/plasma cell malignancies such as Waldenströms macroglobulinemia (WM) and multiple myeloma (MM), protein homeostasis and optimal proteasome functionality are paramount for tumor survival. This is evidenced by the success of 20S proteasome inhibition with bortezomib and carfilzomib, which have demonstrated remarkable clinical benefit in patients with WM or MM. As such, the proteasome degradation pathway represents a highly attractive and clinically validated, yet still largely unexplored therapeutic target. Here, we provide first evidence of the cytotoxic effects and molecular sequelae associated with a novel 19S proteasome DUB inhibitor, VLX1570, which selectively targets USP14 and UCHL5, in preclinical models of B/plasma cell cancers and their drug resistant tumor subclones. Materials: VLX1570 was obtained from Vivolux AB, Sweden. Bortezomib was purchased from Sellekchem, Houston TX. Human myeloma cell lines (OPM2, U266, KMS11), human WM cell lines (BCWM.1, MWCL-1 and RPCI-WM1), their respective bortezomib-resistant (BR) subclones as well as ibrutinib-resistant (IR) derivatives of BCWM.1 and RPCI-WM1 were used in experiments (total n=12). Peripheral blood mononuclear cells (PBMCs) from healthy donors were used to assess for cytotoxicity of VLX1570 in non-tumor cells. Results: A 72hr MTS assay first established sensitivity of plasma cell cancer models towards VLX1570, including drug resistant subclones (EC50 range, 20 – 90nM). Next we assessed whether loss of viability was due to apoptosis and observed dose-dependent annexin-V staining in ~50 – 70% of wild-type MM and WM cells, ~45 – 55% in corresponding BR models and ~50% in IR subclones when exposed to VLX1570 (100nm – 500nM) for 24hrs. VLX1570 was tested at similar concentrations in PBMCs and induced minimal cell death. To understand if VLX1570-induced apoptosis was mitochondrial mediated, we assessed mitochondrial outer membrane permeability (MOMP) in all plasma cell cancer models treated with the DUB inhibitor (100 – 500nM) and found a dose-dependent increase in MOMP (p<0.00025 – 0.000001). Activation of the mitochondrial/intrinsic apoptotic pathway was also evidenced by cleavage of caspase-9 and 3 on immunoblot analysis. As inhibition of protein deubiquitination results in accumulation of polyubiquitinated protein conjugates, we examined global ubiquitinated protein levels and found increasing amounts of high molecular weight poly-ubiquitinated protein in VLX1570 treated tumor cells in a dose-dependent manner. This prompted us to further delineate the potential cellular response mechanisms that relay the antitumor activity of VLX1570 in malignant plasma cells. Immunoblot analysis of drug sensitive and (bortezomib or ibrutinib) resistant MM and WM cell lines revealed several changes in ER stress response proteins, notably induction of HSP70 and splicing of XBP1; the latter event which was less prominent in BR cell lines treated with bortezomib. This suggested the ability of VLX1570 to overcome resistance through a rapid and potent proteotoxic effect, which overwhelmed the tumor cells stress response mechanisms beyond its capacity for survival. Finally, as abnormalities in the NFkB signaling pathway are implicated in malignant plasma cell survival, we found markedly decreased nuclear translocation of NFkB (p-P65) protein in tumor cells treated with VLX1570. Conclusions: The DUBs of the 19S proteasome cap offer an attractive target within the proteasome degradation system and whose inhibition by VLX1570 is able to circumvent mechanisms that support resistance to b-catalytic PI (bortezomib) or BTK inhibitor (ibrutinib) therapy. The studies undertaken thus far, coupled with more rigorous mechanistic and in vivo efficacy analyses currently underway, provides rational for the clinical development of DUB inhibitors for use in malignant B/plasma cell malignancies. Disclosures Martin: Janssen: Honoraria.

