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New Biomarker Data Links KRAS Gene to Vectibix(TM) Clinical Response
Biomarker Analysis from Randomized, Controlled Trial Represents an Advance in the Science of Anti-EGFR Therapy in Metastatic Colorectal Cancer
BARCELONA, Spain--(BUSINESS WIRE)--Sept. 25, 2007--Amgen (NASDAQ: AMGN) today announced the results of a biomarker analysis that supports KRAS as a predictive clinical biomarker that could be used to select patients who are more likely to respond to treatment with Vectibix(TM) (panitumumab) monotherapy.
These data were generated from an analysis of the Phase 3, randomized, controlled clinical trial that investigated the treatment effect of Vectibix in patients with metastatic colorectal cancer (mCRC). Previously reported results from this study demonstrated that Vectibix monotherapy improved progression-free survival ((PFS), HR 0.54; p less than 0.001)) and response rate (10 percent versus 0 percent) in heavily pre-treated patients with mCRC after failure of standard chemotherapy. The new biomarker analysis met its primary and secondary endpoints by demonstrating that the effect of Vectibix on PFS was confined exclusively to the approximately 60 percent of patients whose tumors harbor normal, non-mutated (wild-type) KRAS. No effect of Vectibix therapy was observed in patients who had tumors with mutations in KRAS regardless of the endpoint studied. These data have been shared with U.S. and global regulatory agencies and have been submitted for peer-reviewed publication.
Additionally, pooled data from three Phase 2 trials and a Phase 3 extension study provide supportive evidence regarding the predictive value of KRAS in Vectibix monotherapy. Results were presented during the Presidential Session at the 14th European Cancer Conference (ECCO) in Barcelona, Spain.
Twenty years of study indicate that KRAS plays an important role in cell growth regulation and oncogenesis. In mCRC, the epidermal growth factor receptor (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. Anti-EGFR therapies work by blocking the activation of EGFR, thereby inhibiting downstream events that lead to malignant signaling. However, it is hypothesized that in patients with tumors harboring a mutated KRAS gene, the KRAS protein is always turned "on," regardless of whether the EGFR has been activated or therapeutically inhibited.
Thus, in patients with mutant KRAS, signaling continues despite anti-EGFR therapy. Activated KRAS is detected in approximately 40 percent of metastatic colorectal cancer, depending on the testing method used. Multiple studies support anti-EGFR therapy being significantly more effective in patients with non-mutated KRAS.
"Preclinical research has long implicated the RAS oncogene in cancer biology, but now this research may be translated into patient management," said Roger M. Perlmutter, M.D., Ph.D., executive vice president of Research and Development at Amgen. "In the future, physicians may select treatment options specifically for patients whose tumors harbor the non-mutated KRAS gene."
In a second analysis, patient samples from four mCRC monotherapy studies of safety and efficacy with Vectibix were used to generate the hypothesis that tumors with mutated KRAS are associated with drug resistance. Of the 62 patient samples evaluated in the analysis, 21 had the activated KRAS and none responded to therapy. The analysis also found that there was a statistically significant association between KRAS mutation status and response to Vectibix (p=0.013).
"Being able to select which patients may benefit from treatment would reduce the individual patient and societal burdens often associated with cancer therapy," said Tim Turnham, Ph.D., chief executive officer, Colon Cancer Alliance. "The robustness and outcome of this biomarker analysis is an important step forward in advancing the field of personalized cancer care."
Last week the European Committee for Medicinal Products for Human Use (CHMP) issued a positive opinion recommending a conditional marketing authorization for Vectibix(TM) (panitumumab) in the European Union (EU) for patients with refractory metastatic colorectal cancer with non-mutated (wild-type) KRAS genes.
Vectibix is indicated in the U.S. for the treatment of patients with epidermal growth factor receptor- (EGFR) expressing mCRC after disease progression on or following fluoropyrimidine-, oxaliplatin-, and irinotecan- containing chemotherapy regimens. The effectiveness of Vectibix 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.
Important Product Safety Information
Dermatologic toxicities, related to Vectibix blockade of EGF binding and subsequent inhibition of EGF receptor-mediated signaling 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 89 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 1 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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Christine Regan, 805-447-5476 (U.S. media)
Sabeena Ahmad, 41-41-3692-530 (EU media)
Arvind Sood (investors), 805-447-1060