What is Vectibix?
Vectibix is a concentrate that is made up into a solution for infusion (drip into a vein) containing the active substance panitumumab.
What is Vectibix used for?
Vectibix is indicated for the treatment of patients with metastatic colorectal cancer, a cancer of the large intestine that has spread to other parts of the body. Vectibix is used on its own (monotherapy) in patients whose tumor cells have a protein called epidermal growth factor receptor (EGFR) on their surface and which contain an unmutated " KRAS " gene. KRAS is a gene that, when mutated in cancer cells, stimulates tumor growth. Vectibix is used when therapeutic regimens with combinations of anticancer drugs including "fluoropyrimidine" (for example, 5-fluorouracil), oxaliplatin and irinotecan are no longer effective.
The medicine can only be obtained with a prescription.
How is Vectibix used?
Treatment with Vectibix should be carried out under the supervision of a doctor who specializes in the use of anticancer therapies. Therapy should be started only after the detection of the expression of the unmutated KRAS by a laboratory with adequate experience using reliable methods.
The recommended dose of Vectibix is 6 mg / kg body weight, given once every two weeks as an infusion. The recommended infusion duration is approximately 60 minutes, but higher doses may take 90 minutes.
How does Vectibix work?
The active substance in Vectibix, panitumumab, is a monoclonal antibody. A monoclonal antibody is an antibody (a type of protein) designed to recognize and bind to a specific structure (antigen) present on certain cells in the body. Panitumumab was created to bind with EGFR, a receptor found on the surface of certain cells, including the cells of some tumors. Consequently, tumor cells no longer receive the messages necessary for their growth, progression and diffusion (metastasis) transmitted by the EGFR. Panitumumab does not seem to work in cancer cells that contain the mutated KRAS gene, because the growth of such cells is not
controlled by signals transmitted via EGFR, so they continue to grow even after EGFR receptor inhibition.
How has Vectibix been studied?
The effects of Vectibix were first tested in experimental models before being studied in humans.
Vectibix has been studied in one main study involving a total of 463 patients suffering from colon or rectal cancer, in whom a worsening of the disease had been recorded during or after previous treatment with fluoropyrimidines, oxaliplatin and irinotecan. The efficacy of Vectibix associated with "best supportive care" was compared with that of "best supportive care" alone. The best supportive therapy is any drug or technique that can help the patient, such as antibiotics, painkillers, transfusions and surgery, with the exception of other anticancer drugs. The main measure of effectiveness was the time elapsed until the disease got worse or the patient died. The results of the study were analyzed separately in 243 patients whose tumor presented the unmutated KRAS gene and in 184 patients in whom a mutation of the KRAS gene was observed.
What benefit has Vectibix shown during the studies?
In patients with tumors presenting with non-mutated KRAS, Vectibix prolonged the time interval before disease progression or patient death: in patients treated with Vectibix associated with the best supportive care, the average time recorded was 12.3 weeks, while in subjects treated with the only best supportive care the data collected was 7.3 weeks. On the contrary, there was no positive effect of Vectibix in patients with tumors characterized by mutated KRAS : in this case, the average time interval before progression or death was approximately 7.3 weeks in both groups of patients.
What is the risk associated with Vectibix?
In about 90% of patients treated with Vectibix there are undesirable effects on the skin, mostly mild to moderate. The most common side effects recorded with Vectibix (seen in more than 1 patient in 10) are rash, acneiform dermatitis (acne-like skin inflammation), erythema (skin redness), peeling of the skin, itching, dry skin, fissures skin (skin cracks), paronychia (infection of the tissue surrounding the nail), diarrhea, fatigue, nausea, vomiting, dyspnoea (difficulty breathing) and coughing. For the full list of all side effects reported with Vectibix, see the Package Leaflet.
Vectibix should not be used in people who may be hypersensitive (allergic) to panitumumab or any of the other ingredients. It must also not be used in patients with interstitial pneumonia or pulmonary fibrosis (lung disease).
Why has Vectibix been approved?
The Committee for Medicinal Products for Human Use (CHMP) concluded that the benefits of Vectibix are greater than its risks for the monotherapy treatment of patients with metastatic colorectal cancer expressing the epidemic growth factor receptor (EGFR) after failure of chemotherapeutic regimens containing fluoropyrimidines, oxaliplatin and irinotecan, in the case in which the tumors present the non-mutated KRAS gene ( wild-type ). The Committee therefore recommended the granting of the marketing authorization for Vectibix.
Vectibix has obtained a "conditional approval". This means that more information on the medicine will have to be presented, especially with regard to safety and efficacy in patients with tumors containing unchanged KRAS . The European Medicines Agency (EMEA) will review every new information available and, if necessary, this summary will be updated.
What information is still awaited for Vectibix?
The company that makes Vectibix will provide the results of additional studies related to the safety and efficacy of the medicine in patients with colorectal cancer with and without KRAS mutated as well as the quality of life of patients being treated with the medicine. These include studies aimed at evaluating the use of Vectibix in combination with other drugs, both in patients already treated in the past and in patients who have never received treatment against their cancer, as well as a study intended to confirm the efficacy of Vectibix administered alone at the approved dose.
More information on Vectibix:
On 3 December 2007, the European Commission issued a marketing authorization valid for Vectibix to Amgen Europe BV, valid throughout the European Union.
The full EPAR for Vectibix can be found here.
Last update of this summary: 03-2009.
