Over the past decade, technological innovations such as genome sequencing have allowed scientists to take a closer look at tumour cells and their genetic abnormalities. This is helping them aim vaccines at much more specific targets.

Cancer vaccine research is still in its early phases; however, early results from clinical trials that tested dozens of vaccines against a variety of cancers appear encouraging. The goal is to create vaccines that destroy cancer cells, but some scientists are also testing vaccines that could one day prevent a high-risk individual from developing cancer.

The goal of all vaccines is to “educate” the immune system and give it a preview of a target that needs to be identified and destroyed to keep the body safe. Similarly, a cancer vaccine “teaches” immune cells what a tumour cell “looks like,” allowing them to seek out and destroy those cancer cells.

A cancer vaccine's ability to teach the immune system is what distinguishes it from other immunotherapies that use therapeutic agents such as protein cytokines and antibodies and include strategies such as genetically modifying a patient's immune cells to fight cancer.

Experts say cancer vaccines can potentially destroy cancer cells that might have survived other treatments, stop the tumour from growing or spreading, or prevent the cancer from returning.

Some therapeutic cancer vaccines are based on removing immune cells called dendritic cells.

These cells are collected from a patient's blood sample and exposed, in the laboratory, to the main proteins extracted from the individual's cancer cells. Once taught, these cells are returned to the patient, with the hope of stimulating and training other immune cells, such as T cells, to detect and destroy the cancer.

All vaccines that treat cancer are based on proteins called tumour antigens – a molecule that triggers an immune response when it exists in greater quantity on the surface of cancer cells compared to healthy cells, or when it takes on an abnormal form or has undergone a mutation. When T cells “see” these antigens, they recognise the cells as cancerous and kill them.

Scientists are testing dozens of cancer vaccines, often in conjunction with other immunotherapies. They target different types of cancer, including skin, breast, bladder, prostate, and pancreas.

An important next step for scientists is to figure out why some people respond better to vaccines than others and how long they will be protected. Until then, the hope is that more vaccine candidates will advance to randomised clinical trials so that their safety and effectiveness can be evaluated in a larger number of patients.

Cancer vaccines are still in the early stages of testing and refinement; there is much work to be done, both on the preventative front and on the therapeutic vaccine front, but hope has made progress in this area.

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