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.
The biotechnology company's stock has come under pressure because of safety, reimbursement and label concerns about its anemia drug franchise. Analysts are watching this and other denosumab trials closely to see whether the osteoperosis candidate has the long-term potential to alleviate some of the damage to the stock, which closed Friday at $48.40.
The phase III HALT Breast Cancer trial looked at Amgen's twice-yearly injection in patients who were also receiving Aromatase Inhibitor (AI) therapy, or breast cancer drugs that block the enzyme that affects estrogen in postmenopausal women. Bone loss is an adverse effect of AI therapy.
Patients currently battle bone thinning with Novartis' Reclast and Zometa, and Merck's Fosamax, which Amgen is comparing with denosumab in a head-to-head phase III study expected to end next year.
In the HALT study, Amgen said its denosumab increased bone density that resulted from AI use, and also increased overall bone density of the outer shell of the patients' skeletons. Differences between the patients taking the drug and those in the placebo arm of the study were observable within a month, and within a year there was a 5.5% difference in the lumbar spine bone mineral density between the two patient groups.
In a study presented Friday at a breast-cancer meeting in San Antonio, scientists said Amgen's denosumab, or D-mab, improved bone density of 127 breast-cancer patients given injections every six months for two years, compared with 125 women who received placebo shots. All volunteers were taking cancer treatments known as aromatase inhibitors, which had begun to erode their bones, creating risk of fractures.
After 24 months of study, the spines of women in the D-mab group gained 7.6% in bone-mineral density, compared with continuing bone erosion in the placebo group, reported researcher Georgiana Ellis, associate professor of medicine at the University of Washington, Seattle.
Amgen needs a new hit drug after a year marked by safety problems and sinking sales of its blockbuster anemia drugs Epogen and Aranesp. Kevin Sharer, the Thousand Oaks, Calif., biotech company's chief executive, has extolled D-mab's "blockbuster potential."
Osteoporosis drugs are a $7 billion-a-year market, while bone drugs for cancer patients fetch an additional $1 billion a year. Staple drugs now on the market can cause ulcers of the esophagus and a rare jawbone decay. If D-mab is approved for osteoporosis and cancer patients, some analysts think the drug could command $2 billion in annual sales.