In an effort to boost its sales force without hiring more sales reps, Amgen announced on Tuesday that it has signed a deal with GlaxoSmithKline to co-market its osteoporosis treatment denosumab—currently pending FDA approval.

GSK will paying $120 million up front (along with royalties) to mutually market denosumab, or DMab, in regions where Amgen currently doesn’t have a strong sales force, such as China, India, and Brazil. The companies will tag team commercialization in Europe, Australia, New Zealand, and Mexico. Meanwhile, Amgen will handle all marketing in the United States and Canada.

“Our collaboration with GlaxoSmithKline will help Amgen bring the promise of denosumab to patients in Europe and other parts of the world more effectively than if we commercialized the drug globally on our own,” stated Amgen CEO Kevin Sharer in a release. “Amgen and GlaxoSmithKline together are uniquely positioned to help medical providers and patients understand the clinical promise and economic value of denosumab.”

Amgen is banking on denosumab being a blockbuster treatment, with analysts speculating that the drug could fetch $2 billion by 2018. The twice yearly injectible will go up against Merck’s daily osteo pill Fosamax, which went generic in 2007.