The primary goal of the study is to determine the best dose of an investigational drug to give to patients with multiple myeloma and to evaluate the investigational drug's effectiveness as a treatment for multiple myeloma.

Other specific inclusion/exclusion criteria may apply. In order to determine eligibility, further examination by the investigator is necessary.

Inclusion Criteria:

• Eligible patients must be at least 18 years of age with a diagnosis of multiple myeloma including elevated M-blood/urine protein or a tumor that can be evaluated by the doctor during the investigational drug's treatment.
• The patient's multiple myeloma must have gotten worse during/after previous chemotherapy was given.
• Any side-effects from prior chemotherapy must have subsided
• Blood and urine tests must show adequate bone marrow, liver, and kidney function.

Exclusion Criteria:

Any of the following will exclude patients from study participation:

• indolent or smoldering myeloma or localized plasmacytoma
• hyperviscosity syndrome
• irradiation to 25% or more of bone marrow
• prior high dose chemotherapy with bone marrow or stem cell support
• current participation in other clinical trials
• pregnant or breast-feeding women
• known HIV-positive or AIDS-related illness
• patients planning to have radiation therapy or surgery that would interrupt study therapy in the next 6 months.