Ahmann, Gregory

Abstract We investigated whether interleukin-1β (IL-1β) is differentially expressed in plasma cells from monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients because IL-1β appears to play a major role in the development of lytic bone lesions, the major clinical feature distinguishing MGUS from myeloma. In situ hybridization (ISH) for IL-1β was performed using bone marrow aspirates from 51 MM, 7 smoldering MM, 21 MGUS, and 5 normal control samples. Using the ISH technique IL-1β mRNA was detectable in the plasma cells from 49 of 51 patients with active myeloma and 7 of 7 patients with smoldering myeloma. In contrast, 5 of 21 patients with MGUS and 0 of 5 normal controls had detectable IL-1β message. Bone lesions were present in 40 of the 51 MM patients analyzed, and all 40 patients had IL-1β mRNA by ISH. These results show that greater than 95% of MM patients but less than 25% of MGUS patients are positive for IL-1β production. In the future, continued follow-up of IL-1β positive and negative MGUS patients should determine whether aberrant expression of plasma cell IL-1β is predictive of those MGUS patients that will eventually progress to active myeloma.

Abstract Abstract 2881 Multiple myeloma (MM) is characterized by a remarkable heterogeneity in outcome following standard and high-dose therapies. Significant efforts have been made to identify genetic changes and signatures that can predict clinical outcome and include them in the routine clinical care. Gene expression profiling (GEP) studies have achieved a central role in the study of multiple myeloma (MM), as they become a critical component in the risk-based stratification of the disease. To molecularly stratify disease-risk groups, we performed GEP on purified plasma cells (obtained from the immunobead selection of CD138+ cells) from 489 MM samples in different stages of the disease using the Affymetrix U133Plus2.0 array. A total of 162 probes were analyzed using an in house automated script to generate a GEP report with the most used risk stratification indices and signatures, including the UAMS 70-gene, UAMS class, TC classification, proliferation and centrosome signature, and NFKB activation indices. In a subset of 57 samples, IgH translocations were analyzed using FISH and results were correlated with GEP data. A macrophage index was calculated and used as a surrogate measurement of non-plasma cell contamination. A total of 49 samples (10%) were excluded from subsequent analysis as the macrophage index indicated a significant contamination with no plasma cells, hence potentially compromising the results. The percent of high-risk disease patients identified from different signatures ranged from 26.4% by using high proliferation index to 28.8% with high centrosome signature and 31.3% with high 70-gene index. This percent of high-risk cases based on the 70-gene index is similar to what was found in Total therapy 2 (TT2) and TT3 cohorts. A third of patients (33.2%) were classified as D1 in the TC class, followed by 11q13 (19.3%), D2 (16.4%), 4p16 (13.8%), MAF (6.1%), None (4.7%), D1+D2 (4.5%) and 6p21 (1.8%). The NF-kB pathway was likely activated in 45.5% to 59.5% of cases, depending on the index used for its calculation. High proliferation index and high centrosome signature significantly correlates with 70-gene high-risk group (p<0.0001). Conversely, the activation of NF-kB pathway was not significantly different between high- and low- risk subgroups. TC subgroups D1 (p<0.0001) and 11q13 (p=0.01) were significantly more common in the 70-gene low-risk group. Similarly, TC subgroups 4p16 (p=0.0004), Maf (p=0.02) and D2 (p=0.05) were enriched in the high-risk group. Translocations t(4;14)(p16;q32), t(11;14)(q13;q32) and t(14;16)(q32;q23) were precisely predicted by the TC classification (100% correspondence). Cases with IgH translocations with unknown partner were classified in subgroups D1 (33%), D2 (25%), 6p21 (25%) and Maf (16%). Here we summarized the associations between the most significant gene expression indices and signatures relevant to MM risk-stratification. The multiple variables simultaneously analyzed in an automated way, provide a powerful and fast tool for risk-stratification, helping in the therapeutic decision-making. Disclosures: Stewart: Celgene: Consultancy, Research Funding; Millennium: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; BMS: Consultancy, Research Funding; Onyx Pharmaceuticals: Consultancy, Research Funding. Fonseca:Consulting :Genzyme, Medtronic, BMS, Amgen, Otsuka, Celgene, Intellikine, Lilly Research Support: Cylene, Onyz, Celgene: Consultancy, Research Funding.

