Biased Igλ expression in hypermutated IgD multiple myelomas does not result from receptor revision

Normal IgM−IgD+ CD38+ B cells and IgM−IgD+ multiple myelomas (MM) are characterized by Cμ deletion, biased Igλ expression and hypermutated IgV regions. The predominant Igλ usage has been proposed as resulting from secondary Ig gene rearrangements during extensive clonal expansion in the germinal center environment. Here, four cases of IgDλ MM were studied, to address the question of light chain receptor revision in a 'single cell' model. Detailed analyses of both IGK and IGL alleles of each case were performed by Southern blotting, (RT-) PCR, and sequencing. The expressed IgV genes were extensively mutated and Cμ deletion was confirmed in two cases. In addition, in the four MM a total of six non-functional deletional IGK rearrangements were identified, which proved to be unmutated. We conclude that IgD myelomas indeed originate from (post) germinal center B cells in which, in spite of the fact that they are hypermutated, there is no evidence of receptor revision.</p

IgD multiple myeloma a descriptive report of 17 cases: survival and response to therapy

BACKGROUND: Immunoglobulin D multiple myeloma (MM) is rare and has a poorer prognosis than other MM isotypes. DESIGN AND METHODS: Seventeen patients (pts) diagnosed from 1993 to 2009 with IgD MM were selected from six institutions of Multiple Myeloma Latium-Region GIMEMA Working Group. RESULTS: Median age was 55 years, 14 patients had bone lesions, eight had renal impairment with estimated glomerular filtration rate (eGFR) < 50 ml/min, one serum calcium 65 12 mg/dl, 11 had lambda light chains, five stage III of ISS, six with chromosomal abnormalities. Six pts received conventional chemotherapy (CT): five melphalan + steroids based regimens. Eleven underwent high-doses of chemotherapy with autologous stem cell transplantation (HDT/ASCT), five single and six tandem ASCT: six received bortezomib and/or thalidomide as induction therapy and five VAD. Thalidomide maintenance was used in two pts: one in HDT/ASCT and one in CT group; bortezomib was used in one patient after HDT/ASCT. At a median follow up of 38 (range 19-60) and 50 months (range 17-148) for pts treated with CT and HDT/ASCT, respectively, the overall response rate (ORR) was 83% and 90%. In the group of patients treated with CT, median overall survival (OS) was 34 months (95% CI 15- 54 months), median progression free survival (PFS) was 18 months (95% CI 3-33 months) and median duration of response (DOR) was 7 months (95% CI 5-9 months). Median OS, PFS and DOR were not reached at the time of this analysis in the HDT/ASCT group of patients. Death was observed in 27.3% of pts treated with HDT/ASCT and in 66.7% undergone CT. CONCLUSIONS: Despite the retrospective analysis and the small number of pts our study showed that the use of HDT/ASCT seems to improve also the prognosis of IgD MM patients. Treatment options including new drugs, before and after stem cell transplantation, may further improve the outcomes of these patients