"This opinion, for which a final European Commission decision is pending, is a welcome step forward and one that may lead to additional treatment options for patients facing an aggressive disease with limited treatment options," said Willard H. Dere, M.D., senior vice president and international chief medical officer at Amgen. "Studies have shown that patients taking Vectibix in combination with chemotherapy have a greater chance of living longer without their disease getting worse, in a landscape where few targeted agents have been shown to be effective when used with chemotherapy."
Data from studies 20050203 (PRIME) and 20050181 ('181) showed that adding Vectibix to either FOLFOX or FOLFIRI chemotherapy improved progression-free survival (PFS) versus chemotherapy alone for patients with wild-type KRAS mCRC. Additionally, the overall response rate (ORR) of Vectibix plus chemotherapy was higher than chemotherapy alone. Although numerically greater, the improvement in median overall survival (OS) did not achieve statistical significance in the Vectibix arm of either trial.(1)
The PRIME study evaluated Vectibix (6.0 mg/kg every two weeks) plus FOLFOX versus FOLFOX alone in patients with wild-type KRAS mCRC and found that Vectibix plus FOLFOX significantly improved PFS versus FOLFOX alone (median 9.6 months versus 8.0 months, hazard ratio (HR) 0.80; 95 percent confidence interval (CI): 0.66-0.97; p=0.02).(1) Additionally, combining Vectibix with FOLFOX resulted in numerically greater OS versus FOLFOX alone (median 23.9 months versus 19.7 months, HR 0.83; 95 percent CI: 0.67-1.02), although this was not statistically significant (p=0.072).(1) The ORR achieved with Vectibix plus FOLFOX was higher than FOLFOX alone (55 percent versus 48 percent).(1)
The '181 study showed that adding Vectibix (6.0 mg/kg every two weeks) to FOLFIRI chemotherapy improved median PFS by two months in patients with wild-type KRAS mCRC compared to FOLFIRI alone (median 5.9 months versus 3.9 months; HR 0.73, 95 percent CI: 0.59-0.90; p=0.004). Additionally, the Vectibix combination more than tripled the ORR compared to FOLFIRI alone (35 percent versus 10 percent). Though quantitatively greater (14.5 months versus 12.5 months, HR 0.85), the improvement in median OS (co-primary endpoint) did not achieve statistical significance in the Vectibix arm of the trial (p=0.12).(2)
Adverse event rates included known toxicities associated with anti-epidermal growth factor receptor (EGFR) therapy, such as rash, diarrhea, and hypomagnesemia. Vectibix-related grade 3/4 infusion reactions were reported in less than one percent of patients. (1) In patients with mutated KRAS tumors, outcomes were inferior for those receiving Vectibix plus FOLFOX versus FOLFOX alone.(2,3) Vectibix should only be used in those patients in whom wild-type KRAS status has been confirmed, because of the worse outcomes in patients with mutated KRAS tumors treated with FOLFOX.
The Amgen PRIME and '181 studies were the first Phase 3 studies to prospectively analyze the effect of an EGFR inhibitor based on KRAS status in patients with mCRC.
Vectibix is already approved and established in 40 countries as a monotherapy treatment for patients with wild-type KRAS mCRC, when standard chemotherapy is no longer effective. In the United States (U.S.), Vectibix received accelerated approval in September 2006 as a monotherapy for the treatment of patients with EGFR-expressing mCRC after disease progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens. The use of Vectibix is not recommended in patients whose tumors have KRAS mutations in codon 12 or 13. In Japan and Israel, Vectibix is also approved for use in combination with chemotherapy for patients with wild-type KRAS mCRC.
