Scientists have found that a new drug in early stage tests treated tumours in 38 per cent of patients with melanoma, the deadliest form of skin cancer.

The results are from the first clinical trial of the drug lambrolizumab (MK3475), which was discovered and developed by global health care provider Merck.

Researchers at the University of California, Los Angeles’s Jonsson Comprehensive Cancer analysed 135 patients with advanced metastatic melanoma who were divided into three groups with different treatment regimens.

Overall, 38 per cent of patients taking lambrolizumab saw confirmed improvement of their cancer across all dose levels.

Of those taking the lowest dose of lambrolizumab, 25 per cent showed improvement, while 52 per cent of those who received the highest dose improved.

The rate of any tumour response across all patients was 77 per cent.

Researchers have not yet determined the average duration of response to the drug, because only five patients who had initial responses were taken off the study after their cancers got worse. To date, the longest response has been over one year.

Side effects with lambrolizumab are usually mild and easily managed. These include fatigue, fever, skin rash, loss of skin colour and muscle weakness. Thirteen per cent of patients had side effects that were more severe, including inflammation of the lung or kidney, and thyroid problems.

“This study is showing the highest rate of durable melanoma responses of any drug we have tested thus far for melanoma, and it is doing it without serious side effects in the great majority of patients,” said Dr. Antoni Ribas, professor of medicine in the UCLA division of hematology-oncology, who led the research.

“Lambrolizumab turns on the body’s immune system to attack the cancer, and the immune system seems to remember that the melanoma is the enemy and continues to control it long term,” Dr. Ribas said.

These data have led to a series of additional studies testing lambrolizumab in patients with melanoma and other cancers, including lung cancer.

The results were presented at the 2013 meeting of the American Society of Clinical Oncology in Chicago and will be published in the New England Journal of Medicine.

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