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Background and Objectives: Waldenström macroglobulinemia (WM) and monoclonal gammopathy of undetermined significance (MGUS) are IgM-related disorders in which monoclonal B cells harbor a unique clonotypic rearrangement of the immunoglobulin heavy chain gene (IgH). The aim of this study was to characterize IgH rearrangements in a larger series of IgM-related disorders than any previously described., Design and Methods: Seventy-two patients with monoclonal IgM disorders (64 with WM and eight with IgM-MGUS) were studied to amplify and sequence both VDJH and DJH rearrangements. Twenty-nine of them were also tested for the existence of class switch recombination (CSR)., Results: VDJH and DJH rearrangements were detected in 91% and 42% of WM patients and in 100% and 13% of IgM-MGUS patients, respectively. In WM, the most frequently observed VH family and single segment were VH3 and VH3-23 (76% and 29%, respectively), with their frequencies differing markedly from those that would occur if the rearrangements were random. The VH3-23 segment was never selected in IgM-MGUS. The distribution of both DH and JH families in WM did not differ from that in normal B-lymphocytes. Somatic hypermutation with >2% deviation was seen in 90% of cases of WM and in 71% of IgM-MGUS. DJH rearrangements were more frequent in WM than in MGUS (42% and 13%, respectively). All DJH rearrangements were unmutated, which makes them an attractive target for minimal residual disease investigation. IgM clonotypic transcripts were observed in all cases and IgD in 83%. IgA and/or IgG monoclonal isotypes were seen in three WM cases (14%) but in none of the IgM-MGUS patients., Interpretation and Conclusions: WM and IgM-MGUS exhibit dissimilarities in VDJH and DJH rearrangements that could suggest different differentiation processes. There is evidence that WM cells are able to undergo CSR in vivo, a fact that was initially thought to be impossible in this disease.

Background and Objectives: The detection of PML-RARalpha by real-time polymerase chain reaction (RQ-PCR) is becoming an important tool for monitoring minimal residual disease (MRD) in patients with acute promyelocytic leukemia (APL). However, its clinical value remains to be determined. Our aim was to analyze any associations between the risk of relapse and RQ-PCR results in different phases of treatment, comparing these data with those yielded by conventional qualitative reverse transcriptase-PCR., Design and Methods: Follow-up samples from 145 APL patients treated with the PETHEMA protocols were evaluated by the RQ-PCR protocol (Europe Against Cancer program) and by the RT-PCR method (BIOMED-1 Concerted Action). Hematologic and molecular relapses and relapse-free survival were recorded. We then looked for associations between relapse risk and RQ-PCR results., Results: After induction therapy, no association was found between positive RQ-PCR results and relapse. The PCR result here did not imply any change in the scheduled therapy. After the third consolidation course, two out of three cases with positive RQ-PCR relapsed in contrast to 16 out of 119 (13%) patients with negative RQ-PCR. During maintenance therapy and out-of treatment, all patients with >10 PML-RARalpha normalized copy number (NCN) (n=19) relapsed while all patients with <1 NCN at the end of the study remained in hematologic remission (p<0.0001). In the intermediate group (NCN 1-10) (n=18), the relapse-free survival at 5 years was 60%. Hematologic relapses were predicted if a positive RQ-PCR result had been obtained in a follow-up sample within the previous 4 months., Interpretation and Conclusions: Based on the information provided by RQ-PCR in samples obtained after the end of consolidation and subsequently, a relapse risk stratification could be established for APL patients. This stratification divides patients into three groups: those at high risk of relapse, those with an intermediate risk and those with a low risk of relapse.

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).