Vectibix: importance of establishing wildtype RAS status before treatment of metastatic colorectal cancer


In the treatment of metastatic colorectal cancer, evidence of wildtype RAS status ( at exons 2, 3, and 4 of KRAS and NRAS ) is required before initiating treatment with Panitumumab ( Vectibix ) alone or in combination with other chemotherapy. Inferior progression-free survival and overall survival have been shown in patients with RAS mutations beyond KRAS exon 2 who received Panitumumab combined with FOLFOX ( Oxaliplatin-containing ) chemotherapy versus FOLFOX alone.

Panitumumab 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 carcinoma.

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 chemotherapy based on Oxaliplatin ( eg, FOLFOX ) in all patients with mutant or unknown RAS status. ( Xagena )

Source: Drug Safety Update 2013 volume 7, issue 2: A2

XagenaMedicine_2013


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