A Phase I-Ib/II Study to Determine the Maximum Tolerated Dose (MTD) of AUY922 Alone and in Combination With Bortezomib, With or Without Dexamethasone, in Patients With Relapsed or Refractory Multiple Myeloma.

Inclusion criteria:

* Patients must have a diagnosis of active multiple myeloma.
* Phase I and Phase II part: Patients must have received at least 2 but not more than 4 prior line of therapy and their disease has progressed during or after last therapy.
* Phase Ib part: Patients must have received no more than 2 prior lines of therapy (excluding dexamethasone as single agent).
* ECOG Performance Status of ≤ 2.
* Patients must have acceptable neutrophil and platelet counts as well as adequate kidney and liver function.
* Patients must have magnesium levels above lower limit of normal or correctable with supplements.
* Patients must be willing and able to undergo bone marrow biopsy/aspirate.
* Able to sign informed consent.

Exclusion criteria:

* Prior treatment with any HSP90 or HDAC inhibitor for the treatment of multiple myeloma.
* Patients with unresolved diarrhea ≥ CTCAE grade 2.
* Patients with acute or chronic liver disease.
* Patients using medications that have a relative risk of prolonging the QT interval.
* Clinically significant cardiac diseases.
* Patients with known disorders due to a deficiency in bilirubin glucuronidation (e.g. Gilbert's syndrome).
* Pregnant or lactating women.
* Fertile women of childbearing potential (WCBP) not using adequate contraception.
* Male patients whose partners are WCBP, not using adequate contraception.
* Patients who unwilling or unable to comply with the protocol.
* Phase Ib part: Peripheral neuropathy ≥ CTCAE grade 1.
* Phase Ib part: Prior treatment with bortezomib.

Other protocol-defined inclusion/exclusion criteria may apply