Who's vulnerable to Amgen's new bone drug?

We know who stands to win off the early FDA approval of the bone drug Prolia, and that's Amgen (NASDAQ: AMGN). But who stands to lose? A variety of drugmakers sell drugs for osteoporosis, the indication the FDA granted to Amgen's new treatment. Think Merck (Fosamax), Roche (Boniva), Warner Chilcott (Actonel), Eli Lilly (Forteo and Evista), and Novartis (Reclast and Miacalcin).

Any and all of these companies could see sales slip as doctors go for the latest bone med. But for some of them, at least, generic competition is more of a threat. Fosamax, is already fighting copycat versions, and Actonel also has been fighting an ongoing battle. And with Fosamax off patent--and others on their way to the patent cliff--Amgen will find itself facing rivals that are not only effective, but a lot cheaper. Prolia, for what it's worth, will sell for $825 per injection, wholesale; injections are given every six months.

Analysts say that generic bone drugs are a factor--and that they'll affect Prolia from the get-go. "This will have a somewhat gradual rollout," Cowen & Co.'s Eric Schmidt tells Bloomberg. "Doctors are going to be conservative in adopting a therapy that doesn't yet have a long-term track record. There are very good drugs for osteoporosis with established track records and they're cheap."

It's possible that the osteoporosis treatments most in danger from Prolia are those that, like it, are indicated for women with osteoporosis who are at high risk of fractures. Namely, Eli Lilly's Forteo. But as Amgen's EVP Roger Perlmutter points out in the Wall Street Journal, Prolia might also siphon off patients who haven't responded fully to existing drugs or who would prefer to avoid their current therapy's particular side effects. Patients who forget to take their pills--and so would stick to a once-every-six-months injection more easily--could also move to Prolia. But only time will tell.

- read the Bloomberg story
- get more from the Wall Street Journal