Table 3 Biomarker evaluation of targeted therapies for colorectal cancer
From: A practical guide to biomarkers for the evaluation of colorectal cancer
Biomarkers | Which patients to test | Uses | Use caution |
|---|---|---|---|
Extended RAS Panel (KRAS & NRAS) | Stage IV CRC candidates for anti-EGFR therapy | • Predict resistance to anti-EGFR therapy | • Do not test KRAS only |
BRAF V600E mutational analysis | CRC patients with loss of MLH1/PMS2 by IHC | • Evaluate germline vs. sporadic in MLH1/PMS2 absent tumors | • Do not test on serrated polyp to screen for Lynch syndrome • Caution with BRAF IHC—difficult to interpret |
Stage IV CRC patients | • Predict poor prognosis if mutated • Predict resistance to anti-EGFR therapy (controversial) • Predict response to BRAF V600E inhibitors (investigational) | ||
HER2 overexpression by IHC ± FISH | Clinical trials only | • Predict resistance to anti-HER2 therapy • Predict resistance to anti-EGFR therapy (investigational) | • Do not use the same criteria as HER2 IHC evaluation for upper GI tumor |
MMR status | All primary CRC patients | • Predict response to anti-PDL1 therapy (for advanced stage patients) | |
PIK3CA mutations | Clinical trials only | • Predict possible resistance to anti-EGFR therapy (investigational) • Predict possible improved survival with aspirin use if mutated (investigational) | • Do not deny anti-EGFR therapy if mutated (insufficient data) |
PTEN loss (Expression by IHC or Deletion by FISH) | Clinical trials only | • Predict possible resistance to anti-EGFR therapy (investigational) | • Do not deny anti-EGFR therapy if loss (insufficient data) |
