Fms-like tyrosine kinase 3 internal tandem duplication (FLT3-ITD) is one of the most common genetic lesions in acute myeloid leukemia patients (AML). Although FLT3 tyrosine kinase inhibitors initially exhibit clinical activity, resistance to treatment inevitably occurs within months. PIM kinases are thought to be major drivers of the resistance phenotype and their inhibition in relapsed samples restores cell sensitivity to FLT3 inhibitors. Thus, simultaneous PIM and FLT3 inhibition represents a promising strategy in AML therapy. For such reasons, we have developed SEL24-B489 - a potent, dual PIM and FLT3-ITD inhibitor. SEL24-B489 exhibited significantly broader on-target activity in AML cell lines and primary AML blasts than selective FLT3-ITD or PIM inhibitors. SEL24-B489 also demonstrated marked activity in cells bearing FLT3 tyrosine kinase domain (TKD) mutations that lead to FLT3 inhibitor resistance. Moreover, SEL24-B489 inhibited the growth of a broad panel of AML cell lines in xenograft models with a clear pharmacodynamic-pharmacokinetic relationship. Taken together, our data highlight the unique dual activity of the SEL24-B489 that abrogates the activity of signaling circuits involved in proliferation, inhibition of apoptosis and protein translation/metabolism. These results underscore the therapeutic potential of the dual PIM/FLT3-ITD inhibitor for the treatment of AML.
Sepsis is the leading cause of death in intensive care units worldwide. Current treatments of sepsis are largely supportive and clinical trials using specific pharmacotherapy for sepsis have failed to improve outcomes. Here, we used the lipopolysaccharide (LPS)-stimulated mouse RAW264.7 cell line and AlphaLisa assay for TNFa as a readout to perform a supervised drug repurposing screen for sepsis treatment with compounds targeting epigenetic enzymes, including kinases. We identified the SCH772984 compound, an extracellular signal-regulated kinase (ERK) 1/2 inhibitor, as an effective blocker of TNFa production in vitro. RNA-Seq of the SCH772984-treated RAW264.7 cells at 1, 4, and 24 h time points of LPS challenge followed by functional annotation of differentially expressed genes highlighted the suppression of cellular pathways related to the immune system. SCH772984 treatment improved survival in the LPS-induced lethal endotoxemia and cecal ligation and puncture (CLP) mouse models of sepsis, and reduced plasma levels of Ccl2/Mcp1. Functional analyses of RNA-seq datasets for kidney, lung, liver, and heart tissues from SCH772984-treated animals collected at 6 h and 12 h post-CLP revealed a significant downregulation of pathways related to the immune response and platelets activation but upregulation of the extracellular matrix organization and retinoic acid signaling pathways. Thus, this study defined transcriptome signatures of SCH772984 action in vitro and in vivo, an agent that has the potential to improve sepsis outcome.
