Amgen said the European Commission has granted a conditional marketing authorization to market its colorectal cancer treatment drug Vectibix.

EU approved Vectibix (panitumumab) as monotherapy for the treatment of patients with epidermal growth factor receptor (EGFr) expressing metastatic colorectal cancer (mCRC) with non-mutated (wild-type) KRAS genes after failure of standard chemotherapy regimens.

Vectibix, a fully human anti-EGFr monoclonal antibody, has been granted a positive Commission decision in the European Union (EU) based upon a positive opinion from the European Committee for Medicinal Products for Human Use (CHMP) for marketing authorization in September of this year. This approval is based on a positive benefit / risk assessment in a patient population that currently has few treatment options available to them. As part of the CHMP review, clinical data supporting the utility of KRAS mutation status as a biomarker for clinical outcome were provided.

"It is an exciting time in the oncology arena as we see a shift towards individualized patient care," said Willard Dere, M.D., senior vice president and international chief medical officer, Amgen. "We are pleased that Vectibix has received conditional marketing authorization allowing metastatic colorectal cancer patients to have access to a new targeted treatment option."

These biomarker data were generated from a prospectively defined analysis of the phase III, randomised, controlled clinical trial "408" that investigated the treatment effect of KRAS status (non-mutated versus mutated) in Vectibix patients with mCRC. The analysis demonstrated that the effect of Vectibix on progression-free survival (PFS) was confined exclusively to the approximately 60 percent of patients whose tumours harbour normal, non-mutated (wild-type) KRAS. Vectibix had no clinical benefit in patients who had tumours with mutations in KRAS regardless of the endpoint studied. Previously reported pivotal results from "408" demonstrated that Vectibix monotherapy significantly improved PFS and response rates in heavily pre-treated patients with mCRC after failure of standard chemotherapy versus best supportive care.

KRAS plays an important role in cell growth regulation and oncogenesis. Anti-EGFr therapies work by blocking the activation of EGFr, thereby inhibiting downstream events that lead to malignant signalling. However, in patients with tumours harbouring a mutated or activated KRAS, the KRAS protein is always turned "on" regardless of whether EGFr has been activated or therapeutically inhibited. Thus, in patients with mutated KRAS, signalling continues despite anti-EGFr therapy. Mutant KRAS is detected in approximately 40 percent of CRC tumours.

"Being able to select which patients are more likely to respond to therapy is an important step forward in the treatment of metastatic colorectal cancer," said Professor Eric Van Cutsem, Digestive Oncology Unit, University Hospital, Leuven, Belgium, a Vectibix investigator. "The ability to predict the patient population more likely to respond to Vectibix could potentially reduce drug exposure in patients who we know will not respond."

Vectibix, the first fully human IgG2 monoclonal antibody (MAb) therapy, targets the EGFr, a protein that plays an important role in cancer cell signaling. With its demonstrated efficacy and convenient Q2W dosing schedule Vectibix provides an important option in the management of mCRC patients. Ongoing phase III trials are exploring the potential of administering Vectibix in combination with chemotherapy in the first- and second-line of mCRC, as well as in the head and neck cancer setting.

In the EU, Vectibix is indicated as monotherapy for the treatment of patients with metastatic colorectal carcinoma expressing EGFr with tumours with non-mutated KRAS and after failure of fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.

Approved by the Food and Drug Administration (FDA) in September 2006, Vectibix is indicated in the United States (US) as a single agent for the treatment of patients with EGFr-expressing, metastatic colorectal carcinoma with disease progression on or following fluoropyrimidine-, oxaliplatin- and irinotecan-containing chemotherapy regimens. The effectiveness of Vectibix as a single agent for the treatment of EGFr-expressing, metastatic colorectal carcinoma is based on progression-free survival. Currently, no data are available that demonstrate an improvement in disease-related symptoms or increased survival with Vectibix.

Dermatologic related reactions, a pharmacologic effect observed with epidermal growth factor receptor (EGFr) inhibitors, are experienced with nearly all patients (approximately 90 per cent) treated with Vectibix. The majority of dermatological reactions are mild to moderate in nature. In clinical studies, subsequent to the development of severe dermatological reactions (including stomatitis), infectious complications including sepsis, in rare cases leading to death, and local abscesses requiring incisions and drainage were reported.

Dermatologic toxicities, related to Vectibix blockade of EGF binding and subsequent inhibition of EGF receptor-mediated signalling pathways, included but were not limited to dermatitis acneiform, pruritus, erythema, rash, skin exfoliation, paronychia, dry skin and skin fissures. Dermatologic toxicities were reported in 90 percent of patients treated with Vectibix and were severe in 12 percent of patients. Severe dermatologic toxicities were complicated by infection, including sepsis, septic death and abscesses requiring incisions and drainage. Vectibix may need to be withheld or discontinued for severe dermatologic toxicities.

Severe infusion reactions occurred with Vectibix in approximately one percent of patients. Severe infusion reactions were identified as anaphylactic reactions, bronchospasm, fever, chills and hypotension. Although fatal infusion reactions have not been reported with Vectibix, they have occurred with other monoclonal antibody products. Severe infusion reactions require stopping the infusion and possibly permanently discontinuing Vectibix, depending on the severity and / or persistence of the reaction.

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