Normalization of free light chain kappa/lambda ratio is a robust prognostic indicator of favorable outcome in patients with multiple myeloma

Abstract PURPOSE: To clarify the impact of serum free light chain (sFLC) ratio normalization in patients with multiple myeloma (MM) treated with novel agents. PATIENTS AND METHODS: Treatment response in 126 consecutive patients over 7 years was assessed by IMWG criteria and sFLC assay. RESULTS: Thirty-four patients (27%) showed complete response (CR), 37 (29%) very good partial response (VGPR), 39 (31%) partial response (PR), and 16 (13%) stable disease (SD) or less at a median follow-up of 28 months. Fifty-two patients (41%) with sFLC ratio normalization showed superior progression-free survival (PFS) and overall survival (OS) compared to those who did not (3-year OS, 94% vs. 48%; P 1000 mg/dL) or low ( 70, high LDH, ISS stage 3) showed negative prognostic impacts on PFS and OS on univariate analysis, normal sFLC ratio and achievement of CR emerged as the strongest prognostic predictors for longer OS in MM patients on multivariate analysis. CONCLUSIONS: This study demonstrated the significance of obtaining normal sFLC ratio independent of other clinical variables. Analysis of sFLC ratio could identify the favorable group of patients as well as immunofixation test, and support the inclusion of sFLC ratio as part of the response criteria for MM. © 2012 John Wiley a Sons A/S.