When real patients have unprecedented positive outcomes to a new treatment, it’s tempting to talk about it as a breakthrough for medical science. This describes the excitement around a new report from researchers in Germany of a radical new treatment for lupus.

The patients in the study — five people with severe lupus — went into remission following pioneering CAR T-cell treatment, which uses genetically altered cells.

So what is lupus, why is this such big news and what could it mean for other patients and diseases?

Around five million people are affected by some form of lupus worldwide. The most common form of lupus is SLE. Although not widespread, it is more common than MS.