DETECTION OF CIRCULATING TUMOR-CELLS IN MULTIPLE-MYELOMA BY A PCR-BASED METHOD

Multiple myeloma (MM) is a B-cell malignancy characterized by clonal e xpansion of plasma cells producing monoclonal immunoglobulins. It has been regarded as a tumor typically involving only the bone marrow. The existence of circulating tumor cells has been suggested from phenotyp ic and genotypic studies. However, this issue is still controversial d ue to the limitations of the methods so far used. We describe a novel polymerase chain reaction (PCR) based method using clone-specific immu noglobulin heavy-chain gene sequences as tumor markers. From such sequ ences patient-specific oligonucleotide primers and probes were generat ed, and used to detect tumor cells. Seven MM patients were selected fo r this study, and tumor cells were found in all peripheral blood sampl es. The demonstration of circulating tumor cells suggests some caution when using peripheral blood for autograft procedures, even though its contamination is lower than bone marrow. In conclusion, we describe a specific and sensitive PCR-based method for detecting minimal disease which is of general applicability to all lymphoid malignancies transc ribing rearranged immunoglobulin heavy-chain genes.