UK drug cost-effectiveness agency National Institute for Health and Care Excellence, NICE, has approved the use of US drugmaker Merck’s Keytruda for treatment of certain cases of advanced melanoma.

First of a new category of so-called anti-PD-1 checkpoint inhibitors to reach the market, Keytruda harnesses the immune system to eradicate tumors by making cancer cells visible to the immune system and opening them to attack.

The treatment was greenlighted by NICE only after Merck agreed to supply it to the state health service NHS at an undisclosed discount over the $150,000 per-patient, per-year charged in the US.

UK officials called the approval proof that NHS was keeping pace with the latest innovations in medical science despite pressure on budgets.

The health service’s England division recently announced plans to withdrawing funding from about 20 cancer drugs in an effort to curb soaring costs, saying that removing less cost-effective medicines would free up money in the budget to pay for more advanced treatments.

Keytruda, like other first-generation immunotherapies, is said to have thus far proved effective in only a minority of patients. A number of pharmaceutical companies are currently researching how to improve their efficacy.

Reports say melanoma sufferers have been the first to benefit from treatment with such drugs but indications are now being expanded to include lung cancer and a range of other tumors. Bristol-Myers Squibb, Roche and AstraZeneca also have products in the pipeline.

As many new cancer drugs have been rejected by NICE as too expensive to warrant long-term funding, the UK government has created a special Cancer Drugs Fund to ensure access to the latest medicines.