PRINCETON, N.J. ( TheStreet) -- Bristol-Myers Squibb ( BMY) acquired worldwide rights to an experimental rheumatoid arthritis drug from privately held Alder Pharmaceuticals, the companies announced Tuesday. The drug, ALD518, is an injectable monoclonal antibody that targets and blocks the production of IL-6, a molecule that plays role in the inflammation, swelling, pain and destruction of bone joints. The drug has completed a phase IIa study, to date. ALD518 shares the same mechanism as Roche's rheumatoid arthritis drug Actemra, which is currently under review by the U.S. Food and Drug Administration. In exchange for worldwide rights to ALD518 for all indications but cancer, Alder receives from Bristol $85 million in cash up front, and is eligible for an additional $764 million in future development and regulatory milestone. Alder will also receive royalties based on future ALD518 sales and Bristol may invest up to $20 million in a possible Alder initial public offering. Bristol already markets a rheumatoid arthritis drug, Orencia, and has another oral drug in phase II studies, according to BioMedTracker.com Speaking of oral rheumatoid arthritis drugs, Rigel Pharmaceuticals ( RIGL) is still seeking a partner for its phase II drug candidate, R788.