Monitoring twenty-six chronic myeloid leukemia patients by BCR-ABL mRNA level in bone marrow:a single hospital experience.

Chronic myeloid leukemia (CML) is caused by the BCR-ABL oncogene. The Philadelphia chromosome (Ph) from a reciprocal translocation, t(9;22) (q34;q11) causes a fusion gene, BCR-ABL, that encodes a constitutively active tyrosine kinase. Treatment of CML by imatinib is effective to control the tyrosyl phosphorylation of the protein related to the cell signaling. BCR-ABL mRNA is overexpressed in the minimal residual disease (MRD), known as an early sign of relapse. Between December 2005 and June 2008, we measured BCR-ABL mRNA levels in the bone marrow (BM) from patients by quantitative real-time polymerase chain reaction (RQ-PCR) in Aomori Prefectural Central Hospital. Eighty-six samples from 26 patients were collected. Among the 26 CML patients, 11 patients (42%) were in the pretreatment group. Seven (64%) of the 11 patients achieved complete molecular response (CMR). In the post-treatment group consisting of the remaining 15 patients, 9 (60%) patients achieved CMR. The patients receiving imatinib at a dose over 300 mg per day required 13 (6-77) months [median (range)] to achieve CMR. On the other hand, the patients receiving a dose below 300 mg per day required 29.5 (11-84) months [median (range)]. When BCR-ABL mRNA was detected during the treatment course of patients with CMR, careful observation of BCR-ABL mRNA was useful for tracking the clinical course of patients. In conclusion, the BCR-ABL mRNA level was useful for monitoring the clinical course in 26 patients with CML.

WT1 mRNA level in peripheral blood is a sensitive biomarker for monitoring minimal residual disease in acute myeloid leukemia.

The Wilms' tumor gene 1 (WT1) encodes a transcription factor that is involved in normal cellular development and cell survival. WT1 mRNA is overexpressed in the minimal residual disease (MRD) of patients with hematopoietic malignancy patients, particularly acute myeloid leukemia (AML). MRD represents the condition with the low levels of leukemia cells in the bone marrow and is known as a sign of recurrence. In hematopoietic malignancies, definition of remission is based on the lack of MRD at submicroscopic level. Between December 2005 and June 2008, we started to measure WT1 mRNA levels in the peripheral blood (PB) from patients by quantitative real-time PCR in Aomori Prefectural Central Hospital. Three hundreds and eight samples from 95 patients were evaluated. The patients included AML (55 patients), acute lymphoblastic leukemia (11), myelodysplastic syndrome (20), malignant lymphoma (5), chronic myeloid leukemia (1), prostatic carcinoma (1), and leukopenia (2). Among the 55 AML patients, 21 patients were pretreated with remission induction therapy. In the clinical course of 21 patients, timely therapeutic approaches could be started for relapse by the early detection of WT1 mRNA overexpression before the morphological findings were apparent. Monitoring WT1 mRNA is helpful to identify patients at high-risk relapse. High overall survival rate (71.2%, 15/21, median: 24.6 months, range 1.1-35.6 months) was achieved in 3 years. The overall survival rate of 34 post-treatment patients was 61.7% (median: 23.5 months, range 0.13-126.5 months after treatment start). In conclusion, the WT1 mRNA level is a sensitive biomarker for monitoring MRD.