Almost all patients with multiple myeloma (MM) who survive initial treatment will eventually relapse and require further therapy. Relapsed or refractory MM is usually identified on routine surveillance performed during treatment or after the completion of therapy. (See "Evaluating response to treatment of multiple myeloma", section on 'Response criteria'.)
Treatment options for patients with relapsed or refractory MM include hematopoietic cell transplantation (HCT), a rechallenge of the previous chemotherapy regimen, or a trial of a new regimen. Factors used to determine the choice of therapy include a risk stratification of myeloma (ie, high or standard risk disease), prior treatments used, and the duration of response to these treatments.
The treatment of relapsed or refractory MM will be discussed here. The initial treatment of MM with chemotherapy and the use of HCT are discussed separately. (See "Determination of initial therapy in patients with multiple myeloma" and "Autologous hematopoietic cell transplantation in multiple myeloma" and "Allogeneic hematopoietic cell transplantation in multiple myeloma".)
EVALUATION OF SUSPECTED RELAPSE OR RESISTANCE
Definitions — Patients undergoing chemotherapy for multiple myeloma (MM) are evaluated before each treatment cycle and periodically after the completion of therapy to monitor their disease status. The preferred monitoring method is the measurement of monoclonal (M) protein in the serum or urine and serum free light chain (FLC) levels . An increase in one of these measurements raises the suspicion of progressive disease. (See "Evaluating response to treatment of multiple myeloma".)
Progressive disease (PD) is defined as a 25 percent increase from the lowest response value in any of the following: