It's common for medical articles posted here to have a great-sounding breakthrough in their title, and you then have to read the article to find out it's only been done in mice. "en-mice'd/en-micing" is a term for mods editing titles, here :D
I'm guessing this is rarely tested since animal modeling is usually a gating factor for human testing?
The catch here is that only two targets (PD(L)-1 and CTLA-4) turned out to work well in humans. All of the other immunotherapies that looked mediocre preclinically turned out to also be mediocre or entirely ineffective in humans.