SMAC Mimetic LCL161 Alone or With Cyclophosphamide in Treating Patients With Relapsed or Refractory Multiple Myeloma

This phase II trial studies how well second mitochondrial-derived activator of caspases (SMAC) mimetic LCL161 alone or with cyclophosphamide works in treating patients with multiple myeloma that has returned or does not respond to treatment. Biological therapies, such as SMAC mimetic LCL161, may stimulate the immune system in different ways and stop cancer cells from growing. Drugs used in chemotherapy, such as cyclophosphamide, work in different ways to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. It is not yet known whether giving SMAC mimetic LCL161 alone or with cyclophosphamide is more effective in treating multiple myeloma.