FLT3/ITD and ras-oncogene in acute myeloid leukaemia analyzed in ration to immunophenotype and cytogenetic findings
aSchool of Medicine, Institute of Haematology, University of Belgrade, Belgrad, Yugoslavia, bSchool of Medicine, Institute of Biology, University of Belgrade, Belgrad, Yugoslavia, cInstitute of Genetic Engineering, Belgrad, Yugoslavia, dSchool of Medicine University of Kragujevac, Serbia, Yugoslavia
AIM Numerical and structural chromosomal abnormalities are commonly observed in acute and chronic hematological malignancies. Near tetraploidy and complete tetraploidy have been infrequently reported, mostly in patients with acute lymphoblastic leukaemias while they are rare in acute myeloid leukemias (AML), accompanied almost universally with large and bizarre blasts in peripheral blood. Based on this we present three cases of near tetraploid karyotype while lacking typical cytogenetic findings which characterize acute myeloid leukaemias. We examined the expression of the receptor tyrosine kinase (TRK) FLT3/ITD and ras-oncogene and analyzed these findings with AML immunophenotype at end of disease course. METHODS AML patients were classified using FAB criteria by immunophenotype. Conventional karyotype was performed on bone marrow cells after direct preparation and/or unstimulated 24-48h short-term culture. RT-PCR analysis were used for detection of expression of FLT3/ITD, FLT3 D835 mutation or RAS-oncogene. RESULTS From 326 diagnosed AML patients, only three male (about 1.00 %) shows near tetraploid karyotype. No organomegaly or lymph node enlargement was found by physical examination at presentation. At presentation, mean values of WBC number were 2.6 x 109/l, 8.8 x109/l, and 0.8 x 109/l, while the platelets number was normal. The bone marrow examination showed hyper-cellularity in each case, with 32%, 53% and 90% of blasts, POX positive and by immunophenotype we classified these as M4, M6 and M1. Karyotypes of this patients are: hypertetraploidy 81-85 chromosomes(3), 46 XY(17) (FAB M4); 43-45,X,-Y, t(5;19)(q13;q13), t(10;17)(p10;q10), -13,-14,-16,+2mar1,+2mar2 (cp8)/ 85,XX,-Y, -Y, der (1)add(p?), -2, -4, t(5;19) )(q13;q13), -9, t(10;17)(p10;q10), -13, der (14) add(q31), -16, -17, -19, -20, +2mar1,+2mar2 (cp10)/46, XY(2) (FAB M6 subtype); 88XXY,-Y, -4,-5,-7,+11,+13,+15,-18, -21,-22 (3)/92, XXYY (14)/ 46,XY(3), (FAB M1). On RT-PCR analysis there were no expression of FLT3/ITD, FLT3 D835 mutation nor the RAS-oncogene, implicating the proliferation of more mature cells. The patients were treated with Ara-C in dose of 100 mg/m2 for seven days, with Adriablastin in dose of 45 mg/m2 for three days and Etopiside in dose of 100 mg/m2 following 5 days. Two patients achieved complete remission, which lasted for 25 months in M1 case, and 12 months in M4 case. Patient with near tertraploidy and M6 did not achieve remission and died 6 months after diagnosis. CONCLUSIONS These three cases of near-teraplody karyotype in AML comprise heterogeneous group with respect to hematological and prognostic parameters, response to therapy and immunophenotype subtypes. Taking all these parameters we conclude that near-tetraploidy AML does not represent a distinct category of the disease.
Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in poster session 892 (Susceptibility genes).