fedratinib and Leukemia--Myeloid--Acute

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

Many promising new cancer drugs proceed through preclinical testing and early-phase trials only to fail in late-stage clinical testing. Thus, improved models that better predict survival outcomes and enable the development of biomarkers are needed to identify patients most likely to respond to and benefit from therapy. Here, we describe a comprehensive approach in which we incorporated biobanking, xenografting, and multiplexed phospho-flow (PF) cytometric profiling to study drug response and identify predictive biomarkers in acute myeloid leukemia (AML) patients. To test the efficacy of our approach, we evaluated the investigational JAK2 inhibitor fedratinib (FED) in 64 patient samples. FED robustly reduced leukemia in mouse xenograft models in 59% of cases and was also effective in limiting the protumorigenic activity of leukemia stem cells as shown by serial transplantation assays. In parallel, PF profiling identified FED-mediated reduction in phospho-STAT5 (pSTAT5) levels as a predictive biomarker of in vivo drug response with high specificity (92%) and strong positive predictive value (93%). Unexpectedly, another JAK inhibitor, ruxolitinib (RUX), was ineffective in 8 of 10 FED-responsive samples. Notably, this outcome could be predicted by the status of pSTAT5 signaling, which was unaffected by RUX treatment. Consistent with this observed discrepancy, PF analysis revealed that FED exerted its effects through multiple JAK2-independent mechanisms. Collectively, this work establishes an integrated approach for testing novel anticancer agents that captures the inherent variability of response caused by disease heterogeneity and in parallel, facilitates the identification of predictive biomarkers that can help stratify patients into appropriate clinical trials.

Topics: Animals; Biomarkers; fms-Like Tyrosine Kinase 3; Humans; Leukemia, Myeloid, Acute; Mice; Nitriles; Phosphorylation; Pyrazoles; Pyrimidines; Pyrrolidines; STAT5 Transcription Factor; Sulfonamides; Xenograft Model Antitumor Assays

Janus kinase (JAK) inhibitors are a promising treatment strategy in several hematological malignancies and autoimmune diseases. A number of inhibitors are in clinical development, and two have already reached the market. Unfortunately, all of them are burdened with different toxicity profiles. To check if the JAK inhibitors of different selectivity evoke different responses on JAK2-dependent and independent cells, we have used three acute myeloid leukemia cell lines with confirmed JAK2 mutation status. We have found that JAK inhibitors exert distinct effect on the expression of BCLXL, CCND1 and c-MYC genes, regulated by JAK pathway, in JAK2 wild type cells in comparison to JAK2 V617F-positive cell lines. Moreover, cell cycle analysis showed that inhibitors alter the cycle by arresting cells in different phases. Our results suggest that observed effect of JAK2 inhibitors on transcription and cell cycle level in different cell lines are associated not with activity within JAK family, but presumably with other off-target activities.

Topics: bcl-X Protein; Cell Cycle; Cell Line, Tumor; Cyclin D1; Down-Regulation; Gene Expression; Humans; Imidazoles; Janus Kinases; Leukemia, Myeloid, Acute; Nitriles; Piperidines; Protein Kinase Inhibitors; Pyrazoles; Pyridazines; Pyrimidines; Pyrroles; Pyrrolidines; Sulfonamides

Outcomes in acute myeloid leukemia (AML) remain poor due to high rates of relapse. Thus, there is an urgent unmet medical need for new therapies that can more effectively kill the leukemia stem cells (LSC) and recently recognized preleukemic hematopoietic stem cells (preL-HSC) that can drive relapsed disease. In order to develop such therapies, a better understanding of the biology of these stem cell populations is required. The best functional assays for stem cells are xenotransplantation models using immunodeficient mouse recipients. Here, we present evidence of the clinical validity of such models for studying the biology of AML stem cells and propose a new paradigm for the development of LSC-targeted agents and biomarker tools for patient selection.

Topics: Animals; Antineoplastic Agents; Hematopoietic Stem Cells; Humans; Janus Kinase 2; Leukemia, Myeloid, Acute; Mice; Mice, Inbred NOD; Mice, SCID; Neoplastic Stem Cells; Nitriles; Pyrazoles; Pyrimidines; Pyrrolidines; Reproducibility of Results; Sulfonamides; Xenograft Model Antitumor Assays