Medicine Reason for treatment resistance in malignant melanoma identified

Certain immune cells make black skin cancer resistant to therapies. With this new finding, researchers at the University of Zurich and University Hospital Zurich hope to overcome this resistance.

Metastatic melanoma, as malignant melanoma is technically known, is considered one of the most aggressive types of cancer worldwide, as the University of Zurich emphasized in a press release on the study on Thursday.

Although novel therapies are available, around half of patients who receive such targeted therapy develop resistance to it after six to twelve months, according to the researchers.

In their study, which was published on Thursday in the journal "Cell Reports Medicine", the researchers therefore wanted to understand how these therapies are blocked. To do this, they took tumor cells from patients during treatment and analysed them.

Fighting protective cells

They found two things: firstly, the tumors of patients in whom the disease progressed rapidly despite treatment had an increased level of the gene called POSTN, and secondly, they contained a larger number of a certain type of macrophage, a type of immune cell, in their secretions.

Further analyses with cells and mice showed that this gene can change the macrophages in such a way that they protect the melanoma cells from being killed by the cancer drug.

The research team sees this mechanism as a starting point for combating resistance. Disrupting the protective activity of macrophages could be a strategy to overcome resistance, they wrote in the study.