Abstract
Objectives
Serum free light chain (sFLC) measurements have inherent analytical limitations impacting sFLC clinical interpretation. We evaluated analytical and diagnostic performance of three polyclonal sFLC assays on four analytical platforms.
Methods
sFLC concentration was measured using Diazyme FLC assays (Diazyme) on cobas c501/c503 analyzer (Roche); Freelite assays (The Binding Site) on Optilite analyzer (The Binding Site) and cobas c501 analyzer and Sebia FLC ELISA assays (Sebia) on AP22 ELITE analyzer (DAS). Imprecision, linearity, method comparison vs. Freelite/Optilite, antigen excess detection and reference value verification were assessed. Diagnostic performance was compared on 120 serum samples and on follow-up samples of five patients with κ and λ monoclonal gammopathy.
Results
Method comparison showed excellent correlation with Freelite/Optilite method for all assays. A large proportional negative bias was shown for both Sebia κ and λ ELISA and a significant positive proportional bias for λ in the low (<10 mg/L) Freelite/cobas c501 method. Clinically relevant underestimation of κ sFLC levels due to antigen excess was shown for 7% of each Diazyme/cobas application and for 11 and 32.1% of λ sFLC assay of respectively Diazyme/cobas and Sebia/AP22. sFLC reference values revealed application specific. Cohen’s κ values were (very) good for κ sFLC but only moderate to good for λ sFLC. In 4/10 follow-up patients, significant differences in clinical interpretation between sFLC assays were noticed.
Conclusions
Important analytical limitations remain for all sFLC applications. Differences in reference values and diagnostic performance hamper interchangeability of sFLC assays. Assay specific sFLC decision guidelines are warranted.
Acknowledgments
We gratefully thank manufacturers The Binding Site, Roche and Sebia for in-kind providing reagents for this study.
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Research funding: None declared.
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Author contributions: All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Competing interests: Authors state no conflict of interest.
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Informed consent: Not applicable.
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Ethical approval: The local Institutional Review Board gave ethical approval for this study.
References
1. Caers, J, Garderet, L, Kortüm, KM, O’Dwyer, ME, van de Donk, NWCJ, Binder, M, et al.. European myeloma network recommendations on tools for the diagnosis and monitoring of multiple myeloma: what to use and when. Haematologica 2018;103:1772–84. https://doi.org/10.3324/haematol.2018.189159.Search in Google Scholar
2. Nice guideline Myeloma: diagnosis and management [NG35]. Published: 10/2/2016 (revised 25/10/2018). Available from: https://www.nice.org.uk/guidance/ng35 [Accessed 13 Mar 2022].Search in Google Scholar
3. Kumar, S, Paiva, B, Anderson, KC, Durie, B, Landgren, O, Moreau, P, et al.. International myeloma working group consensus criteria for response and minimal residual disease assessment in multiple myeloma. Lancet Oncol 2016;17:e328–46. https://doi.org/10.1016/s1470-2045(16)30206-6.Search in Google Scholar
4. Rajkumar, SV. Updated diagnostic criteria and staging system for multiple myeloma. Am Soc Clin Oncol Educ Book 2016;35:e418–23. https://doi.org/10.1200/edbk_159009.Search in Google Scholar
5. Rajkumar, SV, Dimopoulos, MA, Palumbo, A, Blade, J, Merlini, G, Mateos, MV, et al.. International myeloma working group updated criteria for the diagnosis of multiple myeloma. Lancet Oncol 2014;15:e538–48. https://doi.org/10.1016/s1470-2045(14)70442-5.Search in Google Scholar
6. Willrich, MA, Katzmann, JA. Laboratory testing requirements for diagnosis and follow-up of multiple myeloma and related plasma cell dyscrasias. Clin Chem Lab Med 2016;54:907–19. https://doi.org/10.1515/cclm-2015-0580.Search in Google Scholar PubMed
7. Henriot, B, Rouger, E, Rousseau, C, Escoffre, M, Sébillot, M, Bendavid, C, et al.. Prognostic value of involved/uninvolved free light chain ratio determined by Freelite and N Latex FLC assays for identification of high-risk smoldering myeloma patients. Clin Chem Lab Med 2019;57:1397–405. https://doi.org/10.1515/cclm-2018-1369.Search in Google Scholar PubMed
8. Jacobs, JF, Tate, JR, Merlini, G. Is accuracy of serum free light chain measurement achievable? Clin Chem Lab Med 2016;54:1021–30. https://doi.org/10.1515/cclm-2015-0879.Search in Google Scholar PubMed
9. Bossuyt, X, Delforge, M, Reynders, M, Dillaerts, D, Sprangers, B, Fostier, K, et al.. Antigen excess detection by automated assays for free light chains. Clin Chem Lab Med 2018;56:e235–8. https://doi.org/10.1515/cclm-2017-0977.Search in Google Scholar PubMed
10. Vercammen, M, Meirlaen, P, Broodtaerts, L, Vande Broek, I, Bossuyt, X. Effect of sample dilution on serum free light chain concentration by immunonepholemetric assay. Clin Chim Acta 2011;412:1798–804. https://doi.org/10.1016/j.cca.2011.06.021.Search in Google Scholar PubMed
11. Carr-Smith, HD, Jenner, EL, Evans, JA, Harding, SJ. Analytical issues of serum free light chain assays and the relative performance of polyclonal and monoclonal based reagents. Clin Chem Lab Med 2016;54:997–1003. https://doi.org/10.1515/cclm-2015-1068.Search in Google Scholar PubMed
