Cancer vaccines help to 'jump start' the immune system against tumour cells.
Vaccines are harmless forms of bacteria, viruses etc that are put into the body to start your immune system responding against certain diseases. They are usually given to help prevent infections, but research is being done to develop vaccines that prevent or treat cancer.
Vaccines are not yet a major type of treatment for cancer, as the immune system is very complex. It has also become clear that cancer cells have different ways of eluding the immune system, which makes creating effective vaccines difficult.
Dendritic cell vaccines have shown the most success so far in treating cancer.
Dendritic cells are special immune cells in the body that help the immune system recognise foreign cells, such as tumour cells. They break down foreign cells into small pieces to reveal the foreign substances (antigens) it contains. Dendritic cells then hold out these antigens, so other immune cells called T-cells can see them. The T-cells then start an immune reaction against any cells in the body that contain these antigens.
Dendritic cell vaccines are made from the dendritic cells of the person that the vaccine will be used in. The process is complex and expensive.
Doctors remove some immune cells from the patient's blood and expose them in the lab to tumour cells or tumour antigens. The dendritic cells are 'taught' to recognise the tumour antigen and identify it as unwanted in the body. These 'educated' dendritic cells are injected back into the patient, where they recognise and target tumour cells with that particular antigen on their surface. They then recruit other immune cells in our body and trigger an immune response to kill the tumour cells.
DCVax is an example of a dendritic cell vaccine. DCVax differs from other immunotherapies that train T-cells to attack cancer cells (such as CAR-T cell therapy listed below), in that most of these immunotherapies attack a single target on the cancer cells - DCVax uses different types of immune cells, mainly dendritic cells, to recognise different targets. It also mobilises signalling molecules with the aim of involving the whole immune system.
Several vaccines for DIPG (Diffuse Intrinsic Pontine Glioma) are being/have been tested in clinical trials. These include an 'EGFRvIII peptide vaccine' and a 'B7-H3 vaccine'. These have tended to be early stage Phase 1 trials that test for safety, so more research needs to be done.