Posted: 5th June 2017
A peer-reviewed scientific publication featuring detailed clinical validation of Seralite®-FLC has been published in the British Journal of Haematology and is now available online. The authorship includes Key Opinion Leaders from Birmingham University such as Professor Mark Drayson along with experts in the field from the University of Leeds, University of Newcastle and University of Arkansas – USA.
The aim of the study was to guide interpretation of Free Light Chain (FLC) testing in clinical practice and specifically discusses appropriate clinical cut-offs for Seralite®-FLC. The study examined blood and urine analysis from 5573 newly diagnosed myeloma patients including 576 light chain only (LCO) and 60 non-secretory (NS) cases. The recommended Freelite® FLC >100mg/L for measuring response was confirmed and an equivalent Seralite®-FLC difference (dFLC) >20mg/L identified. Relapse was identified using a Freelite® FLC increase >200mg/L and found 100% concordance with a corresponding Seralite® dFLC increase >30mg/L.
The key conclusions from this publication are:
“International guidelines for FLC are based upon the Freelite® assay (Dispenzieri, et al 2009, Durie, et al 2006). It is important to recognise that in practice different countries, or indeed laboratories may employ their own thresholds in line with normal ranges generated locally. Incorporation of new technologies such as Seralite®-FLC into clinical practice requires similar evaluation as Freelite®. This is particularly important because although different FLC tests may give very comparable quantitation of normal polyclonal FLC, the anti-FLC antibodies in the tests may have differing affinities for an individual patients monoclonal FLC and thus give different quantitation”
“Despite differences in absolute FLC levels between methods, a high level of diagnostic concordance was demonstrated; 99% in all LCO patients tested. Using ROC analysis in NS patients, we identified for Seralite®-FLC a dFLC level of 20mg/L to be equivalent to the GLT threshold of measurable disease on Freelite®-FLC (iFLC 100mg/L) (Durie, et al 2006). Using a dFLC of 20 mg/L on Seralite®-FLC, 97% of all LCO patients were considered appropriate for disease monitoring with Seralite®-FLC, compared to 98% with the 100 mg/L criterion on Freelite®”
“At relapse, an absolute increase in dFLC of > 30 mg/L by Seralite®-FLC was observed to be equivalent to an absolute increase in iFLC of > 200 mg/L on Freelite®-FLC and provided complete concordance on identification of progressive disease. Again, despite lower levels of absolute FLCs on Seralite®-FLC at this time point, an increase in disease activity from remission could clearly be demonstrated.”
This important publication highlights the importance of clinically validating different FLC methods fully to understand appropriate thresholds. The authors conclude that as a rapid test, Seralite®-FLC is able to overcome delays in FLC result availability to accelerate patient diagnosis and quickly inform on patient responses to therapy. Full access to this article can be obtained via the link: http://onlinelibrary.wiley.com/doi/10.1111/bjh.14753/full
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