12. Cotten, SW, Shajani-Yi, Z, Cervinski, MA, Voorhees, T, Tuchman, SA, Korpi-Steiner, N. Reference intervals and diagnostic ranges for serum free κ and free λ immunoglobulin light chains vary by instrument platform: implications for classification of patient results in a multi-center study. Clin Biochem 2018;58:100–7. https://doi.org/10.1016/j.clinbiochem.2018.06.003.Search in Google Scholar PubMed
13. Muluhngwi, P, Sharp, CN, Pozzi, N, Elin, RJ, Jortani, SA. Verification of newly FDA-approved kappa and lambda free light chain assays on a previously untested platform. J Appl Lab Med 2019;4:323–30. https://doi.org/10.1373/jalm.2019.029215.Search in Google Scholar PubMed
14. Smith, A, Wu, AHB. Analytical and clinical concordance of free light chain assay. Pract Lab Med 2018;13:e00112. https://doi.org/10.1016/j.plabm.2018.e00112.Search in Google Scholar PubMed PubMed Central
15. Jacobs, JFM, de Kat Angelino, CM, Brouwers, HMLM, Croockewit, SA, Joosten, I, van der Molen, RG. Evaluation of a new free light chain ELISA assay: bringing coherence with electrophoretic methods. Clin Chem Lab Med 2018;56:312–22. https://doi.org/10.1515/cclm-2017-0339.Search in Google Scholar PubMed
16. Lutteri, L, Aldenhoff, MC, Cavalier, E. Evaluation of the new Sebia free light chain assay using the AP22 ELITE instrument. Clin Chim Acta 2018;487:161–7. https://doi.org/10.1016/j.cca.2018.09.030.Search in Google Scholar PubMed
17. Clinical and Laboratory Standards Institute (CLSI). Evaluation of precision performance of quantitative measurement methods; EP5-A2 Approved guideline, 2nd ed. Wayne, PA: CLSI; 2004.Search in Google Scholar
18. Clinical and Laboratory Standards Institute (CLSI). Evaluation of the linearity of quantitative measurement procedures: a statistical approach; EP6-A Approved guideline. Wayne, PA: CLSI; 2003.Search in Google Scholar
19. Clinical and Laboratory Standards Institute (CLSI). Method comparison and bias estimation using patient samples; EP9-A3 approved guideline, 2nd ed. Wayne, PA: CLSI; 2013.Search in Google Scholar
20. Clinical and Laboratory Standards Institute (CLSI). Defining, Establishing, and Verifying Reference Intervals in the Clinical Laboratory; EP28-A3c approved Guideline, 3rd ed. Wayne, PA: CLSI; 2010.Search in Google Scholar
21. Hansen, CT, Münster, A-M, Nielsen, L, Pedersen, P, Abildgaard, N. Clinical and preclinical validation of the serum free light chain assay: identification of the critical difference for optimized clinical use. Eur J Hematol 2012;89:458–68. https://doi.org/10.1111/ejh.12013.Search in Google Scholar PubMed
22. Caponi, L, Romiti, N, Koni, E, Fiore, AD, Paolicchi, A, Franzini, M. Inter-assay variability in automated serum free light chain assays and their use in the clinical laboratory. Crit Rev Clin Lab Sci 2020;57:73–85. https://doi.org/10.1080/10408363.2019.1670133.Search in Google Scholar PubMed
23. Graziani, MS. Measurement of free light chains – pros and cons of current methods. Clin Chem Lab Med 2016;54:1015–20. https://doi.org/10.1515/cclm-2015-1062.Search in Google Scholar PubMed
24. Hutchison, CA, Plant, T, Drayson, M, Cockwell, P, Kountouri, M, Basnayake, K, et al.. Serum free light chain measurement aids the diagnosis of myeloma in patients with severe renal failure. BMC Nephrol 2008;9:11. https://doi.org/10.1186/1471-2369-9-11.Search in Google Scholar PubMed PubMed Central
25. Hutchison, CA, Harding, S, Hewins, P, Mead, GP, Townsend, J, Bradwell, AR, et al.. Quantitative assessment of serum and urinary polyclonal free light chains in patients with chronic kidney disease. Clin J Am Soc Nephrol 2008;3:1684–90. https://doi.org/10.2215/cjn.02290508.Search in Google Scholar PubMed PubMed Central
26. Jacobs, JF, Hoedemakers, RM, Teunissen, E, te Velthuis, H. N Latex FLC serum free light-chain assays in patients with renal impairment. Clin Chem Lab Med 2014;52:853–9. https://doi.org/10.1515/cclm-2013-0864.Search in Google Scholar PubMed
27. Messiaen, AS, De Sloovere, MMW, Claus, PE, Vercammen, M, Van Hoovels, L, Heylen, O, et al.. Performance evaluation of serum free light chain analysis: nephelometry vs turbidimetry, monoclonal vs polyclonal reagents. Am J Clin Pathol 2017;147:611–22. https://doi.org/10.1093/ajcp/aqx037.Search in Google Scholar PubMed
28. Bossuyt, X, Delforge, M, Reynders, M, Dillaerts, D, Sprangers, B, Fostier, K, et al.. Diagnostic thresholds for three light chains in multipele myeloma depend on the assay used. Leukemia 2018;32:1815–8. https://doi.org/10.1038/s41375-018-0041-0.Search in Google Scholar PubMed
29. Caillon, H, Avet-Loiseau, H, Attal, M, Moreau, P, Decaux, O, Dejoie, T. Comparison of Sebia free light chain assay with freelite assay for the clinical management of diagnosis, response, and relapse assessment in multiple myeloma. Clin Lymphoma Myeloma Leuk 2019;19:e228–37. https://doi.org/10.1016/j.clml.2019.01.007.Search in Google Scholar PubMed
Supplementary Material
The online version of this article offers supplementary material (https://doi.org/10.1515/cclm-2022-0347).
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