The use of CD138 positively selected marrow samples increases the applicability of minimal residual disease assessment by PCR in patients with multiple myeloma

Abstract

We have evaluated the use of CD138+ positively selected bone marrow samples to identify a molecular target for minimal residual disease assessment by polymerase chain reaction (PCR) in 25 untreated patients with multiple myeloma. A fraction of each sample was used for CD138+ selection, and the rest served as a reference control. VDJH, DJH, and Kde gene rearrangements were tested for amplification according to the BIOMED-2 Concerted Action. PCR products were directly sequenced in an automated ABI 3130 DNA sequencer using Big-Dye terminators. Within the CD138+ selected group, VDJH rearrangements were detected in all cases (100%), DJH in 16 (64%), and Kde in 18 (72%) cases; whereas in the control samples, VDJH, DJH, and Kde rearrangements were detected in 19 (76%), 11 (44%), and 12 (48%) cases, respectively. After sequencing, 24 (96%) cases within the CD138+ group had a PCR target for MRD detection compared with 15 (60%) cases in the control group. We conclude that the use of CD138+ positively selected bone marrow samples increases the applicability of minimal residual disease studies by PCR in patients with multiple myeloma.