The purpose of the study is to select the dose regimen of CDC-501 that provides the most promising evidence of efficacy.

• Subject must be diagnosed with multiple myeloma (with measurable M-Protein in serum and/or urine), and be considered to have disease progression after at least two cycles of treatment or have relapsed after treatment.
• Subject must understand and voluntarily sign an informed consent document.
• Subject must not have received corticosteroids, other chemotherapy, thalidomide, or other investigational agents, within 21 days of baseline
• ECOG (Zubrod) performance status of 0 to 2.
• Subject must be able to adhere to the study visit schedule and other protocol requirements.
• Women of childbearing potential (WCBP ) must have a negative serum or urine pregnancy test within 7 days of baseline. In addition, sexually active WCBP must agree to use adequate contraceptive methods (oral, injectable, or implantable hormonal contraceptive; tubal ligation; intra-uterine device; barrier contraceptive with spermicide; or vasectomized partner) while on study drug.