West Coast Editor

As promised, Amgen Inc. began dosing patients in two pivotal Phase III trials of AMG 162, its fully human monoclonal antibody designed to treat post-menopausal osteoporosis (PMO) and treatment-induced bone loss.

"PMO is the big [indication], but certainly we're talking about a serious unmet need" in the other, said Andrea Rothschild, spokeswoman for Thousand Oaks, Calif.-based Amgen.

The company's stock (NASDAQ:AMGN) closed Tuesday at $53.90, up 67 cents.

The drug targets the receptor activator of nuclear factor kappa B ligand, known as the RANK ligand, which is the primary mediator of bone resorption. Earlier trials have shown AMG 162 inhibits osteoclasts, which may be involved in a number of bone-loss conditions. The pathway, Rothschild noted, was discovered and described by Amgen scientists, and Amgen said earlier this year that the Phase III trials would be starting soon.

About 200 million women worldwide are believed to suffer from osteoporosis, according to the International Osteoporosis Foundation. Of those, nearly half are expected to experience a fracture that could limit their mobility, prevent an active lifestyle or even shorten life span.

Treatment-induced bone loss (TIBL), including bone loss associated with the use of glucocorticoids, immunosuppressives and hormone ablative therapies, is a somewhat smaller market. The prevalence of TIBL in the U.S. is estimated at about 290,000 patients, and only a small fraction get treatment.

"When we say 290,000, we're only talking about TIBL in the oncology area, which is where we're focused," Rothschild said.

Another company is based on work done on the RANK ligand - Auxeris Therapeutics Inc., of St. Louis, where scientists at Washington University crystallized the ligand. Privately held Auxeris is taking aim at bone metastasis with its injectable antiresorptive agent AUX 202, expected to enter the clinic next year. (See BioWorld Today, April 12, 2004.)

"We're also looking at bone metastasis, and bone erosion in rheumatoid arthritis," Rothschild said. "We're investigating that now."

She told BioWorld Today that the company has not provided an estimate of when the Phase III studies might finish.

"Generally, osteoporosis trials are very long," she said. "They can be a few years in duration." The TIBL "may not be quite as long" as the PMO, she added. Amgen plans to present Phase II results in October at the annual meeting of the American Society for Bone and Mineral Research in Seattle.

Separately, Amgen and Salt Lake City-based NPS Pharmaceuticals Inc. entered a deal for the latter to promote Kineret (anakinra) for moderate to severe rheumatoid arthritis in the U.S. Terms were not disclosed. In the European Union, the interleukin-1 receptor antagonist is co-promoted by Biovitrum AB, of Stockholm, Sweden.

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