Inclusion Criteria:

• Diagnosis of multiple myeloma per IWG criteria
• Have received at least 1 but no more than 4 prior lines of therapy
• Have failed to respond to the most recently administered anti-myeloma therapy
• Have a life expectancy of at least 3 months
• ECOG performance status <3
• At registration absolute neutrophil count > 1x10^9/L and platelet count >50 x 10^9/L unsupported
• At registration bilirubin less than 1.5 x upper limit of normal and transaminases less than 2 x upper limit of normal and serum creatinin less than 0.19 mmol/L
• Written informed consent
• Must agree to adequate contraceptive measure if indicated

Exclusion Criteria:

• Patients with monoclonal gammopathy of undetermined significance
• Known or suspected hypersensitivity to CYT997
• Patient with uncontrolled intercurrent illness
• Active infections or other illnesses that precludes chemotherapy administration or patient compliance.
• Pregnant or lactating women.
• Patients who have received any other investigational agents in the last 3 weeks prior to the start of treatment.
• Patients with the following conditions will be excluded:

myocardial infarction or stroke within 6 months unstable angina pectoris or acute ischemic changes on ECG history of diabetic retinopathy symptomatic peripheral arterial disease major surgery in the last 30 days

• Patients with uncontrolled diarrhoea despite optimal medication and those with any history of acute gastrointestinal bleeding
• Patients with a baseline prolongation of the QTc interval of CTC Grade 1 (QTc > 0.45-0.47 sec) or greater
• Patients with impaired cardiac function or clinically significant cardiac diseases, including any one of the following:

LVEF < 45% as determined by MUGA scan or echocardiogram; complete left bundle branch block; obligate use of a cardiac pacemaker; congenital long QT syndrome; history or presence of ventricular tachyarrhythmia; presence of unstable atrial fibrillation (ventricular response > 100 bpm). Patients with stable atrial fibrillation are eligible, provided they do not meet any of the other cardiac exclusion criteria; clinically significant resting bradycardia (< 50 bpm); right bundle branch block + left anterior hemiblock (bifasicular block); angina pectoris ≤ 3 months prior to starting study drug; acute MI ≤ 3 months prior to starting study drug; or other clinically significant heart disease (e.g., CHF, uncontrolled hypertension, history of labile hypertension, or history of poor compliance with an antihypertensive regimen).

• Patients currently receiving treatment with medications known to prolong the QTc interval and/or to induce Torsades de Pointes arrhythmia.