The aim of this trial is to determine whether bortezomib improves response and delays progression for multiple myeloma patients after high dose therapy and autologous stem cell transplant. It will also assess the effect of bortezomib treatment on patient bone health.

Inclusion Criteria:

• MM patients who have received high dose Melphalan with ASCT 3-4 months prior to registration and have not progressed
• Age 18 - 70 years
• Life expectancy > 6 months
• Written informed consent
• Creatinine < 400µmol/L
• Bilirubin < 3x upper limit of normal
• WHO performance status 0-2
• Contraceptive precautions where appropriate

Exclusion Criteria:

• Received bortezomib previously
• On, or planned for, steroid therapy
• Poor performance status (ECOG ≥ 3)
• Disease progression at any stage
• Past history of polio, cord compression or other neurological condition resulting in persisting neurological deficit ≥ grade 2
• Severe hepatic impairment, indicated by bilirubin ≥ 3x upper limit of normal, or AST > 2.5x upper limit of normal
• Pregnant or lactating women
• Allergic reaction attributable to bortezomib or to compounds containing boron or mannitol
• Severe cardiovascular disease
• History of acute infiltrative pulmonary or pericardial disease
• History of hypotension or has decreased blood pressure
• Peripheral neuropathy ≥ grade 2, or neuropathic pain
• Serious medical or psychiatric illness likely to interfere with participation in this clinical study
• Received any drugs or agents that inhibit or induce CYP2C19 or CYP3A4 within 14 days before the first dose of bortezomib
• Need for therapy with concomitant CYP 3A4 or CYP2C19 inhibitors
• Have received an experimental drug or used an experimental medical device within 4 weeks before the planned start of treatment