Abstract Background: Normalization of serum free light chain ratio (FLCr) following achievement of a complete response (CR) to therapy denotes a stringent CR in multiple myeloma, and is associated with improved overall survival (OS). However, its value in patients achieving less than a CR is not clear. We hypothesized that patients in whom FLCr normalizes with the initial anti-myeloma therapy will have an improved outcome, even in the absence of a CR. Methods: We analyzed the medical records of patients with MM who were evaluated at Mayo Clinic, Rochester, MN between January 2004 and December 2011, seen within 90 days of diagnosis. We selected patients with measurable disease on serum protein electrophoresis, defined as a serum M-spike ≥1 g/dl at the time of diagnosis. Then, we excluded all patients with negative immunofixation for monoclonal M-protein in serum and urine at their first response as well as those who did not have serum FLC results available from the time of their first best response. M protein measurements were collected serially from the time of diagnosis until the time of the first relapse or last follow up date if no relapse was recorded. Progression-free survival (PFS) and OS were analyzed using the Kaplan-Meier method. Results: Out of the 1354 MM patients seen at our institution during this period, a total of 453 patients were included in our study. The median age of the cohort at the time of diagnosis was 65 (range, 29-91); 49% were older than 65 years and 284 (63%) were male. The estimated median follow up for the whole cohort was 66 months (95% CI; 61, 71); 241 patients were alive with a median follow up of 4.7 years (range, 0.4 to 10). Three hundred and seventy three (82%) patients had relapsed following the initial therapy with a median time to progression (TTP) of 19.5 months (95% CI; 18, 22) and PFS of 19 months (95% CI; 17, 20). The median OS for the entire cohort is 67 months (95% CI; 59, 73). The median time to the best first response was 6.9 months (range: 0.3-83 months). At the time of the best first response 154 patients (34%) had normal FLCr. Patients with normal FLCr had a longer PFS (29 vs. 16 months, P< .0001) and OS (91 vs. 58 months, P= .0002). We then examined the impact of FLCr normalization on survival outcomes according to their IMWG response categories. We found that FLCr normalization had a favorable impact on PFS in each of the three groups [very good partial response (VGPR), Partial response (PR), and Stable disease (SD)], However, when looking at the OS, only patients with PR had a better OS associated with a normal sFLC κ/λ ratio (Table 1). Conclusions: Obtaining a normal sFLC ratio appears to confer a more favorable prognosis irrespective of the depth of the response, suggesting an important role for serial-sFLC measurements in disease monitoring even in patients who achieve only a PR to therapy as their best response. This supports the inclusion of sFLC at all levels of response included in the current International Myeloma Working Group (IMWG) criteria. Abstract 3427. Table 1 Effect of FLCr normalization according to IMWG response categories SD PR VGPR Normal FLCr Abnormal FLCr p-value Normal FLCr Abnormal FLCr p-value Normal FLCr Abnormal FLCr p-value Number of patients 7 70 62 157 85 60 PFS, month, median (95% CI) 27 (14, 36) 7 (5, 12) < .02 26 (20, 36) 17 (13, 20) .0005 29 (23, 32) 21 (18, 26) .03 OS, months, median (95% CI) 68 (49, 68) 41 (31, 61) > .1 NR (65, NR) 61 (50, NR) .004 74 (67, 107) 73 (59, NR) > .9 • Abbreviations: NR; statistically not reached •• Progressive disease (PD) was not included because none of the 12 patients achieved a normal FLCr. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Multiple Myeloma (MM) patients have a substantially reduced Health related Quality of Life (HQOL) at diagnosis (dx) due to disease related symptoms like bone pain (58%) and fatigue (32%). HQOL monitoring is becoming increasingly important, owing to improved survival and the impact of treatment-related toxicity. As a result HQOL assessments are increasingly being used in clinical trials, but the literature regarding the relationship between HQOL and outcomes in MM is sparse. We used the Mayo Clinic “Hematology Patient Reported Symptom Screen” (HPRSS) to assess the impact of HQOL on outcomes in newly dx patients with MM. Methods:We retrospectively reviewed charts of 453 patients