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Multiple myeloma is a heterogeneous disease whose pathogenesis has not been completely elucidated. Although B-cell receptors play a crucial role in myeloma pathogenesis, the impact of clonal immunoglobulin heavy-chain features in the outcome has not been extensively explored. Here we present the characterization of complete heavy-chain gene rearrangements in 413 myeloma patients treated in Spanish trials, including 113 patients characterized by next-generation sequencing. Compared to the normal B-cell repertoire, gene selection was biased in myeloma, with significant overrepresentation of IGHV3, IGHD2 and IGHD3, as well as IGHJ4 gene groups. Hypermutation was high in our patients (median: 8.8%). Interestingly, regarding patients who are not candidates for transplantation, a high hypermutation rate (≥7%) and the use of IGHD2 and IGHD3 groups were associated with improved prognostic features and longer survival rates in the univariate analyses. Multivariate analysis revealed prolonged progression-free survival rates for patients using IGHD2/IGHD3 groups (HR: 0.552, 95% CI: 0.361−0.845, p = 0.006), as well as prolonged overall survival rates for patients with hypermutation ≥7% (HR: 0.291, 95% CI: 0.137−0.618, p = 0.001). Our results provide new insights into the molecular characterization of multiple myeloma, highlighting the need to evaluate some of these clonal rearrangement characteristics as new potential prognostic markers., This work was partially supported by the Instituto de Salud Carlos III (ISCIII), Spanish Ministry of Economy and Competitiveness PI15/01956, CIBERONC-CB16/12/00233, and “Una manera de hacer Europa” (Innocampus; CEI-2010-1-0010)”. M.G.-A., I.P.-C., and C.J. are supported by the Fundación Española de Hematología y Hemoterapia (FEHH, co-funded by Fundación Cris in the latter case), A.M. by the European Social Fund and the Spanish Education Council through the University of Salamanca, and M.E.S. by the ISCIII (CPII18/00028). All Spanish funding is co-sponsored by the European Union FEDER program.

This is an open-access paper., The B-cell compartment in which multiple myeloma stem cells reside remains unclear. We investigated the potential presence of mature, surface-membrane immunoglobulin-positive B lymphocytes clonally related to the tumor bone marrow plasma cells among different subsets of peripheral blood B cells from ten patients (7 with multiple myeloma and 3 with monoclonal gammopathies of undetermined significance). The presence of clonotypic immunoglobulin heavy chain gene rearrangements was determined in multiple highly-purified fractions of peripheral blood B-lymphocytes including surface-membrane IgM+ CD27- naïve B-lymphocytes, plus surface-membrane IgG+, IgA+ and IgM+ memory CD27+ B cells, and normal circulating plasma cells, in addition to (mono)clonal plasma cells, by a highly-specific and sensitive allele-specific oligonucleotide polymerase chain reaction directed to the CDR3 sequence of the rearranged IGH gene of tumor plasma cells from individual patients. Our results showed systematic absence of clonotypic rearrangements in all the different B-cell subsets analyzed, including M-compo-nent isotype-matched memory B-lymphocytes, at frequencies, This work was supported by grants from European Union FP6 STREP MSCNet (N. E06005FF), Cooperative Research Thematic Network on Cancer (RTICs; RTICC RD06/0020/0035-FEDER, RD06/0020/0006, RD12/0036/0048, RD12/0036/0069 and G03/136), Instituto de Salud Carlos III/Subdirección General de Investigación Sanitaria Ministerio de Sanidad y Consumo (FIS: PI060339; 02/0905; 01/0089/01-02;PS09/01897, and PI06/0824-FEDER), Asociacion Española Contra el Cancer AECC (GCB120981SAN) and Gerencia Regional de Salud de Castilla y León; Ayuda de Excelencia de Castilla y León, Consejería de Educación (EDU/894/2009, GR37) Junta de Castilla y León, Valladolid, Spain. LST received a CAPES/Ministério da Educação scholarship from the Brazilian Government.

Identification and characterization of genetic alterations are essential for diagnosis of multiple myeloma and may guide therapeutic decisions. Currently, genomic analysis of myeloma to cover the diverse range of alterations with prognostic impact requires fluorescence in situ hybridization (FISH), single nucleotide polymorphism arrays, and sequencing techniques, which are costly and labor intensive and require large numbers of plasma cells. To overcome these limitations, we designed a targeted-capture next-generation sequencing approach for one-step identification of IGH translocations, V(D)J clonal rearrangements, the IgH isotype, and somatic mutations to rapidly identify risk groups and specific targetable molecular lesions. Forty-eight newly diagnosed myeloma patients were tested with the panel, which included IGH and six genes that are recurrently mutated in myeloma: NRAS, KRAS, HRAS, TP53, MYC, and BRAF. We identified 14 of 17 IGH translocations previously detected by FISH and three confirmed translocations not detected by FISH, with the additional advantage of breakpoint identification, which can be used as a target for evaluating minimal residual disease. IgH subclass and V(D)J rearrangements were identified in 77% and 65% of patients, respectively. Mutation analysis revealed the presence of missense protein-coding alterations in at least one of the evaluating genes in 16 of 48 patients (33%). This method may represent a time- and cost-effective diagnostic method for the molecular characterization of multiple myeloma.

