azd-6244 and Leukemia--Myeloid--Acute

The clinical relevance of targeting the RAS/RAF/MEK/ERK pathway, activated in 70% to 80% of patients with acute myelogenous leukemia (AML), is unknown.. Selumetinib is an oral small-molecule inhibitor of MAP-ERK kinase (MEK)-1/2. Forty-seven patients with relapsed/refractory AML or 60 years old or more with untreated AML were enrolled on a phase II study. Patients were stratified by FLT3 ITD mutation status. The primary endpoint was response rate (complete, partial, and minor). Leukemia cells were analyzed for extracellular signal-regulated kinase (ERK) and mTOR phosphorylation.. Common drug-related toxicities were grade 1-2 diarrhea, fatigue, nausea, vomiting, and skin rash. In the FLT3 wild-type cohort, six of 36 (17%) patients had a response [one partial response, three minor responses, two unconfirmed minor responses (uMR)]. No patient with FLT3 ITD responded. NRAS and KRAS mutations were detected in 7% and 2% of patients, respectively. The sole patient with KRAS mutation had uMR with hematologic improvement in platelets. Baseline p-ERK activation was observed in 85% of patients analyzed but did not correlate with a response. A single-nucleotide polymorphism (SNP) rs3733542 in exon 18 of the KIT gene was detected in significantly higher number of patients with response/stable disease compared with nonresponders (60% vs. 23%; P = 0.027).. Selumetinib is associated with modest single-agent antileukemic activity in advanced AML. However, given its favorable toxicity profile, combination with drugs that target other signaling pathways in AML should be considered. The potential association of SNP rs3733542 in exon 18 of the KIT gene with antileukemic activity of selumetinib is intriguing, but will require validation in larger trials.

Topics: Administration, Oral; Adult; Aged; Aged, 80 and over; Antineoplastic Agents; Benzimidazoles; Female; fms-Like Tyrosine Kinase 3; Genes, ras; Humans; Leukemia, Myeloid, Acute; Male; Middle Aged; Mitogen-Activated Protein Kinase Kinases; Mutation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-kit; Treatment Outcome

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

Aberrant activation of multiple signaling pathways is common in acute myelogenous leukemia (AML) cells, which can be linked to a poor prognosis for patients with this disease. Previous research with mTOR or MEK inhibitors revealed cytostatic, rather than cytotoxic, effects in in vitro and in vivo AML models. We evaluated the combination effect of the mTOR inhibitor AZD8055 and the MEK inhibitor selumetinib on human AML cell lines and primary AML samples. This combination demonstrated synergistic proapoptotic effects in AML cells with high basal activation of MEK and mTOR. We next incorporated the BH3 mimetic ABT-737 into this combination regimen to block Bcl-2, which further enhanced the apoptogenic effect of MEK/mTOR inhibition. The combination treatment also had a striking proapoptotic effect in CD33(+)/CD34(+) AML progenitor cells from primary AML samples with NRAS mutations. Mechanistically, upregulation of the proapoptotic protein Bim, accompanied by the downregulation of the antiapoptotic protein Mcl-1 (mainly via protein degradation), seemed to play critical roles in enhancing the combination drug effect. Furthermore, the modulation of survivin, Bax, Puma, and X-chromosome-linked inhibitor of apoptosis protein (XIAP) expression suggested a role for mitochondria-mediated apoptosis in the cytotoxicity of the drug combination. Consequently, the concomitant blockade of prosurvival MEK/mTOR signaling and the deactivation of Bcl-2 could provide a mechanism-based integrated therapeutic strategy for the eradication of AML cells.

Topics: Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzimidazoles; Cell Proliferation; Drug Synergism; Gene Expression; Humans; Leukemia, Myeloid, Acute; MAP Kinase Kinase Kinases; MAP Kinase Signaling System; Morpholines; Proto-Oncogene Proteins c-bcl-2; Signal Transduction; TOR Serine-Threonine Kinases; Transfection; U937 Cells

