Osteoporosis: On the Cutting Edge of Bone Health
Advances in research are changing the way osteoporosis experts think about this widespread disease.
New Osteoporosis Treatments continued...
The identification of the high bone mass gene and the chemical signaling
pathway it involves has opened up a wide range of new possibilities for
osteoporosis treatment. "The prospect here is to build an osteoporosis drug or
drugs that cause the body to act as if it has that mutation, building up more
bone," says Heaney. He believes that drugs aimed at this pathway are already in
human testing, but it may take some time before they can come to market.
"Because this pathway acts on other areas of the body besides bone, you have to
be sure that your drug isn't producing unintended results elsewhere."
Scientists are also investigating new compounds, called vitamin D analogs,
as potential osteoporosis treatments. These drugs are, essentially, a
supercharged version of vitamin D supplements -- molecules that have been
altered, based on vitamin D's structure, to minimize bone loss and maximize
One of these drugs, 2MD, has shown great promise in animal models of
osteoporosis, and is now being studied in humans. "It dramatically stimulates
bone formation, and if we are able to see anything that even vaguely
approximates the same kind of results in humans, this is going to be huge,"
says Neil Binkley, MD, co-director of the Osteoporosis Clinical Center and
Research Program at the University of Wisconsin-Madison. Another plus: because
the drug is based on vitamin D, Binkley predicts that there may not be any
unusual side effects, and it may even boost the immune system's function the
way that natural vitamin D does.
One drug that is closer to approval is an experimental treatment called
denosumab. This twice-yearly injection is now in Phase III clinical trials, and
has been shown to improve bone density. Denosumab is aimed at an entirely new
target for osteoporosis: a protein called RANK ligand. This protein plays a key
role in the process by which cells called osteoclasts break down bone. And
researchers hope the drug will help keep the process of bone loss in check with
bone replacement. Denosumab could be on the market as soon as late 2008.
"Osteoporosis is a fairly young field," says Binkley. "When I was in medical
school, you diagnosed osteoporosis only after someone broke a bone, just as we
used to only diagnose heart disease after a heart attack. We know more now, and
we're developing better tools to diagnose, treat, and prevent