Introduction VDJH usage description in B-cell hematological malignancies has brought new insights into the clonal differentiation and clinical implications for certain pathologies, improving patients' care, although no correlation has been made in MM. We present the largest-to-date VDJH gene repertoire analysis in MM, consisting in biological and clinical data from 413 patients. This database was used to comprehensively investigate the characteristics of VDJH rearrangements: gene segment usage, somatic hypermutation (SHM), CDR3 characterization, and immunoglobulin stereotyped clusters assessment. We also investigated the potential relationship of these molecular features with the outcome. Methods Newly diagnosed MM patients were included in the study. All were managed according to the recommendations of the GEM-PETHEMA Spanish MM group, including the inclusion of most patients in the GEM2000 and GEM2005 schemes. Monoclonal assessment was carried out with FR1 VH-JH amplification, following the BIOMED-2 methods. Moreover, 113 cases were also analyzed by NGS using the LymphoTrack IGH FR1 assay (Invivoscribe Tech, San Diego, CA). VDJH usage and mutational status were analyzed with IMGT-V-Quest. ClustalX2.0 was used to perform clustering analysis with CDR3 regions from our cohort and 1117 additional sequences obtained from IMGT/LIGM-DB corresponding to unique rearrangements from both normal and tumor human B cells. Molecular and clinical data were used to perform survival studies. Results The overall VDJH detection rate was 92.5% (382/413), including 376 patients with only one detectable rearrangement, five with a biallelic rearrangement, and one with a biclonal rearrangement, also detectable by flow cytometry. Thus, 388 rearrangements where detected: 362 were productive, and 26 unproductive. Gene segments were identified in productive rearrangements. VH repertoire in MM reflected its normal counterpart, with IGHV3 being the predominant selected family, followed by IGHV4, IGHV1, IGHV2 and IGHV5. IGHD and IGHJ segment usage showed a skewed distribution, with IGHD2 and IGHD3 families accounting for 55.5% of cases, and IGHJ4 and IGHJ6 accounting for 70.8%. SHM level could be identified in 349/362 productive sequences (mean: 9.16%, SD 3.95) with statistically significant differences between certain IGHV families, namely IGHV2 was less hypermutated than IGHV1 or IGHV4. We could also collect other rearrangement features: nucleotide addition by TdT appeared in 92.5% for N1 and 88.6% for N2, with evidence of exonuclease activity in all cases. CDR3 mean length was 16±4 aminoacids (median 15, range 6-29), with preference for Gly, Ala, Asp, Tyr (~10% each one). The R/S mutation ratio was 2.39 for CDRs versus 1.74 for FWRs, showing the high influence of antigen selection over the former. No stereotyped clusters were found in our cohort. Relationship between these finding and clinical evolution was done through univariate and multivariate analyses. A shorter Progression-Free Survival (PFS) related to well-known clinical factors: presence of plasmacytomas, poor performance status or ISS stages, response to therapy, and poor-risk cytogenetics (p Conclusions VDJH usage somatic hypermutation levels and CDR3 composition in multiple myeloma resembles the normal mature B cell repertoire. In contrast to Chronic Lymphocytic Leukemia (CLL), Mantle Cell Lymphoma or Marginal Zone Lymphoma, stereotyped receptors were absent in MM, which shows no evidence of autoantigen-driven selection. Cases with SHM levels below 7% were associated with aggressive outcome that, in the same line of CLL, would reflect the expansion of more immature clones in these cases. More studies are needed to deepen in the clinical meaning of these new findings. Disclosures Puig: Celgene: Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria. Ocio:Takeda: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Seattle Genetics: Consultancy; Pharmamar: Consultancy; AbbVie: Consultancy; Novartis: Consultancy, Honoraria; Sanofi: Research Funding; BMS: Consultancy; Amgen: Consultancy, Honoraria, Research Funding; Mundipharma: Research Funding; Celgene: Consultancy, Honoraria, Research Funding; Array Pharmaceuticals: Research Funding. Mateos:Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; GSK: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees. Lahuerta:Amgen: Honoraria; Janssen: Honoraria; Celgene: Honoraria. San-Miguel:Celgene: Consultancy; Sanofi: Consultancy; Janssen: Consultancy; MSD: Consultancy; Novartis: Consultancy; Takeda: Consultancy; Amgen: Consultancy; Brystol-Myers Squibb: Consultancy; Roche: Membership on an entity's Board of Directors or advisory committees. García-Sanz:Incyte: Consultancy; Amgen Inc.: Research Funding; Gilead: Research Funding; Spanish Government: Research Funding; Pharmacyclics: Research Funding; Hospira: Research Funding; BMS: Consultancy, Honoraria; Takeda: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses.

The human leukocyte antigen (HLA) system could play an essential role in multiple myeloma (MM) disease control. This report describes the results comparing HLA-DRB1 phenotypic frequencies in 181 MM patients (53 smoldering/indolent MM and 128 symptomatic MM patients) and healthy individuals. Higher DRB1*01 phenotypic frequencies were found in the smoldering patients compared with symptomatic MM patients (38% vs 14%, P = 0.001) and with the healthy individuals (38% vs 22%, P = 0.01). Additionally, higher DRB1*07 phenotypic frequencies were found in symptomatic MM compared with control population (38% vs 28%, P = 0.01). The present data suggest that HLA-DRB1*01 individuals may have a better ability to efficiently present myeloma-related antigens to immunocompetent cells, which could favor a better immune response against the tumor. This would translate into a more appropriate disease control associated with more indolent disease and prolonged survival.

RAN, ZHX2 and RCBTB2 (CHC1L) expression was evaluated by quantitative real time reverse transcription polymerase chain reaction in plasma cells from 85 monoclonal gammopathies: 58 symptomatic multiple myeloma (MM) (52 untreated, six relapsed), eight smouldering MM, five monoclonal gammopathy of undetermined significance, four plasma cell leukaemias and 10 myeloid cell lines. ZHX2 was weakly expressed in high-risk/proliferative disease compared to low-risk or indolent disease. High ZHX2 expression was associated with better response and longer survival after high-dose therapy. RCBTB2 expression was weaker in hyperdiploid versus non-hyperdiploid cases while RAN was more expressed in symptomatic MM and cell lines.

