Okay, not really. Instead of being misleading, the title really offers up a couple of key clues to really understanding the book. The deal is that Jesse, the narrator, is making a book about his best friend Rise. Technically, it's a biography because Jesse is writing it about someone else, but he and Rise refer to it as an autobiography because Rise is the one telling the story. If this doesn't sit quite right with you, then follow that instinct. See, we don't think Rise's "autobiography" is the one the title ultimately refers to.
Jesse's official goal in working on this so-called autobiography is to understand what on earth is going on with Rise, who seems to have recently received a personality implant. What happens in the process, though, is that Jesse takes a good, long look at the world around him. As he does, he ends up telling his story to readers—and in this way, the word "autobiography" in the title seems more like a reference to Jesse than to Rise. In writing the autobiography of his dead brother, Jesse writes at least a chapter of his own story.
Feeling a little dizzy from those mental gymnastics? Here's a breather for you: The "brother" part of the title is pretty straightforward. Jesse thinks of Rise as a brother because they've been best friends their entire lives. And when Rise dies, well, the autobiography of Rise's life that Jesse's been working on ceases to be about his living brother.