Refining amyloid complete hematological response: Quantitative serum free light chains superior to ratio

Eli Muchtar, Morie A. Gertz, Martha Q. Lacy, Nelson Leung, Francis K. Buadi, David Dingli, Suzanne R. Hayman, Ronald S Go, Prashant Kapoor, Wilson Gonsalves, Taxiarchis V. Kourelis, Rahma Warsame, Yi Lisa Hwa, Amie Fonder, Miriam Hobbs, Stephen Russell, John A. Lust, Mustaqeem Siddiqui, S. Vincent Rajkumar, Robert A. KyleShaji K. Kumar, Angela Dispenzieri

Research output: Contribution to journalArticle

Abstract

Response assessment in light chain (AL) amyloidosis is based on serum and urine monoclonal protein studies. Newly diagnosed patients (n = 373) who achieved very good partial response or complete response (CR) to first line therapy were assessed for the survival impact of each of the monoclonal protein studies. At end of therapy (EOT), negative serum/urine immunofixation (IFE) was achieved in 61% of patients, 72% achieved normal serum free light chain ratio (sFLCR), and the median involved free light chain (iFLC) and difference between involved to uninvolved light chain (dFLC) were 17 mg/L and 5 mg/L, respectively. Overall, 46% of patients achieved a CR at EOT. At EOT, iFLC ≤20 mg/L and dFLC ≤10 mg/L were additive in survival discrimination to negative serum/urine IFE and were independent predictors of overall survival. In contrast, normalization of sFLCR did not add survival discrimination to serum/urine IFE and was not independent predictor of survival. We propose a new definition for hematological CR to include serum/urine IFE negativity plus iFLC ≤20 mg/L or dFLC ≤10 mg/L, instead of the current definition of serum/urine IFE negativity and normal sFLCR. Complete response using dFLC ≤10 mg/L had the best performance in those with significant renal dysfunction and by light chain isotype, making it the preferred partner to IFE. Validation of these results in a multicenter cohort is warranted.

Original languageEnglish (US)
JournalAmerican journal of hematology
DOIs
StateAccepted/In press - 2020

ASJC Scopus subject areas

  • Hematology

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