early normalization of free light chains predicts better outcomes in patients with multiple myeloma

Background: the half-life of free light chain is short and can be used as an early marker for tumor response in patients with multiple myeloma [mm]. this prospective study is aimed at evaluating whether early light chain response can predict response to treatment in patients with mm. materials and methods: thirty six patients with a diagnosis of mm and with an abnormal to normal light chain ratio of > 10 were included in this study. results: the median age at presentation was 56 years. fourteen patients had lambda light chain disease, whereas 22 patients had kappa light chain disease. twenty-four patients [66.6%] had reduction of abnormal to normal light chain ratio to < 10 after 2 cycles, of whom 15 [62.5%] achieved a cr or vgpr after 6 cycles. among 12 patients who did not have reduction of abnormal to normal light chain ratio to < 10, only 1 patient achieved cr while 11 patients [91.6%] achieved a pr or less[fishers exact p=0.004]. median follow-up was 13 months. median progression-free survival for the entire cohort was 15 months. one-year progression-free survival was 77% vs 57.1%, [p= 0.008], respectively for patients with early normalization and those who did not show early normalization. conclusion: early light chain response after 2 cycles of chemotherapy is a good predictor for treatment response in patients with mm treated with bortezomib based chemotherapy. treatment intensification based on early light chain response merits further evaluation in a prospective trial