Just volumes one and two. Both were pretty good. Vol two made me soo sad though, but it was still literary quality. Have you ever read it? What did you think of it?
Alita is like my favorite manga. I can really see why James Cameron wants to make a movie trilogy out of it. I don't really have a preference for transhumanism works, but I could read Alita wonder about herself all day.
The sequel Last Order is pretty good too, though it retcons the original ending (Author was depressed, so he ended Alita a lot quicker than he originally planned). Last Order is currently in the middle of what I can only say is a parody of shounen tournament arcs.
You've peaked my interest, I'll give it a read.