Anisa Scott

Bio: Anisa Scott is an academic researcher from Durham University. The author has contributed to research in topics: Prodrug & Heat shock protein. The author has an hindex of 7, co-authored 7 publications receiving 613 citations. Previous affiliations of Anisa Scott include University of Virginia.

SNX2112, a Synthetic Heat Shock Protein 90 Inhibitor, Has Potent Antitumor Activity against HER Kinase–Dependent Cancers

Abstract: Purpose: The heat shock protein 90 (Hsp90) chaperone plays an important role in transformation by regulating the conformational maturation and stability of oncogenic kinases and transcription factors. Ansamycins, such as 17-(allylamino)-17-demethoxygeldanmycin (17-AAG), inhibit Hsp90 function; induce the degradation of Hsp90 client proteins such as HER2, and have shown activity in early clinical trials. However, the utility of these drugs has been limited by their hepatotoxicity, poor solubility, and poorly tolerated formulations. Experimental Design: We determined the pharmacodynamic and antitumor properties of a novel, synthetic Hsp90 inhibitor, SNX-2112, in cell culture and xenograft models of HER kinase–dependent cancers. Results: We show in a panel of tumor cell lines that SNX-2112 and its prodrug SNX-5542 are Hsp90 inhibitors with properties and potency similar to that of 17-AAG, including: degradation of HER2, mutant epidermal growth factor receptor, and other client proteins, inhibition of extracellular signal-regulated kinase and Akt activation, and induction of a Rb-dependent G 1 arrest with subsequent apoptosis. SNX-5542 can be administered to mice orally on a daily schedule. Following oral administration, SNX-5542 is rapidly converted to SNX-2112, which accumulates in tumors relative to normal tissues. A single dose of SNX-5542 causes HER2 degradation and inhibits its downstream signaling for up to 24 h, and daily dosing results in regression of HER2-dependent xenografts. SNX-5542 also shows greater activity than 17-AAG in a non–small cell lung cancer xenograft model expressing mutant EGFR. Conclusions: These results suggest that Hsp90 inhibition with SNX-2112 (delivered as a prodrug) may represent a promising therapeutic strategy for tumors whose growth and survival is dependent on Hsp90 clients.

Discovery of novel 2-aminobenzamide inhibitors of heat shock protein 90 as potent, selective and orally active antitumor agents.

Abstract: A novel class of heat shock protein 90 (Hsp90) inhibitors was developed from an unbiased screen to identify protein targets for a diverse compound library These indol-4-one and indazol-4-one derived 2-aminobenzamides showed strong binding affinity to Hsp90, and optimized analogues exhibited nanomolar antiproliferative activity across multiple cancer cell lines Heat shock protein 70 (Hsp70) induction and specific client protein degradation in cells on treatment with the inhibitors supported Hsp90 inhibition as the mechanism of action Computational chemistry and X-ray crystallographic analysis of selected member compounds clearly defined the protein-inhibitor interaction and assisted the design of analogues 4-[6,6-Dimethyl-4-oxo-3-(trifluoromethyl)-4,5,6,7-tetrahydro-1H-indazol-1-yl]-2-[(trans-4-hydroxycyclohexyl)amino]benzamide (SNX-2112, 9) was identified as highly selective and potent (IC(50) Her2 = 11 nM, HT-29 = 3 nM); its prodrug amino-acetic acid 4-[2-carbamoyl-5-(6,6-dimethyl-4-oxo-3-trifluoromethyl-4,5,6,7-tetrahydro-indazol-1-yl)-phenylamino]-cyclohexyl ester methanesulfonate (SNX-5422, 10) was orally bioavailable and efficacious in a broad range of xenograft tumor models (eg 67% growth delay in a HT-29 model) and is now in multiple phase I clinical trials

Brain-permeable small-molecule inhibitors of Hsp90 prevent alpha-synuclein oligomer formation and rescue alpha-synuclein-induced toxicity.

Abstract: Aggregation of α-synuclein (αsyn) is a hallmark of sporadic and familial Parkinson's disease (PD) and dementia with Lewy bodies. Lewy bodies contain αsyn and several heat shock proteins (Hsp), a family of molecular chaperones up-regulated by the cell under stress. We have previously shown that direct expression of Hsp70 and pharmacological up-regulation of Hsp70 by geldanamycin, an Hsp90 inhibitor, are protective against αsyn-induced toxicity and prevent aggregation in culture. Here, we use a novel protein complementation assay to screen a series of small-molecule Hsp90 inhibitors for their ability to prevent αsyn oligomerization and rescue toxicity. By use of this assay, we found that several compounds prevented αsyn oligomerization as measured by decreased luciferase activity, led to a reduction in high-molecular-mass oligomeric αsyn, and protected against αsyn cytotoxicity. A lead compound, SNX-0723 (2-fluoro-6-[(3 S )-tetrahydrofuran-3-ylamino]-4-(3,6,6-trimethyl-4-oxo-4,5,6,7-tetrahydro-1 H -indol-1-yl)benzamide) was determined to have an EC50 for inhibition of αsyn oligomerization of approximately 48 nM and was able to rescue αsyn-induced toxicity. In vivo assessment of SNX-0723 showed significant brain concentrations along with induction of brain Hsp70. With a low EC50, brain permeability, and oral availability, these novel inhibitors represent an exciting new therapeutic strategy for PD.

Targeting of multiple signaling pathways by the Hsp90 inhibitor SNX-2112 in EGFR resistance models as a single agent or in combination with erlotinib.