Results from studies performed over the last 25 years indicate that KRAS plays an important role in cell growth regulation. In mCRC, EGFR transmits signals through a set of intracellular proteins. Upon reaching the nucleus, these signals instruct the cancer cell to reproduce and metastasize, leading to cancer progression.(4) Anti-EGFR antibody therapies work by inhibiting the activation of EGFR, thereby inhibiting downstream events that lead to malignant signaling. However, in patients whose tumors harbor a mutated KRAS gene, the KRAS protein is always turned "on", regardless of whether the EGFR has been activated or therapeutically inhibited. KRAS mutations occur in approximately 40 to 50 percent of mCRC patients.(5,6)
About Colorectal Cancer
Colorectal cancer is the third most common cancer worldwide in men and the second most common in women. In 2008, approximately 1.23 million cases of colorectal cancer were diagnosed globally.(7) In 2008, there were an estimated 333,330 new cases of colorectal cancer in the EU.(8)
Vectibix is the first fully human anti-EGFR antibody approved by the U.S. Food and Drug Administration (FDA) for the treatment of mCRC. Vectibix was approved in the U.S. in September 2006 as a monotherapy for the treatment of patients with EGFR-expressing mCRC after 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 mCRC is based on PFS. More than half of patients who receive Vectibix monotherapy respond to treatment with an average six month PFS benefit. Currently no data are available that demonstrate an improvement in disease-related symptoms or increased survival with Vectibix.
Retrospective subset analyses of mCRC trials have not shown a treatment benefit for Vectibix in patients whose tumors had KRAS mutations in codon 12 or 13. Use of Vectibix is not recommended for the treatment of mCRC with these mutations.(9)
In December 2007, the European Commission granted a conditional marketing authorization for Vectibix as a monotherapy for the treatment of patients with EGFR-expressing mCRC with non-mutated (wild-type) KRAS after failure of fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy regimens.(10) Vectibix has been launched in more than 30 European countries, Russia, Israel, Australia, Canada and Japan. Applications in the rest of the world are pending.
Amgen discovers, develops, manufactures and delivers innovative human therapeutics. A biotechnology pioneer since 1980, Amgen was one of the first companies to realize the new science's promise by bringing safe and effective medicines from lab, to manufacturing plant, to patient. Amgen therapeutics have changed the practice of medicine, helping millions of people around the world in the fight against cancer, kidney disease, rheumatoid arthritis, bone disease and other serious illnesses. With a deep and broad pipeline of potential new medicines, Amgen remains committed to advancing science to dramatically improve people's lives.
1. Peeters, M et al. Randomized Phase III Study of Panitumumab With Fluorouracil, Leucovorin, and Irinotecan (FOLFIRI) Compared With FOLFIRI Alone As Second-Line Treatment in Patients With Metastatic Colorectal Cancer. J Clin Oncol 28, 2010.
2. Adverse event rates were comparable across arms with the exception of known toxicities associated with EGFR therapy such as rash, diarrhea and hypomagnesemia. Vectibix-related grade 3 infusion reactions were reported for two patients (less than one percent).
3. In general, adverse events rates were comparable across arms with the exception of known toxicities associated with anti-epidermal growth factor receptor (EGFR) therapy such as rash, diarrhea, and hypomagnesemia. Vectibix-related grade 3/4 infusion reactions were reported in less than one percent of patients.
4. Malumbres, M. and Barbacid, M. RAS oncogenes: the first 30 years. Nature Reviews Cancer. 3:459-65, 2003.
5. Karapentis C, S. Snell, L, E. The Laboratory Assessment of KRAS Mutation Status in Colorectal Cancer. Asia, Pacific Journal of Oncology and Hematology. 2010.
6. Friday BB and Adjei AA. K-ras as a target for cancer therapy. Biochim. Biophys. Acta 1756: 127-144, 2005
7. Ferlay J, Shin HR, Bray F, Forman D, Mathers C and Parkin DM. GLOBOCAN 2008, Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 10. Lyon, France: International Agency for Research on Cancer; 2010
8. Ferlay J, Parkin DM, Steliarova-Foucher E. Estimates of cancer incidence and mortality in Europe in 2008. Eur J Cancer. 2010 Mar; 46(4):765-81. Epub 2010 Jan 29.
9. Vectibix (panitumumab) [prescribing information]. Thousand Oaks, Calif: Amgen; 2011.
10. Vectibix (panitumumab) SPC. Thousand Oaks, Calif: Amgen; 2011