A cocktail of drugs can reduce advanced skin cancer tumours by more than 80 per cent, say scientists.
Researchers say they are `very excited` by the results, which have never been seen in melanoma, a type of skin cancer, before.
They used a combination of immunotherapy drug ipilimumab and the investigational antibody drug nivolumab, and found that the mixture led to long-lasting tumour shrinkage in more than half of patients with metastatic, or spreading, melanoma.
Several patients experienced tumour shrinkage of more than 80 percent within 12 weeks of receiving the drugs, and the shrinkage was long lasting.
The results showed that 40 percent of patients who received varying dosages had an objective response - meaning at least a 50 percent reduction in tumour size.
Side effects from the drug combination were manageable and often reversible, the results from the clinical trial, published in in The New England Journal of Medicine and presented at the Annual Meeting of the American Society of Clinical Oncology (ASCO), showed.
Dr Jeff Wolchok, of the Memorial Sloan-Kettering Cancer Center, said: `We are very excited about the response rates these patients have experienced.
Dr Wolchok said ipilimumab, which has already been approved for skin cancer treatment, blocks a inhibitory marker called CTLA-4.
Nivolumab blocks the receptor PD-1, and this further activates T cells in a different manner, allowing them to continue the attack.
However, Dr Wolchok notes that not all patients respond to immunotherapy and determining why some patients do not is becoming an extremely important part of advancing this field.
The researchers plan to carry out further and more detailed trials this month.