In oncology, AFP-L3 is an isoform of alpha-fetoprotein (AFP), a substance typically used in the triple test during pregnancy and for screening chronic liver disease patients for hepatocellular carcinoma (HCC).
AFP-L3 binds strongly to LCA via an additional α 1-6 fucose residue attached at the reducing terminus of N-acetylglucosamine; this is in contrast to the L1 isoform.
The L3 isoform is specific to malignant tumors and its detected presence can serve to identify patients whom need increased monitoring for the development of HCC in high risk populations (i.e. chronic hepatitis B and C and/or liver cirrhosis).
AFP-L3% is the standard for quantifying the L3 isoform of AFP in serum of high risk chronic liver disease (CLD) patients.
Ultimately AFP-L3% may be used as a rule-in or rule-out assay for transplantation consideration and/or an intermediate step in surveillance precluding costly imaging on patients with fluctuating AFP results but negative for HCC.