A team of British scientists at London’s Guy’s Hospital are banking on the body’s military to step up as they use a new vaccine-based treatment to destroy cancerous tumors. They’ve just administered it to their first patient, a woman with advanced cervical cancer, as part of a trial run.

For years as we’ve armed our best physicians with radiation, scalpels, and chemicals, they’ve attacked cancer from the outside, killing tumors within while minimizing collateral damage. We’ve gotten so used to thinking about beating cancer with human-made weapons that we forget our body’s got its own army to fight diseases — the immune system.

The new vaccine works by activating the body’s immune system and turns it against the cells that form cancerous tumors. What’s tricky is that cancer cells are actually just regular cells on overdrive, so making sure the immune system can differentiate between the two is critical.

One way to pinpoint a cancer cell is to target the engine that puts it into overdrive: a souped-up, mutated version of an enzyme known as hTERT that causes it to divide continuously. The vaccine contains a small chunk of hTERT that it presents to the immune system’s cells — like putting hounds onto the scent — in hopes that they’ll target and kill cells that have a matching piece.

In addition to getting the vaccine, patients in the Phase I trial will also get a low dose of a chemotherapy drug to kickstart their immune systems. The immune systems of people with advanced cancer are usually too weak to kill diseased cells without any external help. With the vaccine, the researchers hope the body will get a bit of a boost.

The study’s first patient was injected with the vaccine in early February and has yet to experience the flu-like symptoms doctors warned might arise.

We’ve used vaccines to prevent cancer in the past, but using them to treat cancer is pretty new territory. Until now, the FDA has only approved one — a prostate cancer vaccine called Sipuleucel-T — but the British study, it’s hoped, will pave the way for many more to come.