LONDON, July 5 (Reuters) - Bristol-Myers Squibb's immunotherapy drug Opdivo is not worth using on the state health service for treating kidney cancer, Britain's healthcare cost-effectiveness watchdog said on Tuesday.

The draft decision from the National Institute for Health and Care Excellence (NICE) is a blow for the U.S. drugmaker, which has had mixed fortunes under a British system.

Opdivo is recommended by NICE for melanoma but not for lung cancer. Bristol-Myers said the latest NICE verdict highlighted the limitations of the current process for accessing first-in-class medicines on the country's National Health Service.

(Reporting by Ben Hirschler, editing by Louise Heavens)