Scientists successfully test vaccine against metastatic melanoma

By Kim Schiffmann, in News · 11-08-2019 16:00:00 · 0 Comments
Scientists successfully test vaccine against metastatic melanoma

Scientists have successfully tested a vaccine against metastatic melanoma, an aggressive skin cancer that spreads to other organs

The study, coordinated in Portugal by researcher Helena Florindo of the Faculty of Pharmacy of the University of Lisbon, was published in the British journal Nature Nanotechnology.

The experimental vaccine was used in mice with metastatic melanoma, a type of cancer in which patients respond poorly to immunotherapy (treatment in which immune cells are activated to fight the tumour).

In this case, Helena Florindo’s team, in partnership with a working group at the Tel Aviv University of Israel, created a vaccine that could “train” the immune system to react against biological markers of tumour cells and destroy only these cells, avoiding adverse effects on healthy cells or organs (as with chemotherapy).

The scientists explained to Lusa that the vaccine has in its composition a simple sugar (mannose) and a sequence of two peptides (protein fractions) that is present in melanoma cells.

The vaccine will not act on the tumour, but on the dendritic cells, which are part of the immune system, which protects the body against invading agents.

According to Helena Florindo, these cells "will recognise the vaccine and make it visible" to other cells of the immune system, T lymphocytes, which play a key role in the self-destruction of cancer cells. In the end, dendritic cells will "show" T cells that "it is against these [vaccine-inoculated] peptides that they have to react," said the University of Lisbon researcher.

In their experiment with mice with metastatic melanoma, the team of scientists found that the vaccine only works in practice if, in parallel a drug ‘ibrutinib’ is administered, which will block the function of immunosuppressive cells, cells that inhibit the body’s immune response and which researchers have detected in rodent tumours in association with decreased T lymphocytes.

Rodents who receive three doses of vaccine – one dose per week – in combination with immunotherapy for more aggressive melanoma and the drug ibrutinib remained alive in 70% of the cases within two months.

In contrast, mice that only received immunotherapy in combination with the drug survived in 20% of the situations at the same time and those vaccinated and treated with immunotherapy remained alive in only 7% of the cases.

The animals that received no treatment died after 28 days.

Before testing the therapeutic effect of the vaccine on diseased mice, scientists verified its prophylactic effect when rodents were vaccinated before developing aggressive cancer: half of the animals survived “for a long time” after also receiving three doses of the vaccine combined with immunotherapy against metastatic melanoma.

In the next step, the scientific team, which plans to patent the vaccine and produce it on industrial scale for retesting in animals and then in humans, will study the implications of the vaccine for pancreatic cancer, whose patients have a “very low” survival chance.


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