Many cancer treatments are notoriously savage on the body. Drugs often attack both healthy cells and tumour cells, causing a plethora of side effects. 

Immunotherapies that help the immune system recognise and attack cancer cells are no different. Although they have prolonged the lives of countless patients, they work in only a subset of patients.

One study found that fewer than 30% of breast cancer patients responded to one of the most common forms of immunotherapy.

But what if drugs could be engineered to attack only tumour cells and spare the rest of the body?