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 46 patients with acute leukemia (AL) (1st CR n = 24; 2nd CR n = 9, in relapse n = 13) after allogeneic bone marrow or peripheral blood stem cell transplantation. Prior to allogeneic transplant, wt-1 transcripts were detected by PCR in 38 of 46 patients (83%) with AL. After transplant, in 14 of 38 patients (37%) wt-1 transcripts were detected in at least one PCR assay at a median of 12 months post transplant (range 1-89 months). Twelve of the 38 patients relapsed after transplant, but only seven of the 12 were wt-1 positive after transplant. In five relapsing patients the wt-1 test remained negative 0 to 3 months prior to relapse. On the other hand, only seven of 14 patients with a positive test for wt-1 after transplant, relapsed consecutively. 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 chromosomal abnormality. In 32 of 45 samples (71%) the results for the MRD marker and wt-1 transcript were concordant, but differed in 13 patients. We conclude that detection of wt-1 transcripts does not predict leukemic relapse reliably and is therefore not a suitable MRD marker in patients with acute leukemia after allogeneic BM or PBSC transplantation.