From Waldenström's macroglobulinemia to aggressive diffuse large B-cell lymphoma: a whole-exome analysis of abnormalities leading to transformation.

Transformation of Waldenström's macroglobulinemia (WM) to diffuse large B-cell lymphoma (DLBCL) occurs in up to 10% of patients and is associated with an adverse outcome. Here we performed the first whole-exome sequencing study of WM patients who evolved to DLBCL and report the genetic alterations that may drive this process. Our results demonstrate that transformation depends on the frequency and specificity of acquired variants, rather than on the duration of its evolution. We did not find a common pattern of mutations at diagnosis or transformation; however, there were certain abnormalities that were present in a high proportion of clonal tumor cells and conserved during this transition, suggesting that they have a key role as early drivers. In addition, recurrent mutations gained in some genes at transformation (for example, PIM1, FRYL and HNF1B) represent cooperating events in the selection of the clones responsible for disease progression. Detailed comparison reveals the gene abnormalities at diagnosis and transformation to be consistent with a branching model of evolution. Finally, the frequent mutation observed in the CD79B gene in this specific subset of patients implies that it is a potential biomarker predicting transformation in WM.

Reprogramming human B cells into induced pluripotent stem cells and its enhancement by C/EBPα.

B cells have been shown to be refractory to reprogramming and B-cell-derived induced pluripotent stem cells (iPSC) have only been generated from murine B cells engineered to carry doxycycline-inducible Oct4, Sox2, Klf4 and Myc (OSKM) cassette in every tissue and from EBV/SV40LT-immortalized lymphoblastoid cell lines. Here, we show for the first time that freshly isolated non-cultured human cord blood (CB)- and peripheral blood (PB)-derived CD19+CD20+ B cells can be reprogrammed to iPSCs carrying complete VDJH immunoglobulin (Ig) gene monoclonal rearrangements using non-integrative tetracistronic, but not monocistronic, OSKM-expressing Sendai Virus. Co-expression of C/EBPα with OSKM facilitates iPSC generation from both CB- and PB-derived B cells. We also demonstrate that myeloid cells are much easier to reprogram than B and T lymphocytes. Differentiation potential back into the cell type of their origin of B-cell-, T-cell-, myeloid- and fibroblast-iPSCs is not skewed, suggesting that their differentiation does not seem influenced by 'epigenetic memory'. Our data reflect the actual cell-autonomous reprogramming capacity of human primary B cells because biased reprogramming was avoided by using freshly isolated primary cells, not exposed to cytokine cocktails favoring proliferation, differentiation or survival. The ability to reprogram CB/PB-derived primary human B cells offers an unprecedented opportunity for studying developmental B lymphopoiesis and modeling B-cell malignancies.

Critical evaluation of ASO RQ-PCR for minimal residual disease evaluation in multiple myeloma. A comparative analysis with flow cytometry.

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<0.001), being reflective of treatment intensity. Patients with <10(-4) residual tumor cells showed longer progression-free survival (PFS) compared with the rest (not reached (NR) vs 31 months, P=0.002), with similar results observed with MFC. Among complete responders (n=62), PCR discriminated two risk groups with different PFS (49 vs 26 months, P=0.001) and overall survival (NR vs 60 months, P=0.008). Thus, although less applicable than MFC, ASO RQ-PCR is a powerful technique to assess treatment efficacy and risk stratification in MM.

MYD88 L265P is a marker highly characteristic of, but not restricted to, Waldenström's macroglobulinemia.

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.

Frequency of HLA-A, -B and -DRB1 specificities and haplotypic associations in the population of Castilla y León (northwest-central Spain).

