Minimal residual disease monitoring in multiple myeloma

Traditionally, response to treatment in multiple myeloma has been measured by the serum or urinary paraprotein and the percentage of plasma cells in the bone marrow. The use of allogeneic and autologous transplantation has increased the complete response rate and overall survival in patients with myeloma, and in order to assess the effects of such treatments accurately more sensitive methods for assessing residual disease have been introduced. The aim of this chapter, therefore, is to describe the available techniques to assess response, monitor residual disease and predict relapse in myeloma. The traditional techniques of paraprotein measurement using electrophoresis and immunofixation are compared with more sensitive approaches involving the polymerase chain reaction for detecting rearrangements of the immunoglobulin heavy-chain region and flow cytometry for detecting malignant plasma cells. Emphasis is placed on the advantages and disadvantages of each method and its utility in the clinical setting.