GlaxoSmithKline (GSK) is to work with Synta Pharmaceuticals on the development of a new skin cancer drug, in a deal which could be worth £493m.
Synta will fund the development of STA-4783, which is aimed at treating metastatic melanoma, the most deadly form of skin cancer.
The companies will jointly sell the drug in the USA and Synta will receive a share of the profits.
Synta said the drug worked by overloading cancerous cells with oxygen, which effectively makes them self-destruct. Non-cancerous cells have a much higher tolerance for oxygen, and so are unaffected by the medication.
Currently there are very few drugs on the market for people with advanced skin cancer, which kills 70% of sufferers within one year.