(Refiled for dropped word in lead)
* “Disappointed” if denosumab not superior to Zometa
* Expects to see osteonecrosis of the jaw
* Sees upside for Vectibix (Adds comments)
By Deena Beasley
THOUSAND OAKS, Calif., June 16 (Reuters) - Amgen Inc (AMGN.O) believes its experimental bone drug, denosumab, works at least as well as Zometa to reduce the risk of fractures in cancer patients and some data suggests it could well be superior, according to Amgen’s chief medical officer.
“I would be disappointed if we aren’t superior,” Sean Harper, also the company’s head of global product development, told Reuters in an interview.
Amgen expects to announce during the third quarter of this year results from a large trial comparing denosumab to Zometa, sold by Novartis AG NOVN.VX, in patients with advanced breast cancer. Results from a similar trial involving other solid tumors are expected in the fourth quarter.
The studies are designed to show that denosumab is not inferior to Zometa, a bisphosphonate that is the current standard of care, for treating cancer patients whose disease has spread to the bone.
Denosumab is seen as key to Amgen’s future now that growth of its flagship anemia drug franchise has waned due to safety concerns.
“It’s easy to forget that the company underwent a large transformation in 2001,” Harper said, adding that since he joined Amgen seven years ago, $17 billion has been spent on research and development and the clinical pipeline has tripled.
Amgen filed last year for U.S. regulatory approval of denosumab as a treatment for osteoporosis in post-menopausal women. The injectable drug is a monoclonal antibody designed to block a protein needed by bone-destroying cells called osteoclasts.
As long as denosumab works as well as Zometa, Harper said he is “quite confident” of commercial success since the Amgen drug is unlikely to cause the kind of kidney toxicity associated with the bisphosphonate. He also said the fact denosumab is given by injection, rather than an intravenous infusion, is an advantage.
Another side effect of bisphosphonates, osteonecrosis of the jaw, or ONJ, “is an open question,” Harper said.
He said Amgen expects to see some cases of jawbone deterioration in denosumab patients enrolled in the cancer trials, but no one knows if the disease is linked to interruption of bone resorption or has more to do with the buildup of bisphosphonates in bone, particularly the jaw.
“If we show clear superiority with regard to skeletal related events ... and aren’t burdening the patients with more toxicity as a trade off, I don’t see any reason why people wouldn’t switch over to denosumab,” Harper added.
The Amgen executive also said upcoming trial results for Vectibix hold promise for improving the commercial outlook for the colon cancer drug, which is currently approved only as a third-line treatment.
“Eighty five percent of colorectal market is in first and second line therapy,” Harper said. “Our ability to gain a label that covers the whole spectrum would be very important.”
Amgen expects to have data by September from two large trials of Vectibix that for the first time have stratified nearly all enrolled patients for a biomarker known as KRAS.
Colon cancer patients whose tumors contain the normal version of the KRAS gene have been shown to respond to drugs like Vectibix or Erbitux, sold by Eli Lilly (LLY.N) and Bristol-Myers Squibb (BMY.N), while those with a mutated KRAS gene do not benefit from the drugs.
Sales of Vectibix, which totaled $153 million last year, have lagged those of Erbitux, which is approved for earlier-stage cancer.
“I think there is some potential for the product to have more uptake,” Harper said.
Reporting by Deena Beasley; Editing by Andre Grenon, Bernard Orr