Amgen Inc. banked $20 million and picked up a Japanese partner for its promising late-stage antibody denosumab, which is being developed for several bone-loss indications, including osteoporosis and cancer treatment-induced bone loss.

Tokyo-based Daiichi Sankyo Co. Ltd. gained exclusive rights to develop and commercialize denosumab in Japan, in exchange for the $20 million up-front fee and about $150 million to cover a portion of the worldwide development costs for the drug through 2009. Amgen also would receive an undisclosed royalty rate on net sales in Japan.

The agreement also provides Amgen access to Daiichi Sankyo's intellectual property relating to denosumab. Amgen retains sole rights to the compound for the rest of the world.

"The bottom line is that we really felt like this partnership maximizes" the product's potential, "both clinically and commercially," said Anne McNickle, Amgen spokeswoman, particularly since Daiichi Sankyo has a "range of commercial capabilities in the primary care and hospital markets."

One of the shining stars of Amgen's late-stage pipeline, denosumab is a fully human monoclonal antibody designed to target RANK ligand, a primary mediator of the formation, function and survival of osteoclasts. It is a drug that might end up showing efficacy in multiple indications involving bone loss, including bone metastases, multiple myeloma and bone erosions in rheumatoid arthritis, Amgen said.

Under the agreement, Daiichi Sankyo has rights to denosumab for any indications that Amgen pursues in the U.S. and Europe, but for now, the "key indications" are in oncology and postmenopausal osteoporosis, McNickle told BioWorld Today. The product is in Phase III development in both indications.

Earlier this year, the Thousand Oaks, Calif.-based company reported data from a 332-patient study in postmenopausal osteoporosis, showing that the drug met all its primary and secondary endpoints. Another Phase III study is testing the drug in cancer patients undergoing hormone ablation therapy. The company declined to disclose a timeline for filing anticipated biologics license applications.

Amgen's stock (NASDAQ:AMGN) barely registered the deal, gaining 82 cents Thursday to close at $55.95, hardly surprising given that the biggest concern among investors these days is the effect a proposal by the Center for Medicare & Medicaid Services to no longer pay for erythropoiesis-stimulating agents, such as Amgen's top-selling Aranesp and Epogen, in certain cases might have on the company's bottom line. Amgen responded last month to the proposal, and CMS could issue a decision by late summer.

In addition to denosumab, the big biotech also is in late-stage development with AMG 531, a thrombopoiesis-stimulating Fc-peptide fusion protein, which recently yielded positive Phase III data in immune thrombocytopenic purpura and is on track for regulatory filings later this year.

The company also recently added to its pipeline through two June acquisitions: Amgen is picking up a Phase II-stage drug for chronic kidney disease by buying Santa Clara, Calif.-based Ilypsa Inc. for $420 million, and is gaining rights to a Phase II-stage DPP-IV inhibitor for Type II diabetes in its $300 million buyout of Cambridge, Mass.-based Alantos Pharmaceuticals Inc. Both of those deals are set to close in the third quarter. (See BioWorld Today, June 6, 2007, and June 7, 2007.)