To evaluate the safety and efficacy of lenalidomide with dexamethasone in Japanese patients with previously treated multiple myeloma.

Inclusion Criteria:

• Must understand and voluntarily sign the informed consent form

• Age ≥ 20 years at the time of signing the informed consent form

• Subjects with previously treated multiple myeloma defined as follows:

  • Subjects must have received at least 1 prior anti-myeloma drug treatment regimen; and
  • Considered to have progression of disease (PD) that occurred either during or following the completion of the last anti-myeloma treatment regimen utilized prior to enrollment into this study

• Measurable levels of M-protein in serum (greater than or equal to 0.5 g/dL [5g/L]) or urine (greater than or equal to 0.2 g excreted in a 24-hour collection sample)

• Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 2

• Must be able to adhere to the study visit schedule and other protocol requirements

• Females of childbearing potential (FCBP) must agree to use one or more of the following forms of contraception or abstain from heterosexual contact completely and have the male partners use a condom on the occasion of heterosexual contact in the following periods below:

  • For at least 28 days before starting study drug (in particular, the subject must abstain from heterosexual contact for 2 weeks prior to prescribing lenalidomide).
  • During the treatment phase (including the dose withholding period) For at least 28 days after the discontinuation/completion of the study drug (Methods of contraception)
  • Birth control pills
  • Intrauterine device (IUD)
  • Bilateral tubal ligation (FCBP must be referred to a health care provider who is familiar with contraceptive methods, if needed).

• Male subject must agree to use a condom during sexual contact with female irrespective of pregnancy potential

• Subjects must agree that study drug must be immediately discontinued, if pregnancy or a positive pregnancy test does occur in a female study subject or the partner of a male study subject during study participation

Exclusion Criteria:

• Pregnant or lactating females

• Subjects with a history of acute myocardial infarction within the past 6 months before starting the study drugs

• Subjects with any history or concurrent conditions of deep vein thrombosis or pulmonary embolus within the past 3 years before starting study drugs

• Subjects with tuberculous diseases, herpes simplex keratitis, systemic mycosis or other active infectious diseases

• Subjects with non-controlled diabetes, hypertension, digestive ulcer or glaucoma

• Subjects with posterior subcapsular cataracts

• Subjects with peripheral neuropathy of ≥Grade 2

• Subjects with any history or concurrent conditions which the Principal Investigator / subinvestigators consider inappropriate for participation in this study, and subjects with a serious disease or a mental disease, which is considered to become more risky if the subjects participate in this study.

• Subjects with a history of desquamative (blistering) rash while taking thalidomide

• Subjects with a history of using lenalidomide

• Subjects who have used thalidomide within 28 days before starting the study drugs

• Subjects with a history of hypersensitivity to dexamethasone

• Subjects who discontinued treatment due to grade 3 or 4 toxicity from high dose dexamethasone

• Subjects with a surgical wound after a visceral surgery performed recently

• Subjects who have undergone radiation therapy within 14 days before starting the study drugs

• Subjects who have used a chemotherapeutic agent, an immunomodulating agent or a study drug (a drug not commercially available) intended for the treatment of multiple myeloma (MM) within 28 days before starting the study drug

• Subjects with any history or concurrent conditions of malignancies, other than MM, unless the subject has been free of the disease for 3 years:

  • Basal cell carcinoma of the skin,
  • Squamous cell carcinoma of the skin,
  • Carcinoma in situ of the cervix,
  • Carcinoma in situ of the breast,
  • Incidental histologic finding of prostate cancer Tumor, Lymph Nodes, Metastasis (TNM) stage of T1a or T1b)

• Known human immunodeficiency virus (HIV) infection or HIV-1 positivity

• Subjects who have been diagnosed as an hepatitis b virus (HBV) carrier

• Subjects who are applicable to any of the following abnormal laboratory findings:

  • Absolute neutrophil count : < 1,000 /μL (1.0×10^9 /L)
  • Platelet count: <75,000 /μL (75×10^9 /L)
  • Aspartate aminotransferase (AST)/serum glutamic oxaloacetic transaminase (SGOT) or alanine aminotransferase (ALT)/serum glutamic-pyruvic transaminase (SGPT): > 3.0 times the upper limit of the standard range
  • Creatinine clearance: < 30 mL/min

Safety Population = includes all participants who received at least one dose of study drug

Day 1 of study drug through 28 days after the last dose of study drug; maximum treatment duration was 60.3 weeks