A de novo hit-to-lead effort involving the redesign of benzimidazole-containing antagonists of the CXCR4 receptor resulted in the discovery of a novel series of 1,2,3,4-tetrahydroisoquinoline (TIQ) analogues. In general, this series of compounds show good potencies (3−650 nM) in assays involving CXCR4 function, including both inhibition of attachment of X4 HIV-1 IIIB virus in MAGI-CCR5/ CXCR4 cells and inhibition of calcium release in Chem-1 cells. Series profiling permitted the identification of TIQ-(R)-stereoisomer 15 as a potent and selective CXCR4 antagonist lead candidate with a promising in vitro profile. The drug-like properties of 15 were determined in ADME in vitro studies, revealing low metabolic liability potential. Further in vivo evaluations included pharmacokinetic experiments in rats and mice, where 15 was shown to have oral bioavailability (F = 63%) and resulted in the mobilization of white blood cells (WBCs) in a dose-dependent manner.

To date, outcomes for all Phase III clinical trials for traumatic brain injury (TBI) have been negative. The recent disappointing results of the Progesterone for the Treatment of Traumatic Brain Injury (ProTECT) and Study of a Neuroprotective Agent, Progesterone, in Severe Traumatic Brain Injury (SyNAPSe) Phase III trials for progesterone in TBI have triggered considerable speculation about the reasons for the negative outcomes of these two studies in particular and for those of all previous Phase III TBI clinical trials in general. Among the factors proposed to explain the ProTECT III and SyNAPSe results, the investigators themselves and others have cited: 1) the pathophysiological complexity of TBI itself; 2) issues with the quality and clinical relevance of the preclinical animal models; 3) insufficiently sensitive clinical endpoints; and 4) inappropriate clinical trial designs and strategies. This paper highlights three critical trial design factors that may have contributed substantially to the negative outcomes: 1) suboptimal doses and treatment durations in the Phase II studies; 2) the strategic decision not to perform Phase IIB studies to optimize these variables before initiating Phase III; and 3) the lack of incorporation of the preclinical and Chinese Phase II results, as well as allometric scaling principles, into the Phase III designs. Given these circumstances and the exceptional pleiotropic potential of progesterone as a TBI (and stroke) therapeutic, we are advocating a return to Phase IIB testing. We advocate the incorporation of dose and schedule optimization focused on lower doses and a longer duration of treatment, combined with the addressing of other potential trial design problems raised by the authors in the recently published trial results.

The measles virus (MeV), a member of the paramyxovirus family, is an important cause of pediatric morbidity and mortality worldwide. In an effort to provide therapeutic treatments for improved measles management, we previously identified a small, non-nucleoside organic inhibitor of the viral RNA-dependent RNA polymerase (RdRp) by means of high-throughput screening (HTS). Subsequent structure-activity relationship (SAR) studies around the corresponding pyrazole carboxamide scaffold led to the discovery of 2 (AS-136a), a first generation lead with low nanomolar potency against life MeV and attractive physical properties suitable for development. However, its poor water solubility and low oral bioavailability (F) in the rat suggested that the lead could benefit from further SAR studies to improve the biophysical characteristics of the compound. Optimization of in vitro potency and aqueous solubility led to the discovery of 2o (ERDRP-00519), a potent inhibitor of MeV (EC50 = 60 nM) with aqueous solubility of approximately 60 μg/ml. The agent shows a 10-fold exposure (AUC/Cmax) increase in the rat model relative to 2, displays near dose proportionality in the range of 10 mg/kg to 50 mg/kg, and exhibits good oral bioavailability (F = 39%) in the rat. The significant solubility increase appears linked to the improved oral bioavailability.

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Enigmol is a synthetic, orally active 1-deoxysphingoid base analogue that has demonstrated promising activity against prostate cancer. In these studies, the pharmacologic roles of stereochemistry and N-methylation in the structure of enigmols were examined. A novel enantioselective synthesis of all four possible 2S-diastereoisomers of enigmol (2-aminooctadecane-3,5-diols) from l-alanine is reported, which features a Liebeskind−Srogl cross-coupling reaction between l-alanine thiol ester and (E)-pentadec-1-enylboronic acid as the key step. In vitro biological evaluation of the four enigmol diastereoisomers and 2S,3S,5S-N-methylenigmol against two prostate cancer cell lines (PC-3 and LNCaP) indicates that all but one diastereomer demonstrate potent oncolytic activity. In nude mouse xenograft models of human prostate cancer, enigmol was equally effective as standard prostate cancer therapies (androgen deprivation or docetaxel), and two of the enigmol diastereomers, 2S,3S,5R-enigmol and 2S,3R,5S-enigmol, also caused statistically significant inhibition of tumor growth. A pharmacokinetic profile of enigmol and N-methylenigmol is also presented.