Molecular Monitoring of Minimal Residual Disease in the Peripheral Blood of Patients with Multiple Myeloma

Abstract

The prognostic relevance of minimal residual disease (MRD) in patients with multiple myeloma is still an open question. In bone marrow, the level of residual myeloma cells is associated with treatment outcome, but the role of clonotypic cells in the peripheral blood (PB) for the prognosis of patients is not identified yet. In this study, we retrospectively analyzed MRD by quantitative real-time IgH-PCR (IgH-qPCR) in the PB of 42 patients undergoing high-dose therapy followed by autologous PB stem cell transplantation as first-line therapy for multiple myeloma. The MRD level of PB samples was in median 40-fold lower than in bone marrow samples, collected on the same day, with a wide intra- and interindividual variation (range, .4- to 4628-fold). The presence or absence of detectable MRD levels in PB did not correlate with the serological remission status. Still, patients with negative PCR results in PB 3 months after high-dose therapy and PB stem cell transplantation had lower International Staging System stage (P = .01), lower levels of β2-microglobulin (P = .02), higher hemoglobin levels (P = .01), and a prolonged event-free (median, 15 versus 4 months; P = .004) and overall (median, 52 versus 17 months; P = .03) survival. Importantly, by sequential monitoring of clonotypic cells in PB, in 19 of 29 patients (66%) with progressive disease, an increase of the 2IgH/β-actin ratio of at least 1 log step could be detected in median 4 months (range, .8 to 13 months) before the relapse was diagnosed on the basis of the European Group for Blood and Marrow Transplantation criteria. These patients with a molecular relapse in PB before a serological relapse had a significantly shorter overall survival than other patients (median, 17 months versus median not reached, P = .02). In conclusion, IgH-qPCR is a sensitive technique for the detection of clonotypic cells in PB, which precede clinical relapse. Future studies are needed to evaluate whether these circulating tumor cells play a role in promoting disease recurrence.

Quantitative polymerase chain reaction analysis with allele-specific oligonucleotide primers for individual IgH VDJ regions to evaluate tumor burden in myeloma patients

“…All raw data are shown in a Supplementary Table E2 (online only, available at www.exphem.org). The ASO-PCR is powerful and sensitive for detecting MRD [4,[7][8][9][13][14][15][16][17], but it has some limitations. One problem is the cost of designing patient-specific ASO primers.…”

Long-term results of the GIMEMA VEL-03-096 trial in MM patients receiving VTD consolidation after ASCT: MRD kinetics' impact on survival

“…3 Both these approaches proved highly predictive for outcome discrimination in different therapeutic settings, including autologous stem cell transplantation (ASCT) and allogeneic transplantation, with or without the inclusion of novel non-chemotherapeutic agents. [4][5][6][7][8][9][10][11][12] Our group already reported some full MRD responses (18% by nested PCR) following a consolidation program with bortezomib, thalidomide and dexamethasone in 39 MM patients, obtaining at least very good partial remission after ASCT: moreover, patients achieving a low post-consolidation tumor burden by real-time quantitative (RQ)-PCR had lower risk of clinical relapse. 5 However, our work, along with other available reports, had a too short follow-up to address additional relevant issues such as (1) the long-term outcome of patients achieving MRD responses in the absence of further treatment and particularly the impact of MRD response on overall survival (OS); (2) the prognostic impact of MRD kinetics during post-consolidation phases and in particular the outcome of patients experiencing MRD reappearance; (3) the time lag between MRD reappearance and clinical relapse.…”

Minimal residual disease testing after stem cell transplantation for multiple myeloma

“…28 This technique is applicable in 90% of patients and the sensitivity is sufficient to detect 1 atypical plasma cell in 10 000 to 100 000 total plasma cells (10 − 4 to 10 − 5 ) in the BM. [28][29][30][31] Antibody panel design is an essential and difficult part of MFC testing for MRD in patients with MM. Identification of appropriate antigens, panel testing for optimal monoclonal antibody and fluorochrome combinations, and validation in clinical trials must take place before a standard panel can be established.…”

“…38 As an alternative, ASO realtime quantitative PCR provides an accurate quantification of residual disease, thus overcoming the problem. Several reports using this technique have been published, showing effective outcome discrimination in the transplant setting 29,[39][40][41][42][43] (Table 5). …”