Identification and Optimization of Benzimidazole Sulfonamides as Orally Bioavailable Sphingosine 1-Phosphate Receptor 1 Antagonists with in Vivo Activity.

We report here a novel series of benzimidazole sulfonamides that act as antagonists of the S1P1 receptor, identified by exploiting an understanding of the pharmacophore of a high throughput screening (HTS)-derived series of compounds described previously. Lead compound 2 potently inhibits S1P-induced receptor internalization in a cell-based assay (EC50 = 0.05 µM), but has poor physical properties and metabolic stability. Evolution of this compound through structure-activity relationship development and property optimization led to in vivo probes such as 4. However, this compound was unexpectedly found to be a potent CYP3A inducer in human hepatocytes, and thus further chemistry efforts were directed at addressing this liability. By employing a pregnane X receptor (PXR) reporter gene assay to prioritize compounds for further testing in human hepatocytes, we identified lipophilicity as a key molecular property influencing the likelihood of P450 induction. Ultimately, we have identified compounds such as 46 and 47, which demonstrate the desired S1P1 antagonist activity while having greatly reduced risk of CYP3A induction in humans. These compounds have excellent oral bioavailability in preclinical species and exhibit pharmacodynamic effects of S1P1 antagonism in several in vivo models following oral dosing. Relatively modest antitumor activity was observed in multiple xenograft models, however, suggesting that selective S1P1 antagonists would have limited utility as anticancer therapeutics as single agents.

Discovery of a novel class of dimeric Smac mimetics as potent IAP antagonists resulting in a clinical candidate for the treatment of cancer (AZD5582).

A series of dimeric compounds based on the AVPI motif of Smac were designed and prepared as antagonists of the inhibitor of apoptosis proteins (IAPs). Optimization of cellular potency, physical properties, and pharmacokinetic parameters led to the identification of compound 14 (AZD5582), which binds potently to the BIR3 domains of cIAP1, cIAP2, and XIAP (IC50 = 15, 21, and 15 nM, respectively). This compound causes cIAP1 degradation and induces apoptosis in the MDA-MB-231 breast cancer cell line at subnanomolar concentrations in vitro. When administered intravenously to MDA-MB-231 xenograft-bearing mice, 14 results in cIAP1 degradation and caspase-3 cleavage within tumor cells and causes substantial tumor regressions following two weekly doses of 3.0 mg/kg. Antiproliferative effects are observed with 14 in only a small subset of the over 200 cancer cell lines examined, consistent with other published IAP inhibitors. As a result of its in vitro and in vivo profile, 14 was nominated as a candidate for clinical development.

Discovery of bacterial NAD⁺-dependent DNA ligase inhibitors: improvements in clearance of adenosine series.

Optimization of clearance of adenosine inhibitors of bacterial NAD(+)-dependent DNA ligase is discussed. To reduce Cytochrome P-450-mediated metabolic clearance, many strategies were explored; however, most modifications resulted in compounds with reduced antibacterial activity and/or unchanged total clearance. The alkyl side chains of the 2-cycloalkoxyadenosines were fluorinated, and compounds with moderate antibacterial activity and favorable pharmacokinetic properties in rat and dog were identified.