The Tasmanian devil facial tumour (DFT) cells may use a molecular deception – common in human cancers – that could allow the deadly disease to avoid the animal’s immune system, according to our new research published this month.
Recently it was discovered that DFT cells effectively hide from the immune system by not expressing key immune recognition molecules.
Our new discovery that DFT cells contain this “molecular shield” in response to inflammation represents another important step towards understanding the disease and developing more potent ways of preventing or treating it.
So how does this shield work? First, we need to look at some of the recent developments in the treatment of cancers in general.
Cancer treatment has undergone a revolution in recent years. Gone are the days when surgery and harsh chemotherapy regimens are the only options.
Now cancer immunotherapy can stimulate the immune system to kill cancer cells. In 2013 this was named the breakthrough of the year in one of the top science journals in the world.
Since 2013 the immunotherapies that target what we call immune checkpoint molecules have continued to make great progress and have recently been approved as first line defences for some cancers.
Checkpoint molecules are critical for keeping the immune system in balance. Every time that the accelerator is pressed in the immune system, there is always at least one, and often several, means of stepping on the brakes.
These checks and balances are necessary because even though the primary job of the immune system is to protect us from disease, the immune system wields powerful weapons that can inflict collateral damage to critical tissues and organ systems when it is aimed at the wrong target.
In recent years the aptly-named checkpoint molecules – “programmed death-1” (PD-1) and “programmed death ligand 1” (PD-L1) – have emerged to be critical regulators of the anti-cancer immune response.
The PD-L1 molecule is used by many types of cancer as a molecular shield to protect the malignant cells from anti-cancer immune responses.