[H-oCT1 gene expression as a predictor of major and complete molecular response to imatinib of chronic myeloid leukemia. Single center experience]

Chronic myeloid leukemia is a clonal disorder caused by formation of chimeric BCR/ABL gene and bcr/abl protein with abnormally high tyrosine kinase activity. The use of imatinib--the first tyrosine kinase inhibitor results in achievement of hematologic, cytogenetic and molecular response in majority of patients. However despite its high efficacy not all patients respond to imatinib, whereas others lose an initial response. Imatinib is a substrate of human organic cation transporter-1 (hOCT1), which actively delivers the drug into the cells, and efflux transporters. To identify potential imatinib failures, we investigated the expression of hOCT1 using real-time quantitative reverse transcription-polymerase chain reaction (RQ-PCR) in 155 CML patients. Patients with low pretreatment hOCT1 expression had inferior major and complete molecular response (MMR and CMR) rates (p = 0.0001, p = 0.0001) achieved any time or at 18 months of imatinib treatment (p = 0.023, p = 0.022). The expression of hOCT1 is important in determining the clinical response to imatinib. The analysis of hOCT1 expression by RQ-PCR is convenient and clinically available, and the results could help in introduction of optimal first line therapy in CML patients.

[Genotyping and minimal residual disease study in children with acute myeloid leukemia: preliminary results]

The aim of the paper is to present the initial results of molecular examination which was started in 2006 for children with acute myeloid leukemia. Better knowledge of biology of this disease, can result in establishing of new risk factors what allows more precise patient stratification to different therapeutic groups. Study was obtained patients until to 18 years of age treated according to AML-BFM 2004 INTERIM protocol in 14 centers of the Polish Pediatric Leukemia/Lymphoma Study Group. Mononuclear cells were collected from bone marrow on time points established according to the AML-BFM 2004 INTERIM protocol. Collected cells were isolated on Ficoll gradient, and RNA and DNA were isolated using TRIZOL reagent. To synthesize cDNA an amount of 1 mg of total RNA was used. To perform quantitative RT-PCR and RQ-PCR reactions 4 fusion gene transcripts (AML1-ETO, CBFb-MYH11, PML-RARA /subtype bcrl and bcr3/) were used according to the protocol established by Europe Against Cancer Program. An expression of WT1 gene was tested additionally. An analysis of ABL control gene was used to normalize of achieved results. Determination of duplication of FLT3 gene in DNA sample was performed with starters complementary to JM region. Genotyping was performed in 75 patients with acute myeloid leukemia so far. AML1-ETO fusion gene transcript was found in 14 patients (19%). PML-RARA (subtype bcr3) and CBFB-MYH11 gene transcripts were detected in 3 (4%) and 3 (4%) patients, respectively. Duplication of FLT3 gene was found in 4 (5.3%) cases. Between 67 tested children over expression of WT1 was present in 51 patients (76%). Analysis of MRD level in subsequent time points showed systematic decrease of number of fusion gene transcript copies and gene WT1 expression. To establish the rate of molecular marker presence in AML in children and the influence of the presence of MRD on the treatment results as well, the study has to be conducted on a larger group of patients with longer follow-up.