Validation of a Drosophila model of wild-type and T315I mutated BCR-ABL1 in chronic myeloid leukemia: an effective platform for treatment screening

Chronic myeloid leukemia (CML) is caused by a balanced chromosomal translocation resulting in the formation of BCR-ABL1 fusion gene encoding a constitutively active BCR-ABL1 tyrosine kinase, which activates multiple signal transduction pathways leading to malignant transformation. Standard treatment of CML is based on tyrosine kinase inhibitors (TKI); however, some mutations have proven elusive particularly the T315I mutation. Drosophila melanogaster is an established in vivo model for human diseases including cancer. The targeted expression of chimeric human/fly and full human BCR-ABL1 in Drosophila eyes has been shown to result in detrimental effects. In this study, we expressed human BCR-ABL1(p210) and the resistant BCR-ABL1(p)(210/T315I) fusion oncogenes in Drosophila eyes. Expression of BCR-ABL1(p210/T315I) resulted in a severe distortion of the ommatidial architecture of adult eyes with a more prominent rough eye phenotype compared to milder phenotypes in BCR-ABL1( )(p210)reflecting a stronger oncogenic potential of the mutant. We then assessed the efficacy of the currently used TKI in BCR-ABL1(p210) and BCR-ABL1(p210/T315I) expressing flies. Treatment of BCR-ABL1(p210/T315I) expressing flies with potent kinase inhibitors (dasatinib and ponatinib) resulted in the rescue of ommatidial loss and the restoration of normal development. Taken together, we provide a CML tailored BCR-ABL1(p)(210) and BCR-ABL1(p210/T315I) fly model which can be used to test new compounds with improved therapeutic indices.