UPDATE 1-Amgen cancer trial shows denosumab strengthens bone
(Adds bone density changes from baseline, paragraphs 12-13)
LOS ANGELES, Dec 14 (Reuters) - Amgen Inc (AMGN.O) said on Friday that osteoporosis drug denosumab, the biotechnology company's most important new offering, increased bone strength in women receiving hormone therapy for breast cancer.
Amgen's first complete analysis of Phase 3 denosumab data, which showed a 5.5 percent increase in bone strength in drug-treated patients after 12 months, will help investors gauge if the drug can generate revenue of $1 billion to $2 billion a year and offset declines in Amgen's key anemia business.
Amgen announced in July that the company-funded study showed denosumab strengthened bones thinned by estrogen-depleting breast cancer drugs known as aromatase inhibitors.
Researchers said on Friday that denosumab, which is administered by injection twice a year, increased bone density in the spongy part of the bone.
It also demonstrated the added benefit of strengthening cortical bone, the dense outer shell of the skeleton that is responsible for the support and protective function of the skeleton, they said.
"In this study, denosumab data looks promising and, as a clinician, I look forward to having a potential alternative to existing therapies," said lead investigator Dr. Georgiana Kehr Ellis, from the oncology division at the University of Washington School of Medicine in Seattle.
"We are very encouraged by our results," said Roger Dansey, global director of development for Amgen's denosumab oncology program.
The study involved 252 early-stage breast cancer patients who had below-average bone density, but had not progressed to osteoporosis. All of the participants were required to take calcium and vitamin D daily.
Each of the women had bone loss in at least one of three sites: lumbar spine, total hip or femoral neck -- a common site of fractures where the ball at the top of the leg bone breaks off.
At 12 and 24 months, lumbar spine bone mineral density in the denosumab group increased 5.5 percent and 7.6 percent, respectively, compared with the placebo group.
Researchers said increases in bone density were consistently observed at 12 and 24 months at the total hip and total body, and at predominantly cortical sites at the femoral neck and distal radius, a common site of wrist fractures.
They also said the denosumab group's lumbar spine bone density at 12 months increased 4.8 percent from baseline, while the placebo group recorded a 0.7 percent decrease from baseline.
At two years, the denosumab arm's lumbar spine bone density was up 6.2 percent from baseline versus the placebo arm's 1.4 percent decrease.
Nineteen women, or 15 percent, in the denosumab arm experienced serious adverse effects, compared with 11, or 9 percent, in the placebo arm. None of the adverse events in either group were considered treatment-related.
Two deaths, one in each group, were reported in the study. Researchers said the deaths were not considered treatment- related.
Analysts have cautioned that denosumab, also referred to as dmab, would face an uphill battle in the competitive $7 billion global osteoporosis market.
If approved, it would face off with Merck & Co Inc's (MRK.N) popular Fosamax, which will soon lose patent protection, as well as newer drugs such as Novartis AG's (NOVN.VX) Reclast and Zometa, which is indicated for use in cancer patients.
"Dmab must be better than Zometa to be relevant," said Friedman, Billings, Ramsey & Co, who expects denosumab to have peak sales of around $900 million by 2012. (Reporting by Lisa Baertlein; Editing by Andre Grenon, Gary Hill)
