Sergio Mantegani

Inhibition of protein–protein interactions: The discovery of druglike β‐catenin inhibitors by combining virtual and biophysical screening

The interaction between β‐catenin and Tcf family members is crucial for the Wnt signal transduction pathway, which is commonly mutated in cancer. This interaction extends over a very large surface area (4800 Å2), and inhibiting such interactions using low molecular weight inhibitors is a challenge. However, protein surfaces frequently contain “hot spots,” small patches that are the main mediators of binding affinity. By making tight interactions with a hot spot, a small molecule can compete with a protein. The Tcf3/Tcf4‐binding surface on β‐catenin contains a well‐defined hot spot around residues K435 and R469. A 17,700 compounds subset of the Pharmacia corporate collection was docked to this hot spot with the QXP program; 22 of the best scoring compounds were put into a biophysical (NMR and ITC) screening funnel, where specific binding to β‐catenin, competition with Tcf4 and finally binding constants were determined. This process led to the discovery of three druglike, low molecular weight Tcf4‐competitive compounds with the tightest binder having a KD of 450 nM. Our approach can be used in several situations (e.g., when selecting compounds from external collections, when no biochemical functional assay is available, or when no HTS is envisioned), and it may be generally applicable to the identification of inhibitors of protein–protein interactions. Proteins 2006.

Synthesis and nidation inhibitory activity of a new class of ergoline derivatives

Abstract The synthesis and the nidation inhibitory activity (indirect evidence of prolactin activity) of a new class of ergolinyl-acylureas is described. Some structure—activity relationship considerations are also reported. N -[3-(Dimethyl-amino)propyl]- N -[(ethylamino)carbonyl]-6-(2-propenyl)ergoline-8β-carboxamide (laboratory code FCE 21336; international non-proprietary name cabergoline) was the most interesting compound of the series and is now under extensive clinical evaluation in treatment of hyperprolactinemic disorders.

The generation of purinome-targeted libraries as a means to diversify ATP-mimetic chemical classes for lead finding

The generation of novel chemotypes in support of our oncology research projects expanded in recent years from a canonical design of kinase-targeted compound libraries to a broader interpretation of purinome-targeted libraries (PTL) addressing the specificity of cancer relevant targets such as kinases and ATPases. Successful screening of structurally diverse ATP-binding targets requires compound libraries covering multiple design elements, which may include phosphate surrogate moieties in ATPase inhibitors or far reaching lipophilic residues stabilizing inactive kinase conformations. Here, we exemplify the design and preparation of drug-like combinatorial libraries and report significantly enhanced screening performance on purinomic targets. We compared overall hit rates of PTL with a simultaneously tested unbiased collection of 200,000 compounds and found consistent superiority of the targeted libraries in all cases. We also analyzed the performance of the largest targeted libraries in comparison with each other and often found striking differences in how a specific target responds to various chemotypes and to whole collections.Graphical Abstract

NMS-E973, a Novel Synthetic Inhibitor of Hsp90 with Activity against Multiple Models of Drug Resistance to Targeted Agents, Including Intracranial Metastases

Purpose: Recent developments of second generation Hsp90 inhibitors suggested a potential for development of this class of molecules also in tumors that have become resistant to molecular targeted agents. Disease progression is often due to brain metastases, sometimes related to insufficient drug concentrations within the brain. Our objective was to identify and characterize a novel inhibitor of Hsp90 able to cross the blood–brain barrier (BBB). Experimental Design: Here is described a detailed biochemical and crystallographic characterization of NMS-E973. Mechanism-based anticancer activity was described in cell models, including models of resistance to kinase inhibitors. Pharmacokinetics properties were followed in plasma, tumor, liver, and brain. In vivo activity and pharmacodynamics, as well as the pharmacokinetic/pharmacodynamic relationships, were evaluated in xenografts, including an intracranially implanted melanoma model. Results: NMS-E973, representative of a novel isoxazole-derived class of Hsp90 inhibitors, binds Hsp90α with subnanomolar affinity and high selectivity towards kinases, as well as other ATPases. It possesses potent antiproliferative activity against tumor cell lines and a favorable pharmacokinetic profile, with selective retention in tumor tissue and ability to cross the BBB. NMS-E973 induces tumor shrinkage in different human tumor xenografts, and is highly active in models of resistance to kinase inhibitors. Moreover, consistent with its brain penetration, NMS-E973 is active also in an intracranially implanted melanoma model. Conclusions: Overall, the efficacy profile of NMS-E973 suggests a potential for development in different clinical settings, including tumors that have become resistant to molecular targeted agents, particularly in cases of tumors which reside beyond the BBB. Clin Cancer Res; 19(13); 3520–32. ©2013 AACR.

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.

An Easy Entry to (1S, 2S) and (1R, 2R)-Threo-Ifenprodil

Abstract A facile and practical synthesis of enantiomerically pure (L) or (D)-threo-Ifenprodil was accomplished from (1S, 2S)- and (1R, 2R)-threo-1-(p-nitrophenyl)-2-amino-propan-1, 3-diol via 3-phenylthio derivatives followed by Raney nickel reduction and conversion of the aromatic amine into phenol.

Abstract A213: Potent anticancer activity in vitro and in vivo by NMS‐E973, a novel synthetic inhibitor of HSP90

The molecular chaperone heat shock protein 90 (HSP90) is essential for the conformational maturation and stability of a variety of proteins, including kinases, transcription factors, telomerase, and other key proteins implicated in cancer development and progression. The simultaneous block of multiple signaling pathways that is induced by Hsp90 inhibition makes this approach potentially attractive in a broad range of cancer types. Prototype geldanamicyn‐derivative HSP90 inhibitors have already shown efficacy in different types of tumors, but possess liabilities inherent to the class which may ultimately limit their development. Here we describe the in vitro and in vivo characterisation of NMS‐E973, representative of a novel class of non‐ansamycin Hsp90 inhibitors. NMS‐E973 binds HSP90 with picomolar affinity, as revealed by Surface Plasmon Resonance analysis, whereas selectivity screening showed no significant activity against a broad panel of kinases, as well as other ATPases. NMS‐E973, when profiled against a panel of 91 tumor cell lines of various tissue origins, showed widespread antiproliferative activity. On‐target mechanism was confirmed in multiple cell lines by observation of dose and time dependent degradation of specific oncogenes, parallel blockade of the PI3K and RAF/MEK/ERK pathways, and upregulation of HSP70, a well‐known feedback response to HSP90 inhibition. In vivo, NMS‐E973 had a favourable pharmacokinetic profile, good tolerability, selective retention in tumors, and induced tumor shrinkage in multiple human xenograft models in nude mice. In the B‐RAF V600E driven A375 melanoma model, for which a multi‐cycle regimen was adopted, shrinkage was observed both during the first treatment cycle, as well as after successive re‐challenge of larger, regrown tumor masses. In conclusion, NMS‐E973 is a novel, potent non‐ansamycin like inhibitor of HSP90, with efficacy and pharmacokinetic properties compatible with clinical development. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):A213.