Antonella Ermoli

Cdc7 Kinase Inhibitors: 5-Heteroaryl-3-Carboxamido-2-Aryl Pyrroles as Potential Antitumor Agents. 1. Lead Finding

Cdc7 serine/threonine kinase is a key regulator of DNA synthesis in eukaryotic organisms. Cdc7 inhibition through siRNA or prototype small molecules causes p53 independent apoptosis in tumor cells while reversibly arresting cell cycle progression in primary fibroblasts. This implies that Cdc7 kinase could be considered a potential target for anticancer therapy. We previously reported that pyrrolopyridinones (e.g., 1) are potent and selective inhibitors of Cdc7 kinase, with good cellular potency and in vitro ADME properties but with suboptimal pharmacokinetic profiles. Here we report on a new chemical class of 5-heteroaryl-3-carboxamido-2-substituted pyrroles (1A) that offers advantages of chemistry diversification and synthetic simplification. This work led to the identification of compound 18, with biochemical data and ADME profile similar to those of compound 1 but characterized by superior efficacy in an in vivo model. Derivative 18 represents a new lead compound worthy of further investigation toward the ultimate goal of identifying a clinical candidate.

Cell division cycle 7 kinase inhibitors: 1H-pyrrolo[2,3-b]pyridines, synthesis and structure-activity relationships.

Cdc7 kinase has recently emerged as an attractive target for cancer therapy and low-molecular-weight inhibitors of Cdc7 kinase have been found to be effective in the inhibition of tumor growth in animal models. In this paper, we describe synthesis and structure-activity relationships of new 1H-pyrrolo[2,3-b]pyridine derivatives identified as inhibitors of Cdc7 kinase. Progress from (Z)-2-phenyl-5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethylene)-3,5-dihydro-4H-imidazol-4-one (1) to [(Z)-2-(benzylamino)-5-(1H-pyrrolo[2,3-b]pyridin-3-ylmethylene)-1,3-thiazol-4(5H)-one] (42), a potent ATP mimetic inhibitor of Cdc7 kinase with IC(50) value of 7 nM, is also reported.

Discovery of Nms-E973 as Novel, Selective and Potent Inhibitor of Heat Shock Protein 90 (Hsp90).

Novel small molecule inhibitors of heat shock protein 90 (Hsp90) were discovered with the help of a fragment based drug discovery approach (FBDD) and subsequent optimization with a combination of structure guided design, parallel synthesis and application of medicinal chemistry principles. These efforts led to the identification of compound 18 (NMS-E973), which displayed significant efficacy in a human ovarian A2780 xenograft tumor model, with a mechanism of action confirmed in vivo by typical modulation of known Hsp90 client proteins, and with a favorable pharmacokinetic and safety profile.

Preparation of novel 3,7-, 7,9- and 1,7-disubstituted guanines

Abstract Treatment of guanosine with arylmethyl halides in N,N-dimethylacetamide results in a series of 3,7-bis(arylmethyl) guanines and 7,9-bis(arylmethyl)guaninium halides. The same reaction on 7-arylmethyl guanines yields 3,7- and 7,9- differently disubstituted guanines. When 7-arylmethyl guanines are reacted with (hetero)arylmethyl halides in the presence of sodium hydride in N,N-dimethylformamide, 3,7- and 1,7-disubstituted guanines are obtained. All of these compounds, but one, are new and the preparation of 3,7-bis(substituted) guanines from guanosine as well as of 3,7- and 1,7-di(hetero)arylmethyl guanines from 7-substituted guanine is unprecedented.

Abstract 2082: NMS-E668, a potent and selective RET kinase inhibitor characterized by specificity towards VEGFR2 and high antitumor efficacy against RET-driven models

RET, a receptor tyrosine kinase (RTK) expressed mainly in neural crest-derived tissues, plays a role in cell growth and differentiation and its physiological activation depends upon binding to the GDNF family. Genetic aberrations leading to constitutive RET activation are well-established as oncogenic events. Activating point mutations of RET, for example, are present in ca. 70% of medullary thyroid carcinoma patients including all hereditary cases, while RET gene rearrangements resulting in production of activated RET fusion proteins occur in approximately 10% of sporadic papillary thyroid carcinomas. More recently, recurring RET gene rearrangements have also been found in 1-2 % of lung adenocarcinomas and subsets of other solid tumors including colorectal and salivary gland carcinomas. Thus RET kinase represents an actionable therapeutic target in multiple clinical settings with high medical need. Consequently several small-molecule inhibitors targeting this kinase have been explored in clinical settings. A common feature of most advanced agents is their lack of selectivity and in particular their potent cross-reactivity against VEGFR2, an RTK whose inhibition is associated with serious, dose-limiting cardiovascular toxicity. Indeed, the high homology between the two kinases renders identification of ATP competitive compounds that selectively inhibit RET over VEGFR2 a highly challenging task. Here we describe the preclinical activity of NMS-E668, a potent and selective ATP-competitive RET inhibitor characterized by favorable activity, selectivity and ADME profiles. Biochemically, NMS-E668 has an excellent selectivity profile against a panel of >50 kinases, notably including >10-fold selectivity over VEGFR2. Selectivity of NMS-E668 for RET vs. VEGFR2 was confirmed in NIH-3T3 cells engineered to express activated forms of these kinases. NMS-E668 potently (IC50 circa 50 nM) and selectively inhibited proliferation of RET-dependent tumor cells, including TT medullary carcinoma cells harboring a RET C634W activating point mutation and LC2/ad lung carcinoma cells bearing the oncogenic fusion protein CCDC6-RET. NMS-E668 also potently inhibited IL3-independent growth of Ba/F3 cells expressing KIF5B-RET, the RET rearrangement that is most commonly found in lung adenocarcinomas. Cellular mechanism studies confirmed that NMS-E668 inhibits RET autophosphorylation and downstream signaling at doses consistent with antiproliferative activity. Tested in vivo against KIF5B-RET-driven Ba/F3 tumors, NMS-E668 displayed >90% tumor growth inhibition accompanied by target modulation following oral administration at 10 and 20 mg/kg, with prolonged tumor regressions observed at the higher dose. Thus NMS-E668, a potent and VEGFR2-sparing RET inhibitor is an innovative and highly promising candidate for further development. Citation Format: Elena Ardini, Patrizia Banfi, Nilla Avanzi, Marina Ciomei, Paolo Polucci, Alessandra Cirla, Antonella Ermoli, Ilaria Motto, Elena Casale, Giulia Canevari, Cinzia Cristiani, Sonia Troiani, Federico Riccardi Sirtori, Nadia Amboldi, Dario Ballinari, Francesco Caprera, Eduard Felder, Arturo Galvani, Daniele Donati, Antonella Isacchi, Maria Menichincheri. NMS-E668, a potent and selective RET kinase inhibitor characterized by specificity towards VEGFR2 and high antitumor efficacy against RET-driven models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2082. doi:10.1158/1538-7445.AM2017-2082