This study evaluated the differences in clinical features of 1077 newly diagnosed AL amyloidosis patients with renal involvement (n = 229, 21%), both cardiac and renal involvement (n = 443, 41%) and cardiac involvement (n = 405, 38%). Significant differences in dFLC (difference in involved and uninvolved light chains) were noted (renal, both, cardiac median: 83, 234 and 349 mg/l, P < 0.001). The proportion of patients with ≥ 10% bone marrow plasma cells (BMPCs) was lowest in renal only patients: 44%, 57%, 64%, respectively, P < 0.001. In a multivariate linear regression model incorporating organ involvement type and BMPCs ≥10%, organ involvement was a significant predictor of dFLC (P < 0.001). Median overall survival (OS) across the three groups was 83 vs. 19 vs. 16 months (P < 0.001) in patients not undergoing transplant and 5-year OS in patients undergoing transplant was 90% vs. 75% vs. 64% (P = 0.007), respectively. In conclusion, renal involvement alone or renal + cardiac involvement in AL amyloidosis is associated with lower circulating light chain burden, which cannot be fully explained by BMPC burden alone. Increased sensitivity of the kidney to light chains, given significant interactions with the renal tubular system and secretion of modified light chain products may play a role in pathogenesis of renal AL amyloidosis and warrants further investigation.
Keywords: free light chains; heart; kidney; light chain amyloidosis; survival.
© 2019 British Society for Haematology and John Wiley & Sons Ltd.