The object of cancer vaccine is to activate the immune system so that it attacks and kills the tumor cells. Multiple myeloma cells produce a particularly good target for immune attack, ie, the unique myeloma protein produced by the multiple myeloma cells. We have shown in a mouse model that T lymphocytes can recognize the myeloma protein and successfully combat the multiple myeloma cells. However, if the multiple myeloma cells for some reason evade the initial attack, the increasingly high myeloma protein concentration will in the long run incapacitate (tolerize) the T cells. We wish to see if we can maneuver the multiple myeloma patient into a "rematch" situation where T cells once again can respond to vaccination and attack residual multiple myeloma cells. Specifically, we will monitor myeloma protein concentrations in patients undergoing high-dose chemotherapy with autologous stem cell support. We will then test if myeloma protein concentrations decrease sufficiently so that myeloma protein-specific T cells reemerge. In addition, more powerful strategies for vaccination will be developed.