Combination Study of Pomalidomide, Marizomib, and Low-Dose Dexamethasone in Relapsed and Refractory Multiple Myeloma

This is a Phase 1 clinical trial to evaluate a new combination of drugs for the treatment of relapsed or refractory (drug-resistant) multiple myeloma. The drugs being studied are: * Pomalidomide (POMALYST®) is a drug that affects the immune system (an immunomodulatory drug) that has been approved by the United States (US) Food and Drug Administration (FDA) for the treatment of multiple myeloma. * Marizomib is an investigational drug being developed by Triphase that is being studied for the treatment of multiple myeloma. Investigational drugs are drugs that have not yet been approved by health authorities, such as the FDA, for general use but have been approved for use in specific clinical studies. Marizomib inhibits a cellular machine called the proteasome, which destroys unnecessary or damaged proteins. Other proteasome inhibitors have been shown to be effective in the treatment of multiple myeloma. * Dexamethasone is a corticosteroid drug that affects the immune system (an immunomodulatory drug) that has been approved by the FDA for the treatment of multiple myeloma. This is the first study to evaluate the three-drug combination of pomalidomide (POM), marizomib (MRZ), and dexamethasone (LD-DEX) in humans. Pomalidomide, alone or in combination with dexamethasone, is approved by the FDA for the treatment of relapsed or refractory multiple myeloma. The primary objective of this study is to determine the best drug dosing levels for this three-drug combination, including the highest safe doses and/or the recommended doses for future clinical studies of this drug combination. The secondary purposes of this study are to determine the safety of this drug combination and its effectiveness in treating relapsed or refractory multiple myeloma. The study will include examination of levels of all three drugs in the blood during various time points during treatment.