Clinical relevance of minimal residual disease monitoring in mature B-cell disorders: role of qualitative and quantitative PCR-based strategies

Although current treatments can induce clinically complete remissions in a high proportion of patients with mature B-cell disorders (MBCD), most of them actually relapse, because of the persistence of residual tumour cells which are undetectable using conventional diagnostic procedures. Qualitative polymerase-chain-reaction (PCR) based methods are increasingly used for minimal residual disease (MRD) detection, and provide useful prognostic information. In recent years these assays have been integrated by reliable quantitative PCR-approaches that are likely to further increase the prognostic impact of MRD analysis in MBCD. In this review current approaches for qualitative and quantitative detection of MRD in MBCD are summarised. In addition, the prognostic aspects of molecular monitoring in the autologous and allogeneic transplantation setting are summarised. The experience accumulated over the past decade shows that PCR analysis has a prognostic impact in most MBCD especially when treated with high-dose regimens. Major advantages coming from the introduction of molecular monitoring in clinical programs have been: i) a rapid evaluation of the anti-tumour activity of innovative treatments; and ii) an early identification of patients with a high-risk of disease recurrence.