- Previous treatment with imatinib mesylate resulting in: i) Hematologic Resistance / Hematologic Refractory: Based on a physician's (documented) decision to discontinue imatinib mesylate treatment due to failure of continued benefit or no benefit to the patient, ii) Imatinib Mesylate Intolerance: any toxicity resulting in a physician's (documented) decision to discontinue imatinib mesylate treatment.