Activating mutations in the RAS oncogene occur frequently in human leukemias. Direct targeting of RAS has proven to be challenging, although targeting of downstream RAS mediators, such as MEK, is currently being tested clinically. Given the complexity of RAS signaling, it is likely that combinations of targeted agents will be more effective than single agents.. A chemical screen using RAS-dependent leukemia cells was developed to identify compounds with unanticipated activity in the presence of an MEK inhibitor and led to identification of inhibitors of IGF1R. Results were validated using cell-based proliferation, apoptosis, cell-cycle, and gene knockdown assays; immunoprecipitation and immunoblotting; and a noninvasive in vivo bioluminescence model of acute myeloid leukemia (AML).. Mechanistically, IGF1R protein expression/activity was substantially increased in mutant RAS-expressing cells, and suppression of RAS led to decreases in IGF1R. Synergy between MEK and IGF1R inhibitors correlated with induction of apoptosis, inhibition of cell-cycle progression, and decreased phospho-S6 and phospho-4E-BP1. In vivo, NSG mice tail veins injected with OCI-AML3-luc+ cells showed significantly lower tumor burden following 1 week of daily oral administration of 50 mg/kg NVP-AEW541 (IGF1R inhibitor) combined with 25 mg/kg AZD6244 (MEK inhibitor), as compared with mice treated with either agent alone. Drug combination effects observed in cell-based assays were generalized to additional mutant RAS-positive neoplasms.. The finding that downstream inhibitors of RAS signaling and IGF1R inhibitors have synergistic activity warrants further clinical investigation of IGF1R and RAS signaling inhibition as a potential treatment strategy for RAS-driven malignancies.

Topics: Animals; Apoptosis; Benzimidazoles; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Female; Genes, ras; Humans; Leukemia, Myeloid, Acute; Mice; Mitogen-Activated Protein Kinase Kinases; Pyrimidines; Pyrroles; Receptor, IGF Type 1; Signal Transduction; Small Molecule Libraries; Up-Regulation

The mitogen-activated protein kinase/ERK kinase (MEK)/ERK pathway was shown to be constitutively activated in a large number of acute myelogenous leukemia (AML) cells, suggesting the important roles of this pro-survival signaling in leukemogenesis and proliferation of AML cells. This study explored the impact of the MEK inhibitor AZD6244 on the effect of cytarabien (AraC), one of the most commonly used anti-leukemia agents, to induce growth arrest and apoptosis of AML cells. AZD6244 effectively blocked AraC-induced MEK/ERK activation and enhanced its ability to induce growth arrest and apoptosis of NB4 and HL60 cells in parallel with induction of DNA damage as measured by detection of gamma-H2AX by Western Blot analysis, resulting in enhanced expression of p21( waf1 ) and downregulation of c-Myc and Bcl-xl in these cells. Enhanced induction of apoptosis mediated by combination of AZD6244 and AraC was also shown in freshly isolated AML cells (n = 3). Taken together, concomitant administration of AraC and the inhibitor of MEK/ERK signaling may be useful for treatment of individuals with AML.

Topics: Apoptosis; Benzimidazoles; Cell Cycle; Cell Cycle Proteins; Cell Differentiation; Cell Proliferation; Cytarabine; DNA Damage; Drug Synergism; Enzyme Activation; Extracellular Signal-Regulated MAP Kinases; Gene Expression Regulation, Leukemic; Histones; HL-60 Cells; Humans; Leukemia, Myeloid, Acute; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase Kinases

The FMS-like tyrosine kinase 3 (FLT3) is a cell surface receptor tyrosine kinase. Activating mutations of this gene occur in nearly 30% of acute myelogenous leukemia (AML) patients. These mutations, in part, result in activation of mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathways. In this study, we found that AZD6244 (ARRY-142886), a novel inhibitor of MEK1/2 kinases, effectively inhibited the proliferation of acute biphenotypic leukemia MV4-11 and acute monocytic leukemia MOLM13 cells. The concentrations that inhibited 50% growth were approximately 0.3 and 1.2 microM, respectively, as measured by thymidine uptake on day 2 of culture. AZD6244 potently down-regulated the levels of phospho-ERK1/2 and its downstream effector, p-p70S6K, in the MV4-11 and MOLM13 cells as measured by Western blot analysis. Interestingly, when AZD6244 was combined with sunitinib, a FLT3 kinase inhibitor, growth inhibition and apoptosis of both MV4-11 and MOLM13 cells were synergistically enhanced in association with further down-regulation of phospho-ERK1/2 and p-p70S6K in these cells. Taken together, concomitant blockade of FLT3 and MEK signaling represents a promising treatment strategy for individuals with leukemia who possess activating mutations of FLT3.

Topics: Aged; Aged, 80 and over; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Benzimidazoles; Cell Proliferation; Female; fms-Like Tyrosine Kinase 3; Humans; Indoles; Leukemia; Leukemia, Megakaryoblastic, Acute; Leukemia, Myeloid, Acute; Male; MAP Kinase Kinase 1; Middle Aged; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mutation; Pyrroles; Ribosomal Protein S6 Kinases, 70-kDa; Signal Transduction; Sunitinib; Tumor Cells, Cultured

Topics: Acetylation; Apoptosis; Benzamides; Benzimidazoles; Cyclin-Dependent Kinase Inhibitor p21; Drug Synergism; Extracellular Signal-Regulated MAP Kinases; Histone Deacetylase Inhibitors; Histones; Humans; Leukemia, Myeloid, Acute; MAP Kinase Signaling System; Promoter Regions, Genetic; Pyridines