Evaluation of Serum Free Light Chains In Chinese Multiple Myeloma Patients

Serum Free-Light Chain (sFLC) Assay is a sensitive tool recently used for diagnosis and response assessment of plasma cell disorders, especially in light chain multiple myeloma, nonsecretory multiple myeloma and primary amyloidosis. According to assemble analysis of multiple large-scale clinical research results, guideline of sFLC analysis was introduced by IMWG in 2008. But sFLC assay has not been routinely used in China and the clinical significance of the item has been explored in this study.

Serum specimens from 36 cases of MM patients identified by IFE were analyzed. The median age was 56.2(36-74). 24(66.7%) patients were male. The M protein type was IgG in 50%, IgA in 22%, IgD in 3%, light chain in 25%. According to D-S staging, 11% pts was inIIA, 58% in IIIA, 31% in IIIB. 8% patients was in±of ISS staging, 17% inII and 75% in III. Normal range for FLC measurements is as follows: κ3.3–13.1 mg/L, λ5.7–26.3 mg/L, and κ/λ ratio of 0.26–1.65.

Abnormal rFLCs were detected 100% in 14 newly-diagnosed patients. 86% patients had measurable disease. In κ-MM patients, levels of sFLC-κ were (553.1±471) mg/L; sFLC-λ were (14.2±4) mg/L; the median of rFLC was 32.62. In λ-MM patients, levels of sFLC-κ were (5.3±2.67) mg/L; sFLC-λ were (2503±1043) mg/L; the median of rFLC was 0.002.

22 MM patients were detected during the follow up after treatment. Abnormal clonal rFLC could be found 100% in 3 PD patients, 66.7% in 12 PR/SD patients and 0 in 7 ≥VGPR patients. There was no statistical significance between sFLC and sTLC (p≥0.05). The value of iFLC in ≥VGPR group was statistical different from other response assessment groups (p<0.05). In 24 patients with measurable disease (9 with κ-MM,15 with λ-MM), an elevated level of iFLC was associated with increased myeloma cells in bone marrow and β2-microglobulin, but not with ALB, LDH.

sFLC assay is a highly sensitive diagnostic and response monitoring tool for multiple myeloma. An elevated level of iFLC was associated with increased myeloma cells in bone marrow and β2-microglobulin, but not with ALB, LDH in measurable disease. More patients and longer follow-up are needed to further evaluate the diagnostic and prognostic significance of this judgment parameter.

No relevant conflicts of interest to declare.