Amgen will review the CHMP opinion and consider appropriate next steps, as Amgen believes that Vectibix in combination with chemotherapy provides an important treatment option for patients with wild-type KRAS mCRC. Amgen remains committed to patients with this aggressive disease, for whom there are limited treatment options.
Vectibix is already approved and established in more than 30 countries outside of the United States (U.S.) as a monotherapy treatment for patients with wild-type KRAS mCRC, when standard chemotherapy is no longer effective. In the 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. Furthermore, use of Vectibix is not recommended in patients whose tumors have KRAS mutations in codon 12 or 13. In Japan and Israel, Vectibix is approved for use in combination with chemotherapy for patients with wild-type KRAS mCRC.
Data from studies 20050203 (PRIME) and 20050181 ('181') showed that adding Vectibix to FOLFOX and FOLFIRI chemotherapy, respectively, improved progression-free survival (PFS) versus chemotherapy alone in patients with wild-type KRAS mCRC. Patients taking this combination have a greater chance of living longer without their disease getting worse. Additionally, the response rate 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.(1-2)
In general, adverse events rates were comparable across arms in both studies, with the exception of known toxicities associated with anti-EGFR therapy, such as rash, diarrhea, and hypomagnesemia. Vectibix-related grade 3/4 infusion reactions were reported in less than one percent of patients. In patients with mutated KRAS tumors, outcomes were inferior for those receiving Vectibix plus FOLFOX versus FOLFOX alone. (3-4)
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.(5) 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 40-50 percent of mCRC patients.(6-7)
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.(viii) In 2008, there were an estimated 333,330 new cases of colorectal cancer in the EU.(9)
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 progression-free survival. 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 colorectal cancer with these mutations.(10)
In December 2007, the European Medicine Agency (EMA) 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.(11) Vectibix has been launched in more than 30 European Union countries, Russia, Israel, Switzerland, Australia, Canada and Japan. Applications in the rest of the world are pending.
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1. Douillard, JE et al. Randomized, Phase 3 Study (PRIME) of Panitumumab with FOLFOX4 versus FOLFOX4 Alone as First-Line Treatment in Patients With Previously Untreated Metastatic Colorectal Cancer. J Clin Oncol 28. 2010.
2. 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.
3. Adverse event 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 infusion reactions were reported for two patients (less than 1 percent).
4. 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.
5. Malumbres, M. and Barbacid, M. RAS oncogenes: the first 30 years. Nature Reviews Cancer. 3:459-65, 2003.
6. Karapentis C, S. Snell, L, E. The Laboratory Assessment of KRAS Mutation Status in Colorectal Cancer.Asia, Pacific Journal of Oncology and Hematology. 2010. 7. Friday BB and Adjei AA. K-ras as a target for cancer therapy. Biochim. Biophys. Acta 1756: 127-144, 2005.
8. 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.
9. 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.
10. Vectibix (panitumumab) [prescribing information]. Thousand Oaks, Calif: Amgen; 2011.
11. Vectibix (panitumumab) SPC. Thousand Oaks, Calif: Amgen; 2011.