In Korea, VMP is most commonly used as frontline treatment in patients with newly diagnosed MM who were ineligible for high-dose therapy. Recently National Insurance began to reimburse the second-line LD when the bortezomib-containing treatment failed to salvage the patients. Patients who have relapsed MM after exposure to the above agents and have progressive disease have a short life expectancy. Third-line therapy is needed for retrieving the patients hereafter. And substantial proportion of patients will attain an advanced age. To examine if time to disease progression is maintained and tolerability is improved with lower dexamethasone dose, the dose of dexamethasone is reduced when at least a minimal response is achieved after 3 months of treatment with the initial dose. Three months later (6 months after the initial treatment), the response remains in stable disease, 2nd dose reduction (dexamethasone 10mg or prednisone 50mg) will be carried out.