Not-so-quietly tucked away in its fourth-quarter earnings announcement last week, Amgen (Nasdaq: AMGN) released data from its top pipeline drug candidate. The drug, denosumab, represents Amgen's biggest chance at near-term salvation from the financial slump it is experiencing as a result of troubles with its anemia drug franchise.

Denosumab is currently in multiple phase 3 clinical trials as a treatment to help prevent bone loss and fractures in a variety of conditions, including osteoporosis and cancer (as well as cancer treatments, which can cause similar problems). The phase 3 study results announced last week were some of the first late-stage results released. The study tested denosumab against Merck's (NYSE: MRK) osteoporosis drug Fosamax as osteoporosis treatments.

The study results announced last week won't serve as the sole pivotal trial leading to a regulatory filing on the drug as a treatment for osteoporosis, but they are the first of a whole slew of clinical-trial results related to denosumab we can expect to see in 2008. No data on last week's study results was released, except that denosumab outperformed Fosamax in improving bone mineral density.

In the second half of the year, data on denosumab is expected from a large osteoporosis study of the drug. Also expected are results from a trial testing it as a treatment for bone loss in patients undergoing prostate-cancer treatment. If all goes according to plan, Amgen will file a marketing application for denosumab with the FDA later this year.

Amgen announced its acquisition of Abgenix in 2005. Its main reason for doing the more than $2.2 billion deal was to eliminate the royalties it would have to pay on sales of denosumab, as well as on colorectal cancer treatment Vectibix, if the drugs were approved for marketing. Vectibix received marketing approval in 2006, but sales haven't been what investors were hoping for after the drug failed an important label-expanding clinical trial.

The market for osteoporosis drugs will be in the billions this year, even with Merck's blockbuster Fosamax losing patent in the coming months. Other drugs, including Roche and GlaxoSmithKline's (NYSE: GSK) Boniva, are still growing strongly, and so is Eli Lilly's (NYSE: LLY) Forteo.

While Vectibix and denosumab weren't the only benefits Amgen enjoyed in its deal for Abgenix, they were the big prizes in the acquisition. With Vectibix not performing as planned, it will come down to denosumab to determine whether the Abgenix acquisition was a good one. It looks like 2008 will be the year we find out.

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Fool contributor Brian Lawler does not own shares of any company mentioned in this article. Eli Lilly and GlaxoSmithKline are active Income Investor picks. The Fool has an A+ disclosure policy.