Amgen Inc. is banking on the combination of its 30 years in the branded biologics business and Watson Pharmaceuticals Inc.'s commercial experience with generics to give the partners a leg up in a space that has become crowded with competitors who aspire to be big players in biosimilars.

Last month, Amgen and Watson partnered to co-develop and commercialize biosimilars of cancer antibodies worldwide. Watson will provide up to $400 million toward development costs, and Amgen will be responsible for development and manufacturing. Watson will receive royalties and sales milestones.