Haematologica 2004;89: supplement no. 6 - Supplements ...

VIII Congress of the Italian Society of Experimental Hematology, Pavia, September 14-16, 200449centage of apoptotic cells by flow cytometry for thedetection of annexin V positive cells. In K562s Imatinibincubation reduced the proliferation rate of48%, MG132 of 45%, BAY11-7082 of 40% andPS1145 of 65%. The reduction of proliferation wasassociated with an increase of apoptosis, 30% withImatinib, 25% with both proteasome inhibitors, 28%with BAY11-7082. Similar results were obtained inKCls cells. By contrast Imatinib incubation of K562rand KClr did not result in a significant inhibition ofproliferation. By contrast, the proteasome inhibitorsinduced a reduction of proliferation of 70%, BAY11-7082 and PS1145 of 10% and 22% respectively.Interestingly, the combination of Imatinib withMG132 or PS341 induced a reduction of proliferationof 82% and 89% respectively, and the induction ofapoptosis 54% and 40%. The association of Imatinibwith BAY11-7082 resulted in a reduction of proliferationof 87% and an increased of apoptosis of 59%and the association with PS1145 reduced the proliferationof 87% and increased apoptosis of 67%.Similar results were obtained in CML patients resistantto Imatinib. The association of Imatinib withMG132 resulted in a decrease of proliferation of47%, (range 35-64%) and increase of apoptosis of62%. (range 51-89%). Similar results were obtainedwith thw association of PS341 (mean reduction ofproliferation of 49%. The association with BAY andPS1145 decreased the proliferation of 57 and 61%respectively (range 35-69% for BAY and 29-72% forPS1145) and both increased apoptosis with meanvalue of 56% and 60%. Moreover the colony growthobtained from BM cells after incubations was inhibitedof 70% and 81% with the association of Imatinibwith MG132 and PS341, and was inhibited of61 and 79% with the association with BAY andPS1145 respectively. Finally, these data were confirmedby the experiments performed on K562 cellstransfected with IKb super-repressor which blocksNF-KB in the inactive status. In line with the resultsdescribed, these cells showed a proliferative arrestand an increase of the apoptosis rate. We concludethat NF-kB inhibitors present a potential activity inImatinib resistant cells and particularly, the combinationof Imatinib and NF-kB inhibitors is able tostrongly block the proliferation and to induce apoptosisin cell lines and CML patients resistant to Imatinibtherapy. The combination of Imatinib and NF-KB inhibitors may therefore represent an attractivetherapy for CML resistant patients.CO-48PREDICTION OF RESPONSE TO IMATINIB BY PROSPECTIVEQUANTITATION OF BCR-ABL TRANSCRIPT IN LATE CHRONICPHASE CHONIC MYELOID LEUKEMIA PATIENTSMartinelli G, 1 Rosti G, 1 Pane F, 3 Amabile M, 1Soverini S, 1 Izzo B, 3 Giannini B, 1 Poerio A, 1 CilloniD, 2 Terragna C, 1 Ottaviani E,1 Grafone T,1 De VivoA, 1 Testoni N, 1 Bassi S, 1 Rege Cambrin G, 2 BonifaziF, 1 Gottardi E, 2 Trabacchi E,1 Alberti D, 4 SalvatoreF, 3 Saglio G, 2 Baccarani M 1 (Study and writingcommittee for the Italian Cooperative Study Groupon Chronic Myeloid Leukemia)From the 1 Institute of Hematology and MedicalOncology “L. and A. Seràgnoli”, University of Bologna;2 Division of Hematology and Internal Medicine,Department of Clinical and Biological Science, Universityof Turin; 3 CEINGE Biotecnologie Avanzateand Department of Biochemistry and Medical Biotechnology,University of Naples Federico II; 4 NovartisPharma, Origgio; ItalyImatinib mesylate (STI571), a specific Bcr-Abl tyrosine-kinasesignal-transduction inhibitor, has shownantileukemic activity in clinical studies, becomingthe standard therapy for Philadelphia chromosomepositive(Ph+) chronic myeloid leukemia. Predictionof response to imatinib cannot be anticipated withcertainty by repeated examination of bone marrowmetaphases for the presence of the Ph chromosome.The quantitative reverse-transcriptase polymerasechain reaction (QRT-PCR) has proved extremely valuablefor assessing and monitoring minimal residualdisease in patients who achieve Ph negativity withimatinib mesylate, but few data are available on theuse of QRT-PCR for predicting response to the drug.We used this method on 191 out of 324 chronicmyeloid leukemia patients in the late chronic phaseentered into a phase II clinical trial conducted by theItalian Cooperative Study Group on Chronic MyeloidLeukemia with imatinib 400 mg/day administeredorally as second-line therapy. Bone marrow sampleswere collected before treatment, after 3, 6 and 12months or at the end of study treatment (12 months)while peripheral blood samples were obtained after2, 3, 6, 10, 14, 20 and 52 weeks of therapy. QRT-PCRanalysis was standardized and performed in threedifferent laboratories, and the amount of Bcr-Abltranscript was expressed as the ratio of Bcr-Abl toβ2-microglobulin (β2M). Before imatinib therapy, wefound a different amount of neoplastic transcript inbone marrow and peripheral blood (p>0.001), reflectingthe higher percentage of myeloid precursor inbone marrow. In the nonresponders, the Bcr-Abl:β2M ratio in bone marrow remained substantiallystable during the treatment, while in patientsobtaining a complete, stable cytogenetic responsehaematologica vol. 89[suppl. n. 6]:september 2004