Amgen has announced the presentation of detailed results of a Phase 3 study with panitumumab (marketed as Vectibix) and best supportive care (BSC) compared to BSC alone in metastatic colorectal cancer (mCRC).
The study met its primary endpoint, demonstrating a statistically significant improvement in overall survival (OS) in patients with chemorefractory wild type KRAS (exon 2) mCRC (377 total).
This is the first Phase 3 panitumumab study to include an analysis of efficacy of panitumumab by wild-type KRAS (exon 2) and in wild-type RAS tumour mutation status in its primary analysis, providing important information about OS in these populations.
These results, in addition to secondary endpoint data, were presented at the 2016 Gastrointestinal Cancers Symposium (GICS) in San Francisco.
The study (GICS abstract #642) showed that patients with wild-type KRAS (exon 2) mCRC treated with panitumumab and BSC achieved a median OS of 10 months compared to 7.4 months for patients treated with BSC alone (hazard ratio [HR]=0.73, 95 percent confidence interval [CI]=0.57-0.93, p=0.0096).
Data from a key secondary endpoint showed that patients with wild-type RAS (absence of mutations in exons 2, 3 and 4 of KRAS and NRAS) mCRC treated with Vectibix and BSC achieved a median OS of 10 months compared to 6.9 months for patients treated with BSC alone (n=270; HR=0.70, 95 percent CI=0.53-0.93, p=0.0135).
Patients with mutant RAS mCRC did not benefit from panitumumab treatment (n=54; OS HR=0.99, 95 percent CI=0.49-2.00).
The safety profile was comparable to the known safety profile of panitumumab when administered as a single agent, with skin, nail, gastrointestinal and electrolyte disorders being the most frequently reported adverse events.
“As well as providing additional insights into the way Vectibix [panitumumab] works in mCRC, these data support expanding biomarker screening to include wild-type RAS,” said Sean E. Harper, M.D., executive vice president of Research and Development at Amgen.
Colorectal cancer is the third most common cancer worldwide, with approximately 1.2 million cases occurring globally each year.1, 2
Approximately 20 percent of colon cancers are diagnosed at the metastatic stage, when the disease has already spread to distant organs, a diagnosis associated with only a 12 percent five-year survival rate.3
Using molecular approaches to identify unique genetic signatures in mCRC has the potential to help improve treatment outcomes.
Of the few biomarkers in colorectal cancer, RAS genes (KRAS, NRAS) have a validated impact on treatment outcomes.4, 5
1. Ferlay J, Soerjomataram I, Ervik M, et al. GLOBOCAN 2012 v1.0, Cancer Incidence and Mortality Worldwide: IARC CancerBase No. 11. http://globocan.iarc.fr/Pages/fact_sheets_cancer.aspx. Accessed June 9, 2015.
2. Jemal. Global Cancer Statistics. CA Cancer J Clin. 2011;61:69-90.
3. Colon Cancer Alliance. Get Information: What is Colon Cancer: Statistics. Accessed Dec. 3, 2015. Available at: http://www.ccalliance.org/get-information/what-is-colon-cancer/statistics/
4. Fight Colorectal Cancer. Biomarker Testing for Colorectal Cancer: Common Biomarker Tests for Colon Cancer. Accessed Dec. 3, 2015. Available at: http://fightcolorectalcancer.org/fightcrc-fightit/biomarker-testing-for-colorectal-cancer/
5. Colon Cancer Alliance. Get Information: Treatment: Biomarkers. Know Your Biomarker. Accessed Dec. 3, 2015. Available at: http://www.ccalliance.org/get-information/treatment/biomarkers/
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