ARM I: Patients receive X box binding protein-1(XBP1)-US/XBP1-SP/CD138/CS1 multipeptide vaccine PVX-410 subcutaneously (SC) every 2 weeks for 3 doses before transplant and on days 1, 15, and 30 and tetanus and influenza vaccines intramuscularly (IM) with the 3rd dose vaccine dose before transplant. Patients receive conditioning regimen comprising high-dose melphalan intravenously (IV) on day -2 and undergo autologous CD34 hematopoietic stem cell transplant (HSCT) on day 0. Patients also receive autologous donor lymphocyte (DLI) IV on day 2.