Abstract: Inhibition of Hsp90 has emerged as a therapeutic strategy to target NSCLC subtypes, which are refractory to epidermal growth factor receptor (EGFR) inhibitor-based treatment. We report on a novel small molecule inhibitor of Hsp90, SNX-2112, and an orally bioavailable prodrug analog, SNX-5422. In cellular models of wild-type or mutant EGFR (L858R and T790M mutations), SNX-2112 alone and in combination with erlotinib inhibited EGF activation of pAKT(473) and pSTAT3(705). pERK1/2 and pS6 were also potently inhibited by similar treatments. SNX-2112 reduced EGF cross-talk and activation of the c-Met receptor by causing c-Met degradation. In NCI-H1975 xenograft models, SNX-5422 showed activity as a single agent and in combination with erlotinib resulted in prolonged animal survival at reduced compound concentrations relative to either compound alone. These results support the advanced evaluation of SNX-5422 as a treatment for non-small cell lung cancer (NSCLC), especially in cases where the cancer is driven by c-Met amplification or mutated EGFR forms that are resistant to EGFR inhibitors.

Mitogen-activated protein (MAP) kinase pathways: regulation and physiological functions.

Abstract: Mitogen-activated protein (MAP) kinases comprise a family of ubiquitous proline-directed, protein-serine/threonine kinases, which participate in signal transduction pathways that control intracellular events including acute responses to hormones and major developmental changes in organisms. MAP kinases lie in protein kinase cascades. This review discusses the regulation and functions of mammalian MAP kinases. Nonenzymatic mechanisms that impact MAP kinase functions and findings from gene disruption studies are highlighted. Particular emphasis is on ERK1/2.

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

Abstract: Pd-catalyzed cross-coupling reactions that form C–N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C–N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

Transcription factor AP-1 regulation by mitogen-activated protein kinase signal transduction pathways

Abstract: Mitogen-activated protein (MAP) kinases are proline-directed serine/threonine kinases that are activated by dual phosphorylation on threonine and tyrosine residues in response to a wide array of extracellular stimuli. Three distinct groups of MAP kinases have been identified in mammalian cells [extracellular-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38]. These MAP kinases are mediators of signal transduction from the cell surface to the nucleus. One nuclear target of these MAP kinase signaling pathways is the transcription factor AP-1. MAP kinases regulate AP-1 transcriptional activity by multiple mechanisms. Here we review recent progress towards understanding AP-1 regulation by the ERK, JNK, and p38 MAP kinase signal transduction pathways.

ESR1 ligand-binding domain mutations in hormone-resistant breast cancer

Abstract: Sarat Chandarlapaty and colleagues report the identification of mutations in the ESR1 gene affecting the ligand-binding domain of the encoded estrogen receptor in 20% of metastatic hormone-resistant breast cancers. They determine that the mutant receptor has a hormone-independent active state that likely promotes resistance to estrogen-depriving therapies. Seventy percent of breast cancers express estrogen receptor (ER), and most of these are sensitive to ER inhibition. However, many such tumors for unknown reasons become refractory to inhibition of estrogen action in the metastatic setting. We conducted a comprehensive genetic analysis of two independent cohorts of metastatic ER-positive breast tumors and identified mutations in ESR1 affecting the ligand-binding domain (LBD) in 14 of 80 cases. These included highly recurrent mutations encoding p.Tyr537Ser, p.Tyr537Asn and p.Asp538Gly alterations. Molecular dynamics simulations suggest that the structures of the Tyr537Ser and Asp538Gly mutants involve hydrogen bonding of the mutant amino acids with Asp351, thus favoring the agonist conformation of the receptor. Consistent with this model, mutant receptors drive ER-dependent transcription and proliferation in the absence of hormone and reduce the efficacy of ER antagonists. These data implicate LBD-mutant forms of ER in mediating clinical resistance to hormonal therapy and suggest that more potent ER antagonists may be of substantial therapeutic benefit.

Hsp90 molecular chaperone inhibitors: are we there yet?

Abstract: Heat shock protein (Hsp) 90 is an ATP-dependent molecular chaperone exploited by malignant cells to support activated oncoproteins, including many cancer-associated kinases and transcription factors, and is essential for oncogenic transformation. Originally viewed with skepticism, Hsp90 inhibitors are now actively pursued by the pharmaceutical industry, with 17 agents having entered clinical trials. Hsp90’s druggability was established using the natural products geldanamycin and radicicol which mimic the unusual ATP structure adopted in the chaperone’s N-terminal nucleotide-binding pocket and cause potent and selective blockade of ATP binding/hydrolysis, inhibit chaperone function, deplete oncogenic clients, and demonstrate antitumor activity. Preclinical data with these natural products have heightened interest in Hsp90 as a drug target, and 17-allylamino-17-demethoxygeldanamycin (17-AAG, tanespimycin) has demonstrated clinical activity (as defined by RECIST criteria) in HER2+ breast cancer. Many optimized synthetic small molecule Hsp90 inhibitors from diverse chemotypes are now in clinical trials. We review the discovery and development of Hsp90 inhibitors and assess their future potential. There has been significant learning from experience in both the basic biology and the translational drug development around Hsp90, enhanced by the use of Hsp90 inhibitors as chemical probes. Success will likely lie in treating cancers addicted to particular driver oncogene products, such as HER2, ALK, EGFR and BRAF, that are sensitive Hsp90 clients, as well as in malignancies, especially multiple myeloma, where buffering of proteotoxic stress is critical for survival. We discuss approaches to enhancing the effectiveness of Hsp90 inhibitors and highlight new chaperone and stress response pathway targets, including HSF1 and Hsp70.