Quantitative polymerase chain reaction (PCR) with patient-specific, allele-specific
oligonucleotide (ASO) primers for individual
immunoglobulin H VDJ region (ASO-PCR) amplification was performed using several sources of clinical material, including
mRNA from peripheral blood cells (PBMNCs), whole bone marrow cells (BMMNCs), and the CD20+ CD38- B-cell population in bone marrow, as well as
cell-free DNA from the sera of patients with
multiple myeloma (MM). We designed the ASO primers and produced sufficient PCR fragments to evaluate
tumor burden in 20 of 30 bone marrow samples at diagnosis. Polymerase chain reaction amplification efficiency depended on primer sequences because the production of ASO-PCR fragments did not correlate with serum M-
protein levels. However, the ASO-PCR levels in BMMNCs showed statistically significant correlations with those in PBMNCs and CD20+ CD38- B-cells. The good association between the BMMNC and PBMNC data indicated that PBMNCs could be a suitable source for monitoring
minimal residual disease (MRD). In the case of
cell-free DNA, ASO-PCR levels showed a unique pattern and remained high even
after treatment. Because the sequence information for each ASO-PCR product was identical to the original, the
cell-free DNA might also be useful for evaluating MRD. Moreover, the ASO-PCR products were clearly detected in 17 of 22
mRNA samples from CD20+ CD38- populations, suggesting that MM clones might exist in relatively earlier stages of B cells than in plasma cells. Thus, ASO-PCR analysis using various clinical materials is useful for detecting MRD in MM patients as well as for clarifying MM pathogenesis.