BRAF V600E is the most frequent oncogenic protein kinase mutation known. Furthermore, inhibitors targeting ''active'' protein kinases have demonstrated significant utility in the therapeutic repertoire against cancer. Therefore, we pursued the development of specific kinase inhibitors targeting B-Raf, and the V600E allele in particular. By using a structure-guided discovery approach, a potent and selective inhibitor of active B-Raf has been discovered. PLX4720, a 7-azaindole derivative that inhibits B-Raf V600E with an IC50 of 13 nM, defines a class of kinase inhibitor with marked selectivity in both biochemical and cellular assays. PLX4720 preferentially inhibits the active B-Raf V600E kinase compared with a broad spectrum of other kinases, and potent cytotoxic effects are also exclusive to cells bearing the V600E allele. Consistent with the high degree of selectivity, ERK phosphorylation is potently inhibited by PLX4720 in B-Raf V600E -bearing tumor cell lines but not in cells lacking oncogenic B-Raf. In melanoma models, PLX4720 induces cell cycle arrest and apoptosis exclusively in B-Raf V600E -positive cells. In B-Raf V600E -dependent tumor xenograft models, orally dosed PLX4720 causes significant tumor growth delays, including tumor regressions, without evidence of toxicity. The work described here represents the entire discovery process, from initial identification through structural and biological studies in animal models to a promising therapeutic for testing in cancer patients bearing B-Raf V600E -driven tumors.cancer ͉ cell signaling ͉ melanoma ͉ phosphorylation ͉ protein kinases O ncogenic mutations in the BRAF gene (1) correlate with increased severity and decreased response to chemotherapy in a wide variety of human tumors (2-4). Hence, direct therapeutic inhibition of oncogenic B-Raf kinase activity affords an avenue to treat these tumors. The therapeutic approach of targeting oncogenic kinase activity has proved very valuable in oncology (5, 6). Recently, we have described the technique termed scaffold-based drug discovery, a strategy for identifying small molecule inhibitors of cyclic nucleotide phosphodiesterases (7). Here, we describe an expansion of this strategy to discover a scaffold targeting protein kinases, and we report the elaboration of this scaffold into the potent and selective B-Raf V600E inhibitor PLX4720. Because a majority of all melanomas harbor an activating missense mutation (V600E) in the B-Raf oncogene (1), targeted inhibition of the V600E gene product is a particularly rational therapeutic goal in this otherwise therapy-resistant tumor type. Previous generations of B-Raf inhibitors possess Raf inhibitory activity at low nanomolar concentrations (8-13); however, the relative therapeutic efficacy of such inhibitors has been hampered by the lack of bioavailability or by the number of nonspecific targets that are also affected (14, 15). The development of highly specific and effectual inhibitors of the BRAF V600E gene product would provide insight into the true therapeutic rele...

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The pim-1 kinase is a true oncogene that has been implicated in the development of leukemias, lymphomas, and prostate cancer, and is the target of drug development programs. We have used experimental approaches to identify a selective, cell-permeable, small-molecule inhibitor of the pim-1 kinase to foster basic and translational studies of the enzyme. We used an ELISA-based kinase assay to screen a diversity library of potential kinase inhibitors. The flavonol quercetagetin (3,3 ¶,4 ¶,5,6,7-hydroxyflavone) was identified as a moderately potent, ATP-competitive inhibitor (IC 50 , 0.34 Mmol/L). Resolution of the crystal structure of PIM1 in complex with quercetagetin or two other flavonoids revealed a spectrum of binding poses and hydrogen-bonding patterns in spite of strong similarity of the ligands. Quercetagetin was a highly selective inhibitor of PIM1 compared with PIM2 and seven other serine-threonine kinases. Quercetagetin was able to inhibit PIM1 activity in intact RWPE2 prostate cancer cells in a dose-dependent manner (ED 50 , 5.5 Mmol/L). RWPE2 cells treated with quercetagetin showed pronounced growth inhibition at inhibitor concentrations that blocked PIM1 kinase activity. Furthermore, the ability of quercetagetin to inhibit the growth of other prostate epithelial cell lines varied in proportion to their levels of PIM1 protein.Quercetagetin can function as a moderately potent and selective, cell-permeable inhibitor of the pim-1 kinase, and may be useful for proof-of-concept studies to support the development of clinically useful PIM1 inhibitors.

Our data demonstrate that a significant subgroup of ER/PR-negative and triple-negative breast cancers express FRA, and its expression is associated with worse clinical outcome.

Inflammation and cancer, two therapeutic areas historically addressed by separate drug discovery efforts, are now coupled in treatment approaches by a growing understanding of the dynamic molecular dialogues between immune and cancer cells. Agents that target specific compartments of the immune system, therefore, not only bring new disease modifying modalities to inflammatory diseases, but also offer a new avenue to cancer therapy by disrupting immune components of the microenvironment that foster tumor growth, progression, immune evasion, and treatment resistance. McDonough feline sarcoma viral (v-fms) oncogene homolog (FMS) and v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT) are two hematopoietic cell surface receptors that regulate the development and function of macrophages and mast cells, respectively. We disclose a highly specific dual FMS and KIT kinase inhibitor developed from a multifaceted chemical scaffold. As expected, this inhibitor blocks the activation of macrophages, osteoclasts, and mast cells controlled by these two receptors. More importantly, the dual FMS and KIT inhibition profile has translated into a combination of benefits in preclinical disease models of inflammation and cancer.cancer bone metastasis | CSF1R | rheumatoid arthritis | scaffold-based drug design