with newly dx MM seen at Mayo Clinic, Rochester from 2009 to 2014. All patients who visit Mayo clinic hematology clinic complete a 3-point questionnaire (HPRSS) on pain, fatigue and quality of life (QOL) (scored on a scale of 0-10; with 0 being the least fatigue or pain and 10 being the best QOL). Pain, fatigue and QOL scores documented at the time of dx and at 6 months were collected. JMP version 10 was used for the data analysis. Results: The median age at diagnosis was 67 years (range, 33-95); 60% were male. The estimated median OS for the cohort was 21 m (95% CI19, 23); 387 (85%) of the patients were alive at last follow up and the median OS for the population was not reached. The median (IQR) scores for pain, fatigue and QOL were 4 (2, 6), 3 (1, 5), and 7 (5, 9), respectively. First, we examined the relationship between each of the scores (dichotomized at the median) and the baseline characteristics. Higher fatigue scores were associated with lower Hb and serum albumin and higher beta 2 microglobulin, LDH and marrow plasmacytosis. Higher pain scores were seen in female patients, and associated with higher B2M, serum calcium and lytic bone lesions. Lower QOL scores were associated with lower absolute lymphocyte count and serum albumin levels. Next, we examined the relationship between the scores and the OS from diagnosis. The overall survival was inferior for patients with higher pain scores, fatigue scores and lower QOL scores (Figure). In a multivariable analysis, fatigue scores were most strongly associated with survival outcome. Patients with adverse scores in two or more of pain, fatigue and QOL had significantly inferior outcomes (Figure). In univariate analysis, age, B2M, LDH, FISH high risk and the presence of two or more adverse scores were all significantly associated with poorer OS. In a multivariable analysis, age, LDH and the presence >=2 adverse scores were all associated with shorter OS. Of the 453 patients included in the study, 222 patients had pain, fatigue and QOL scores at 6 month from diagnosis. At 6 months, the median (IQR) scores for pain, fatigue and QOL were 2 (1, 5), 4 (2, 5), and 7 (5, 9), respectively; suggesting improved pain, worsened fatigue and static QOL scores. Improvement in the scores by at least one point was seen in 50%, 49% and 38% for the fatigue, pain and QOL scores. While the pain and fatigue scores at 6 months correlated inversely with OS, improvements in the scores in any of the three were not associated with any improved outcomes. Conclusion: A simple, patient reported scoring system for pain, fatigue, and overall perceived QOL at the time of diagnosis is a powerful predictor of survival outcomes in patients with newly diagnosed MM and should be considered routinely in clinical practice. The results of these patient reported measures can be utilized to develop risk-adapted trials in patients with MM. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Abstract Background: Amyloid light chain (AL) amyloidosis is caused by the deposition of misfolded light chain (LC) proteins, which may cause organ failure and death. Current treatments, which target the plasma cells that produce LC, induce organ responses in only 30% to 40% of patients. There is a substantial need for a safe and effective amyloid-directed therapy to improve recovery of organ function. NEOD001, a monoclonal antibody that targets misfolded LC, is hypothesized to neutralize circulating LC aggregates and to clear insoluble organ deposits. In an ongoing phase 1/2 study (NCT02613182; Gertz M et al. J Clin Oncol. 2016;34(10):1097-1103) in 27 patients with AL amyloidosis and persistent organ dysfunction, monthly NEOD001 infusions were well tolerated and produced no infusion-related hypersensitivity reactions. In a best response analysis of subjects who fulfilled eligibility criteria at baseline, 57% met cardiac and 60% met renal response criteria. Supported by these positive results, the current study (VITAL; NCT02312206) is a randomized, double-blind, placebo-controlled, phase 3 trial of NEOD001 in patients with cardiac AL amyloidosis. Here we present the study design for this trial in progress. Patients and Methods: Eligible patients (estimated enrollment, 236) with a diagnosis of AL amyloidosis (newly diagnosed, treatment naive) and cardiac dysfunction (N-terminal probrain natriuretic peptide [NT-proBNP] ≥650 and <8500 pg/mL, clinical