The frequencies of human leukocyte antigen (HLA) class I and class II specificities and haplotypic associations were determined in 1940 unrelated donors from Castilla y León and compared with other Iberian, Mediterranean and European populations. Specificities were determined using polymerase chain reaction reverse sequence-specific oligonucleotide or polymerase chain reaction sequence-specific primer techniques. In the analysis, 19, 29 and 13 specificities were found for HLA-A, -B and -DRB1, respectively, with HLA-A*02 (26%), -A*01 (11%), -B*44 (16%), -B*35 (10%), -DRB1*07 (16%) and -DRB1*13 (14%) showing the highest frequencies. In addition, 10 common HLA-A-B-DRB1 haplotypic associations were observed, A*01-B*08-DRB1*03 (3%) and A*29-B*44-DRB1*07 (3%) being the most frequent ones. These findings indicate that the population of Castilla y León is genetically equidistant from the Portuguese and other Spanish populations and shares a common origin with other Iberian populations, in which European, Mediterranean and North African genetic components are present; this is in agreement with the historical and genetic background of the population. These data contribute to a better understanding of the genetic structure of the Iberian Peninsula and provide a healthy control population from our region that should be useful for the study of disease associations.

Molecular and flow cytometry characterization during the follow-up of three simultaneous lymphoproliferative disorders: hairy cell leukemia, monoclonal B-cell lymphocytosis, and CD4(++) /CD8(+/- dim) T-large granular lymphocytosis--a case report.

The simultaneous diagnosis of hairy cell leukemia and monoclonal B-cell lymphocytosis with the characteristics of "indolent" chronic lymphocytic leukemia is rare but not unknown. However, an association with a third clonal lymphoproliferative disorder has not previously been described. We report the simultaneous presence of hairy cell leukemia, monoclonal B-cell lymphocytosis, and alpha beta CD4(++) /CD8(+) T-cell large granular lymphocytosis in a 63-year-old man. After the diagnosis, the three lymphoproliferative disorders (i.e., two of B-cell lineage and one of T-cell lineage) were characterized by analysis of multiple sequential bone marrow and peripheral blood samples using flow cytometry and molecular techniques. We discuss these findings in the context of chronic antigen stimulation, immunosuppression, and apoptotic pathway alterations, which might be implicated in the accumulation of these abnormal clones in the same patient. Because the phenotype of the three clones is compatible with fully differentiated B lymphocytes (consistent with a postgerminal origin) and T-CD4(++) cells, we favor the possibility of an antigen-driven mechanism and a dysregulation of homeostatic apoptosis in this patient.

The presence of DRB1*01 allele in multiple myeloma patients is associated with an indolent disease.

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.

Low expression of ZHX2, but not RCBTB2 or RAN, is associated with poor outcome in multiple myeloma.

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.

Hyperhomocysteinemia is a risk factor of recurrent coronary event in young patients irrespective to the MTHFR C677T polymorphism.

Despite the well-known pro-coagulant effect of hyperhomocysteinemia, data is limited regarding the result on recurrent coronary event (RCE) in young people. One hundred and forty patients <55 years old with a first acute coronary syndrome (ACS) were prospectively followed for a mean (+/-S.D.) follow-up of 49+/-14 months in order to investigate the relationship between homocysteine levels (tHcy) at admission and the incidence of RCE. The tHcy values were divided into quartiles to examine their relationship with end points. Furthermore, we determined the effect of C677T methylene tetrahydrofolate reductase (MTHFR) polymorphism, as well as other risk factors for developing a RCE. The median plasma homocysteine concentration was 9.6 mumol/L (interquartile range, 3.7). In the screening of MTHFR C677T polymorphism in patients with ACS, the T allele frequency was 0.4 and the genotype frequency distributions were in Hardy-Weinberg equilibrium. At time of final evaluation, 49 (35%) of the 140 valuable patients had developed a RCE. Increasing numbers of RCE were observed for increasing quartiles of tHcy according to Kaplan-Meier survival (Log-rank test=0.0092). The MTHFR C677T polymorphism was not associated with an increased incidence of RCE. In multivariate analysis, the variables independently associated with a higher risk of RCE were age older than 45 years [HR=2.7; (95% CI, 1.3-6.1); p=0.030], body mass index more than 25 [HR=2.6; (95% CI, 1.1-5.9); p=0.034] and tHcy levels into quartile 4 (tHcy>12.37 mumol/L) [HR=2.5; (95% CI, 1.1-4.7); p=0.04]. Elevated plasma homocysteine level at admission is an independent risk factor for RCE after the first episode of ACS in young patients irrespective of the status of MTHFR C677T.

