Changes in N-terminal proBNP levels in patients who reached complete remission, partial remission, or who did not respond to chemotherapy. (A) Nine patients in whom the amyloidogenic FLCs disappeared at immunofixation. (B) Thirteen patients in whom amyloidogenic FLCs decreased by more than 50%, but were still present at immunofixation. (C) Twenty-nine patients in whom FLCs remained stable or increased. The differences between A and B (P = .04), B and C (P = .001), and A and C (P < .001) were statistically significant by Mann-Whitney U test.