Actually, any school wants a damn good reason for transferring, regardless of if it's DO to DO, MD to MD, or DO to MD...it's not like undergrad where you can just say "Well, I'm tired of this school, let's try a new one."
In addition to what Tim mentioned, I also know that the University of Oklahoma and the University of Indiana will consider transfers from DO programs, but, again, your reason has to be compelling. Generally speaking, just saying, "Well, I'm a state resident, and if you let me transfer I'll save 10 grand a year" isn't going to cut it.
Basically, the answer is yes, it is possible to transfer DO --> MD, but not likely.