Maintenance treatment of multiple myeloma.

In multiple myeloma (MM), low-cost maintenance treatment has some attractions, since maintenance of a small tumor is usually compatible with a fairly healthy state. However, the great majority of the studies of maintenance treatment have failed to show any clinical benefit. Based on simple theoretical consideration, it is shown that in MM response duration and survival are affected primarily by the residual tumor mass after primary treatment, and by the kinetics of the tumor. Continuation of maintenance treatment is likely to have a moderate effect. The main cause of that is identified in the presence or in the development of a substantial proportion of drug-resistant cells. Preliminary data suggest that only alpha-interferon can be useful for maintenance, and that it can act by slowing down the kinetics of the tumor.