A Phase 3, Multicenter, Randomized, Open-Label Study to Compare the Efficacy and Safety of Pomalidomide in Combination With Low-Dose Dexamethasone Versus High-Dose Dexamethasone in Subjects With Refractory Multiple Myeloma or Relapsed and Refractory Multiple Myeloma and Companion Study

Inclusion Criteria:

* Must be ≥ 18 years of age
* Subjects must have documented diagnosis of multiple myeloma and have measurable disease
* Subjects must have undergone prior treatment with ≥ 2 treatment lines of anti-myeloma therapy
* Subjects must have either refractory or relapsed and refractory disease defined as documented disease progression during or within 60 days of completing their last myeloma therapy
* All subjects must have received at least 2 consecutive cycles of prior treatment that included lenalidomide and bortezomib
* All subjects must have failed treatment with both lenalidomide and bortezomib in one of the following ways: 1) Documented progressive disease on or within 60 days of completing treatment with lenalidomide and/or bortezomib, or 2) In case of prior response \[≥ partial response (PR)\] to lenalidomide or bortezomib, subjects must have relapsed within 6 months after stopping treatment with lenalidomide and/or bortezomib-containing regimens, or 3) Subjects who have not had a ≥ minimal response (MR) and have developed intolerance/toxicity after a minimum of two cycles of lenalidomide- and/or bortezomib-containing regimen
* Patients must have received adequate prior alkylator therapy
* Eastern Cooperative Oncology Group (ECOG) performance status score of 0, 1, or 2
* Females of childbearing potential (FCBP) must not become pregnant for 28 days prior to initiation of study drug, during the study, and for 28 days after discontinuation
* Females must agree to abstain from breastfeeding during study participation and 28 days after study drug discontinuation
* Males must agree to use a latex condom during any sexual during the study and for 28 days following discontinuation from this study
* Males must also agree to refrain from donating semen or sperm while on pomalidomide and for 28 days after discontinuation from this study

Exclusion Criteria:

* Any of the following laboratory abnormalities:

  * Absolute neutrophil count (ANC) \< 1,000/μL
  * Platelet count \< 75,000/ μL for subjects in whom \< 50% of bone marrow nucleated cells are plasma cells
  * Creatinine clearance \< 45 mL/min
  * Corrected serum calcium \> 14 mg/dL
  * Hemoglobin ≤ 8 g/dL
  * Serum glutamic oxaloacetic transaminase (SGOT)/ aspartate aminotransferase (AST) or transaminase, serum glutamic pyruvic (SGPT)/ alanine aminotransferase (ALT) \> 3.0 x upper limit of normal (ULN)
  * Serum total bilirubin \> 2.0 mg/dL
* Previous therapy with pomalidomide
* Hypersensitivity to thalidomide, lenalidomide, or dexamethasone
* Resistance to high-dose dexamethasone used in the last line of therapy
* Peripheral neuropathy ≥ Grade 2
* Subjects who received an allogeneic bone marrow or allogeneic peripheral blood stem cell transplant
* Subjects who are planning for or who are eligible for stem cell transplant
* Subjects with any one of the following: 1) Congestive heart failure, 2) Myocardial infarction within 12 months prior to starting study treatment, 3) Unstable or poorly controlled angina pectoris, including Prinzmetal variant angina pectoris
* Subjects who received any of the following within the last 14 days of initiation of study treatment: 1) Plasmapheresis, 2) Major surgery, 3) Radiation therapy, 4) Use of any anti-myeloma drug therapy
* Use of any investigational agents within 28 days or 5 half-lives (whichever is longer) of treatment
* Subjects with conditions requiring chronic steroid or immunosuppressive treatment
* Any condition including the presence of laboratory abnormalities, which places the subject at unacceptable risk if he/she were to participate in the study
* Incidence of gastrointestinal disease that may significantly alter the absorption of pomalidomide
* Subjects unable or unwilling to undergo antithrombotic prophylactic treatment
* Any serious medical condition, laboratory abnormality, or psychiatric illness that would prevent the subjects from signing the informed consent form
* Pregnant or breastfeeding females
* Known human immunodeficiency virus (HIV) positivity or active infectious hepatitis A, B, or C