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(Adds details, background, GSK statement)
April 3 (Reuters) - Amgen Inc said it would end anagreement with GlaxoSmithKline Plc for the marketing ofits osteoporosis drug in some regions outside the United States.
Amgen said it would take over the marketing of the drug,sold under the brand name Prolia, in most areas under theagreement, including the European Union, Switzerland, Norway,Russia and Mexico, by Dec. 31.
GSK will continue to market the drug in Australia, Amgensaid in a regulatory filing. (http://link.reuters.com/cax28v)
"GSK and Amgen have reached a mutual agreement to end theirexisting agreement...," a GSK spokesman said in an emailedstatement, adding, "This new arrangement will allow GSK toincrease focus on executing important new product launches overthe next few years."
Amgen said it would pay GSK $275 million over the rest ofthe year and reimburse the British drugmaker $15 million forcosts incurred during the transition period.
Prolia generated worldwide sales of $744 million in 2013, a58 percent increase from a year earlier. (http://link.reuters.com/mux28v)
According to the agreement signed in July 2009, Amgenretained the rights to market the drug in the United States andCanada as a treatment for osteoporosis and other conditions andas a treatment for cancer in Europe, Australia, New Zealand andMexico.
Amgen also said on Thursday that GSK would continue tomarket the drug as a treatment for conditions other thanosteoporosis in countries such as China, Brazil, India and SouthKorea.
GSK holds the marketing rights in these regions until 2024,according to Amgen's annual report.
Amgen is developing the drug in late-stage studies as atreatment for other forms of osteoporosis, includingglucocorticoid-induced osteoporosis and male osteoporosis.
The company is also testing the drug, denosumab, as atreatment for cancer-related bone damage.
Denosumab is sold under the brand name Prolia as a treatmentfor three conditions, including postmenopausal osteoporosis inwomen at high risk of fracture.
The drug is approved in the United States as a treatment forgiant cell tumor of the bone and is sold under the brand nameXgeva. (Reporting by Vrinda Manocha in Bangalore; Editing by SimonJennings)