Multiple myeloma (MM) pathogenesis has been explained for many years by the cancer biology dogma introduced in 1976 by Peter Nowell:1 first, a single plasma cell would be immortalized by an error in the immunoglobulin genes rearrangement process; then, a progressive stepwise acquisition of somatic cell mutations would induce a sequential selection, leading to domination by the fittest clone.2 In line with this idea of ‘myeloma stability’, single-nucleotide polymorphism arrays studies in diagnostic-relapse paired samples have revealed the presence of common clonal characteristics.3 Biologically, the M-protein remains usually constant across MM evolution, to the point that it is conventionally used to monitor treatment response and disease progress. Further, the variable domain of the rearranged immunoglobulin heavy-chain genes (or CDR3 region) has been used as a patient-specific myeloma fingerprint in minimal residual disease (MRD) studies.

Contaminating tumour cells in apheresis products have proved to influence the outcome of patients with multiple myeloma (MM) undergoing autologous stem cell transplantation (APBSCT). The gene scanning of clonally rearranged VDJ segments of the heavy chain immunoglobulin gene (VDJH) is a reproducible and easy to perform technique that can be optimised for clinical laboratories. We used it to analyse the aphereses of 27 MM patients undergoing APBSCT with clonally detectable VDJH segments, and 14 of them yielded monoclonal peaks in at least one apheresis product. The presence of positive results was not related to any pre-transplant characteristics, except the age at diagnosis (lower in patients with negative products, P = 0.04). Moreover, a better pre-transplant response trended to associate with a negative result (P = 0.069). Patients with clonally free products were more likely to obtain a better response to transplant (complete remission, 54% vs 28%;90% reduction in the M-component, 93% vs 43% P = 0.028). In addition, patients transplanted with polyclonal products had longer progression-free survival, (39 vs 19 months, P = 0.037) and overall survival (81% vs 28% at 5 years, P = 0.045) than those transplanted with monoclonal apheresis. In summary, the gene scanning of apheresis products is a useful and clinically relevant technique in MM transplanted patients.

Introduction: A model of a stepwise malignant transformation has been proposed for the pathogenesis of monoclonal gammopathies. In this model, cell cycle regulators play a central role as a source of genetic events; particulary, p16/INK4a gene acts as a tumoral suppressor gene and, recently, inactivation of this gene through a methylation mechanism, has been observed in multiple myeloma patients. Under the diagnosis of monoclonal gammopathies there is a broad spectrum of disorders with very diAerent outcomes, ranging from indolent courses, such as those of monoclonal gammopathy of undetermined significance, Waldestron macroglobulinemia and smoldering multiple myeloma, to aggressive diseases such as symptomatic MM and primary plasma cell leukemia. To the best of our knowledge, the activity of p16 gene has not been evaluated and compared in these diAerent subtypes of monoclonal gammopathies. Materials and methods: The methylation status of the p16 gene was analysed in a group of 159 patients with monoclonal gammopathies (40 monoclonal gammopathy of uncertain significance, eight Waldenstrom Macroglobulinemia, eight smoldering multiple myeloma, 98 symptomatic multiple myeloma and five primary plasma cell leukemia) using three diAerent assays (restriction enzymes and PCR or S-B and modification by sodium bisulphite). Results: Forty-one of 98 MM patients (41.8%) as well as four of the five (80%) primary PCL patients showed methylation of the p16 gene, while none of the patients with monoclonal gammopathy of undetermined significance, Waldenstrom Macroglobulinemia or smoldering multiple myeloma displayed a methylation status. Conclusion: These findings suggest that the methylation of the p16 gene could be a relevant oncogenic event in the monoclonal gammopathies evolution being associated with the most aggressive forms. The Hematology Journal (2001) 2, 146-149

In the present paper, we report on the use of the heteroduplex PCR technique to detect the presence of clonally rearranged VDJ segments of the heavy chain immunoglobulin gene (VDJH) in the apheresis products of patients with multiple myeloma (MM) undergoing autologous peripheral blood stem cell (APBSC) transplantation. Twenty-three out of 31 MM patients undergoing APBSC transplantation with VDJH segments clonally rearranged detected at diagnosis were included in the study. Samples of the apheresis products were PCR amplified using JHand VH (FRIII and FRII) consensus primers and subsequently analyzed with the heteroduplex technique, and compared with those obtained at diagnosis. 52% of cases yielded positive results (presence of clonally rearranged VDJH segments in at least one apheresis). The presence of positive results in the apheresis products was not related to any pre-transplant characteristics with the exception of response status at transplant. Thus, while no one patient with positive apheresis products was in complete remission (CR), negative immunofixation, before the transplant, five cases (46%) with negative apheresis were already in CR at transplant (P = 0.01). The remaining six cases with heteroduplex PCR negative apheresis were in partial remission before transplant. Patients with clonally free products were more likely to obtain CR following transplant (64% vs 17%, P = 0.02) and a longer progression-free survival, (40 months in patients transplanted with polyclonal products vs 20 with monoclonal ones, P = 0.03). These results were consistent when the overall survival was considered, since it was better in those patients with negative apheresis than it was in those with positive (83% vs36% at 5 years from diagnosis, P = 0.01). These findings indicate that the presence of clonality rearranged VDJH segments is related to the response and outcome in MM transplanted patients.

