Ixazomib + Pomalidomide + Dexamethasone In MM

This is a Phase I/II clinical trial. A Phase I clinical trial tests the safety of an investigational drug and tries to define the appropriate dose of the investigational drug to use for further studies. "Investigational" means that the drug is being studied. The FDA has approved both pomalidomide and ixazomib individually for the treatment of multiple myeloma. Dexamethasone, also FDA approved, is a type of steroid and is usually combined with other chemotherapy for the treatment of blood cancers, such as myeloma and leukemias. * Ixazomib targets a part of cells called proteasomes. It works by slowing down or blocking proteasomes from doing their job of digesting proteins. In myeloma cells, there is a greater need for proteasomes to digest proteins; the buildup of excess proteins causes cell death. * Pomalidomide has also been shown to cause tumor cell deaths. Dexamethasone can stop white blood cells from traveling to areas myeloma cells are causing damage. When combined with myeloma drugs, it sometimes makes those drugs work better. In this research study, the investigators are: * Testing the safety of ixazomib when given with pomalidomide and dexamethasone * Pomalidomide and ixazomib are given individually for the treatment of multiple myeloma. Dexamethasone is also given for multiple myeloma * Ixazomib when combined with pomalidomide and dexamethasone may help control the disease * Ixazomib is FDA approved to treat multiple myeloma * The investigators are looking for the highest dose of ixazomib that can be given safely in combination with pomalidomide and dexamethasone