Intravascular B Cell Lymphoma

I was wondering if anyone has any experience with Intravascular B Cell Lymphoma? My Dad was recently diagnosed with this very rare, aggressive sub-type of NHL. Apparently it's so rare that it is usually found post-mortem so we are so grateful for the doctors who didn't give up until they found out what was really going on.

He has had his first R-CHOP cycle and will be receiving 5 more. He will also be receiving 3 Methotrexate infusions in between. The doctors are not giving him a very good prognosis but I am hoping to find others who have dealt with this type of NHL to see what their experiences have been. And also to see what other treatments have been tried. Any information would be greatly appreciated!