U.K-based GlaxoSmithKline Plc has paid U.S. biotech Synta Pharmaceuticals Inc $ 25 million dollars as a milestone payment, under their agreement for the ongoing development of metastatic melanoma cancer treatment elesclomol, in phase III trials.

The injectable drug is undergoing a late-stage clinical trial to treat the type of skin cancer that has spread elsewhere in the body.

Elesclomol, designed to start apoptosis, or programmed cell death, in cancer cells, has not yet been been approved in any market.

Synta said it could earn two additional payments of $ 25 million dollars for completing enrollment in the trial and if the trial meets the primary endpoint, or if the two companies decide to file for regulatory approval.

The collaboration between the companies has a potential total of $ 585 million dollars in development and regulatory milestone payments.