TCRgammadelta+ large granular lymphocyte leukemias reflect the spectrum of normal antigen-selected TCRgammadelta+ T-cells.

T-cell large granular lymphocytes (LGL) proliferations range from reactive expansions of activated T cells to T-cell leukemias and show variable clinical presentation and disease course. The vast majority of T-LGL proliferations express TCRalphabeta. Much less is known about the characteristics and pathogenesis of TCRgammadelta+ cases. We evaluated 44 patients with clonal TCRgammadelta+ T-LGL proliferations with respect to clinical data, immunophenotype and TCR gene rearrangement pattern. TCRgammadelta+ T-LGL leukemia patients had similar clinical presentations as TCRalphabeta+ T-LGL leukemia patients. Their course was indolent and 61% of patients were symptomatic. The most common clinical manifestations were chronic cytopenias - neutropenia (48%), anemia (23%), thrombocytopenia (9%), pancytopenia (2%) - and to a lesser extent splenomegaly (18%). Also multiple associated autoimmune (34%) and hematological (14%) disorders were found. Leukemic LGLs were predominantly positive for CD2, CD5, CD7, CD8, and CD57, whereas variable expression was seen for CD16, CD56, CD11b, and CD11c. The Vgamma9/Vdelta2 immunophenotype was found in 48% of cases and 43% of cases was positive for Vdelta1, reflecting the TCR-spectrum of normal TCRgammadelta+ T-cells in adult PB. Identification of the well-defined post-thymic Vdelta2-Jdelta1 selection determinant in all evaluable Vgamma9+/Vdelta2+ patients, is suggestive of common (super)antigen involvement in the pathogenesis of these TCRgammadelta+ T-LGL leukemia patients.

Incomplete DJH rearrangements of the IgH gene are frequent in multiple myeloma patients: immunobiological characteristics and clinical implications.

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.

Incomplete DJH rearrangements as a novel tumor target for minimal residual disease quantitation in multiple myeloma using real-time PCR.

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.

Gene scanning of VDJH-amplified segments is a clinically relevant technique to detect contaminating tumor cells in the apheresis products of multiple myeloma patients undergoing autologous peripheral blood stem cell transplantation.

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.

Immunophenotypic analysis of the TCR-Vbeta repertoire in 98 persistent expansions of CD3(+)/TCR-alphabeta(+) large granular lymphocytes: utility in assessing clonality and insights into the pathogenesis of the disease.

At present, a major challenge in the initial diagnosis of leukemia of large granular lymphocytes (LGLs) is to establish the clonal nature of the expanded population. In the present study we have analyzed by flow cytometry immunophenotyping the TCR-Vbeta repertoire of 98 consecutive cases of persistent expansions of CD4(+) or CD8(+bright) CD3(+)/TCR-alphabeta(+) LGLs and compared the results with those obtained in molecular studies of TCR-beta gene rearrangements. Fifty-eight cases were considered to be monoclonal in molecular studies whereas in the remaining 40 cases there was no evidence for monoclonality (11 cases were considered oligoclonal and 29 polyclonal). The TCR-Vbeta repertoire was biased to the preferential use of one or more TCR-Vbeta families in 96% of cases, a total of 124 TCR-Vbeta expansions being diagnosed: one TCR-Vbeta expansion in 71 cases and two or more TCR-Vbeta expansions in 23 cases. The highest TCR-Vbeta expansion observed in each case was higher among monoclonal (74 +/- 19%) as compared to nonmonoclonal cases (24 +/- 14%) (P = 0.001), as did the fraction of LGLs that exhibited a TCR-Vbeta-restricted pattern (86 +/- 16% and 42 +/- 23%, respectively; P = 0.0001); by contrast, the proportion of cases displaying more than one TCR-Vbeta expansion was higher in the latter group: 7% versus 48%, respectively (P = 0.001). Results obtained in oligoclonal cases were intermediate between those obtained in polyclonal and monoclonal cases and similar results were observed for CD4(+) as for CD8(+bright) T-cell expansions. TCR-Vbeta families expressed in CD8(+bright) T-cell-LGL proliferations showed a pattern of distribution that mimics the frequency at which the individual TCR-Vbeta families are represented in normal peripheral blood T cells. Assuming that a given proliferation of LGLs is monoclonal whenever there is an expansion of a given TCR-Vbeta family of at least 40% of the total CD4(+) or CD8(+bright) T-cell compartment, we were able to predict clonality with a sensitivity of 93% and a specificity of 80%. By increasing the cut-off value to 60%, sensitivity and specificity were of 81% and 100%. In summary, our results suggest that flow cytometry immunophenotypic analysis of the TCR-Vbeta repertoire is a powerful screening tool for the assessment of T-cell clonality in persistent expansions of TCR-alphabeta(+) LGLs.

