How do you treat GIST with de-differentiation to pleomorphic sarcoma on chronic therapy with imatinib?

Once a GIST, always a GIST. Sarcomas that are driven by a translocation can behave badly but they never ever get rid of their translocation.

Possibly by saying the GIST has de-differentiated your pathologist is telling you the GIST looks more aggressive. Or maybe it was never was GIST in the first p...