Freelite® Serum Free Light Chains Can Be Identified in 98% of AL Amyloidosis Patients 

AL amyloidosis is a protein conformation disorder characterized by the accumulation of monoclonal free light chain fragments as amyloid deposits. For patients with either primary systemic amyloidosis or light chain deposition disease, sensitivity of immunofixation electrophoresis (IFE) is low. These patients often do not have an M-protein peak and consequently it has been difficult to monitor their hematological response. Freelite® can aid diagnosis and follow up in these patients.¹

 Figure 1. Kaplan-Meier estimate of survival in 137 patients with AL showing a reduction of free light chain concentrations by greater than 50% following chemotherapy was associated with increased survival.²

• "Serum free light chain assay is required for investigation in suspected AL amyloid patients".
• "Treatment strategies in individual patients are presently best guided by their early effect on quantifiable measurements of circulating free immunoglobulin light chains".
• Reduction of amyloidogenic serum free light chain concentration can suppress accumulation of AL amyloid deposits.
• Use of serum FLC (free light chain) "measurement enables response to chemotherapy to be evaluated effectively and rapidly, for example, on a monthly basis during cyclical treatments".

A consensus opinion from the 10th International Symposium on Amyloid and Amyloidosis states:³

• "All patients should have an immunonephelometric immunoglobulin serum-free light chain assay."
• "The use of the serum free light chain assay has been important for quantification of hematologic responses and has been proposed as a useful tool to define hematologic response."

In a 2006 publication the authors concluded that the absolute levels of immunoglobulin free light chain appeared more relevant than the FLC ratio.⁴ Also that the achievement of a low absolute level of the involved immunoglobulin FLC was the best predictor of hematologic response, organ response and overall survival after peripheral blood stem cell transplantation.

Summary

• Serum free light chains have a circulation life of several hours compared to several weeks for intact immunoglobulin, and so can be a much earlier indicator of response to therapy.⁵
• Serum free light chains provide a more sensitive marker than electrophoresis and immunofixation in serum. This enables detection of most amyloidosis from a serum sample.