Identification and Optimization of Small Molecule Pyrazolopyrimidine TLR7 Agonists for Applications in Immuno-oncology.

Small molecule toll-like receptor (TLR) 7 agonists have gathered considerable interest as promising therapeutic agents for applications in cancer immunotherapy. Herein, we describe the development and optimization of a series of novel TLR7 agonists through systematic structure-activity relationship studies focusing on modification of the phenylpiperidine side chain. Additional refinement of ADME properties culminated in the discovery of compound 14, which displayed nanomolar reporter assay activity and favorable drug-like properties. Compound 14 demonstrated excellent in vivo pharmacokinetic/pharmacodynamic profiles and synergistic antitumor activity when administered in combination with aPD1 antibody, suggesting opportunities of employing 14 in immuno-oncology therapies with immune checkpoint blockade agents.

Discovery of Novel TLR7 Agonists as Systemic Agent for Combination With aPD1 for Use in Immuno-oncology.

We have designed and developed novel and selective TLR7 agonists that exhibited potent receptor activity in a cell-based reporter assay. In vitro, these agonists significantly induced secretion of cytokines IL-6, IL-1ß, IL-10, TNFa, IFNa, and IP-10 in human and mouse whole blood. Pharmacokinetic and pharmacodynamic studies in mice showed a significant secretion of IFNα and TNFα cytokines. When combined with aPD1 in a CT-26 tumor model, the lead compound showed strong synergistic antitumor activity with complete tumor regression in 8/10 mice dosed using the intravenous route. Structure-activity relationship studies enabled by structure-based designs of TLR7 agonists are disclosed.

Modulation of cofilin phosphorylation by inhibition of the Lim family kinases.

A series of aminothiazoles that are potent inhibitors of LIM kinases 1 and 2 is described. Appropriate choice of substituents led to molecules with good selectivity for either enzyme. An advanced member of the series was shown to effectively interfere with the phosphorylation of the LIM kinases substrate cofilin. Consistent with the important role of the LIM kinases in regulating cytoskeletal structure, treated cells displayed dramatically reduced F-actin content.

SAR of PXR transactivation in benzimidazole-based IGF-1R kinase inhibitors.

The SAR of PXR transactivation by 3-(benzimidazol-2-yl)-pyridine-2-one based ATP competitive inhibitors of Insulin-like Growth Factor 1 Receptor kinase (IGF-1R) is discussed. Compounds without PXR transactivation, with in vivo antitumor activity, reduced protein binding and improved oral exposure are presented.

Identification of a nonkinase target mediating cytotoxicity of novel kinase inhibitors.

In developing inhibitors of the LIM kinases, the initial lead molecules combined potent target inhibition with potent cytotoxic activity. However, as subsequent compounds were evaluated, the cytotoxic activity separated from inhibition of LIM kinases. A rapid determination of the cytotoxic mechanism and its molecular target was enabled by integrating data from two robust core technologies. High-content assays and gene expression profiling both indicated an effect on microtubule stability. Although the cytotoxic compounds are still kinase inhibitors, and their structures did not predict tubulin as an obvious target, these results provided the impetus to test their effects on microtubule polymerization directly. Unexpectedly, we confirmed tubulin itself as a molecular target of the cytotoxic kinase inhibitor compounds. This general approach to mechanism of action questions could be extended to larger data sets of quantified phenotypic and gene expression data.

Effects of a non-peptide CRF antagonist (DMP696) on the behavioral and endocrine sequelae of maternal separation.

We examined whether blockade of corticotropin-releasing factor (CRF) receptors by a non-peptide CRF antagonist (DMP696) would attenuate the stress hyper-responsiveness that occurs in response to maternal separation. In a social interaction test as well as the elevated plus maze, adult male rats, which had been maternally separated as infants, displayed more anxiety-like behavior compared with handled rats. DMP696 increased social interaction in both groups. In the elevated plus maze however, DMP696 significantly increased open arm time in the maternally separated rats but not in the handled group whereas chlordiazepoxide increased open arm time in both groups. DMP696 also appeared to block stress-induced ACTH secretion more readily in the maternally separated group compared with the handled rats. These observations suggest that CRF antagonists are particularly effective in animals that are hyper-responsive to stress and may therefore have utility in the treatment of anxiety and affective disorders where CRF has been implicated.