Abstract Introduction: FISH is able to recognize chromosomal deletions and translocations with a greater sensitivity than conventional cytogenetics. Specific abnormalities have been associated with prognosis. Initial observations suggest a poor outcome for patients with -17p13.1, chromosome 13 abnormalities (Δ13) and t(4;14)(p16.3;q32). In contrast a good outcome has been shown in some series for patients with t(11;14)(q13;q32). We analyzed the value of FISH in patients receiving high dose therapy . Patients and Methods: We studied by cIg-FISH 226 patients undergoing high dose therapy at Mayo Clinic between 1/1990 and 9/2001. All patients had a pretransplant cIg-FISH done on cytospin slides from marrow aspirates for t(11;14)(q13;q32), t(4;14)(p16.3;q32), and -17p13.1(p53). Information was available regarding Δ13 for all patients (+ in 52%). Results: The prevalence of the abnormalities were: t(11;14)(q13;q32) 17% (n=197), t(4;14)(p16.3;q32) 13% (n=153), and -17p13.1 11% (n=168). The overall survival (OS)was significantly shortened in patients with t(4;14)(p16.3;q32) (18.2 vs. 43.3 mo, p=0.001) (figure) and patients with -17p13.1 (14.7 vs. 38.6 mo, p=.01). OS was not different for patients with the t(11;14)(q13;q32) (36.2 vs. 34.8 mo, p=ns). Likewise time to progression (TTP) was shortened in patients with t(4;14)(p16.3;q32) (8.5 vs 17.7 mo, p=.001) and -17p13.1 (8.3 vs. 16.2 mo, p=0.005). TTP was also not affected significantly by the t(11;14)(q13;q32) (20.7 vs. 14.9 mo, p=NS). To dissect the specific contribution of t(4;14)(p16.3;q32) we did a subset analysis of patients who also had Δ13, since 85% of patients with t(4;14)(p16.3;q32) are expected to have Δ13. Of 84 studied for both abnormalities 22 had both Δ13 and t(4;14)(p16.3;q32). The OS was significantly shorter in patients with both abnormalities versus those with Δ13 alone (26.6 vs. 18.2 months, p=0.001). When a multivariable analysis of the impact of Δ13 and t(4;14)(p16.3;q32) were placed into a Cox model the hazard function for t(4;14)(p16.3;q32) was greater than Δ13 (2.6 versus 1.6). Δ13 had only borderline significance in this model (p=0.06). Conclusion: We have been unable to corroborate the improved outcome after transplant for patients with t(11;14)(q13;q32). As has been reported in patients with conventional and high dose therapy -17p13(p53) and t(4;14)(p16.3;q32) have clinical importance for estimation of OS and TTP. In this patient group the t(4;14)(p16.3;q32) carried a greater adverse impact than did Δ13, and identifies a subset of patients whose time to progression is 8.5 months. These patients likely do not benefit from autologous transplant and are candidates for novel therapeutic approaches. Outcome Successful determination Patients with translocation or deletion Survival (months) with/without abnormality Time to Progression (months) with/without abnormality * p<0.01;**p<0.001 t(11;14)(q13;q32) 197 34(17%) 36.2/34.8 20.7/14.9 p53 168 18(11%) 14.7/38.6 * 8.3/16.2 * t(4;14)(p16.3;q32) 153 26(17%) 18.2/43.3 **figure 8.5/17.7 ** t(4;14)(p16.3;q32)/Δ13+ patients 84 22(26%) 18.2/26.6 8.2/12.8 * Figure Figure

