14-methyl-20-oxa-5-7-14-26-tetraazatetracyclo(19.3.1.1(2-6).1(8-12))heptacosa-1(25)-2(26)-3-5-8(27)-9-11-16-21-23-decaene and Leukemia--Myeloid--Acute

The novel multi-kinase inhibitor TG02 has selectivity against cell cycle and transcriptional cyclin dependent kinases (CDKs) as well as fms-like tyrosine kinase receptor-3 (FLT3). Inhibition of transcriptional CDKs preferentially depletes short-lived proteins such as MCL1. We evaluated the in vitro toxicity of TG02 to primary acute myeloid leukaemia (AML) cells in the presence of survival signalling pathway activation by cytokines and fibronectin. One hundred nanomolar TG02 induced a median decrease of 40% in bulk cell survival and 43% in the CD34(+) CD38(-) CD123(+) subset. A 90% inhibitory concentration of 500 nmol/l indicated that TG02 toxicity is not halted by protective cell cycle arrest. Samples with FLT3 internal tandem duplication were not preferentially targeted. By flow cytometry, TG02 treatment caused loss of RNA Polymerase II serine 2 phosphorylation in patient samples, which correlated strongly with BAX activation (R(2) =0·89), suggesting these as potential biomarkers for clinical studies. MCL1 and XIAP expression also decreased. Repeated brief exposure to TG02 in MOLM-13 cells did not result in compensatory up-regulation of survival protein expression. In conclusion, TG02 is potently cytotoxic towards CD34(+) CD38(-) CD123(+) and bulk AML cells, despite protective signalling pathway activation. This antitumour activity is most likely mediated by dephosphorylation of RNA Polymerase II leading to depletion of survival molecules such as MCL1 and XIAP, with subsequent BAX activation and apoptosis.

Topics: Antigens, CD; Apoptosis; bcl-2-Associated X Protein; Drug Screening Assays, Antitumor; Female; Heterocyclic Compounds, 4 or More Rings; HL-60 Cells; Humans; Leukemia, Myeloid, Acute; Male; Myeloid Cell Leukemia Sequence 1 Protein; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-bcl-2; RNA Polymerase II; Signal Transduction; U937 Cells; X-Linked Inhibitor of Apoptosis Protein

Kinase inhibitors are important cancer therapeutics. Polypharmacology is commonly observed, requiring thorough target deconvolution to understand drug mechanism of action. Using chemical proteomics, we analyzed the target spectrum of 243 clinically evaluated kinase drugs. The data revealed previously unknown targets for established drugs, offered a perspective on the "druggable" kinome, highlighted (non)kinase off-targets, and suggested potential therapeutic applications. Integration of phosphoproteomic data refined drug-affected pathways, identified response markers, and strengthened rationale for combination treatments. We exemplify translational value by discovering SIK2 (salt-inducible kinase 2) inhibitors that modulate cytokine production in primary cells, by identifying drugs against the lung cancer survival marker MELK (maternal embryonic leucine zipper kinase), and by repurposing cabozantinib to treat FLT3-ITD-positive acute myeloid leukemia. This resource, available via the ProteomicsDB database, should facilitate basic, clinical, and drug discovery research and aid clinical decision-making.

Topics: Animals; Antineoplastic Agents; Cell Line, Tumor; Cytokines; Drug Discovery; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Lung Neoplasms; Mice; Molecular Targeted Therapy; Protein Kinase Inhibitors; Protein Serine-Threonine Kinases; Proteomics; Xenograft Model Antitumor Assays

TG02 is a novel pyrimidine-based multi-kinase inhibitor that inhibits CDKs 1, 2, 7 and 9 together with JAK2 and FLT3. It dose-dependently inhibits signaling pathways downstream of CDKs, JAK2 and FLT3 in cancer cells with the main targets being CDKs. TG02 is anti-proliferative in a broad range of tumor cell lines, inducing G1 cell cycle arrest and apoptosis. Primary cultures of progenitor cells derived from acute myeloid leukemia (AML) and polycythemia vera patients are very sensitive to TG02. Comparison with reference inhibitors that block only one of the main targets of TG02 demonstrate the benefit of combined CDK and JAK2/FLT3 inhibition in cell lines as well as primary cells. In vivo, TG02 exhibits favorable pharmacokinetics after oral dosing in xenograft models and accumulates in tumor tissues, inducing an effective blockade of both CDK and STAT signaling. TG02 induces tumor regression after oral dosing on both daily and intermittent schedules in a murine model of mutant-FLT3 leukemia (MV4-11) and prolongs survival in a disseminated AML model with wild-type FLT3 and JAK2 (HL-60). These data demonstrate that TG02 is active in various models of leukemia and provide a rationale for the ongoing clinical evaluation of TG02 in patients with advanced leukemias.

Topics: Animals; Antineoplastic Agents; Cell Line, Transformed; Cyclin-Dependent Kinases; Disease Models, Animal; Female; fms-Like Tyrosine Kinase 3; Heterocyclic Compounds, 4 or More Rings; Humans; Janus Kinase 2; Leukemia, Myeloid, Acute; Mice; Mice, Inbred BALB C; Protein Kinase Inhibitors