Skin cancer patients in England and Wales are to become the first in Europe to benefit from a powerful combination of drugs.
The National Institute for Health and Care Excellence (Nice) has approved the combination therapy of Opdivo (nivolumab) and Yervoy (ipilimumab) for people with melanoma that has spread around the body.
The drugs can stall progression of advanced melanoma by an average of eight months compared with standard treatment and have been found to wipe out tumours in around a fifth of patients.
Around 1,300 people could be eligible for the immunotherapy drugs every year, in one of the fastest drug appraisals carried out by Nice.
Nice approved the drugs within weeks of them receiving their licence from the European Medicines Agency.
People with advanced skin cancer currently live less than two years on average. Melanoma accounts for around 1,750 deaths in England every year. Around 12,200 people were diagnosed with the disease in 2013, the most recent figures available.
Professor Carole Longson, director of the health technology evaluation centre at Nice, said: "After one of the fastest drug appraisals Nice has carried out, these promising new immunotherapy treatments for advanced melanoma look set to significantly extend the life of people with the condition.
"The evidence we examined was very promising and I know further trials are ongoing which have also released encouraging data."
In April, the results of a phase II study into the drugs showed startling results.
Of 95 patients given the combined treatment, more than 60% were still alive after two years and, of those, a fifth (22%) had no detectable tumours remaining.
Dr James Larkin, consultant medical oncologist at the Royal Marsden Hospital in London, has treated patients with the drugs as part of another on-going trial.
He said the immunotherapy drugs - which enable the body's immune system to fight tumours - are "an effective two-pronged attack against the cancer".
The drugs are known as "checkpoint inhibitors" and interrupt two different signalling pathways to take the brakes off the immune system.
Each blocks a separate receptor "switch" on immune system T-cells that weakens the immune response and can be activated by molecules released by tumours. Ipilimumab targets a receptor called CTLA-4 while nivolumab targets the PD-1 receptor.
Checkpoint inhibitors can have side effects, including causing diarrhoea and liver damage.
The drugs have also shown a promising effect on other cancers, including advanced lung cancer.
Research presented at the American Society of Clinical Oncology (Asco) conference last week showed that of 38 patients given the drugs, 47% responded, with more than 83% still alive after a year.
Cancer Research UK has said combining immunotherapy drugs has the potential to benefit thousands of patients with cancer, at all stages of the disease.