Researchers from Aarhus University, Denmark have discovered a new form of immunotherapy that has so far been tested on animal models that makes it probable that oncologists in the future may be able to treat some of the patients who are not responding to existing types of immunotherapy. Instead of attacking the cancer cells directly, the new technique targets and removes a subtype of immune cells known as macrophages, after which the immune system itself begins to attack the cancer.
In collaboration with teams in France, the UK and USA, the researchers were able to show that the serious form of skin cancer 'malignant melanoma' can be defeated by using the new method. This variant of skin cancer accounts for eighty per cent of all deaths from melanomas.
Lead author, Professor Dr Anders Etzerodt, commented in an interview with Thailand Medical News"We've studied what happens to the tumour when it is exposed to targeted treatment that removes precisely ten per cent of the macrophages that are supporting the cancer tumour instead of fighting it.The most important result is that the depletion of this specific type of macrophage causes the tumour to shrink, which is triggered by a subsequent mobilisation of new macrophages and, ultimately, also an activation of the so-called T cells which attack the tumour"
The type of macrophages which the researchers have removed express a specific receptor, CD163, on the cell surface. Unlike other macrophages, these are known to have an undesirable effect in connection with cancer. Instead of recognising cancer as unwanted tissue, the macrophage sees the tumours as normal tissue that needs help with regeneration. It is also widely recognised that survival rates are worse if there are many macrophages, which express the CD163 receptor in the tumour.
"When the peacekeeping macrophages in the tumour are removed, the attackers can instead be mobilised, after which the T cells and a number of other macrophages collaborate to attack the tumour. What's interesting is that the whole thing happens by itself as soon as we remove a tenth of the macrophages that express CD163, and that these appear to want to 'decide' which immune cells can be allowed to get into and out of the tumour," Professor Anders further commented.
Anders Etzerodt adds that discovering that it is actually possible to target medical chemotherapy treatment so that it precisely hits the macrophages that are negative markers for survival is in itself an important finding.
Professor Anders Etzerodt and research partners are currently testing whether the technique works just as well on mice with other kinds of cancer in which CD163 is a sign of low survival rates. These ongoing research projects focus on both cancer of the ovaries and cancer of the pancreas, and Anders Etzerodt does not hide the fact that there are still unanswered questions and issues that need to be dealt with but is still pursuing further studies .
Reference: Anders Etzerodt et al, Specific targeting of CD163+ TAMs mobilizes inflammatory monocytes and promotes T cell–mediated tumor regression, The Journal of Experimental Medicine (2019). DOI: 10.1084/jem.20182124