Glioblastomas are an extremely aggressive type of brain tumour, which is why the news this week of a vaccine that has shown promise in fighting them is so exciting. And this comes right off the back of the announcement of another trial of the world’s first personalised mRNA vaccine for melanoma, a kind of skin cancer. Ian Sample talks to Prof Alan Melcher of the Institute of Cancer Research about how these vaccines work and whether they could one day be used to target cancer before it is even detectable on scans. Help support our independent journalism at theguardian.com/sciencepod