SAN DIEGO Serum free light chain (FLC) measurements correlate more closely with clinical outcomes than urine assessments in patients with light chain multiple myeloma, according to a study presented at the American Society of Hematology (ASH) 58th Annual Meeting and Exposition.1

The IFM-2009 trial randomly assigned 113 patients to receive either 8 cycles of rituximab, bortezomib, and dexamethasone (RVD) for RVD followed by high-dose melphalan with autologous stem cell rescue, and 2 additional RVD treatments. All patients received lenalidomide maintenance therapy for 1 year. Researchers prospectively measured serum and urine FLC concentrations and assessed minimal residual disease (MRD) at the end of consolidation therapy.

Although researchers identified clonal disease in 100% of patients at diagnosis by an abnormal κ/λ serum FLC ratio or by immunofixation electrophoresis, results showed that urine protein electrophoresis identified only 64% of patients as having measurable disease. Researchers observed similarly discordant results throughout monitoring.

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“Serum FLC analysis is a more sensitive indicator of disease than urine analysis at all time points evaluated” said principal investigator Thomas Dejoie, PharmD, Biochemistry Laboratory, Centre Hospitalier Universitaire-Nantes, France.

Patients with quantifiable disease by serum FLC or an abnormal κ/λ serum FLC ratio had a poor progression-free survival, while quantifiable disease by urine protein electrophoresis and immunofixation electrophoresis were not significantly predictive of progression-free survival.

“Serum but not urine FLC measurements provide prognostic information for progression-free survival and overall survival,” said Dr Dejoie.

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These findings suggest that monitoring with the serum FLC assay is more clinically relevant than with 24-hour urine after 3 cycles of therapy in patients with light chain multiple myeloma.

“Serum FLC measurements should be considered the method of choice for monitoring light chain multiple myeloma patients, whereas urine exploration may remain a rational practice to monitor renal function in these patients,” Dr Dejoie concluded.


  1. Dejoie T, Attal M, Moreau P, Avet-Loiseau H. Serum free light chain responses have greater concordance with clinical outcomes than those assessed by urine electrophoresis in light chain multiple myeloma patients. Paper presented at: American Society of Hematology (ASH) 58th Annual Meeting and Exposition; December 3-6, 2016; San Diego, CA.