Study of SyB L-0501 to Treat Relapsed/Refractory Multiple Myeloma

The administration of SyB L-0501 at 90 mg/m\^2/day by 60-minute intravenous infusion for 2 consecutive days followed by 26 days of monitoring. This is considered to be one cycle and may be repeated up to 6 times. Dose reduction or discontinuation is permitted from the second cycle as necessary according to adverse events and the results of monitoring during the previous cycle.