hemCR in AL amyloidosis requires the absence of monoclonal protein by IFE and normal serum FLCR. Recent literature suggests that an iFLC <20 mg/L or dFLC <10 mg/L may more accurately predict outcomes after treatment. We evaluated overall survival in 340 patients treated with high-dose melphalan and SCT. There were total of 305 patients evaluable 6 months after SCT, 90 achieved hemCR, 132 dFLC <10 mg/L, 118 iFLC <20 mg/L, and 176 normal FLCR. Of 215 patients without hemCR, 65 had dFLC <10 mg/L, and 86 had normal FLCR. OS in those achieving dFLC <10 mg/L or normal FLCR without hemCR was inferior to those achieving hemCR. OS was not significantly different in patients achieving iFLC <20 mg/L without hemCR compared with hemCR. Of those with hemCR, OS was not significantly improved if dFLC <10 mg/L was also achieved, but OS was improved for those with hemCR who also attained iFLC <20 mg/L.

The findings of this study demonstrated the absence of monoclonal protein in IFE and iFLC <20 mg/L as independent predictors of survival. Attainment of hemCR remains a treatment goal, although achieving iFLC <20 mg/L may also predict improved OS.

Reference: https://www.nature.com/articles/s41408-020-00354-7