Alicia Regueiro-Ren

Phospholipidosis as a Function of Basicity, Lipophilicity, and Volume of Distribution of Compounds

Drug-induced phospholipidosis (PLD) is an adaptive histologic alteration that is seen with various marketed drugs and often encountered during drug development. Various in silico and in vitro cell-based methods have been developed to predict the PLD-inducing potential of compounds. These methods rely on the inherent physicochemical properties of the molecule and, as such, tend to overpredict compounds as PLD inducers. Recognizing that the distribution of compounds into tissues or tissue accumulation is likely a key factor in PLD induction, in addition to key physicochemical properties, we developed a model to predict PLD in vivo using the measures of basicity (pK(a)), lipophilicity (ClogP), and volume of distribution (V(d)). Using sets of PLD inducers and noninducers, we demonstrate improved concordance with this method. Furthermore, we propose a screening paradigm that includes a combination of various methods to predict the in vivo PLD-inducing potential of compounds, which may be especially useful in lead identification and optimization processes in drug discovery.

Improving Physical Properties via CH Oxidation: Chemical and Enzymatic Approaches†

Physicochemical properties constitute a key factor for the success of a drug candidate. Whereas many strategies to improve the physicochemical properties of small heterocycle-type leads exist, complex hydrocarbon skeletons are more challenging to derivatize because of the absence of functional groups. A variety of C-H oxidation methods have been explored on the betulin skeleton to improve the solubility of this very bioactive, yet poorly water-soluble, natural product. Capitalizing on the innate reactivity of the molecule, as well as the few molecular handles present on the core, allowed oxidations at different positions across the pentacyclic structure. Enzymatic oxidations afforded several orthogonal oxidations to chemical methods. Solubility measurements showed an enhancement for many of the synthesized compounds.

Discovery and Preclinical Characterization of the Cyclopropylindolobenzazepine BMS-791325, A Potent Allosteric Inhibitor of the Hepatitis C Virus NS5B Polymerase.

Described herein are structure-activity relationship studies that resulted in the optimization of the activity of members of a class of cyclopropyl-fused indolobenzazepine HCV NS5B polymerase inhibitors. Subsequent iterations of analogue design and syntheses successfully addressed off-target activities, most notably human pregnane X receptor (hPXR) transactivation, and led to significant improvements in the physicochemical properties of lead compounds. Those analogues exhibiting improved solubility and membrane permeability were shown to have notably enhanced pharmacokinetic profiles. Additionally, a series of alkyl bridged piperazine carboxamides was identified as being of particular interest, and from which the compound BMS-791325 (2) was found to have distinguishing antiviral, safety, and pharmacokinetic properties that resulted in its selection for clinical evaluation.

Inhibitors of human immunodeficiency virus type 1 (HIV-1) attachment. 12. Structure-activity relationships associated with 4-fluoro-6-azaindole derivatives leading to the identification of 1-(4-benzoylpiperazin-1-yl)-2-(4-fluoro-7-[1,2,3]triazol-1-yl-1h-pyrrolo[2,3-c]pyridin-3-yl)ethane-1,2-dione (BMS-585248).

A series of highly potent HIV-1 attachment inhibitors with 4-fluoro-6-azaindole core heterocycles that target the viral envelope protein gp120 has been prepared. Substitution in the 7-position of the azaindole core with amides (12a,b), C-linked heterocycles (12c-l), and N-linked heterocycles (12m-u) provided compounds with subnanomolar potency in a pseudotype infectivity assay and good pharmacokinetic profiles in vivo. A predictive model was developed from the initial SAR in which the potency of the analogues correlated with the ability of the substituent in the 7-position of the azaindole to adopt a coplanar conformation by either forming internal hydrogen bonds or avoiding repulsive substitution patterns. 1-(4-Benzoylpiperazin-1-yl)-2-(4-fluoro-7-[1,2,3]triazol-1-yl-1H-pyrrolo[2,3-c]pyridin-3-yl)ethane-1,2-dione (BMS-585248, 12m) exhibited much improved in vitro potency and pharmacokinetic properties than the previous clinical candidate BMS-488043 (1). The predicted low clearance in humans, modest protein binding, and good potency in the presence of 40% human serum for 12m led to its selection for human clinical studies.

