[The characteristics of 62 cases of CD20-positive multiple myeloma]

To explore the clinical and laboratory characteristics of mutiple myeloma patients with CD20 expression.

Review the data of mutiple myeloma patients and analyze the clinical and laboratory characteristics of CD20 positive patients, compared with CD20 negative patients.

(1)Totally 465 cases of newly-diagnosed MM were collected with CD20 expression status detected by multi-color flow cytometry. Sixty two patients (13.3%) were CD20 positive and the others were negative. (2)No statistical differences were found between CD20 positive and negative groups about the sex ratio, age predominance, D-S staging, ISS staging, renal insufficiency rate, platelet count, LDH level and classifications by paraprotein(all P value>0.05). (3)Compared with those of CD20 negative patients, the hemoglobulin value(74.5 g/L vs 83.5 g/L, P=0.021), extramedullary involvement rate (3.5% vs 13.7%, P=0.029), CD56-positive rate(36.7% vs 68.8%,P=0.000), t(4;14)translocation rate(2.4% vs 24.0%, P=0.001) in CD20 positive patients were lower statistically. (4)Compared with those of CD20 negative patients, the percentage of plasma cells (0.400 vs 0.295, P=0.045) by marrow smear differential counting, the percentage of myeloma cells(20.0% vs 6.8%, P=0.000) by multi-color flow cytometry analysis, CD45-positive rate(12.1% vs 4.5%, P=0.018), CD79a-positive rate(9.8% vs 1.5%, P=0.013) and t(11;14) translocation rate(60.5% vs 14.4%, P=0.000)in CD20 positive patients were higher statistically. (5)There was no statistical differences about the overall response rate (ORR), complete response rate (CRR), TTP(time to progression), PFS(progression free survival) and overall survival (OS) between CD20 positive and negative groups.

CD20 positive rate is 13.3% in multiple myeloma pateints according to our data. CD20 poaitive myeloma were prone to residing in bone marrow and affecting erythropoiesis. Atypical immunophenotypes were more common, and the incidence of t(11;14) were increased markedly while that of t(4;14)were rare for CD20 positive multiple myeloma.