Abstract Waldenström macroglobulinemia (WM) is a lymphoid neoplasm associated with accumulation of lymphoplasmacytic cells in the bone marrow and an elevated monoclonal IgM in the serum. Although the genetic and molecular mechanisms behind the pathogenesis of WM are not well understood, losses of the long arm of chromosome 6 have been found as the only recurrent genomic aberration. These deletions, mostly starting at 6q21, are observed in upwards of 50% of patients and involve the majority of the clonal cells. To better characterize pathologic gene expression signatures in different types of WM at the molecular level (6q deleted versus not), we examined gene expression level changes of more than 20000 human gene probes in bone marrow tissues of clinically proven WM patients. We used Affymetrix HG-U133A v2 chips (n = 24). Clonal cells were purified using a combination of anti-CD138 and anti-CD19 Miltenyi™ magnetic microbeads. Based on cIgM-FISH results, we classified samples into two groups - 6q normal (ND) group and 6q deletion (D) group. We then proceeded to identify genes that showed differential expression between the two groups. We selected 165 differentially expressed genes (DEG) using SAM, and underwent further investigation of biological annotations of them using Gene Ontology™ (GO) terms. Among165 DEG, only 32 showed high level of expression in ND group compared to D group while 133 showed high level of expression in D group. As expected, all genes that reside in 6q region showed under-expression in D group, constituting 53% (17 genes) of genes under-expressed in D group (32 genes). According to GO analysis, the 6q-deletion-induced under-expression affects many biological processes, and is associated with a transcriptional upregulation of downstream genetic cascades. This likely indicates release of regulatory control by a tumor suppressor gene. Genes involved in cell growth and maintenance, cell communication and morphogenesis are also over-expressed in D group. Interestingly, a gene that is involved in innate immune response and inflammatory response shows under-expression in D group but is not accounted for by other mechanisms. In similar vein, a gene that is involved in negative regulation of cytokine biosynthesis showed over-expression in D group. We think these transcriptional characteristics can provide basic framework for differentiating subtypes of WM and search for genes associated with WM pathogenesis

We investigated whether interleukin-1β (IL-1β) is differentially expressed in plasma cells from monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM) patients because IL-1β appears to play a major role in the development of lytic bone lesions, the major clinical feature distinguishing MGUS from myeloma. In situ hybridization (ISH) for IL-1β was performed using bone marrow aspirates from 51 MM, 7 smoldering MM, 21 MGUS, and 5 normal control samples. Using the ISH technique IL-1β mRNA was detectable in the plasma cells from 49 of 51 patients with active myeloma and 7 of 7 patients with smoldering myeloma. In contrast, 5 of 21 patients with MGUS and 0 of 5 normal controls had detectable IL-1β message. Bone lesions were present in 40 of the 51 MM patients analyzed, and all 40 patients had IL-1β mRNA by ISH. These results show that greater than 95% of MM patients but less than 25% of MGUS patients are positive for IL-1β production. In the future, continued follow-up of IL-1β positive and negative MGUS patients should determine whether aberrant expression of plasma cell IL-1β is predictive of those MGUS patients that will eventually progress to active myeloma.

