By Mary Welch

Allelix Biopharmaceuticals Inc. reported positive results from a Phase II study with its human parathyroid hormone, ALX1-11, for post-menopausal osteoporosis.

Bone mass density increased significantly after one year, said Jerry Ormiston, manager of investor relations for Mississauga, Ontario-based Allelix.

"We believe it is the largest increase in bone mass in one year of any agent available today," he said.

The Phase II trials were conducted in 18 centers in the U.S. and Canada and involved 217 patients. One-fourth of those patients received a placebo, and the other three-fourths were divided into groups receiving low, medium and high doses of ALX1-11.

"The trial showed that, at the highest dosage, after one year, there was a 7 percent increase in bone density in the lower spine," Ormiston said. The primary endpoint was bone mass density at the lumbar spine, with secondary endpoints being bone mass density at the hip and total body.

After 12 months of patients giving themselves subcutaneous injections of ALX1-11, there was a dose-related increase in bone mass density of the lumbar spine of 2.6, 4.6 and 7 percent at the low, middle and high doses, respectively. All results were significantly different from the placebo, and there seemed to be a positive effect of the treatment in the hip after 12 months as well.

"Many of these patients were in the danger zone, with imminent bone fractures," Ormiston said. "The key [to helping] osteoporosis patients is faster bone density."

John Dietrich, senior vice president of research and development, said researchers found "a slight decrease in total body bone mass, but we believe it is due to parathyroid ability to increase bone turnover, and will eventually fill in," he said. "We saw similar results in our animal studies and it did fill in. We don't consider this a problem at all."

Most current therapies, such as bisphosphonates and hormone replacement therapy, act by thwarting the work of osteoclasts, which are responsible for the breakdown of bone. ALX1-11, on the other hand, boosts the activity of bone-building cells, called osteoblasts. Older women, because of the drastic drop in estrogen following menopause, have a one-in-four chance of suffering a broken bone caused by osteoporosis. For older men, that risk is one in eight. An estimated eight million people suffer from osteoporosis, with another 18 million at risk.

ALX1-11 will be studied in a NASA experiment aboard the space shuttle Discovery, as part of a mission scheduled to launch Thursday. The drug will be administered to bone cells in a culture. The identical experiment will be conducted on earth at the same time.

"The purpose is to compare bone growth and try to understand the role of gravity in bone growth," Ormiston said. "Bone loss is four to 10 times faster without gravity, so the shuttle will be a unique environment to understand bone mass density and its loss and growth."

In September, Allelix's partner partner for the product, Astra AB, of Sodertalje, Sweden, dropped the alliance following a corporate restructuring. The deal, signed in June 1996, was for C$50 million (US$32.3 million) and, so far, more than C$30 million have gone into Allelix's coffers. The most recent milestone payment came last November, when Astra paid $C17.1 million for finishing Phase II trials. (See BioWorld Today, Sept. 28, 1998, p. 1.)

The company is taking a "parallel" approach to the future of ALX1-11. Allelix will present the study's results at the American Society for Bone and Mineral Research in December in San Francisco. Meanwhile, the company is meeting with other potential partners to take ALX1-11 into Phase III studies, while preparing the data and marketing license.

"By the end of the year, we'll know the probability of whether or not we'll have a partner and how strong the commitment will be," Ormiston said. "As to whether we would actually conduct Phase III trials ourselves, we will determine that after our talks with potential partners. That's down the road."

Allelix's stock (TSE:AXB.TO) closed Friday at $3.10, up $0.60. *