Cyclin-dependent kinase 8 inhibitors (CDK8i) have anti-cancer activity in human acute myeloid leukaemia (AML) cell lines both in vitro and in vivo. Activity of CDK8i often involves deregulation of super-enhancer-associated genes in AML cell lines. Previous studies established SEL120 as a specific CDK8 inhibitor active in AML cells with increased STAT1/5 signalling pathways. Differential gene expression analysis demonstrated high enrichment of leukaemia stem cell (LSC) signatures in responding cells, linked to resistance to standard therapies and relapsed disease. Cells sensitive to SEL120 treatment were positive for CD34 and negative for lineage commitment surface markers. SEL120 markedly reduced STAT5 phosphorylation on serine 726 (STAT5 pS726) in sensitive cell lines. Prolonged SEL120 treatment led to significant downregulation of CD34 and induction of lineage commitment markers. Transcriptomic analysis revealed that SEL120 regulated many genes involved in differentiation and apoptosis. We observed synergistic effects of SEL120 with standard of care cytotoxic drugs such as cytarabine. Treatment of AML cells with cytarabine spared many CD34+ cells, which could be effectively eradicated by subsequent treatment with SEL120. Many cell lines which were resistant to SEL120 treatment could be sensitized by concomitant treatment with BH3 mimetic agent ABT-199. Combination of both compounds resulted in potent induction of apoptosis in AML cells in vitro and in vivo. Treatment of mice bearing subcutaneously implanted human leukaemia cell lines resulted in significant tumour growth inhibition, whereas cotreatment with ABT-199 led to complete regressions at doses which were vey well tolerated by animals. Next we have selected patient derived primary AML cells using gene expression signatures identifying SEL120 -responder cell lines. In these cells SEL120 significantly reduced viability, induced apoptosis and lineage commitment. Further, the same cells were implanted into NOD scid gamma mice. Animals succumbed to AML, diagnosed by a significant presence of human CD45/CD34 positive leukaemia cells in a peripheral blood and splenomegaly. Stand-alone treatment with SEL120 resulted in the complete remission of AML cells in a peripheral blood and bone marrow, and reduced spleen weight, without symptoms of compound-related toxicity. These results validate SEL120 as a promising agent in the treatment of AML. Citation Format: Milena Mazan, Eliza Majewska, Michal Mikula, Katarzyna Wiklik, Michal Combik, Aniela Golas, Magdalena Masiejczyk, Elzbieta Fiedor, Anna Polak, Magdalena Cybulska, Aleksandra Grochowska, Michal Kopczynski, Urszula Kuklinska, Zuzanna Sandowska-Markiewicz, Malgorzata Statkiewicz, Agnieszka Paziewska, Michalina Dabrowska, Arkadiusz Bialas, Maciej Mikulski, Renata Windak, Jerzy Ostrowski, Przemyslaw Juszczynski, Krzysztof Brzozka, Tomasz Rzymski. SEL120, a potent and specific inhibitor of CDK8 induces complete remission in human patient derived xenograft models of acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1306.
Deregulated transcription, one of the key features of acute myelogenous leukemia (AML), remains largely unactionable by recently approved therapies. Preclinical studies indicate that targeting Cyclin Dependent Kinase 8 (CDK8) may be a novel therapeutic strategy for AML. CDK8 and its paralog CDK19, restrain activation of super-enhancer-associated tumor suppressors and lineage commitment genes in AML cells. SEL120 is a first-in-class, specific and selective inhibitor of CDK8/CDK19 and has shown activity in preclinical AML models. Preclinical characterization of SEL120 demonstrated a unique mechanism of action, related to known functions of CDK8 in the regulation of transcription. Cells sensitive to SEL120 show enrichment for leukemia stem cells (LSCs) signatures and higher signal transducer and activator of transcription 5 (STAT5) levels. Treatment with SEL120 reduced STAT5 phosphorylation in sensitive cell lines both in vitro and in vivo. Transcriptomic analysis of AML cells revealed that SEL120 regulated genes involved in lineage controlling functions. Specifically, trimethylation of lysine 27 on histone H3 (H3K27me3) by the polycomb repressive complex 2 (PRC2), was proposed to maintain the stemness of LSCs by preventing differentiation. Derepression of lineage commitment genes marked with H3K27me3, was one of the earliest transcriptional events in sensitive cells treated with SEL120. Consistent with its transcriptional effects, SEL120 induced differentiation of AML cells. Additionally SEL120 significantly repressed the MYC Proto-Oncogene-dependent transcriptomic signatures. Efficacy of SEL120 in AML was confirmed in models with high translational potential, including patient-derived AML cells (PDC) in vitro and in vivo. PDCs treated with SEL120 showed reduced viability, induction of apoptotic cell death and differentiation commitment. Administration of SEL120 in orthotopic AML patient-derived xenograft models reduced tumor burden to the level undetectable by flow cytometry, decreased splenomegaly and resulted in partial bone marrow recovery. CLI120-001 is a first-in-human, open-label, multi-center, modified 3+3 dose escalation phase Ib study of SEL120 with a dose-escalation cohort (DC) followed by an enrichment cohort (EC) in adult patients with AML or high-risk myelodysplastic syndrome who have relapsed or refractory disease and have received no more than 3 prior lines of therapy. Other key inclusion criteria are Eastern Cooperative Oncology Group performance status of 0-2, white blood cell (WBC) count <10000/µL (prior hydroxyurea is permitted to reduce WBC), platelet count >10000/µL, adequate organ function defined as: aspartate aminotransferase and alanine aminotransferase ≤3x the upper limit of normal (ULN), total bilirubin ≤1.5x ULN, creatinine clearance ≥60 ml/min, left ventricular ejection fraction ≥40%. Major exclusion criteria include Q to T wave interval corrected for heart rate (QTc) ≥450 ms, taking concomitant medications that are known to be strong inhibitors or inducers of cytochrome P450 1A2 or that can prolong QTc and/or cause torsade de pointes. The primary objective of the study is to assess safety and tolerability of SEL120 and to establish the recommended dose (RD) for further clinical development. Secondary objectives include evaluation of preliminary anti-leukemic activity and characterization of the pharmacokinetic profile of SEL120. The exploratory objective is to assess pharmacodynamics of SEL120 by using relevant biomarkers, including STAT5 pS726, transcriptional profiling by RNAseq and immunophenotypic changes related to stemness and differentiation of AML cells. SEL120 is administered as a single oral dose every other day for a total of 7 doses i.e. on days 1, 3, 5, 7, 9, 11 and 13, in a 21-day treatment cycle. Patients receive SEL120 until disease progression, unacceptable toxicity, or withdrawal of consent. The DC is now enrolling patients who are treated at dose levels defined by a modified Fibonacci sequence, and will end with selection of the RD based on all available study data. In the EC, additional patients will be treated at the RD to further support the evaluation of the RD of SEL120 monotherapy. The study is currently running in the United States and is planned to be completed in 2020. The ClinicalTrials.gov Identifier: NCT04021368. Disclosures Borthakur: Eli Lilly and Co.: Research Funding; FTC Therapeutics: Membership on an entity's Board of Directors or advisory committees; Agensys: Research Funding; Eisai: Research Funding; Oncoceutics: Research Funding; Oncoceutics, Inc.: Research Funding; BioTheryX: Membership on an entity's Board of Directors or advisory committees; GSK: Research Funding; NKarta: Consultancy; Cyclacel: Research Funding; Argenx: Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; BioLine Rx: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Research Funding; Bayer Healthcare AG: Research Funding; Novartis: Research Funding; Cantargia AB: Research Funding; Strategia Therapeutics: Research Funding; BMS: Research Funding; PTC Therapeutics: Consultancy; Xbiotech USA: Research Funding; AbbVie: Research Funding; Arvinas: Research Funding; Polaris: Research Funding; Merck: Research Funding; AstraZeneca: Research Funding; Tetralogic Pharmaceuticals: Research Funding. Abboud:Jazz Pharma: Speakers Bureau; Novartis: Other: Member on an entity's Board of Directors or advisory committees (Ended 12/30/2017), Research Funding; Agios: Other: Member on an entity's Board of Directors or advisory committees (Ended 12/30/2017); Tetraphase Pharmaceuticals: Consultancy, Honoraria; Seattle Genetics: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; NKarta: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Bayer: Consultancy, Honoraria. Nazha:Abbvie: Consultancy; Incyte: Speakers Bureau; Daiichi Sankyo: Consultancy; Jazz Pharmacutical: Research Funding; Novartis: Speakers Bureau; MEI: Other: Data monitoring Committee; Tolero, Karyopharma: Honoraria. Mazan:Selvita S.A.: Employment. Majewska:Selvita S.A.: Employment. Wiklik:Selvita S.A.: Employment. Golas:Selvita S.A.: Employment. Bialas:Selvita S.A.: Employment. Windak:Selvita S.A.: Employment. Juszczynski:Selvita S.A.: Consultancy, Membership on an entity's Board of Directors or advisory committees. Chrom:Selvita S.A.: Employment. Rzymski:Selvita S.A.: Employment, Equity Ownership. Brzózka:Selvita S.A.: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees.
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