Avastin is a pretty interesting drug, and a pretty powerful one. Here is the Wikipedia entry for it:
http://en.wikipedia.org/wiki/AvastinThe technical name is Bevacizumab, which no one can pronounce.
It is a monoclonal antibody that inhibits formation of new blood vessels, and is used to treat a variety of cancers, and apparently also for macular degeneration of the eye, among other things. It is not specific for NF2 or acoustic neuromas. The side effects have mostly to do with inhibiting the formation of good blood vessels, so using it is a balancing act.
I suspect it would be considered too risky for holding a simple acoustic neuroma in check, but it sounds promising for NF2. In time, the technology may produce refined versions that are more specific, with fewer side effects, that can be used for a wider range of conditions. Progress is being made!
Steve