Idiotype-specific immunotherapy in multiple myeloma: suggestions for future directions of research.

Multiple myeloma (MM) remains a difficult-to-cure cancer and less than 20% of patients achieve long-term survival irrespective of the treatment delivered, including high-dose chemotherapy. Thus, new treatment modalities are urgently needed. Myeloma cells produce a monoclonal immunoglobulin (Ig) which is a truly tumor-specific antigen. The tumor-specific antigenic determinants are localized in the variable regions of the monoclonal Ig and are termed idiotopes (Id). Id-vaccination, i.e., vaccination with the autologous monoclonal Ig, has been performed in MM patients in order to elicit tumor-specific immune responses and possibly elimination of myeloma cells. However, clinical trials have not given the promising results obtained in mice. This review focuses on tolerance mechanisms that might hinder Id-specific immune responses in MM patients. New strategies for Id vaccination in MM are discussed.