A new class of compounds, 4-anilino-3-quinolinecarbonitrile Src kinase inhibitors, has been synthesized. One member of this class, SKI606, is a dual-specificity inhibitor of both Src family and Abl kinases. To investigate the effect in vitro of SKI-606, we analyzed human cell lines from CML patients in blast crisis (K562, MK2, LAMA) and CD34+ from 8 patients in CML blast crisis using a wide range of concentrations (0.01μM-10μM) of this novel agent. In K562, MK2 and LAMA84 we observed a decrease in cell viability after treatment with SKI. The effects of this compound on cell cycle progression and on apoptotic cell death shown an accumulation of G1/S phase in our sperimental model. The antiproliferative and cytostatic effects of SKI-606 was confirmed by a general decrease of bcr-abl protein expression and a reduced protein tyrosine phosphorylation. We analyze Lyn and Hck phosphorylation in whole cell extracts from K562 cells. Blots of these samples were probed with antibody anti Hck phosphorylated and Lyn phosphorylated. Our results show an hypophosphorylation of the two tyrosine kinases .We also demonstrated an increase of Bax and a decrease of Bcl-xl expression and a subsequently activation of Caspase-9. We evaluated the effects of SKI-606 on resistant or sensitive CML patients by treating SKI606 (0.1-10 μM) alone or in combination STI571(only in some patients). In the patients resistant to STI571 with point mutation F359V, Y253H, E255V and E255K was evident a modification of cell cycle progression with an accumulation in G1phase and increment of subdiploid peak. The effect of STI571 not was relevant. Cytofluorimetric analysis of non mutated patients showed an accumulation of cells in phase G1 of cell cycle and a few increment of apoptosis when treated with 1uM of SKI. Data more significative were obtained treating the cells. In one patient with a point mutation F359V we observed a general decrease of bcr-abl protein expression and a reduced protein phosphorylation in tyr 245. In the same patient an hypophosphorylation of Hck and Lyn was observed We obtained the same results we for two patients in which we didn’t find any mutation . Our study thus showed a potential therapeutic usefulness of the drug in treatment of CML, particularly in blast crisis phase. Ongoing gene expression profiles will contribute to further understanding of the drug mechanism.

[Proc Amer Assoc Cancer Res, Volume 46, 2005]