signs of heart failure, left ventricular wall thickness >12 mm, or cardiac biopsy-detected amyloidosis) and with estimated glomerular filtration rate ≥30 mL/min/1.73 m2 will be randomly assigned (1:1) to receive NEOD001 (24 mg/kg q28d) plus standard of care (SOC) chemotherapy or placebo plus SOC therapy. Subjects will be stratified according to Mayo Clinic stage, renal stage, and 6-minute walk test (6MWT) distance. The primary end point is a composite, evidence-based measure consisting of all-cause mortality or cardiac hospitalization. Key secondary end points include cardiac response measured by NT-proBNP (as defined by Comenzo RL et al. Leukemia. 2012;26(11):2317-2325) and change in 6MWT distance, Short Form-36 Health Survey response, Neuropathy Impairment Score-Lower Limb and renal response (as defined by Palladini G et al. Blood. 2014;124(15):2325-2332). Disclosures Liedtke: Gilead: Research Funding; Pfizer: Consultancy, Research Funding; Novartis: Research Funding; Amgen: Consultancy, Research Funding; Prothena: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Celgene: Research Funding. Merlini:Takeda and Janssen-Cilag: Honoraria. Landau:Janssen: Consultancy; Spectrum Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Onyx/Amgen: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Honoraria, Membership on an entity's Board of Directors or advisory committees. Comenzo:Takeda: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Prothena: Consultancy, Research Funding; Karyopharm: Research Funding. Sanchorawala:Prothena: Research Funding; Takeda: Research Funding; Celgene: Research Funding. Weiss:Janssen: Consultancy, Other: Travel, accommodations, Research Funding; Millennium: Consultancy, Other: Travel, accommodations; GlaxoSmithKline: Consultancy; Prothena: Other: Travel, accommodations, Research Funding; Novartis: Consultancy. Zonder:Array Biopharma: Consultancy; Prothena: Consultancy; Celgene: Consultancy, Research Funding; BMS: Consultancy; Takeda: Consultancy; Janssen: Consultancy; Seattle Genetics: Consultancy. Walling:Stealth: Consultancy; KaloBios: Consultancy; Exelixis: Consultancy; Newgen: Consultancy; Mateon (was Oxigene): Consultancy; Apex: Consultancy; Corcept: Consultancy; Aduro: Consultancy; Prothena: Consultancy; BioMarin: Equity Ownership; Amgen: Equity Ownership, Patents & Royalties; NuMedii: Consultancy; Pharm-Olam: Consultancy; Crown Bioscience: Consultancy; Codexis: Consultancy; Upsher Smith: Consultancy, Patents & Royalties. Kinney:Prothena: Employment, Equity Ownership, Other: Leadership. Koller:Prothena: Employment, Equity Ownership, Other: Travel, accommodations. Gertz:Ionis: Research Funding; Prothena Therapeutics: Research Funding; Novartis: Research Funding; Alnylam Pharmaceuticals: Research Funding; Annexon Biosciences: Research Funding; Research to Practice: Honoraria, Speakers Bureau; Med Learning Group: Honoraria, Speakers Bureau; Celgene: Honoraria; NCI Frederick: Honoraria; Sandoz Inc: Honoraria; GSK: Honoraria.

Abstract Background: Cytogenetic evaluation using fluorescence in situ hybridization (FISH) at the time of diagnosis is essential for initial risk stratification in multiple myeloma. The presence of specific cytogenetic abnormalities is known to confer a poor prognosis, less is known about the cumulative effect of multiple cytogenetic high-risk abnormalities. We aimed to evaluate the prognostic implications of the presence of multiple cytogenetic high-risk abnormalities at the time of diagnosis. Methods: We studied 226 patients who were diagnosed with multiple myeloma between July 2004 and July 2014 at Mayo Clinic Rochester, underwent FISH evaluation within six months of diagnosis, and presented with cytogenetic high-risk abnormalities. High-risk cytogenetics were defined as t(4;14), t(14;16), t(14;20), del(17p), or gain(1q). Bone marrow aspirates were evaluated for deletions, monosomies, trisomies, and tetrasomies using chromosome- or centromere-specific FISH probes. IGH rearrangements were evaluated using an IGH break-apart probe and evaluating up to five potential partners (FGFR3, CCND1, CCND3, MAF, and MAFB). Kaplan-Meier overall survival estimates were calculated and the log-rank test was used to compare overall survival in patients with single and multiple cytogenetic high-risk abnormalities. A multivariable-adjusted Cox regression model was used to assess the effect of