Phase 3 results encouraging for Amgen’s panitumumab drug for colorectal cancer

Trial for Vectibix indicates improved overall survival in chemorefractory wild-type KRAS metastatic colorectal cancer vs. best supportive care

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THOUSAND OAKS, Calif.—Following hot on the heels of one bit of good news and immediately preceding another, Amgen announced recently that a Phase 3 study evaluating Vectibix (panitumumab) and best supportive care (BSC) met its primary endpoint, demonstrating a statistically significant improvement in overall survival (OS) in patients with chemorefractory wild-type KRAS (exon 2) metastatic colorectal cancer (mCRC) compared to those patients treated with BSC alone.
The Vectibix treatment arm further showed statistical significance for all key secondary endpoints including OS in patients with wild-type RAS (absence of mutations in exons 2, 3 and 4 of KRAS and NRAS) mCRC.
“Amgen has been at the forefront of researching personalized approaches to treating cancer, and the Vectibix clinical program continues to underscore the importance of identifying options for patients based on their cancer’s genetic makeup,” said Dr. Sean E. Harper, executive vice president of research and development at Amgen. “These positive overall survival results for Vectibix reinforce the importance of KRAS and RAS biomarkers in making treatment decisions in metastatic colorectal cancer.”
This Phase 3 global, multicenter, randomized, open-label study was designed to evaluate the survival benefit of Vectibix and best BSC compared to BSC in chemorefractory wild-type KRAS and wild-type RAS (absence of mutations in exons 2, 3 and 4 of KRAS and NRAS) mCRC and, as noted above, one primary endpoint was OS. Results were also positive for all key secondary endpoints, which included progression-free survival (PFS) in patients with wild-type KRAS mCRC, as well as OS and PFS in patients with wild-type RAS. Patients were randomized 1:1 to receive 6 mg/kg of Vectibix every 14 days and BSC, or BSC alone (as defined by the investigator).
Amgen notes that 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 United States in September 2006 as a monotherapy for the treatment of patients with EGFR-expressing mCRC after disease progression after prior treatment with fluoropyrimidine-, oxaliplatin-, and irinotecan-containing chemotherapy. In May 2014, the FDA approved Vectibix for use in combination with FOLFOX, as first-line treatment in patients with wild-type KRAS (exon 2) mCRC. With this approval, Vectibix became the first-and-only biologic therapy indicated for use with FOLFOX, one of the most commonly used chemotherapy regimens, in the first-line treatment of mCRC for patients with wild-type KRAS mCRC.
About a week before this news, Amgen reported the unanimous recommendation for approval of its drug Repatha (evolocumab) by the FDA’s Endocrinologic and Metabolic Drugs Advisory Committee for treating homozygous familial hypercholesterolemia—the panel did, however, offer up some concerns that while the drug seemed effective at lowering the low-density lipoprotein cholesterol, it wanted to see evidence that the drug would actually decreases incidents of heart attacks and strokes. That, of course, would require a larger outcomes clinical trial
Market-watchers say Repatha has the potential to be a billion-dollar drug in the busy cholesterol therapy market.
Just a day after the news of the Vectibix trial results, Amgen announced positive interim results from its open-label extension of the global Phase 2, double-blind, placebo-controlled study evaluating the safety and efficacy of AMG 334 for the prevention of episodic migraine. Patients who entered the open-label phase received AMG 334 70 mg monthly and experienced a sustained reduction in monthly migraine days at week 52.
At one year, patients receiving AMG 334 70 mg experienced an average of a -4.9-day reduction from a baseline of 8.7 mean monthly migraine days, regardless of treatment received during the blinded phase. The 50 percent responder rate (greater than 50 percent reduction in monthly migraine days) was 62 percent at 52 weeks. Additional responder rates were reported for the first time: at 52 weeks the 75 percent responder rate was 38 percent and the 100 percent responder rate was 19 percent.
“These long-term data further demonstrate that AMG 334 provided meaningful benefit to these patients with fewer migraine days and more days with the ability to participate in work and social activities each month,” said Harper. “The sustained safety and efficacy shown in this interim analysis adds to the growing body of evidence that reinforces the potential of AMG 334 for patients with this debilitating condition. We look forward to advancing the program to help fill an unmet need in migraine prevention.”
AMG 334 is a fully human monoclonal antibody under investigation for the prevention of migraine. AMG 334 targets the calcitonin gene-related peptide receptor, which is believed to transmit signals that can cause incapacitating pain.

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