The detection of wt-1 transcripts is not associated with an increased leukemic relapse rate in patients with acute leukemia after allogeneic bone marrow or peripheral blood stem cell transplantation

We studied the role of wt-1 as a minimal residual disease (MRD) marker in 4 6 patients with acute leukemia (AL) (1st CR n = 24; 2nd CR n = 9, in relaps e n = 13) after allogeneic bone marrow or peripheral blood stem cell transp lantation. Prior to allogeneic transplant, wt-1 transcripts were detected b y PCR in 38 of 46 patients (83%) with AL. After transplant, in 14 of 38 pat ients (37%) wt-1 transcripts were detected in at least one PCR assay at a m edian of 12 months post transplant (range 1-89 months). Twelve of the 38 pa tients relapsed after transplant, but only seven of the 12 were wt-1 positi ve after transplant. In five relapsing patients the wt-1 test remained nega tive 0 to 3 months prior to relapse. On the other hand, only seven of 14 pa tients with a positive test for wt-1 after transplant, relapsed consecutive ly. In 17 of the 46 study patients chromosomal abnormalities had been found prior to transplant (AML-M4eo with inv16 n = 7, AML-M2 with t(8;21) n = 3, AML-M3 with t(15;17) n = 1, AML-M5 with t(4;11) n = 1, ALL with t(9;22) n = 5). In these 17 patients, we analyzed the wt-I transcript simultaneously with a specific chimeric transcript characteristic for the corresponding ch romosomal abnormality. In 32 of 45 samples (71%) the results for the MRD ma rker and wt-1 transcript were concordant, but differed in 13 patients. We c onclude that detection of wt-1 transcripts does not predict leukemic relaps e reliably and is therefore not a suitable MRD marker in patients with acut e leukemia after allogeneic BM or PBSC transplantation.