Importance of establishing wildtype RAS (KRAS and NRAS) status before treatment of metastatic colorectal cancer.
Article date: September 2013
Panitumumab (Vectibix) is a treatment for adults with metastatic colorectal cancer. It is given alone or in combination with other chemotherapy.
New safety information is available based on subset analysis of data from a randomised, multicentre phase III study (PRIME study 20050203) of panitumumab plus FOLFOX versus FOLFOX alone in patients with previously untreated wildtype KRAS metastatic colorectal cancer. FOLFOX is an oxaliplatin-containing chemotherapy regimen used for treatment of colorectal cancer.
The outcomes of this retrospective analysis indicate inferior progression-free survival and overall survival in patients with RAS mutations beyond KRAS exon 2 who received panitumumab combined with FOLFOX chemotherapy versus FOLFOX alone.
These findings are important and emphasise that panitumumab is contraindicated in combination with oxaliplatin-based chemotherapy in patients with mutant RAS (at exons 2, 3, or 4 of KRAS and NRAS), or in whom RAS status is unknown.
It is also important that evidence of wildtype RAS status is established before initiation of treatment with panitumumab in all patients.
Advice for healthcare professionals:
- evidence of wildtype RAS status (at exons 2, 3 and 4 of KRAS and NRAS) is required before initiating treatment with panitumumab
- RAS mutation status should be determined by an experienced laboratory using a validated test method
- panitumumab is contraindicated in combination with oxaliplatin-containing chemotherapy (eg, FOLFOX) in all patients with mutant or unknown RAS status
Article citation: Drug Safety Update September 2013 volume 7, issue 2: A2.