multiple cytogenetic high-risk abnormalities on overall survival adjusting for age, sex, and Revised International Staging System (R-ISS) stage. P-values below 0.05 were considered statistically significant. Results: The median age at diagnosis was 65 years (32 - 90), 129 (57%) of the patients were male. The median overall survival was 3.5 years (3.1 - 4.9) for the entire cohort (n = 226), 4.0 years (3.3 - 5.1) for those with one cytogenetic high-risk abnormality (n = 182, 80%), and 2.6 years (1.7 - 3.1) for those with two cytogenetic high-risk abnormalities (n = 44, 20%). There were no patients with more than two cytogenetic high-risk abnormalities. Ninety-eight patients (45%) had a high-risk translocation, 77 (35%) had del(17p), 39 (18%) had a high-risk translocation plus del(17p), and 5 (2%) had gain(1q) plus either a high-risk translocation or del(17p). Figure 1 shows the Kaplan-Meier overall survival estimates stratified by the number of cytogenetic high-risk abnormalities (n = 226). The presence of two cytogenetic high-risk abnormalities (compared to one) was of prognostic significance after adjusting for age, sex, and R-ISS stage (HR 2.01, 95% CI 1.27 - 3.19, p = 0.003, n = 205). Conclusions: Approximately one in five patients with newly diagnosed high-risk multiple myeloma presented with two high-risk abnormalities at the time of diagnosis. These patients experienced inferior overall survival suggesting a cumulative effect of multiple cytogenetic high-risk abnormalities. The relatively low number of observed gain(1q) was likely related to the fact that not all patients were evaluated for that abnormality. Therefore the presented hazard ratio represents a conservative effect estimate and may underestimate the true effect. Figure 1 Figure 1. Disclosures Dispenzieri: GSK: Membership on an entity's Board of Directors or advisory committees; Jannsen: Research Funding; Alnylam: Research Funding; Celgene: Research Funding; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; pfizer: Research Funding. Kapoor:Takeda: Research Funding; Celgene: Research Funding; Amgen: Research Funding. Kumar:Janssen: Consultancy, Research Funding; BMS: Consultancy; AbbVie: Research Funding; Millennium: Consultancy, Research Funding; Onyx: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Skyline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Array BioPharma: Consultancy, Research Funding; Noxxon Pharma: Consultancy, Research Funding; Kesios: Consultancy; Glycomimetics: Consultancy.

Introduction: The clinical presentation and frequency of organ involvement are quite distinct in patients with IgM amyloidosis compared to patients with non-IgM amyloidosis, with less heart involvement and more nerve, soft tissue and lung involvement in IgM patients. It has been observed that immunoglobulin light chain variable region (IGVL) gene and gene family of the plasma cell clone impact phenotypic manifestations in AL amyloidosis, particularly organ tropism. (Kourelis et al. Blood. 2017;129). Given the variability in clinical features amongst patients with IgM vs. non IgM AL amyloidosis, we hypothesized that IGVL gene usage would be different between these two groups. Methods: Patients with newly diagnosed IgM and non-IgM amyloidosis seen at our institution from 01/2006 to 12/2015 were identified. IGVL gene usage was assessed by liquid chromatography tandem mass spectrometry (LC/MS/MS) as previously described. (Vrana et al Blood 2009;Dasari et al J of Proteome Res; Kourelis et al. Blood. 2017). Mass spectrometry data for IGVL analysis was obtained from clinically available data. LC/MS/MS was performed on available archival specimens when such data was not available clinically. Results: Patients with newly diagnosed amyloidosis who had sufficient mass spectrometry data on fat aspirate or tissue biopsy for IGVL gene usage identification were included (IgM AL, N=44 and Non-IgM AL, N=391). Clinical Features: As expected, differences were noted in baseline characteristics of patients with IgM vs. non-IgM AL amyloidosis. Patients with IgM amyloidosis were older (68 vs. 64 years, p=0.04) and more likely to have kappa as the involved light chain (34% vs. 25%, p=0.2), though the difference did not reach statistical significance. IgM amyloidosis patients had lower difference in involved and uninvolved free light chains (dFLC) (15.5 vs. 25.8 mg/dL, p=0.01) and lower NTProBNP