ANAHEIM, Calif., March 21 -- New chemicals that, if successful, could become the first osteoporosis treatment to stimulate new bone growth -- rather than merely retard bone loss -- were described here today at a national meeting of the American Chemical Society, the world's largest scientific society. Researchers from the Seattle biotechnology company ZymoGenetics Incorporated said their new compounds are showing positive results in animals and, unlike other bone-growth candidates, can be put in a pill.
In humans, bone undergoes continuous remodeling, with cells called osteoclasts "eating up"old bone as osteoblast cells replace it with new bone. Osteoporosis, which affects some 15-20 million Americans, is caused by increased bone breakdown without new bone formation. The result is a loss of bone mass and increased susceptibility to fractures, most commonly in those age 45 and older. The cost of treatments associated with osteoporosis in the U.S. has been estimated at $3.8 billion annually.
Current treatments, including estrogens, all act to decrease bone loss. They can't do anything about bone that is already gone and, therefore, are not helpful to everyone. "Our new bone forming agents may have better and more widespread utility for treatment of osteoporosis," said ZymoGenetics senior scientist Nand Baindur, Ph.D.
There are currently no drugs available to help grow bone. Researchers have tried giving patients proteins that the body naturally uses to stimulate osteoblasts, such as parathyroid hormone and bone morphogenic proteins (BMPs). But, according to Dr. Baindur, those clinical trials have been mostly unsuccessful or inconclusive. Furthermore, he explains that proteins are big molecules which can usually be given only by injection and don't hold up well in the body. Even if such treatments worked, he adds, the proteins are generally difficult to formulate and manufacture, tending to eventually make them expensive.