Identification and Characterization of BMS-955176, a Second-Generation HIV-1 Maturation Inhibitor with Improved Potency, Antiviral Spectrum, and Gag Polymorphic Coverage

ABSTRACT BMS-955176 is a second-generation human immunodeficiency virus type 1 (HIV-1) maturation inhibitor (MI). A first-generation MI, bevirimat, showed clinical efficacy in early-phase studies, but ∼50% of subjects had viruses with reduced susceptibility associated with naturally occurring polymorphisms in Gag near the site of MI action. MI potency was optimized using a panel of engineered reporter viruses containing site-directed polymorphic changes in Gag that reduce susceptibility to bevirimat (including V362I, V370A/M/Δ, and T371A/Δ), leading incrementally to the identification of BMS-955176. BMS-955176 exhibits potent activity (50% effective concentration [EC50], 3.9 ± 3.4 nM [mean ± standard deviation]) toward a library (n = 87) of gag/pr recombinant viruses representing 96.5% of subtype B polymorphic Gag diversity near the CA/SP1 cleavage site. BMS-955176 exhibited a median EC50 of 21 nM toward a library of subtype B clinical isolates assayed in peripheral blood mononuclear cells (PBMCs). Potent activity was maintained against a panel of reverse transcriptase, protease, and integrase inhibitor-resistant viruses, with EC50s similar to those for the wild-type virus. A 5.4-fold reduction in EC50 occurred in the presence of 40% human serum plus 27 mg/ml of human serum albumin (HSA), which corresponded well to an in vitro measurement of 86% human serum binding. Time-of-addition and pseudotype reporter virus studies confirm a mechanism of action for the compound that occurs late in the virus replication cycle. BMS-955176 inhibits HIV-1 protease cleavage at the CA/SP1 junction within Gag in virus-like particles (VLPs) and in HIV-1-infected cells, and it binds reversibly and with high affinity to assembled Gag in purified HIV-1 VLPs. Finally, in vitro combination studies showed no antagonistic interactions with representative antiretrovirals (ARVs) of other mechanistic classes. In conclusion, BMS-955176 is a second-generation MI with potent in vitro anti-HIV-1 activity and a greatly improved preclinical profile compared to that of bevirimat.

Discovery of BMS-955176, a Second Generation HIV-1 Maturation Inhibitor with Broad Spectrum Antiviral Activity

HIV-1 maturation inhibition (MI) has been clinically validated as an approach to the control of HIV-1 infection. However, identifying an MI with both broad polymorphic spectrum coverage and good oral exposure has been challenging. Herein, we describe the design, synthesis, and preclinical characterization of a potent, orally active, second generation HIV-1 MI, BMS-955176 (2), which is currently in Phase IIb clinical trials as part of a combination antiretroviral regimen.

Mild deprotection of 2-(trimethylsilyl)ethyl esters

Abstract A method for the deprotection of 2-(trimethylsilyl)ethyl (TMSE) esters is described. Treatment of carboxylic esters with NaH in DMF cleanly produces the deprotected acid after extractive work-up. This method can be applied to sterically-hindered substrates as well as esters containing fluoride-labile functionality. A tandem alkylation/ester deprotection procedure is also presented.

Inhibitors of HIV-1 maturation: Development of structure–activity relationship for C-28 amides based on C-3 benzoic acid-modified triterpenoids

We have recently reported on the discovery of a C-3 benzoic acid (1) as a suitable replacement for the dimethyl succinate side chain of bevirimat (2), an HIV-1 maturation inhibitor that reached Phase II clinical trials before being discontinued. Recent SAR studies aimed at improving the antiviral properties of 2 have shown that the benzoic acid moiety conferred topographical constraint to the pharmacophore and was associated with a lower shift in potency in the presence of human serum albumin. In this manuscript, we describe efforts to improve the polymorphic coverage of the C-3 benzoic acid chemotype through modifications at the C-28 position of the triterpenoid core. The dimethylaminoethyl amides 17 and 23 delivered improved potency toward bevirimat-resistant viruses while increasing C24 in rat oral PK studies.

Inhibitors of human immunodeficiency virus type 1 (HIV-1) attachment 13. Synthesis and profiling of a novel amminium prodrug of the HIV-1 attachment inhibitor BMS-585248.

In vitro studies suggested that the ammonium salt 2 could be a viable prodrug of the HIV-1 attachment inhibitor 1. Increased systemic exposure of the parent drug 1 following oral administration of the amminium salt 2 when compared to similar studies using solution dosing of the parent compound was observed in the in vivo studies in both rats and dogs. At high doses, the improvement in oral exposure of the parent drug was even more evident, indicating that the increased solubility of the amminium salt 2 can overcome dissolution-limited absorption and demonstrating the potential utility of this compound as a prodrug of 1.

Developments in Antiviral Drug Design, Discovery and Development in 2004

This article summarizes key aspects of progress made during 2004 toward the design, discovery and development of antiviral agents for clinical use. Important developments in the identification, characterization and clinical utility of inhibitors of human immunodeficiency virus; the hepatitis viruses, hepatitis B, hepatitis C; the herpes family of viruses, herpes simplex viruses 1 and 2, varicella zoster virus, Epstein-Barr virus and human cytomegalovirus; the respiratory viruses, influenza, respiratory syncytial virus, human metapneumovirus, picornaviruses, measles and the severe acute respiratory syndrome coronavirus; human papilloma virus; rotavirus; Ebola virus and West Nile virus, are reviewed.