Here we show that in vivo application of targeted nonvirally delivered synthetic bcr-abl siRNA in a female patient with recurrent Philadelphia chromosome positive chronic myeloid leukemia (CML) resistant to imatinib (Y253F mutation) and chemotherapy after allogeneic hematopoietic stem cell transplantation can silence the expression of bcr-abl gene.
AP24534 inhibited all tested BCR-ABL mutants in cellular and biochemical assays, suppressed BCR-ABL(T315I)-driven tumor growth in mice, and completely abrogated resistance in cell-based mutagenesis screens.
NVP-BEZ235 in combination with nilotinib also inhibited tumor growth in a xenograft model and inhibited the growth of primary T315I mutant cells and ponatinib-resistant cells.
Moreover, in mouse tumor xenografts, S116836 significantly inhibits the growth and volume of tumors expressing the WT or T315I mutant BCR-ABL without causing significant cardiotoxicity.
The in vivo efficacy validation of p-niclosamide, a water soluble derivative of niclosamide, showed that p-niclosamide significantly inhibited the tumor burden of nude mice subcutaneously bearing T315I-BCR-ABL-expressing CML cells, and prolonged the survival of allografted leukemic mice harboring BaF3-T315I-BCR-ABL.
In the present study, an allele-specific oligonucleotide reverse transcriptase polymerase chain reaction assay was used to detect T315I mutation in a cohort of 60 imatinib-resistant CML patients.
The aim of this study was to evaluate proliferation inhibition and apoptosis induction by down-regulating PPP2R5C gene expression in the imatinib-sensitive and imatinib-resistant CML cell lines K562, K562R (imatinib resistant without an Abl gene mutation), 32D-Bcr-Abl WT (imatinib-sensitive murine CML cell line with a wild type Abl gene) and 32D-Bcr-Abl T315I (imatinib resistant with a T315I Abl gene mutation) and primary cells from CML patients by RNA interference.
We conclude that (a) amino acid substitutions at seven residues (M244V, G250E, Y253F/H, E255K/V, T315I, M351T, and F359V) account for 85% of all resistance-associated mutations; (b) the search for mutations is important both in case of imatinib failure and in case of loss of response at the hematologic or cytogenetic level; (c) advanced-phase chronic myeloid leukemia and Ph+ ALL patients have a higher likelihood of developing imatinib-resistant mutations; and (d) the presence of either P-loop or T315I mutations in imatinib-treated patients should warn the clinician to reconsider the therapeutic strategy.
BCR-ABL kinase domain mutation analysis in chronic myeloid leukemia patients treated with tyrosine kinase inhibitors: recommendations from an expert panel on behalf of European LeukemiaNet.
Taken together, our data demonstrate that the lower growth ability of KBM5-T315ICML cells might be related to the decreased expression of glycolysis-related genes and ROS levels, and this will be used to identify therapeutic targets for imatinib resistance in CML.
In a xenograft model, PD0332991, but not imatinib, suppressed dissemination of Ph(+) ALL having the T315I mutation and prolonged survival, demonstrating that this reagent would be a new therapeutic modality for relapsed CML-LC and Ph(+) ALL patients after treatment with tyrosine kinase inhibitors.
Taken together, we provide chronic myeloid leukemia tailored BCR-ABL1p210 and BCR-ABL1p210/T315I fly model which can be used to test new compounds with improved therapeutic indices.
In the United States, ponatinib has received accelerated approval for adults with T315I-positive chronic myeloid leukemia (CML) or T315I (gatekeeper mutation)-positive, Philadelphia chromosome-positive, acute lymphoblastic leukemia (Ph + ALL), and patients with CML or Ph + ALL for whom no other TKI therapy is indicated.
Allogeneic transplantation remains an important therapeutic option for CML-CP harboring the T315I mutation, patients who fail 2nd generation TKIs, and for all patients in advanced phase disease.
Here we further report that (i) PtPT induces apoptosis in Bcr-Abl wild-type and Bcr-Abl-T315I mutation cells including the primary mononuclear cells from CML patients clinically resistant to IM, as well as inhibits the growth of IM-resistant Bcr-Abl-T315I xenografts in vivo; (ii) PtPT downregulates Bcr-Abl level through restraining Bcr-Abl transcription, and decreasing Bcr-Abl protein mediated by DUBs inhibition-induced caspase activation; (iii) UPS inhibition is required for PtPT-induced caspase activation and cell apoptosis.
To our knowledge, this is the second case of a T315I-bearing chronic myeloid leukemia patient displaying satisfactory response to the combination therapy of dasatinib and IFN-α.
The observation of responses in 3 patients with T315I phenotype-refractory CML or Ph-positive ALL, at doses of MK-0457 associated with no significant extramedullary toxicity, is very encouraging.