Background
Phase III, open-label RCT. 2686 patients with KRAS exon 2 wild-type (WT) stage III colon cancer after curative resection. Tested the addition of cetuximab to mFOLFOX6 adjuvant chemotherapy in a biomarker-selected population (KRAS WT), based on cetuximab's established benefit in KRAS WT metastatic CRC. An additional KRAS mutant cohort was also enrolled.
Interventions and follow up
Arm A: mFOLFOX6 × 12 cycles (6 mo) + cetuximab 400mg/m² IV loading then 250mg/m² IV weekly
Arm B: mFOLFOX6 × 12 cycles alone
Primary endpoint: Disease-free survival (DFS) in KRAS WT patients
mFollow up: 28 mo
Arm B: mFOLFOX6 × 12 cycles alone
Primary endpoint: Disease-free survival (DFS) in KRAS WT patients
mFollow up: 28 mo
Results
DFS (KRAS WT): HR 0.92, 95% CI 0.78–1.09, P=.30 — not significant
OS (KRAS WT): HR 1.01 — not significant
DFS (KRAS mutant, exploratory): HR 1.21 — trend toward harm with cetuximab
OS (KRAS WT): HR 1.01 — not significant
DFS (KRAS mutant, exploratory): HR 1.21 — trend toward harm with cetuximab
Adverse events
Dermatologic/infusion: Acneiform rash grade ≥3 15.3% vs 0%; infusion reactions 1.5% vs 0%
GI/overall: Diarrhea grade ≥3 14.9% vs 10.1%; overall grade ≥3 AEs 72.8% vs 51.7%; treatment discontinuation due to toxicity 18.2% vs 4.2%
GI/overall: Diarrhea grade ≥3 14.9% vs 10.1%; overall grade ≥3 AEs 72.8% vs 51.7%; treatment discontinuation due to toxicity 18.2% vs 4.2%
Conclusions
Adding cetuximab to adjuvant mFOLFOX6 did not improve DFS in KRAS WT stage III colon cancer and was associated with substantially more toxicity. The KRAS mutant cohort showed a non-significant trend toward worse outcomes with cetuximab, consistent with metastatic CRC data. N0147 established that anti-EGFR therapy has no role in adjuvant colon cancer.
Key Limitations
Key Limitations: Only KRAS exon 2 was required to be WT at enrollment — patients with NRAS or KRAS exon 3/4 mutations (extended RAS) were not excluded, meaning some enrolled patients would not benefit even in the metastatic setting by current standards. The trial was stopped early due to a pre-planned futility analysis, limiting power. The added toxicity of cetuximab (18% discontinuation rate) may have compromised chemotherapy delivery in the experimental arm. The failure parallels PETACC-8, providing strong concordant evidence against EGFR inhibition in the adjuvant setting.
Clinical Context
N0147 and PETACC-8 together definitively established that anti-EGFR antibodies (cetuximab, panitumumab) have no role in adjuvant colon cancer, even in RAS WT patients. The biological basis for the discordance between metastatic benefit and adjuvant failure for EGFR inhibitors remains unclear but may relate to tumor microenvironment differences between micro- and macro-metastatic disease. EGFR inhibitors remain metastatic-only agents in CRC.
References
References: Alberts SR et al, JAMA 2012