News

Vectibix plus FOLFOX Approved for Initial Therapy in Colorectal Cancer

The United States Food and Drug Administration (FDA) has approved the treatment combination consisting of the Vectibix (panitumumab) plus the chemotherapy regimen referred to as FOLFOX as initial therapy in advanced colorectal cancer.

Specifically, the Vectibix/FOLFOX regimen is approved for patients with epidermal growth factor receptor (EGFR)-expressing cancer who do not have a mutation in exon 2 of the KRAS gene.

The EGFR pathway refers to a normal biologic pathway within many cells that is, in part, responsible for cellular growth and replication. Among patients considered EGFR-positive, there is an abnormality within the pathway, often caused by a genetic mutation that creates uncontrolled spread of the cancer. Vectibix is an agent that is targeted against the EGFR pathway; however, its effectiveness is not demonstrated among patients who do not have a mutation with the exon 2 portion of the KRAS gene. Therefore, Vectibix is approved for patients with EGFR-expressing cancers who do not have the KRAS (exon 2) mutation (these patients are referred to as having wild-type KRAS). Vectibix has a prior approval for treatment of wild-type KRAS advanced colorectal cancers

In conjunction with this approval, the FDA has also approved a laboratory test to ascertain KRAS mutation status to be used prior to Vectibix delivery. The test is referred to as the therascreen KRAS test.

The FOLFOX chemotherapy regimen consists of the chemotherapy agents Eloxatin (oxaliplatin), 5-fluorouracil and leucovorin and is a common type of regimen used for advanced colorectal cancer.

The new indication for the Vectibix/FOLFOX combination to be used as initial therapy was prompted from results of two large clinical trials referred to as the PRIME and ASPECT trials. The PRIME trial included patients with advanced colorectal cancer who were EGFR-positive, but had wild-type KRAS tumors in exon2. Patients were treated with either Vectibix plus FOLFOX or FOLFOX alone.

Progression-free survival was 9.6 months among those treated with Vectibix/FOLFOX compared with 8.0 months among those treated with FOLFOX only.
Overall survival was 23.8 months for those treated with Vectibix/FOLFOX compared with 19.4 months for those treated with FOLFOX only.
The ASPECT trial included patients with advanced colorectal cancer who were treated with either Vectibix or Erbitux (cetuximab) as a single agent among patients who have not responded to prior chemotherapy. Erbitux is a targeted agent that is FDA approved for the treatment of colorectal cancer.

The overall goal of the trial was met, which was that Vectibix provided at least the same survival benefit, if not better, than Erbitux.
Reference: Amgen. News Release: FDA Approves First-Line Use of Vectibix® (Panitumumab) Plus FOLFOX for Patients with Wild-Type KRAS Metastatic Colorectal Cancer. Available at: http://www.amgen.com/media/media_pr_detail.jsp?releaseID=1934128. Accessed June 2, 2014.

United States Food and Drug Administration (FDA). Label and Approval History: Approved Label. Available at: http://www.accessdata.fda.gov/drugsatfda_docs/label/2014/125147s186lbl.pdf. Accessed June 2, 2014.