Inclusion Criteria:

1. Histologically confirmed diagnosis of GIST which is unresectable and/or metastatic and either:

   • no prior therapy with imatinib or any investigational therapies (e.g .sunitinib). Note: newly diagnosed patients may have received up to 14 days imatinib treatment for disease management while awaiting study start.
   • recurrent GIST after stopping adjuvant treatment with imatinib and no subsequent treatment with any other investigational therapies (for example sunitinib).
2. At least one measurable site of disease on CT/MRI scan
3. Performance status ≤ 2 (capable of self-care but unable to carry out any work)
4. Normal organ, electrolyte and marrow function

Exclusion Criteria:

1. Prior treatment with nilotinib or any other drug in this class or other targeted therapy agents with the exception of adjuvant imatinib.
2. Disease progression during adjuvant therapy with imatinib
3. Prior or concommitant malignancy that is currently clinically significant or currently requires active intervention.
4. Impaired cardiac function

Other protocol-defined inclusion/exclusion criteria may apply