For a long time, immunotherapy was considered nonsense by many people in mainstream cancer medicine. It had been tried for years, starting with a German scientist named Paul Ehrlich in 1906. There’d been a lot of other attempts since then, particularly in the 1960s and 1980s, but none of them really worked.

Unfortunately, there was a lot of hype around those efforts each time. So, when they didn’t pan out, the field as a whole...