Durvalumab is a new type of drug for many types of cancer. Laboratory tests show that it works by allowing the immune system to detect cancer and stimulate the immune response. This may help to slow down the growth of cancer or may cause cancer cells to die. Durvalumab has been shown to shrink tumours in animals and has been studied in nearly 2000 people and seems promising but it is not clear if it can offer better results than standard treatment alone.