OBJECTIVETo study the clinical significance of abnormal protein bands (APB) in multiple myeloma (MM) patients treated with bortezomib-based induction regimen and autologous stem cell transplantation (ASCT).

METHODSSixty-eight MM patients submitted to bortezomib-based induction therapy and ASCT from January 2007 to July 2012 were retrospectively studied. Monoclonal protein was detected by immunofixation electrophoresis (IFE).

RESULTSOf all 68 patients, 33 (48.5%) patients had APB. At the first emergence of an APB, two patients with light chain type achieved CR and before transplantation, and thirty-one patients were after transplantation with median time of 104 (ranged 33-404) days. The median duration of APB appearance was 105 (ranged 35-801) days. Patients who developed APB compared with those without APB, had a significantly higher CR plus very good partial response (VGPR) rates (100.0% vs 85.7%%, P=0.017) and CR rates (87.9% vs 62.9%) (P=0.03). There were no significant differences in gender, age, HGB, ALB, β2-microglobulin, M protein type, Durie-Salmon and ISS stages, the case number of first line or second line treatment, induction courses of bortezomib-based regimen, and the mode of ASCT. With a median follow-up of 33.4 (ranged 7.0-71.7) months, patients with APB tended to have a longer overall survival (OS) versus non-APB patients, although no significant difference obtained (P＞0.05). Among APB patients, OS was longer in patients whose appearance of APB occurred ＜6 months after transplantation than those ≥ 6 months, but the significant difference was not obtained yet (P＞0.05).

CONCLUSIONSPatients who developed APB had a significantly better response to bortezomib-based induction regimen followed ASCT. APB emergence has a good prognostic significance.