Abstract Abstract 604 We have conducted a pilot study to interrogate both CpG hyper- and hypomethylation in Multiple Myeloma (MM) using the Illumina GoldenGate (GG) BeadArrayTM high-throughput assay. Specifically, we utilized the Illumina Methylation Cancer Panel I, which spans 1,505 CpG loci selected from 807 genes including known tumor suppressor genes and oncogenes. To date we have profiled 50 CD138+ MM specimens, 4 MM cell lines and 6 normal CD138+ plasma cell samples (each representing a pool of 3-5 individuals) obtained from the bone marrow of patients who have undergone hip or knee replacement surgeries. We have obtained highly reproducible and reliable DNA methylation profiles with an average r2 of greater than 0.98 when the β values were compared between technical replicates. Further, we generated an internal control panel for the array by performing methylation specific PCR (MSP) to determine the methylation status of several genes found on the array (CDKN2A, E-Cadherin, MGMT, hMLH1) in 4 MM cell lines. A differential methylation analysis was conducted between normal plasma cells and MM samples using the BeadStudio Methylation Module v3.2. Differential scores for each CpG locus on the array were generated that correspond to significant differences between groups. Scores greater than (hypermethylation) or less than (hypomethylation) 13 represent ‘Diff scores' that are statistically significant (p values < 0.05) and this cut-off threshold is used to determine differentially methylated loci. Globally, when comparing MM to normal plasma cells, hypomethylation occurred at 42% of probes on the array, and was more common than hypermethylation, which occurred at only 21% of probes. Interestingly, 77% of probes situated in non-CpG islands were hypomethylated compared to 26% or probes in CpG islands. On the contrary hypermethylation occurred mainly in CpG islands (26% of probes) whereas only 7.4% of probes in non-CpG islands were considered hypermethylated. A total of 946 CpG loci were differentially methylated between normal plasma cells and MM. Among the most significantly differentially methylated CpG loci between normal plasma cells and MM were FZD9, ALOX12, MMP-3, MMP-8, and p16. Array comparative genomic hybridization (aCGH) data availabel for this same sample set was used to generate a hyperdiploid index for each sample by identifying those samples with whole chromosome gains at minimally three odd numbered chromosomes. There were 751 CpG loci that were differentially methylated between hypderdiploid and non-hyperdiploid tumors with WEE1, FRZB, ELK1, CLDN4, and SHH being among the most significant. We also applied the pathway enrichment analysis tool GeneGo v5 (Agilent) to these data, which identified cell adhesion/ECM remodeling, developmental pathways and several immune response pathways as the most significantly enriched pathways between normal and plasma cells with ephrin signaling pathways in the context of cell adhesion as the most significantly enriched pathway between hyperdiploid and non-hyperdiploid tumors. We hope to integrate methylation data with orthogonal datasets including gene expression, aCGH, and DNA sequence data being developed as part of the MMRF Genomics Initiative. Further validation of hits will also be followed up by functional studies to assess the true biological relevance of differentially methylated genes. This study represents one of the first methylome interrogation studies in MM and points towards global hypomethylation as possibly an important mechanism driving myelomagenesis. Our data also suggest that differential methylation of genes may be a significant determinant of hyperdiploid biology. Determining the set of critical genes and pathways based on the myeloma methylome is likely to lead to an improved understanding of biological mechanisms involved in myelomagenesis, ultimately leading to new and improved methods of diagnosing and treating this disease. Disclosures: No relevant conflicts of interest to declare.

