Circulating free light chain measurement in the diagnosis, prognostic assessment and evaluation of response of AL amyloidosis: Comparison of Freelite and N latex FLC assays

Giovanni Palladini, Arnaud Jaccard, Paolo Milani, David Lavergne, Andrea Foli, Sebastien Bender, Francesca Lavatelli, Tiziana Bosoni, Veronica Valentini, Laura Pirolini, Giovanni Ferraro, Marco Basset, Francesca Russo, Mario Nuvolone, Riccardo Albertini, Michel Cogne, Giampaolo Merlini

Research output: Contribution to journalArticlepeer-review

Abstract

The measurement of circulating free light chain (FLC) is essential in the diagnosis, prognostic stratification and evaluation of response to therapy in light chain (AL) amyloidosis. For more than 10 years, this has been done with an immunonephelometric assay based on polyclonal antibodies (Freelite), and cutoffs for staging and response assessment have been validated with this method. Recently, a new assay based on monoclonal antibodies (N latex FLC) has been marketed in Europe. We evaluated and compared the clinical performance of the two assays in 426 patients with newly diagnosed AL amyloidosis. We found suboptimal agreement between the two methods, with differences between values obtained with the Freelite and N latex FLC assays increasing with the concentration of clonal FLC. The diagnostic sensitivity of the Freelite (82%) and N latex FLC (84%) assays was similar, and both improved to 98% in combination with serum and urine immunofixation. The concentration of FLC measured with both methods had prognostic significance. Less pronounced decreases in FLC best predicted improved survival with the N latex FLC assay (33% vs. 50%), and there was poor concordance (84%) in discrimination of responders. The two assays have similar diagnostic and prognostic performance. However, they are not interchangeable, and follow-up should be done with either one. New response criteria are needed for the N latex FLC assay.

Original languageEnglish
Pages (from-to)1734-1743
Number of pages10
JournalClinical Chemistry and Laboratory Medicine
Volume55
Issue number11
DOIs
Publication statusPublished - Oct 26 2017

Keywords

  • amyloidosis
  • diagnosis
  • free light chain
  • prognosis
  • response

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, medical

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