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Objective: Of 140 chronic myeloid leukemia patients responding to imatinib with complete cytogenetic remission, 32 exhibited a plateau of BCR-ABL values at >or=0.1% level in a minimum of three subsequent samples (minimal duration, 6 - 9 months). Median follow-up of unchanged BCR-ABL transcript level was 12 months (range, 6 - 64). We tested this group of patient for BCR-ABL mutations to reveal resistance development and to evaluate the risk of disease progression., Materials and Methods: Altogether, 134 samples of peripheral blood of these 32 patients were tested for mutation in BCR-ABL kinase domain., Results: Mutation was detected by direct sequencing in 9 of 32 patients (28%). Loss of complete cytogenetic remission or 1 log rise of BCR-ABL was observed in five of nine patients at a median of 5 months (range, 4-17) since first detection of mutation. One patient with no mutation relapsed 12 months after the start of the BCR-ABL plateau. In 5 of 32 patients without mutation (16%), BCR-ABL level significantly decreased after the first plateau to levels that stayed unchanged for a median of 11 months (range, 7-28)., Conclusion: We show here that the BCR-ABL constant levels >or=0.1% (BCR-ABL plateau) in imatinib-responding patients may indicate mutation analysis. This approach highly reduces the number of examinations for mutation in chronic myeloid leukemia responders and may present cost-effective alternative applicable in clinical practice.

In recent years, several independent prognostic factors in cytogenetically normal acute myeloid leukemia (CN-AML) have been reported. Mutations or the expression levels of certain genes have been often used as molecular markers for prediction of a patient's outcome or for evaluation of treatment outcome. One of them, the gene encoding CCAAT/enhanced binding protein alpha (CEBPA), plays an important role in myeloid differentiation and, when mutated, confers a favorable prognosis for patients with CN-AML. Complete mutation screening of the CEBPA gene is therefore beneficial and requires fast, precise, and sensitive diagnostic tools. Thus, for routine diagnostics, we developed a screening method using high-resolution melt curve analysis prior to direct sequencing, where only positive samples (according to reference) are further sequenced. With this approach, all positive and negative patients were successfully distinguished, and the results obtained were in absolute concordance with the direct sequence analysis.