Abstract Background: Multiple myeloma (MM) is a hematologic cancer characterized by a diversity of genetic lesions-translocations, copy number alterations (CNAs), and single nucleotide variants (SNVs). The prognostic value of translocations and of CNAs has been well established. Determining the clinical significance of SNVs, which are recurrently mutated at much lower frequencies, and how this significance is impacted by translocations and CNAs requires additional, large-scale correlative studies. Such studies can be facilitated by cost-effective targeted sequencing approaches. Hence, we designed a single-platform targeted sequencing approach capable of detecting all three variant types. Methods: We designed oligonucleotide probes complementary to the coding regions of 467 genes and to the IgH and MYC loci, allowing a probe to closely match at most 5 regions within the genome. Genes were selected if they were expressed in an independent RNA-seq MM data set and harbored germline SNP-filtered variants that: (1) occurred with frequency >3%, (2) were clustered in hotspots, (3) occurred in recurrently mutated "cancer genes" (as annotated in COSMIC or MutSig), or (4) occurred in genes involved in DNA repair and/or B-cell biology. IgH and MYC tiling was unbiased (with respect to annotated features within the loci) and spanned from 50 kilobasepairs (kbps) upstream of both regions to 50 kbps downstream of IgH and 100 kbps downstream of MYC. Results: We performed targeted sequencing of 96 CD138-enriched samples derived from MM patients, as well as matched peripheral blood leukocyte normal controls. Sequencing depth (mean 107X) was commensurate with that of available exome sequencing data from these samples (mean 71X). Samples harbored a mean of 25 non-silent variants, including those in known MM-associated genes: NRAS (24%), KRAS (22%), FAM46C (17%), TP53 (10%), DIS3 (8%), and BRAF (3%). Variants detected by both platforms showed a strong correlation (r^2 = 0.8). The capture array detected activating, oncogenic variants in NRAS Q61K (n=3 patients) and KRAS G12C/D/R/V (n=5) that were not detected in exome data. Additionally, we found non-silent, capture-specific variants in MTOR (3%) and in two transcription-related genes that have been previously implicated in cancer: ZFHX4 (5%) and CHD3 (5%). To assess the potential role of deep subclonal variants and our ability to detect them, we performed additional sequencing (mean 565X) on six of the tumor/normal pairs. This revealed 14 manually-reviewed, non-silent variants that were not detected by the initial targeted sequencing. These had a mean variant allele frequency of 2.8% and included mutations in DNMT3A and FAM46C. At least one of these 14 variants occurred in five of the six re-sequenced samples. This highlights the importance of this additional depth, which will be used in future studies. Our approach successfully detected CNAs near expected frequencies, including hyperdiploidy (52%), del(13) (43%), and gain of 1q (35%). Similarly, it inferred IgH translocations at expected frequencies: t(4;14) (14%), t(6;14) (3%), t(11;14) (15%), and t(14;20) (1%). As expected, translocations occur predominantly within the IgH constant region, but also frequently 5' (i.e., telomeric) of the IGHM switch region, and occasionally within the V and D regions. We detected MYC -associated translocations, whose frequencies have been the subject of debate, at 10% (n=9 patients), with five involving IgH, three having both partners in or near MYC, and one having both types. Finally, our platform detected novel IgH translocations with partners near DERL3 (n=2), MYCN (n=1), and FLT3 (n=1). Additional evidence suggests that DERL3 and MYCN may be targets of IgH-induced overexpression: of 84 RNA-seq patient samples, six exhibited outlying expression of DERL3, including one sample in which we detected the translocation in corresponding DNA, and one exhibited outlying expression of MYCN. Conclusion: Our MM-specific targeted sequencing strategy is capable of detecting deeply subclonal SNVs, in addition to CNAs and IgH and MYC translocations. Though additional validation is required, particularly with respect to translocation detection, we anticipate that such technology will soon enable clinical testing on a single sequencing platform. Disclosures Vij: Celgene, Onyx, Takeda, Novartis, BMS, Sanofi, Janssen, Merck: Consultancy; Takeda, Onyx: Research Funding.

