The FDA has approved Vectibix (panitumumab; Amgen) for use in combination with FOLFOX chemotherapy as a first-line treatment in patients with wild-type KRAS (exon 2) metastatic colorectal cancer (mCRC) and the therascreen KRAS RGQ PCR Kit (therascreen KRAS test; Qiagen) as a companion diagnostic for KRAS biomarker mutations in patients with metastatic colorectal cancer.
Vectibix is the first and only biologic that has been shown to offer a significant survival benefit as a first-line treatment in conjunction with FOLFOX. The FDA approval is based on results from the PRIME and ASPECCT clinical trials. The Phase 3 PRIME study of patients with wild-type KRAS tumors in exon 2 showed statistically significant improvement in progression-free survival (PFS) in those taking Vectibix and FOLFOX vs. FOLFOX alone (9.6 vs. 8.0 months, P=0.02) and a 4.4 month improvement in overall survival (OS) vs. FOLFOX alone (23.8 vs. 19.4 months).
The Phase 3 ASPECCT trial met its primary endpoint of non-inferiority compared to Erbitux (cetuximab; Bristol-Myers Squibb) for the treatment of wild-type KRAS metastatic colorectal cancer in patients who have not responded to chemotherapy.
Vectibix is already indicated for treatment of EGFR-expressing mCRC with disease progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.
The therascreen KRAS RGQ PCR Kit is an assay designed to detect KRAS biomarkers that occur in about 40% of colorectal cancer patients. The presence of KRAS mutations can influence response to anti-EGFR treatments such as Vectibix.