We have analyzed the applicability, sensitivity and prognostic value of allele-specific oligonucleotide real-time quantitative PCR (ASO RQ-PCR) as a method for minimal residual disease (MRD) assessment in patients with multiple myeloma (MM), comparing the results with those of multiparameter flow cytometry (MFC). A total of 170 patients enrolled in three consecutive Spanish trials achieving at least partial response after treatment were included. Lack of clonality detection (n = 31), unsuccessful sequencing (n = 17) and suboptimal ASO performance (n = 51) limited the applicability of PCR to 42% of cases. MRD was finally investigated in 103 patients (including 32 previously studied) with persistent disease identified by PCR and MFC in 54% and 46% of cases, respectively. A significant correlation in MRD quantitation by both the techniques was noted (r = 0.881, P

We evaluated the MYD88 L265P mutation in Waldenström's macroglobulinemia (WM) and B-cell lymphoproliferative disorders by specific polymerase chain reaction (PCR) (sensitivity ∼10(-3)). No mutation was seen in normal donors, while it was present in 101/117 (86%) WM patients, 27/31 (87%) IgM monoclonal gammapathies of uncertain significance (MGUS), 3/14 (21%) splenic marginal zone lymphomas and 9/48 (19%) non-germinal center (GC) diffuse large B-cell lymphomas (DLBCLs). The mutation was absent in all 28 GC-DLBCLs, 13 DLBCLs not subclassified, 35 hairy cell leukemias, 39 chronic lymphocytic leukemias (16 with M-component), 25 IgA or IgG-MGUS, 24 multiple myeloma (3 with an IgM isotype), 6 amyloidosis, 9 lymphoplasmacytic lymphomas and 1 IgM-related neuropathy. Among WM and IgM-MGUS, MYD88 L265P mutation was associated with some differences in clinical and biological characteristics, although usually minor; wild-type MYD88 cases had smaller M-component (1.77 vs 2.72 g/dl, P=0.022), more lymphocytosis (24 vs 5%, P=0.006), higher lactate dehydrogenase level (371 vs 265 UI/L, P=0.002), atypical immunophenotype (CD23-CD27+ +FMC7+ +), less Immunoglobulin Heavy Chain Variable gene (IGHV) somatic hypermutation (57 vs 97%, P=0.012) and less IGHV3-23 gene selection (9 vs 27%, P=0.014). These small differences did not lead to different time to first therapy, response to treatment or progression-free or overall survival.

Background and Objectives Minimal residual disease (MRD) assessment by PCR in multiple myeloma (MM) has several shortcomings, including the lack of a suitable target. Kappa deleting element (KDE) rearrangements occur in virtually all Ig-lambda B-cell malignancies and in 1/3 of Ig-kappa are not affected by somatic hypermutation and, as in ALL, could be used as PCR targets. Methods We have first investigated the incidence, gene segment usage, and CDR3 composition of IGK-KDE rearrangements in 96 untreated myeloma patients. Second, we tested 16 KDE gene rearrangements as molecular targets for MRD assessment by RQ-PCR using a germline reverse primer and a germline Taqman probe in combination with allele-specific oligonucleotides (ASO) as forward primers. Results Monoclonal KDE rearrangements were amplified in 45% (43/96) of cases, monoallelic in 2/3 of them (29 cases), and biallellic in the remaining 14 cases. Overall, 88% of cases were successfully sequenced, KDE being equally frequently rearranged with VK and with intron-Recombination signal sequence (RSS). Median numbers of inserted and deleted nucleotides in the junctional region were one and five, respectively. Conclusions Using KDE rearrangements as additional PCR target for MRD assessment in MM improves the applicability of these studies in 9% of cases overall and in 20% of lambda cases. Its use in the latter subset could represent a significant advance.

We have evaluated the use of CD138+ positively selected bone marrow samples to identify a molecular target for minimal residual disease assessment by polymerase chain reaction (PCR) in 25 untreated patients with multiple myeloma. A fraction of each sample was used for CD138+ selection, and the rest served as a reference control. VDJH, DJH, and Kde gene rearrangements were tested for amplification according to the BIOMED-2 Concerted Action. PCR products were directly sequenced in an automated ABI 3130 DNA sequencer using Big-Dye terminators. Within the CD138+ selected group, VDJH rearrangements were detected in all cases (100 %), DJH in 16 (64 %), and Kde in 18 (72 %) cases; whereas in the control samples, VDJH, DJH, and Kde rearrangements were detected in 19 (76 %), 11 (44 %), and 12 (48 %) cases, respectively. After sequencing, 24 (96 %) cases within the CD138+ group had a PCR target for MRD detection compared with 15 (60 %) cases in the control group. We conclude that the use of CD138+ positively selected bone marrow samples increases the applicability of minimal residual disease studies by PCR in patients with multiple myeloma.

Summary. Methylenetetrahydrofolate reductase (MTHFR) plays an important role in carcinogenesis. A decreased incidence of cancer has been reported in the presence of MTHFR 677TT, 1298AC and 1298CC polymorphic variants. We have analysed the MTHFR genotype in 107 multiple myeloma (MM) patients and 86 controls. The MM and control polymorphisms frequencies were: 34% and 48% for 677CC, 53% and 41% for 677CT, 12% and 11% for 677TT; 36% and 43% for 1298AA, 51% and 44% for 1298AC; and 12% and 13% for 1298CC respectively. No statistically significant differences were observed. In addition, no differences were seen according to MM stage, presence of p16 gene hypermethylation or response to treatment.