levels (median: 1987 vs. 2655 pg/mL, p=0.02) compared with non-IgM amyloid patients. Presence of t(11;14) was less common by FISH (30% vs. 48%, p=0.1), though the difference did not reach statistical significance. Patterns of organ involvement were different, with heart involvement being less frequent in IgM patients (64% vs. 76%), while peripheral nerve (30% vs. 18%, p=0.05), soft tissue (41% vs. 21%, p=0.005) and lung involvement (7% vs. 3%, p=0.1) were more common in patients with IgM vs. non-IgM AL amyloidosis. There was no difference in liver (9% vs. 15%), kidney (50% vs. 51%) GI (23% vs. 25%) or autonomic nervous system involvement (18% vs. 14%). IGVL Gene Usage: As shown in Figure 1, IGVL usage differed across the two groups. In the lambda group, LV2-08 (14% vs. 2%, p<0.001) and LV2-14 (36% vs. 10%, p<0.001) were more common in IgM amyloid patients, while LV1-44 (0% vs. 10%, p=0.02) and LV6-57 (2% vs. 18%, p=0.004) were less common in the IgM group. There was also a trend towards less frequent involvement of LV3-01 (2% vs. 12%, p=0.07) in IgM amyloid patients. In the kappa group, KV4-01 (11% vs. 4%, p=0.04) was more common in patients with IgM amyloidosis. Correlation Between IGVL Gene usage and Clinical Features: IGVL gene usage correlated with disease characteristics and differences in the clinical presentation of patients across the two groups. LV2-14 was more commonly seen in IgM amyloid patients (above). It has been previously associated with a higher frequency of peripheral nerve involvement (Kourelis et al. Blood 2017), which was more frequent in IgM group. LV2-14 is also associated with low dFLC levels, which were noted to be lower in the IgM AL cohort. LV1-44 has been associated with higher likelihood of cardiac involvement. LV1-44 was seen less frequently in the IgM amyloid patients, who also had lower rates of cardiac involvement. LV6-57 has been historically associated with higher rates of t(11;14). It was less common in IgM AL patients, who also had lower rates of t(11;14). Conclusions: IGVL gene usage differed significantly in patients with IgM vs. non-IgM amyloidosis, correlating with differences in disease characteristics and organ involvement. This is the first study to our knowledge to report IGVL gene usage differences in IgM vs. non-IgM AL amyloidosis. Differences in IGVL gene usage may explain the distinct clinical presentation seen in IgM amyloidosis, the biology of which has so far remained poorly understood. *SS and SD contributed equally Disclosures Dasari: The Binding Site: Patents & Royalties: US Patent Rights on Mass Spectroscopy Licensing agreement with The Binding Site, Research Funding. Dispenzieri:Alnylam: Research Funding; Celgene: Research Funding; Takeda: Research Funding; Pfizer: Research Funding; Janssen: Consultancy; Akcea: Consultancy; Intellia: Consultancy. Murray:The Binding Site: Patents & Royalties: US Patent Rights on Mass Spectroscopy Licensing agreement with The Binding Site, Research Funding. Kumar:Janssen: Consultancy, Research Funding; Celgene: Consultancy, Research Funding; Takeda: Research Funding. Gertz:Prothena: Honoraria; Alnylam: Honoraria; Ionis: Honoraria; Janssen: Honoraria; Spectrum: Honoraria, Research Funding; Celgene: Honoraria.

BACKGROUND: pPCL is a rare and aggressive form of multiple myeloma (MM) with poor survival outcomes compared to that experienced by MM patients. It has been traditionally defined by the presence of an absolute plasma cell count of > 2000/microL or >20% circulating plasma cells (cPCs) in the peripheral blood. However, several recent studies have validated the optimal cutoff for defining pPCL to be >5% cPCs on a peripheral blood smear due to equally poor outcomes in this less restrictive cohort. Hence, given the rarity of this disease entity, we evaluated the clinical outcomes and cytogenetic features of patients diagnosed with pPCL at our institution with the new proposed definition of pPCL by >5% cPCs on peripheral blood smear that were treated with novel agent induction therapies. METHODS: We evaluated all patients with pPCL diagnosed between 2000 - 2018 evaluated at Mayo Clinic in Rochester, Minnesota. Data regarding these patients were extracted from a prospectively maintained database and from the review of the electronic medical records. Patients were categorized as having high risk cytogenetics if any of the following abnormalities