Abstract Introduction Lenalidomide is an immunomodulatory drug (IMID) used to treat Multiple Myeloma (MM). Although a role for cereblon (CRBN)-mediated degradation of Ikaros proteins (IKZF1 and IKZF3) has been shown, the complete molecular and biochemical mechanisms responsible for lenalidomide-mediated anti-MM activity and/or resistance are undiscovered. Therefore, we aimed to analyze whether IMIDs (thalidomide, lenalidomide, and pomalidomide) are inducing oxidative stress in MM and what determines these drugs varying sensitivity and/or resistance. Methodology Amplex Red Assay has been performed to analyze IMIDs-mediated inhibition of H2O2 decomposition in both, in-vitro and in-vivo assays. Lentiviruses were prepared in 293T cells for CRBN, IgL-λ & IgL-k, and Bim knockdown experiment. Quantification of MM cellular anti-oxidative capacity for determining IMID sensitivity was standardized with H2O2-mediated oxidation of FADH2 and NAD(P)H. To measure apoptosis and gene expression analysis 106 cells were incubated with lenalidomide for 24 to 96 hours before they were examined by annexin-PI and FACS analysis. Gene and protein expression were measured by RT-PCR, western blot, and immunohistochemistry. Results We discovered that IMIDs inhibit peroxidase-mediated decomposition of H2O2 in both, in vitro horseradish peroxidase (HRP) assays and in human MM cell lines (HMCLs). Of the IMIDs analyzed, pomalidomide was the more potent inhibitor. H2O2 treatment effectively degraded IKZF1 and IKZF3 in HMCLs. To confirm the central role of CRBN in IKZF1 and IKZF3 degradation by H2O2-induced oxidative stress, we used CRBN knockdown OPM2 isogeneic cells and the CRBN-overexpressing OCIMY-5 cell line. We treated both sets of isogenic cell lines with lenalidomide and H2O2 for 3 hours, and we showed that H2O2 similarly mediates IKZF1 and IKZF3 degradation in a CRBN-dependent fashion. Next, we tested viability of CRBN present and absent cell lines with increasing concentrations of lenalidomide and H2O2 for 3 days. Lenalidomide-induced cytotoxicity was CRBN dependent, but H2O2 was not after 3 days, as shown by MTT assays. The capacity of MM cells to decompose H2O2 was measured via a biochemical test that quantitatively measured cellular anti-oxidative capacity. IMID sensitivity was well correlated with cellular anti-oxidative capacity, likely, cells more efficiently decompose H2O2was resistant and cells were not sensitive to IMID. This result shows that antioxidant capacity determines lenalidomide sensitivity among HMCLs with similar CRBN protein expression. We discovered that lenalidomide-mediated cytotoxicity in MM was attributable to oxidative damage of intracellular immunoglobulin proteins. By using several sets of isogenic cells lines with and without CRBN expression, we confirmed that lenalidomide treatment caused accumulation of IgL dimers only in CRBN-positive cells. Lenalidomide-induced IgL dimerization lead to decreased secretion and consequent intracellular accumulation of IgL, as evidenced by unchanged IgL mRNA expression, increased total intracellular IgL protein, and decreased secretion of IgL. After 72 hours of lenalidomide treatment we found decreased XBP-1u, increased XBP-1s, and over-expressed GRP78/BiP endoplasmic reticulum stress (ERS) marker proteins in CRBN positive cells but not in CRBN knock-down cells. We observed Bim requirement, especially BimEL, after lenalidomide treatment in CRBN-positive lenalidomide-sensitive cells. Our data reveals that lenalidomide-mediated; progressive ERS can positively enhance bortezomib-induced apoptosis in an in-vitro MM model. We pretreated MM cells with lenalidomide and then treated them with bortezomib. OPM2 cells pretreated with lenalidomide for 2 days clearly showed increased sensitivity to bortezomib-induced apoptosis compared with cells that were not pretreated. Conclusion IMIDs inhibit H2O2 decomposition. Ikaros protein degradation is a consequence of H2O2 mediated oxidative stress. Therefore, cells producing high H2O2 and with less antioxidative capacity are more sensitive to IMIDs. On the basis of this discovery, we would be able to predict which patients will benefit from IMIDs-mediated therapy and develop new drugs other than IMIDs that can inhibit intracellular H2O2 decomposition in MM. At present, CRBN may be required for IMIDs to effectively inhibit H2O2decomposition. Disclosures Chirackal: Mayo Clinic: Patents & Royalties: Filed a professional US patent for quantifying cellular anti-oxidative capacity. Fonseca:Mayo Clinic: Patents & Royalties: Filed a professional US patent for quantifying cellular anti-oxidative capacity.