We have explored the potential role of genetics in the development of osteonecrosis of the jaw (ONJ) in multiple myeloma (MM) patients under bisphosphonate therapy. A genome-wide association study was performed using 500 568 single nucleotide polymorphisms (SNPs) in 2 series of homogeneously treated MM patients, one with ONJ (22 MM cases) and another without ONJ (65 matched MM controls). Four SNPs (rs1934951. rs1934980, rs1341162. and rs17110453) mapped within the cytochrome P450-2C gene (CYP2C8) showed a different distribution between cases and controls with statistically significant differences (P=1.07 × 10-6, P= 4.231 × 10-6, P= 6.22 × 10-6, and P=2.15 × 10-6, respectively). SNP rs1934951 was significantly associated with a higher risk of ONJ development even after Bonferroni correction (P corrected value=.02). Genotyping results displayed an overrepresentation of the T allele in cases compared with controls (48% vs 12%). Thus, individuals homozygous for the T allele had an increased likelihood of developing ONJ (odds ratio 12.75, 95% confidence interval 3.7-43.5) © 2008 by The American Society of Hematology., This work has been partially supported by grants PI06-1354 from the Spanish Fondo de Investigaciones Sanitarias de la Seguridad Social, Red Española de Cancer RD06/0020/0006, and with the support of the Hemato-Oncology Institut, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Hospital Clinic, Barcelona, Spain.

p14/p16 and p15 gene expression was assessed by quantitative polymerase chain reaction in purified plasma cells (PC) from 52 patients with symptomatic multiple myeloma (MM) and seven with smoldering MM in order to clarify the impact of these genes on the proliferative activity of tumor cells and patients' outcome. p15 expression was lower in symptomatic MM than in smoldering SMM (-1.80 vs.1.51,p=0.026); similar results were observed for p14/p16. MM patients whose PC displayed high p15 and/or p14/p16 expression had a lower percentage of S-phase PC than the remaining cases (1.79%+/-1.35 vs. 3.04%+/-1.42, p=0.028), favorable prognostic factors and longer survival (100% vs. 49%at 2.5 years; p=0.007).

Analysis of IgH rearrangements in B-cell malignancies has provided clinical researchers with a wide range of information during the last few years. However, only a few studies have contributed to the characterization of these features in multiple myeloma (MM), and they have been focused on the analysis of the expressed IgH allele only. Comparison between the expressed and the non-functional IgH alleles allows further characterizion of the selection processes to which pre-myeloma cells are submitted.We analyzed a cohort of 84 untreated MM patients in order to characterize their functional VDJH and non-functional DJH rearrangements. The pattern of mutations and gene segment usage for both types of rearrangements was analyzed by polymerase chain reaction and sequencing.VH3 and VH1 family members were over- and under-represented, respectively. VH3-30 and VH3-15 segments were the most frequently used, whereas VH4-34 was found only in non-functional or heavily mutated VDJH rearrangements. DH2 and DH3 family members were over-represented in both VDJH and DJH repertoires, while the DH1 family was under-represented only in the productive VDJH rearrangements. Finally, DH3-22 and DH2-21 gene segments were found to be over-represented in the functional repertoire while segments commonly used by less mature B-cell malignancies, such as DH6-19 or DH3-3, were under-represented.Data reported here help to identify the clonogenic MM cell as a post-germinal center B cell that has undergone selection processes during the germinal center reaction.

The hypervariable regions of immunoglobulin heavy-chain (IgH) rearrangements provide a specific tumor marker in multiple myeloma (MM). Recently, real-time PCR assays have been developed in order to quantify the number of tumor cells after treatment. However, these strategies are hampered by the presence of somatic hypermutation (SH) in VDJH rearrangements from multiple myeloma (MM) patients, which causes mismatches between primers and/or probes and the target, leading to a nonaccurate quantification of tumor cells. Our group has recently described a 60% incidence of incomplete DJH rearrangements in MM patients, with no or very low rates of SH. In this study, we compare the efficiency of a real-time PCR approach for the analysis of both complete and incomplete IgH rearrangements in eight MM patients using only three JH consensus probes. We were able to design an allele-specific oligonucleotide for both the complete and incomplete rearrangement in all patients. DJH rearrangements fulfilled the criteria of effectiveness for real-time PCR in all samples (ie no unspecific amplification, detection of less than 10 tumor cells within 10(5) polyclonal background and correlation coefficients of standard curves higher than 0.98). By contrast, only three out of eight VDJH rearrangements fulfilled these criteria. Further analyses showed that the remaining five VDJH rearrangements carried three or more somatic mutations in the probe and primer sites, leading to a dramatic decrease in the melting temperature. These results support the use of incomplete DJH rearrangements instead of complete somatically mutated VDJH rearrangements for investigation of minimal residual disease in multiple myeloma.

DH-JH rearrangements of the Ig heavy-chain gene (IGH) occur early during B-cell development. Consequently, they are detected in precursor-B-cell acute lymphoblastic leukemias both at diagnosis and relapse. Incomplete DJH rearrangements have also been occasionally reported in mature B-cell lymphoproliferative disorders, but their frequency and immunobiological characteristics have not been studied in detail. We have investigated the frequency and characteristics of incomplete DJH as well as complete VDJH rearrangements in a series of 84 untreated multiple myeloma (MM) patients. The overall detection rate of clonality by amplifying VDJH and DJH rearrangements using family-specific primers was 94%. Interestingly, we found a high frequency (60%) of DJH rearrangements in this group. As expected from an immunological point of view, the vast majority of DJH rearrangements (88%) were unmutated. To the best of our knowledge, this is the first systematic study describing the incidence of incomplete DJH rearrangements in a series of unselected MM patients. These results strongly support the use of DJH rearrangements as PCR targets for clonality studies and, particularly, for quantification of minimal residual disease by real-time quantitative PCR using consensus JH probes in MM patients. The finding of hypermutation in a small proportion of incomplete DJH rearrangements (six out of 50) suggests important biological implications concerning the process of somatic hypermutation. Moreover, our data offer a new insight in the regulatory development model of IGH rearrangements.

