Could a vaccine for cancer be within reach?

It’s probably now the longest running conflict since the Hundred Years’ War: Richard Nixon declared the ‘war on cancer’ 51 years ago. The enemy is still in the field, killing more people than ever as other causes of mortality shrink. But cancer is at last giving ground.

Fresh from its triumph in the race to make a vaccine for Covid-19, the German biotech company BioNTech has announced promising results using a similar vaccine against pancreatic cancer. Of 16 people given the vaccine shortly after they had their tumour surgically removed, eight were cancer-free 18 months later. That may not sound like much and these are small numbers, but they are being greeted with enthusiasm. Pancreatic cancer is usually lethal within a year because it shows few symptoms till it has spread to the rest of the body, and this was just a phase-1 trial, intended to test the safety rather than the efficacy of the treatment.

Before the pandemic, BioNTech had always planned to use its messenger RNA vaccines against cancer, rather than infection. The idea behind the treatment makes sense. You find some fragments of protein unique to the individual patient’s tumour and send in the genetic codes for them in a form that will alert the body’s immune system. It’s like reading the enemy’s codes and supplying the security services with information about enemy agents operating inside your country.

Surviving cancer is a war of attrition against an adaptive enemy. Tumours evolve. Their cells, bent on replicating at all costs, make mistakes and mutate in random ways. The mutants compete to dominate the tumour, which rapidly selects for any variants that resist the body’s defences or the drugs thrown at them. It’s natural selection on steroids. Imagine Russian tanks that breed new ones, some of which become immune to NLAW missiles: they would soon come to dominate the battlefield.