Table 1.

Predictive biomarkers for EGFR MoAb treatment in mCRC

BiomarkerFrequency of alteration in CRCMost frequent alterationsPredictive value for EGFR MoAbs
KRAS30-40% with recent studies suggesting several novel mutations outside of the known hotspots in codons 12 and 13 of exon 2Activating mutation in codons 12 and 13 of exon 2Negative predictor
BRAF10-20%Activating mutation V600E in exon 15Unclear, but possibly little predictive value
PTEN20-40%Loss of protein expression measured by IHCUnclear, secondary to lack of standardized IHC scoring
PIK3CA15-25% with several mutations scattered outside of the known hotspots in exons 9 and 20Mutations in exons 9 and 20, with constitutive activation of PI3K pathwayUnclear, but PI3K pathway activation by PTEN loss or PIK3CA mutations appears to be negative predictor
Amphiregulin, epiregulinNAOverexpression of ligandsHigher values likely positive predictor
FcR polymorphismsAbout 40%FcγRIIa-FcγRIIIa H131H and/or V158V polymorphismUnclear but FcγRIIIa alone may have positive predictive value

Abbreviations: NA, not applicable, continuous variable.