In advanced melanoma patients who do not benefit from existing therapies, personalised anti-cancer vaccines may help in the future. The first test of individual immunotherapie in three melanoma patients achieved good results. The American scientists measured an increase in number and diversity of cancer-fighting T cells, the publication in Science Express shows.
The vaccine works through the recognition of patient specific cancer proteins. These were identified by screening resected melanoma tissue for point mutations, which lead to the production of proteins with one changed amino acid. On average, skin tumours have five hundred of these mutations that can be caused by UV-light. Per patient, seven mutated proteins were selected and exposed to dendritic immune cells harvested from blood of the same patient. After the tumour antigen uptake, the dendritic cells were readministered to the melanoma patients to activate the rest of the immune system.
Blood samples taken before and after the treatment showed that the used tumour antigens provoked a broad response among T cells. “Our results are preliminary, but we think the vaccines have therapeutic potential based on the breadth and remarkable diversity of the T-cell response”, says senior author dr. Gerald Linette, a Washington University medical oncologist leading the clinical trial. Additionally, the three melanoma patients had no adverse effects.
Earlier attempts to generate an immune response against melanomas were based on the recognition of ‘normal’ proteins that are highly expressed by cancer cells. Because these proteins are also found on healthy cells, the vaccines were not very specific. Furthermore, humans have defence mechanisms eliminating immune cells that recognise antigens naturally occurring in the human body. In contrast, the personalised vaccines only react with tumour specific proteins making them more effective than the old immune therapies.
Sources: Eurekalert and Science Express
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