Checkpoint inhibitors (which are the primary driver of improved cancer treatment over the last 15 years and generate > $50B/year in sales) generally don't look very good preclinically. Even their clinical data can be hard to interpret prior to a large scale trial, which led to them almost being shelved.
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.
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.