Revised Mayo Clinic AL Amyloidosis Staging System

Staging system for newly-diagnosed light-chain amyloidosis, incorporating serum free light chains

1. Sum the number of risk factors

2. Determine prognostic stage

Risk factorsRevised Prognostic StageMedian OS (months)1Five-year survival1
0I9459%
1II4042%
2III1420%
3IV614%
Commentary

This prognostic staging system for newly-diagnosed AL (light chain) amyloidosis was developed from a retrospective analysis of 810 patients assessed at the Mayo Clinic.1

On multivariate analysis (which included bone marrow plasma cell percentage, presence of circulating plasma cells, plasma cell labelling index and beta-2 microglobulin), only the serum free light chain difference, NT-proBNP and Troponin T predicted overall survival, and were used in the final staging system. Serum free light chains were determined using the Binding Site Freelite assay, and cTNT and NT-proBNP by Roche Diagnostics assays. The staging system was validated in a cohort of 303 patients who had autologous stem cell transplantation (using pre-transplantation laboratory values) and a cohort of 103 patients enrolled in clinical trials.1

In comparison with a prior three-stage amyloidosis staging system from the Mayo Clinic, which did not incorporate serum free light chains, and which used different cTNT and NT-proBNP thresholds,2 this system offers improved discrimination.1

Acronyms

AL: amyloid light chain
cTNT: cardiac troponin T
NT-ProBNP: N-terminal propeptide of brain natriuretic peptide
OS: overall survival
SFLC: serum free light chain