Usefulness of Whole-Body Diffusion-Weighted MRI (WB-MRI) With Apparent Diffusion Coefficient (ADC) In The Differentiation of Monoclonal Gammopathies

Abstract

e90 on the relationship between heavy/light chain (HLC) analysis, immunofixation electrophoresis (IFE), serum free light chain (sFLC) analysis, and multicolor flowcytometry (MFC) for response evaluation in patients with MM. AIM: To compare HLC immunoassays with conventional methods of disease evaluation. Patients AND Methods: Four hundred and sixty five samples from 128 patients with IgG and IgA MM after treatment were retrospectively analyzed with HLC immunoassays. Myeloma responses were assessed serially after induction therapy according to the IMWG response criteria. Results were compared to SPE, IFE, sFLC assay, and MFC analysis. MFC negativity was defined as < 10-4 MMPCs. HLC-pair suppression was defined as the uninvolved immunoglobulin of the same isotype <50% of the normal range. Overall survival (OS) and progression-free survival (PFS) were calculated by the KaplaneMeier. Results: The number of patient samples at various responses were: sCR, n 1⁄4 99; CR, n 1⁄4 31; VGPR, n 1⁄4 160; PR, n 1⁄4 88; and at diagnosis, n1⁄487. Normal HLC ratio (HLCR) was obtained at sCR, CR, and VGPR in 83 (83%), 29 (93%), and 91 (57%) cases, respectively. In the sera from patients CR, abnormal HLCR and FLC ratio were seen at rates of 9.7% and 22.3%, respectively, and no sera had abnormal value in both assays simultaneously. Thirty-three percent of MFC negative samples were HLCR abnormal and 80% of HLCR normal samples were MFC positive among the patients VGPR. Patients with a normal HLCR had fewer MM-PCs than those with an abnormal HLCR (median 1x10-3.42 vs. 1x10-3.04, respectively, P1⁄40.01). Shorter OS were shown in patients with highly abnormal HLCR (HLCR; 100 or 0.01) at diagnosis than those with normal or less abnormal (not reached vs. not reached, P 1⁄4 0.048). Longer OS were observed in patients who achieved HLCR normalization at best response than in those who did not (not reached vs. 119.7 months, P 1⁄4 0.0007) (Figure 2B). Presence of isotype-matched HLC pair suppression at best response, not at diagnosis, was also associated with poorer OS (not reached vs. not reached, P 1⁄4 0.002). Conclusion: The findings suggest the potential usefulness of HLC immunoassays for monitoring response and prognostication in patients with myeloma. Presence of an abnormal HLCR at best response and HLC pair suppression were also associated with poorer survival.