Yervoy is pretty good stuff. And hey, maybe you can grab 10% a year investing in BMY. I like checkpoint inhibitors. I could see them being used in combination with DC vaccines. But after a long road and many indicators of efficacy, perhaps the best of the whole tumor lysate loaded DC vaccines (DCVax) is coming to the fore. It isn't that they are old news, it's that their road had been a long one. ATMPs take time. I think DCVax will eventually, via label extension, outshine Yervoy, alone and especially in combination with it.
You can take their word for it, and base your investment decisions off that (actually you already have). Led by the hand, so to speak. It's easier, and takes less critical thinking. But the truth is they can't really know, as a large, multi center placebo controlled study testing a DC vaccine utilizing whole tumor lysate has not been completed yet. There really isn't peer reviewed data of this sort out there. They are probably considering only Provenge and perhaps ICT-107.
Like I said, this one's not for you. It takes a certain kind of person.