Porównanie metod ilościowego oznaczania wolnych lekkich łańcuchów (FLC), Hevylite™ (HLC) i immunofiksacji (IFE) w ocenie remisji choroby w szpiczaku plazmocytowym

Abstract

HLC separately measures in pairs light chain types of each intact immunoglobulin (Ig) class generating ratios of monoclonal Ig/non-involved polyclonal Ig concentrations; potentially simplifying assessment of monoclonal protein response. Normalization of FLC ratio is considered higher level of complete remission (CR) in multiple myeloma (MM). To compare IFE, HLC and FLC in assessment of remission we assayed sera from 44 MM patients who underwent autologous stem cell transplantation (ASCT). Of 44 patients in 26 (59%) after ASCT normalization of FLC ratio occurred. In 22 (84.6%) patients with normal FLC ratio also normalization of HLC ratio was noted but in 5 (19%) patients IFE was still positive. Concordance of three tests (IFE negative, HLC ratio normal, FLC normal) was found in 19 (73%) patients. In 21 of 44 (47%) patients after ASCT, normalization of FLC ratio documented sCR. In this group 5 (28%) patients relapsed. Median PFS was 24 months. In patients with CR, VGPR and PR 12 (60%) patients progressed. Median PFS was 12 months. One patient with IgAλ MM, sCR after ASCT and λ FLC clonal escape at relapse and at that time with negative IgAλ IFE and normal IgA HLC ratio illustrates the importance of serum FLC elevation for early detection of clinical relapse, in the absence of any other clinical and laboratory finding. Conclusion. IFE is more sensitive than HLC and FLC assays in detecting residual disease. CR with normalization of HLC and FLC ratios have impact on PFS.