Multiple myeloma (MM) pathogenesis has been explained for many years by the cancer biology dogma introduced by Peter Nowell: first, a single plasma cell would be immortalized by an error in the immunoglobulin genes rearrangement process; then, a progressive stepwise acquisition of somatic cell mutations would induce a sequential selection and domination by the fittest clone. In line with this idea of “myeloma stability”, SNP arrays studies in diagnostic-relapse paired samples have revealed the presence of common clonal characteristics. Biologically, the M-protein remains usually constant across MM evolution and further, the variable domain of the rearranged immunoglobulin heavy chain genes (or CDR3 region) has been used as a patient-specific myeloma fingerprint in minimal residual disease (MRD) studies. However, massive genome studies with Next Generation Sequencing (NGS) have challenged this concept, showing a significant intraclonal heterogeneity at diagnosis with the possible presence of several clonal progenitors or tumor-initiating cells. In this study, we have characterized and compared the CDR3 region in 52-paired samples from 26 MM patients aiming: 1) to assess mono-clonality in MM evolution through the analysis of the CDR3 sequence and, 2) to validate ASO RQ-PCR approaches for MRD in MM, based on the constancy and specificity of the CDR3 region. Samples were obtained at diagnosis and progression (19 pairs) or at 2 different timepoints of progressive disease (7 pairs). Median time between sampling was 2 years. M-protein subtype remained stable in all pairs but 1, associated with a light-chain escape phenomenon. All samples proceeded from bone marrow (BM) except for 2 pairs, composed by BM and extramedullary disease (spleen and testes). Two major cytogenetic changes were identified: increased 13q14 deletion (from 7 to 54%) in 1 pair and increased 17p (p53) deletion (from 5 to 87%) in a further one. Treatments administered between sampling included most of the current approaches used in MM (data not shown). Genomic DNA isolation, PCR amplification and sequencing were performed following conventional methods. Germline VH, DH and JH segments were identified by comparison with public databases. CDR3 region was first identified in all samples and then compared between the two samples in the 26 pairs: the sequence of nucleotides was constantly identical in each pair, including those associated with major cytogenetic changes, a light-chain escape, extramedullar vs. BM infiltration and relapsed (and therefore, treatment selected) vs. refractory disease. Therefore, we can first conclude that the main tumor clone in MM retains a specific signature across all stages of disease evolution that allows the identification of samples as evolutionary related. This major clone signature is not modified by clinical or biological changes in the disease nor under different treatment pressures and would thus identify disease relapse and progression. Our results have also a clear impact on the validity of molecular MRD techniques. The high rate of complete responses (up to 50-60%) currently achieved in MM has prompted the use of new techniques for disease assessment. Today, ASO RQ-PCR, based on the use of specific primers and probes complementary of the VDJH rearrangement, continues to be the most sensitive approach. One pitfall of this technique would be the potential instability of PCR targets over time, which would induce false negative results. In B-cell precursor ALL, this is estimated to happen in 30-40% of cases but has not been deeply evaluated in MM yet. With the present study, we can also conclude that the junction region of the VDJH rearrangement in MM constantly identifies the myeloma cells responsible for relapse and therefore can be used as a reliable target for MRD assessment by ASO RQ-PCR and more recently, by NGS methods. If the CDR3 region remains stable, the novel concept of clonal tiding in MM should not be interpreted as a poly- or oligoclonal but subclonal. In MM, tides can be subclonal, but the ocean remains monoclonal. Disclosures No relevant conflicts of interest to declare.

INTRODUCTION: Several studies have reported the presence of expanded T-cell clones in patients with multiple myeloma (MM), which could be involved in an anti-tumour response and extended survival. The Human Leukocyte Antigen (HLA) system seems to play an essential role in MM control and could influence disease control. This feature has been poorly studied and there are only few data favouring higher incidence of some HLA specifities such as B18 and B5 in myeloma patients. AIM: To compare HLA-DRB1 phenotypic frequencies in smoldering MM versus symptomatic MM patients and control individuals. PATIENTS: A total of 181 patients with a diagnosis of MM were analysed. According to their behaviour patients were classified into two subsets: 128 symptomatic MM who were homogeneously treated according to the GEM-2000 protocol (Spanish Myeloma Group/PETHEMA protocol) and 53 patients with the diagnosis of smoldering MM according to the criteria of the International Myeloma Working Group and who were free of therapy for at least 1 year following diagnosis. Additionally, 1818 healthy donor individuals from the Castilla y Leon registry for hematopoietic stem cell-transplantation were included as control population. All three populations involved Caucasian individuals. METHODS: After genomic DNA extraction, HLA-DRB1 typing at low-resolution level (two digits) was carried out using the PCR-rSSO methodology according to the standards of the European Federation of Immunogenetics. Allele frequencies were estimated by direct counting. Comparisons of allele and phenotype frequencies between populations were performed with the two-sided Fisher’s exact test using GraphPad Prism 4.0 Software. The strength of associations was estimated by the odds ratio (OR), and their 95% confidence intervals (CI) were calculated by Cornfield methods (values of p < 0.05 were considered statistically significant). P-value was corrected (Pc) for the number of valid comparisons made (Bonferroni correction). RESULTS: DRB1 phenotypic frequencies were not significantly different among MM patients and healthy control individual. In contrast, when the two MM cohorts were analyzed, DRB1*01 phenotypic frequencies were significantly higher in the smoldering patients as compared to symptomatic MM patients (37.7% vs. 14.1, p=0.0011, Pc=0.0143, OR: 3.7, 95% CI: 1.76–7.81). Furthermore, DRB1*01 phenotypic frequencies were significantly higher in the smoldering patients as compared to the healthy control individuals (37.7% vs. 21.7%, p=0.0106, Pc>0.05, OR: 2.19, 95% CI: 1.24–3.86). In addition, symptomatic MM patients showed a higher incidence in DRB1*07 phenotypic frequencies as compared to control population (38.3% vs. 27.6%, p=0.0111, Pc>0.05, OR: 1.63, 95% CI: 1.12–2.36). CONCLUSIONS: The present data suggest that HLA-DRB1*01 phenotype is associated with indolent MM and this may reflect a better ability to efficiently present myeloma-related antigens to immunocompetent cells.

