Yes they can be altered by a professional seamstress/tailor. I had a suede dress years ago that had to be altered. It was no problem. Just make sure that the person who is doing it has experience in altering leather. Leather stretches and moves differently from regular fabrics, and if they aren't experienced in working with it it can be easy to mess up.

Robin

P.S. I know how you feel, when I was at my largest I had this incredible pair of leather pants I had found on clearance. They were such a good deal and my favorite pants.. but they were a size 20 and just not worth the time or expense of altering! I plan on buying a new pair when I get to goal