AUY922 is a synthetic Hsp90 inhibitor.  It is not related to the natural products geldanamycin (as is IPI504) or radicicol.

This drug is under development by Novartis.

For details about this compound see this link, a paper by Brough et al in the Journal of Medicinal Chemistry.

A Phase II trial is pending for patients with resistant GIST:

Study of Hsp90 Inhibitor AUY922 for the Treatment of Patients With Refractory Gastrointestinal Stromal Tumor, NCT01404650, Phase II