Molecular characterization of acute myeloblastic leukemia according to the new WHO classification: a different distribution in Central-West Spain.

BACKGROUND AND OBJECTIVES: Molecular analysis has contributed to the identification of several non-random chromosomal translocations, such as t(15;17), t(8:21), inv(16)/t(16;16) and 11q23 abnormalities, typically associated with acute myeloid leukemia (AML). The identification of these chromosomal abnormalities helps not only to define different AML subtypes with distinct prognoses and treatments but also to monitor the disappearance of malignant cells after treatment. Recent reports suggest that the frequency of these alterations may differ according to geographic distribution. However, most of these reports focus on just one or two genetic alterations, which may lead to some selection bias. Appropriate epidemiological studies should be based on unselected consecutive series of patients in which all relevant genes are simultaneously analyzed. The aim of the present study was to explore whether or not the incidence of genetic lesions in Spanish AML patients differs from that reported in other countries. DESIGN AND METHODS: In a series of 145 consecutive un-selected adult patients with AML we simultaneously analyzed the presence of 4 genetic abnormalities, PML/RARalpha for t(15;17), AML1/ETO for t(8;21), CBFbeta/MYH11 for inv(16)/t(16;16) and rearrangements of the MLL gene for 11q23 abnormalities. AML were classified using the new World Health Organization (WHO) classification for hematologic malignancies. The techniques used were standardized according to the recommendations of the European BIOMED-1 Concerted Action. RESULTS: The PML/RARalpha transcript was present in 34 patients (23.4%) (23 were bcr1, 2 bcr2 and 9 bcr3). The AML1/ETO fusion transcript was detected in only 2 cases (1.4%) both with M2 morphology, but 29 other cases with M2 morphology were negative. CBFbeta/MYH11 transcript was present in 9 cases (6.2%) eight of them displaying M4Eo morphology. Finally, 5 cases (3.5%) showed rearrangements of theMLL gene. Our results differ from those reported from the United States and North/Central Europe, particularly regarding the incidence of t(15;17) and t(8;21) translocations. In Spain the frequency of t(15;17) is higher while that of t(8;21) is lower. INTERPRETATION AND CONCLUSIONS: These data add epidemiological information about geographic heterogeneity of such chromosome aberrations in AML and would contribute to the design of specific screening strategies adapted to the incidence in each country.

p16/INK4a gene inactivation by hypermethylation is associated with aggressive variants of monoclonal gammopathies.

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; particularly, 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 different outcomes, ranging from indolent courses, such as those of monoclonal gammopathy of undetermined significance, Waldeströn 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 different 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 Waldenström Macroglobulinemia, eight smoldering multiple myeloma, 98 symptomatic multiple myeloma and five primary plasma cell leukemia) using three different 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, Waldenström 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.

Association of CD4+/CD56+/CD57+/CD8+(dim) large granular lymphocytic leukemia, splenic B-cell lymphoma with circulating villous lymphocytes, and idiopathic erythrocytosis.

In this paper we report a rare association of a splenic marginal zone B-cell lymphoma with villous lymphocytes and a T-cell large granular lymphocytic leukemia coexpressing CD4 and CD8 as well as CD56 and CD57 natural killer-associated markers in an asymptomatic patient investigated because of an occasional finding of erythrocytosis and leukocytosis in routine blood analysis. We also discuss the possible reasons for this particular association.

The detection of contaminating clonal cells in apheresis products is related to response and outcome in multiple myeloma undergoing autologous peripheral blood stem cell transplantation.

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 JH and 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 pretransplant 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% vs 36% 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.