Abstract Immunoglobulin (Ig) light chain (LC)-associated amyloidosis (AL) is a fatal plasma cell (PC) disorder characterized by the overproduction of Ig light chains that deposit in an abnormal conformation as amyloid throughout the body. Lambda LC are involved in amyloid deposition 2–3 times more often than kappa LC, and certain LC Ig variable genes are more frequently involved than others and influence clinical presentation and outcome. AL is a potential complication of any immunoglobulin clonal process, but is most often pathologically associated with minimal clonal expansion of PC, as seen in monoclonal gammopathy of undetermined significance. It is much less commonly observed in patients with multiple myeloma (MM). Because of this, and to our knowledge, there are no cell lines that have been established from AL patients, an experimental tool that would be of great value in studying amyloid formation and the biology of amyloid producing PC. In this study, we have established two cell lines from a 50 yr old female initially diagnosed with AL. Upon initial diagnosis, the BM aspirate consisted of 27% IgG λPC with a PC labeling index (PCLI) of 1.9% and a κ to λratio of <0.1. Amyloid was present in periosteal vessel walls and in the fat aspirate. The first cell line, ALMC-1, was established from BM mononuclear cells isolated from the diagnostic aspirate. The patient received a peripheral blood stem cell transplant (PBSCT) 2 months later, but relapsed within 100 days post-PBSCT with symptomatic myeloma. At relapse, the patient’s BM aspirate consisted of 70% λ+ PC and a PCLI of 20%; the second cell line, ALMC-2 was established from this aspirate. IgVL and IgVH analysis revealed that both cell lines expressed identical sequences and used IgVλ 6–57*01, IgλJ3*02, and IgλC3*03: both used the IgVH VH3–21 gene and the extent of somatic mutation was approximately 4%. Both cell lines produce significant FLC, and studies are currently underway to characterize in vitro amyloid production. We next used fluorescence in situ hybridization (FISH) to identify the genetic defects in this patient’s tumor population before and after transition to symptomatic MM. The initial BM aspirate at time of diagnosis of AL revealed approximately 30% of the PC had clear evidence of c-MYC gene amplification. In the subsequent draws as well as in both cell lines, 100% c-MYC amplification was identified, consistent with clonal selection. FISH analysis also revealed that 40% of cells had p53 deletion upon initial diagnosis, whereas the subsequent samples and cell lines were 100% for p53 deletion. All cells also had an IgH translocation that did not involve any commonly observed chromosome partners. Lastly, we have characterized the cytokine responsiveness of both cell lines. Although some differences are observed between ALMC-1 and ALMC-2, IL-6 and IGF-1 stimulated growth in both cell lines to varying degrees and both lines expressed autocrine IGF-I. In summary, our initial characterization of ALMC-1 and ALMC-2 predicts that these unique cell lines will prove to be an invaluable tool to better understand AL, from the combined perspectives of amyloidogenic protein structure and amyloid formation, genetics, and cell biology. Insight gained from this model system may eventually have an impact in the clinical arena by providing a better understanding of this incurable disease.

Translocations involving immunoglobulin (Ig) loci and chromosome 13 monosomy (Δ13) are frequent cytogenetic findings in multiple myeloma (MM). Similar chromosomal aberrations have been identified in the monoclonal gammopathy of undetermined significance (MGUS), but their prevalence and significance remain uncertain. Bone marrow from 72 patients with MGUS (n = 62) and smoldering MM (n = 10) was evaluated for translocations between the Ig heavy chain (IgH) and chromosomes 4, 11, and 16, translocations involving Ig light chain–lambda (IgL-λ, and Δ13. Fluorescence in situ hybridization (FISH) analysis was done on clonal plasma cells (PCs) detected by immunofluorescence (cIg-FISH) of the cytoplasmic light chain. We also studied cells for cyclin D1 and FGFR3 up-regulation by immunohistochemistry and immunofluorescence, respectively. Twenty-seven (46%) of 59 patients had IgH translocations, and 4 (11%) of 37 had an IgL-λ translocation. A t(11;14)(q13;q32) was found in 15 (25%) of 59 patients, a t(4;14)(p16.3;q32) in 9% of patients, and a t(14;16)(q32;q23) in 5% of patients. All patients with t(4;14)(p16.3;q32) tested (n = 3) had intense cytoplasmic fluorescence with an anti-FGFR3 antibody. PC nuclear staining of cyclin D1 was only observed in patients with t(11;14)(q13;q32); Δ13 was detected in the clonal PCs in 50% of patients. The percentage of abnormal PCs varied with any given abnormality. No obvious clinical or biologic correlations were associated with these chromosome abnormalities. Similar translocations are found in both MGUS and MM, including t(4;14)(p16.3;q32) and t(14;16)(q32;q23). Moreover, Δ13 is common in MGUS and unlikely to play a predominant role in the evolution of MGUS to MM.