Do changes of FLC after 2 cycles of therapy predict for overall or progression-free survival?
Although FLC response after 2 cycles of therapy predicted for eventual overall response, FLC response at 2 months did not predict for OS or PFS regardless of which definition for FLC response was applied (data not shown) and whether or not the survival estimates were done as a univariate analysis or a multivariate analysis incorporating other prognostic variables, including treatment arm, plasma cell labeling index, beta-2 microglobulin, and albumin (data not shown). This held true if reductions were based on the 50% reduction rule or reductions by tertiles. Moreover, whether the cohort of patients with baseline iFLC greater than 0.1 g/L was used or the cohort defined by baseline abnormal ratio and dFLC greater than or equal to 0.05 g/L (5 mg/dL) was used, the results were similar, that is, FLC response did not predict for either OS or PFS.
