Elevated levels of WT1 transcripts in bone marrow harvests are associated with a high relapse risk in patients autografted for acute myeloid leukaemia

Relapse postautograft in acute myeloid leukaemia ( AML), may in part arise from leukaemia cells present in the bone marrow ( BM) inoculum, and the level of minimal residual disease ( MRD) in BM harvests used for autografting may therefore be clinically important. We have used the WT1 transcript as a marker of MRD, which was quantitated by RQ- PCR, in the BM harvests of 24 patients receiving an ABMT for AML. ABL was used as a control gene with WT1 level being normalised to 105 copies of ABL per sample. Median WT1 level was 651 copies ( range = 113 - 32 700) for the 13 patients with relapse- free survival ( RFS) of less than 5 years, and 174 ( range = 0 - 1900) for patients with RFS of over 5 years postautograft ( P < 0.04). The RFS was 10.5 months for patients with WT1 level of > 2000 copies ( n = 5), and has not yet been reached for patients with WT1 level < 2000 ( n = 21), at a median follow- up of 92 months ( P < 0.05). We show that elevated levels of MRD in BM harvests are associated with a higher relapse risk in patients autografted for AML.