p15 and p14/p16 tumor suppressor genes, have been reported to be frequently inactivated by various mechanisms in haematological malignancies such us MM. Alterations of these cell cycle inhibitors in MM display a close correlation with the cell cycle and clinical outcome. We have evaluated by real time quantitative RT-PCR (RQ-PCR) the expression of the p14/p16 and p15 genes in purified bone marrow plasma cells (PBMPC) from MM patients in order to evaluate the possible clinical, biological and prognostic significance of these cell cycle regulators. RNA extracted from purified BMPC from 53 untreated symptomatic MM and a pool of buffy coat from healthy donors (reference value) was analyzed by RQ-PCR using Assays-on-Demand gene expression mixes specific for p14/p16 and p15 genes in an ABI PRISM 7700 SDS (Applied Biosystems, Foster City, CA, USA). Values were corrected with a control gene (ABL). The relative quantification of gene expression was performed through the cycle threshold (CT) increment method. Patients were classified into different groups depending on gene expression values. Thus, according to p15 expression, 29% of patients (n=14) showed higher levels than the control and this group was characterized by the presence of good prognostic markers such us low Lactato dehidrogenase levels (LDH), low b2-microglobulin (B2M) and C-Reactive Protein (CRP) serum levels and absence of monoclonal proteinuria. Similar results were found for p14/p16 expression. Fifteen patients (28%) displayed a high p14/p16 expression and the group was also characterized by good prognostic features: low CRP, B2M and LDH levels. When p14/p16 and p15 genes were simultaneously analyzed, clinical and biological parameters showed a statistically significant correlation with gene expression. Thus patients with low gene expression had a high B2M (≥3 mg/dl) and high C-reactive protein (≥3 mg/dl). As far as survival was concerned, patients with a high p15 expression had a longer overall survival of 100% vs. 58% at 30 months (p=0,01), with the additional value that no deaths have been observed in any such patients. Similar results were observed for the group of patients displaying a high p14/p16 expression since they displayed a much better OS (100% vs. 63% at 30 months, p=0,02). Again, we should note that no deaths have been presented in this group. All these findings were much more evident when the three genes were simultaneously considered. Thus, within the group of 21 patients with at least one of the two genes overexpressed there have been no deaths vs. 11 among the 27 patients with low levels. This resulted in quite different OS curves for the two groups of patients (Figure 1) of 100% vs. 49% at 30 months (p=0,00). In conclusion, these genes significantly determine patients’ outcome thanks to their ability to classify them into different groups with different clinical, biological and outcome characteristics.

Introduction: Waldenström’s Macroglobulinemia (WM) is an uncommon lymphoproliferative disorder characterized by bone marrow infiltration of the lymphoplasmocytic cells and IgM monoclonal gammopathy. The normal counterpart of the WM malignant cell is believed to be a post germinal-center B cell. However, the low frequency of WM has hampered investigation into Immunoglobulin Heavy Chain (IgH) rearrangements in large series of patients and whether preferential use of specific genetic segments or non-functional rearrangements exits. Aim: Molecular characterization in a large cohort of WM patients analyzing their functional, complete VDJH, and non-functional, incomplete DJH, IgH rearrangements, the pattern of somatic hypermutation (SHM) and gene segment usage. Patients and methods: 47 patients with unequivocal diagnosis of WM were included in the study. Bone Marrow samples (always with more than 10% of tumor cell) were used for amplification of clonal rearrangements employing the Biomed-2 strategy (Leukemia2003; 17; 2257), followed by direct automated sequencing in ABI 377 DNA sequencer using Big-Dye terminators (Applied Biosystems, Foster City, CA). Results: All patients showed a monoclonal amplification of at least one VDJH or DJH rearrangement. VDJH monoclonal rearrangements were detected in 42/47 (89.3%) patients while DJH were observed in 20 (42.5%) patients. VH, DH and JH gene segment usage: VH3 gene segment was the most commonly represented family (76,2%) while the other gene segments were scarcely detectable, and VH5 was totally absent. In the complete VDJH rearrangements, DH6 was the family most commonly represented while DH2 (45%) and DH4 (30%) were the most common in the incomplete DJH rearrangement. Regarding JH elements, JH4 (38%) was the most represented in the complete rearrangements and JH5 (46%) in the incomplete rearrangements. Somatic hypermutation: SHM were observed in all except two of the cases (94%, 34 of 36 cases), in which the study could be performed. (median 9,38; range2.9–16.6). In the remaining clonal cases (6 cases, 14.3%) no amplification of FR1 region was obtained, also suggesting the presence of SHM. Conclusions: In this series of patients, we observed the presence of incomplete rearrangements with an incidence similar (44%) to that described in multiple myeloma. The preferential usage for determined families of genetic segments, in VDJH and in DJH, suggests the presence of positive and negative selection processes. Finally, the majority, (94 %) of the cases, presented SHM, although the presence of two patients lacking in SHM suggests a pre-follicular origin for some WM cases.