were present: del 17p, t(4;14), t(14;16) or t(14;20). Chi-square tests and Fisher exact tests were used to compare differences between the sub-groups of interest. Survival analysis was performed by the Kaplan-Meier method and differences assessed using the log rank test. RESULTS: This cohort consisted of 71 patients with pPCL with a median age of 62 years (range: 34-91) of which 33 (46%) were male. The median follow up was 46 months (95% CI: 41 - 90). The median bone marrow plasma cell content was 84% (Range: 10 - 100) and the median plasma cell percentage on the peripheral smear was 23% (range: 5 - 93). There were 48 (68%) patients with >20% cPCs in their peripheral blood smear. Only 23 (32%) patients had concurrent information on the number of cPCs by multiparametric flow cytometry at diagnosis and the median number of cPCs detected was 32,807 per 150,000 events analyzed (Range: 354 - 132,256). There were 15/54 (28%) patients who presented with a creatinine of 2 mg/dL or greater and 17/55 (31%) pts who presented with hypercalcemia (11 mg/dL or greater). Data for ISS classification was available in 45 patients and is as follows: Stage 1- 3 (7%) patients, Stage 2- 10 (22%) patients and Stage 3- 32 (71%) patients. Data on the presence of primary cytogenetic abnormalities were available in 60 (85%) patients of which 29 (49%) had high risk cytogenetics. The distribution of primary cytogenetic abnormalities among this cohort was as follows: t(11;14) - 27 (45%), t(4;14) - 5 (8%), t(14;16) - 8 (13%), t(14;20)- 3(5%) and del 17p- 15(25%). All patients received novel agent induction therapy with 40 (57%) of them having received at least one autologous stem cell transplant and 1 patient undergoing an allogeneic stem cell transplant. The median overall survival (OS) for all pPCL patients in this cohort was 23 months (95% CI: 19 - 38). The OS was similar in patient with 5-19% cPCs vs. >20% cPCs (24 vs. 23 months, P = 0.999). However, when the entire cohort was stratified by cytogenetic risk, the median OS was 51 months for standard risk vs. 19 months for high risk (P = 0.005) (FIGURE). There were only 17 (30%) patients in this cohort who were alive for 48 months or longer since diagnosis (i.e. twice the median OS of this cohort) and they were more likely to not have high risk cytogenetics at diagnosis (P = 0.05). CONCLUSION: In this analysis of one of the largest contemporary cohorts of pPCL patients, the outcomes of patients diagnosed with pPCL remain poor despite the use of novel agent induction therapy. However, some patients appear to do better than expected and this phenomenon may be influenced by the absence of high risk cytogenetics. Disclosures Kumar: Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Research Funding. Dispenzieri:Akcea: Consultancy; Intellia: Consultancy; Janssen: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Alnylam: Research Funding. Dingli:Karyopharm: Research Funding; Rigel: Consultancy; Millenium: Consultancy; Janssen: Consultancy; alexion: Consultancy. Lacy:Celgene: Research Funding. Kapoor:Glaxo Smith Kline: Research Funding; Sanofi: Consultancy, Research Funding; Amgen: Research Funding; Takeda: Honoraria, Research Funding; Cellectar: Consultancy; Celgene: Honoraria; Janssen: Research Funding. Russell:Imanis: Equity Ownership. Leung:Omeros: Research Funding; Takeda: Research Funding; Prothena: Membership on an entity's Board of Directors or advisory committees; Aduro: Membership on an entity's Board of Directors or advisory committees. Gertz:Celgene: Consultancy; Prothena Biosciences Inc: Consultancy; Appellis: Consultancy; Amgen: Consultancy; Springer Publishing: Patents & Royalties; Amyloidosis Foundation: Research Funding; International Waldenstrom Foundation: Research Funding; Janssen: Consultancy; Ionis/Akcea: Consultancy; Alnylam: Consultancy; Annexon: Consultancy; Abbvie: Other: personal fees for Data Safety Monitoring board; Research to Practice: Consultancy; Teva: Speakers Bureau; Medscape: Consultancy, Speakers Bureau; Physicians Education Resource: Consultancy; Pharmacyclics: Membership on an entity's Board of Directors or advisory committees; Proclara: Membership on an entity's Board of Directors or advisory committees; Spectrum: Consultancy, Research Funding; i3Health: Other: Development of educational programs and materials; Johnson and Johnson: Speakers Bureau; DAVA oncology: Speakers Bureau.

