Collection of Transplant Stem Cells for Plasma Cell Myeloma

Background: \- One beneficial treatment for plasma cell myeloma is high-dose chemotherapy followed by stem cell transplant. Researchers want to collect stem cells from the blood for later transplant. Objectives: \- To collect stem cells for transplant as part of treatment for plasma cell myeloma. Eligibility: \- Individuals at least 18 years of age who will have chemotherapy and stem cell transplant for plasma cell myeloma. Design: * Participants will be screened with a physical exam and medical history. Blood and urine samples will be collected. * Participants will have filgrastim injections for 5 days before collection. This will move stem cells from the bone marrow to the blood. * Participants will have apheresis to collect the stem cells. * Participants who need additional apheresis procedures to collect stem cells will have filgrastim and a dose of plerixafor to improve the collection yield.