Multiple myeloma (MM) remains as an incurable disease although new therapies can achieve a high rate of complete remissions (CR). Unfortunately, most patients ultimately relapse due to the persistence of minimal residual disease (MRD), and only a minority could be cured. Detection and quantification of these cells is an important tool for monitoring these patients and predicting a potential relapse. Here we analyze by RQ-PCR the MRD in MM patients achieving CR in order to classify them into different risk categories. MATERIAL AND METHODS: 38 MM patients uniformly treated according to the GEM-2000 (Spanish group for Myeloma) protocol, and that have achieved CR following PBSCT were included in the study. 22 were IgG, 9 IgA, 6 B-J and 1 non-secretory (κ/λ 21/16). 27 were male & 11 female with a median age of 58 (range 48–65). Bone marrow samples obtained at diagnosis and 3 months after transplant were analyzed. Complete (VDJH) and incomplete (DJH) Ig rearrangements were amplified with the Biomed-2 strategy (Leukemia2003;17:2257). PCR clonal products were sequenced on an ABI Prism 377 Sequence detector. VH, DH and JH segments were identified by comparing with germinal sequences on V-Base and BLAST databases. An ASO primer at the N-region was designed for each patient with the OLIGO 6.0 software. RQ-PCR was then performed on an ABI Prism 7700 using the ASO specific forward primer, a JH reverse intronic primer (JH1–6) and a TaqMan probe (JH1,2,4,5, JH3 or JH6) to amplify the patient specific rearrangement. Sample quality and quantity was controlled evaluating the standard curve of the albumin gene amplification. MRD was calculated according to ΔCT method. RESULTS: In 14 out of the cases included in the study, MRD investigation was not possible because the N-region was not longer enough to design the ASO primer (n=3), poor quality in the diagnostic sample to obtain the standard curve (n=8) or low plasma cell infiltration at diagnosis to obtain correct dilutions (n=3). The remaining 24 patients were classified into different risk groups according to the MRD level obtained 3 months after transplantation with a cut-off point of 0.01% tumor cells. Thus, progression free survival (PFS) was longer in those patients with MRD< 10−4 (p=0.03, figure 1A). By contrast, upon comparing the impact on PFS of immofixation (IFX) in these 24 patients that were in CR (defined by conventional electrophoresis criteria), it was observed that patients with IFX (−) didn’t showed a different outcome from those IFX (+) (figure 1B). CONCLUSION: In summary, although RQ-PCR is a labor and time-consuming technique, it is an useful tool for monitoring MRD in MM. The level of 10−4 can contribute to classify patients into 2 groups (high and low MRD) with different risk of relapse that can be used to design specific therapies.

Molecular analysis by PCR of monoclonally rearranged immunoglobulin (Ig) genes can be used for diagnosis in B-cell lymphoproliferative disorders (LPD), as well as for monitoring minimal residual disease (MRD) after treatment. This technique has the risk of false-positive results due to the "background" amplification of similar rearrangements derived from polyclonal B-cells. This problem can be resolved in advance by additional analyses that discern between polyclonal and monoclonal PCR products, such as the heteroduplex analysis. A second problem is that PCR frequently fails to amplify the junction regions, mainly due to somatic mutations frequently present in mature (post-follicular) B-cell lymphoproliferations. The use of additional targets (e.g. Ig light chain genes) can avoid this problem.We studied the specificity of heteroduplex PCR analysis of several Ig junction regions to detect monoclonal products in samples from 84 MM patients and 24 patients with B cell polyclonal disorders.Using two distinct VH consensus primers (FR3 and FR2) in combination with one JH primer, 79% of the MM displayed monoclonal products. The percentage of positive cases was increased by amplification of the Vlamda-Jlamda junction regions or kappa(de) rearrangements, using two or five pairs of consensus primers, respectively. After including these targets in the heteroduplex PCR analysis, 93% of MM cases displayed monoclonal products. None of the polyclonal samples analyzed resulted in monoclonal products. Dilution experiments showed that monoclonal rearrangements could be detected with a sensitivity of at least 10(-2) in a background with30% polyclonal B-cells, the sensitivity increasing up to 10(-3) when the polyclonal background was1% of polyclonal B-cells.Heteroduplex analysis of PCR amplified products is a simple and quick alternative for detecting monoclonally rearranged Ig genes in MM. This can be applied for diagnosis of B cell LPD and as a previous step in MRD strategies.

The p16 gene competes with cyclin D for binding to CDK4/CDK6 and therefore inhibits CDK4/6 complex kinase activity, resulting in dephosphorylation of pRb and related G1 growth arrest. Inactivation of this gene has been involved in a variety of tumors by different mechanisms: homozygous/hemyzygous deletions, point mutations and methylation of a 5' CpG island into exon E1alpha of the p16 gene. Homozygous deletions have been rarely found in multiple myeloma (MM) and no point mutations have been reported. Two recent studies have reported a high prevalence of methylation in the exon E1alpha of the p16 gene, but included only a small number of cases. We have analyzed the methylation pattern of exon E1alpha of the p16 gene in 101 untreated MM and five primary plasma cell leukemias (PCL). A PCR assay, relying on the inability of some restriction enzymes to digest methylated sequences, was used to analyze the methylation status. Southern blot analysis was used to confirm these results. Forty-one of 101 MM patients (40.5%) as well as four of the five (80%) primary PCL patients had shown methylation of the exon E1alpha. Our study confirms that hypermethylation of the p16 gene is a frequent event in MM. Leukemia (2000) 14, 183-187.