The CRF(1) receptor antagonist DMP696 produces anxiolytic effects and inhibits the stress-induced hypothalamic-pituitary-adrenal axis activation without sedation or ataxia in rats.

RATIONALE: CRF(1) antagonists may be effective in the treatment of anxiety disorders while having fewer side effects compared with classical benzodiazepines. OBJECTIVES: The effects of a small molecule selective CRF(1) antagonist DMP696 on anxiety-like behaviors and stress-induced increases in corticosterone in rats exposed to a novel environment and on locomotor activity and motor coordination were determined in rats. These effects of DMP696 were compared with those produced by the classical benzodiazepine chlordiazepoxide (CDP). METHODS: DMP696 or CDP were administered PO, 60 minutes before behavioral testing in rats. Their effects on latency to exit a dark chamber and stress-induced increase in corticosterone in the Defensive Withdrawal test (an animal model of anxiety), locomotor activity, and rotorod performance (measure of ataxia) were determined. RESULTS: DMP696 significantly reduced exit latency and reversed the stress-induced increase in corticosterone in the Defensive Withdrawal test at doses of 3.0-10 mg/kg and higher. In contrast, CDP significantly decreased exit latency at 10 and 30 mg/kg, but not at 100 mg/kg, due to concurrent non-specific side effects. Unlike DMP696, CDP had no effect on the stress-induced increase in corticosterone at lower doses, but resulted in a significant increase at higher doses. DMP696 did not reduce locomotor activity or impair motor coordination at doses up to 30-fold higher than doses effective in the Defensive Withdrawal model. In contrast, CDP produced significant sedation and ataxia at the same doses that were effective in reducing exit latency. CONCLUSIONS: These data suggest that the CRF(1) antagonist DMP696 might retain the therapeutic benefits of classical benzodiazepines but have fewer motoric side effects.

Synthesis and structure-activity relationships of 8-(pyrid-3-yl)pyrazolo[1,5-a]-1,3,5-triazines: potent, orally bioavailable corticotropin releasing factor receptor-1 (CRF1) antagonists.

This report describes the syntheses and structure-activity relationships of 8-(substituted pyridyl)pyrazolo[1,5-a]-1,3,5-triazine corticotropin releasing factor receptor-1 (CRF(1)) receptor antagonists. These CRF(1) receptor antagonists may be potential anxiolytic or antidepressant drugs. This research resulted in the discovery of compound 13-15, which is a potent, selective CRF(1) antagonist (hCRF(1) IC(50) = 6.1 +/- 0.6 nM) with weak affinity for the CRF-binding protein and biogenic amine receptors. This compound also has a good pharmacokinetic profile in dogs. Analogue 13-15 is orally effective in two rat models of anxiety: the defensive withdrawal (situational anxiety) model and the elevated plus maze test. Analogue 13-15 has been advanced to clinical trials.

8-(4-Methoxyphenyl)pyrazolo[1,5-a]-1,3,5-triazines: selective and centrally active corticotropin-releasing factor receptor-1 (CRF1) antagonists.

This report describes the syntheses and structure-activity relationships of 8-(4-methoxyphenyl)pyrazolo[1,5-a]-1,3,5-triazine corticotropin releasing factor receptor-1 (CRF(1)) receptor antagonists. CRF(1) receptor antagonists may be potential anxiolytic or antidepressant drugs. This research culminated in the discovery of analogue 12-3, which is a potent, selective CRF(1) antagonist (hCRF(1) IC(50) = 4.7 +/- 2.0 nM) with weak affinity for the CRF-binding protein and biogenic amine receptors. This compound also has a good pharmacokinetic profile in dogs. Analogue 12-3 is orally effective in two rat models of anxiety: the defensive withdrawal (situational anxiety) model and the elevated plus maze test. Analogue 12-3 has been advanced to clinical trials.