Introduction: Primary cold agglutinin disease (CAD) is a rare disorder and accounts for 15% of all autoimmune hemolytic anemia. It is associated with an underlying monoclonal protein, which is IgM kappa in the majority of patients. The IgM protein triggers complement mediated extravascular hemolysis. The underlying pathophysiology by which autoimmune hemolysis affects only a small subset of patients with IgM monoclonal protein is poorly understood. Changes in the IgM structure via post-translational modifications of light chains (LCs), such as glycosylation are enriched in patients with AL amyloidosis, another rare disorder where disease manifestations are driven by the protein structure. (Kumar S et al Leukemia 2017). We hypothesized that presence of post-translational glycosylation is a potential mechanism allowing the IgM protein to trigger complement mediated hemolysis in CAD. Methods: Serum samples of patients being evaluated for monoclonal protein disorders were analyzed by immuno-enrichment-based matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), termed MASS-FIX. Patients who had an underlying IgM monoclonal protein identified by MASS-FIX from 07/23/2018 to 5/14/2019 were included this study. Glycosylated LCs were identified by the shift in their molecular mass due to the added molecular mass of the carbohydrates. Glycosylation was compared in patients with IgM associated CAD vs. other IgM disorders. Results: 438 unique patients with an IgM monoclonal protein identified on MASS-FIX were included in the study. CAD was present in 3% (n=14) of patients. The primary underlying diagnosis in the remaining patients was monoclonal gammopathy of undetermined significance (MGUS): 47% (n=206), lymphoplasmacytic lymphoma (LPL)/Waldenstrom Macroglobulinemia (WM): 30% (n=132), non-LPL lymphoma: 6% (n=28), AL amyloidosis: 4% (n=19), CLL: 4% (n=18), cryoglobulinemia: 2% (n=10), multiple myeloma: 2% (n=9) and other: 0.5% (n=2) Glycosylation was present in 7% (31/438) of patients in this cohort. Glycosylation was significantly more prevalent in patients with CAD than other IgM gammopathies (64% vs. 5%, p &lt;0.001). CAD was present in 29% of patients with glycosylation and in only 1% of patients without glycosylation, p&lt;0.001. Disease characteristics of patients with CAD, including patients with and without glycosylated LCs are listed in Table 1. No statistically significant differences were observed in the features of CAD patients with and without glycosylation, though sample size was small. All patients (100%) had IgM kappa monoclonal protein. Median M-spike was 0.5 g/dL. The associated disorder was IgM MGUS in 50% of patients, LPL/WM in 29%, marginal zone lymphoma in 14% and a non-specific B-cell lymphoproliferative disorder in 7% of patients. Median hemoglobin was 11.2 g/dL. All patients had characteristic RBC agglutination on peripheral smear. Elevated LDH and undetectable haptoglobin were seen in 100% of patients. Cold agglutinin titer was positive (&gt;1:64) in 12 of 13 patients (85%) in whom it was tested. The remaining patient had a titer of 1:8. Polyspecific Coombs test/direct antiglobin test (DAT) was positive in 100% of patients (n=12 tested) and all patients who were tested with monospecific DAT had an antiC3 antibody (n=10). One patient also had monospecific anti IgG antibody. Transfusions were needed in 21% of patients. Other clinical manifestations included acrocyanosis in 43% (n=6) and Raynaud's phenomenon in 50% (n=7) of patients, respectively. Treatment for CAD included rituximab with or without steroids in 50% (n=7) of patients, rituximab-based chemotherapy in 29% (n=4) of patients, with observation alone in 21% (n=3) of patients. Conclusions: Modification of the IgM immunoglobulin structure by post-translational glycosylation of LCs was significantly more common in patients with CAD compared with other IgM monoclonal gammopathies (64% vs. 5%, p &lt;0.001). CAD was seen in only 1% of patients without glycosylation, while one-third of patients with glycosylation had CAD. This is a novel finding. As MASS FIX is now routinely done for detection of monoclonal proteins at our institution, the presence of LC glycosylation can provide diagnostic clues and can be a potential therapeutic target in the future. Future studies in larger, independent cohorts of patients are needed to confirm these findings. *SS & DLM contributed equally Disclosures Murray: The Binding Site: Patents & Royalties: US Patent Rights on Mass Spectroscopy Licensing agreement with The Binding Site, Research Funding. Dasari:The Binding Site: Patents & Royalties: US Patent Rights on Mass Spectroscopy Licensing agreement with The Binding Site, Research Funding. Kumar:Celgene: Consultancy, Research Funding; Janssen: Consultancy, Research Funding; Takeda: Research Funding. Dispenzieri:Janssen: Consultancy; Pfizer: Research Funding; Takeda: Research Funding; Celgene: Research Funding; Alnylam: Research Funding; Intellia: Consultancy; Akcea: Consultancy. Gertz:Spectrum: Honoraria, Research Funding; Janssen: Honoraria; Celgene: Honoraria; Prothena: Honoraria; Ionis: Honoraria; Alnylam: Honoraria.