Usefulness of quantitative assessment of the WT1 gene transcript as a marker for minimal residual disease detection

Abstract
These data prompted us to analyze by RQ-PCR the WT1 transcript amount in 18 patients (7 acute myeloid leukemia, 2 acute lymphoblastic leukemia, and 9 chronic myelogenous leukemia) before and after allogeneic BMT. The procedure used has been previously described in detail, and ABL was used as a reference gene.2 In agreement with the data of Ogawa et al,1 we are able to confirm that the determination of the WT1 transcript amount can represent a useful marker to monitor the persistence or the reappearance of leukemic cells after allogeneic BMT and that increasing amounts of WT1 transcript are predictive of relapse. Indeed, as already demonstrated by Ogawa et al,1 an increase of WT1 expression above the upper threshold found in controls (see Figure 1) was detected in 5 of 18 patients, and all 5 of the patients relapsed after a period ranging from 1 to 5 months. By contrast, none of the patients who remain within the normal range of WT1 expression relapsed.