Discovery of ZN-c3, a Highly Potent and Selective Wee1 Inhibitor Undergoing Evaluation in Clinical Trials for the Treatment of Cancer.

Wee1 inhibition has received great attention in the past decade as a promising therapy for cancer treatment. Therefore, a potent and selective Wee1 inhibitor is highly desirable. Our efforts to make safer and more efficacious Wee1 inhibitors led to the discovery of compound 16, a highly selective Wee1 inhibitor with balanced potency, ADME, and pharmacokinetic properties. The chiral ethyl moiety of compound 16 provided an unexpected improvement of Wee1 potency. Compound 16, known as ZN-c3, showed excellent in vivo efficacy and is currently being evaluated in phase 2 clinical trials.

Discovery and optimization of a highly efficacious class of 5-aryl-2-aminopyridines as FMS-like tyrosine kinase 3 (FLT3) inhibitors.

Based on a putative binding mode of quizartinib (AC220, 1), a potent FMS-like tyrosine kinase 3 (FLT3) inhibitor in Phase III clinical development, we have designed de novo a simpler aminopyridine-based hinge binding motif. Further optimization focusing on maximizing in vivo efficacy and minimizing CYP3A4 time-dependent inhibition resulted in a highly efficacious compound (6s) in tumor xenograft model for further preclinical development.

Identification of bacteria-selective threonyl-tRNA synthetase substrate inhibitors by structure-based design.

A series of potent and bacteria-selective threonyl-tRNA synthetase (ThrRS) inhibitors have been identified using structure-based drug design. These compounds occupied the substrate binding site of ThrRS and showed excellent binding affinities for all of the bacterial orthologues tested. Some of the compounds displayed greatly improved bacterial selectivity. Key residues responsible for potency and bacteria/human ThrRS selectivity have been identified. Antimicrobial activity has been achieved against wild-type Haemophilus influenzae and efflux-deficient mutants of Escherichia coli and Burkholderia thailandensis.

Discovery of highly potent and selective pan-Aurora kinase inhibitors with enhanced in vivo antitumor therapeutic index.

Serine/threonine protein kinases Aurora A, B, and C play essential roles in cell mitosis and cytokinesis. Currently a number of Aurora kinase inhibitors with different isoform selectivities are being evaluated in the clinic. Herein we report the discovery and characterization of 21c (AC014) and 21i (AC081), two structurally novel, potent, kinome-selective pan-Aurora inhibitors. In the human colon cancer cell line HCT-116, both compounds potently inhibit histone H3 phosphorylation and cell proliferation while inducing 8N polyploidy. Both compounds administered intravenously on intermittent schedules displayed potent and durable antitumor activity in a nude rat HCT-116 tumor xenograft model and exhibited good in vivo tolerability. Taken together, these data support further development of both 21c and 21i as potential therapeutic agents for the treatment of solid tumors and hematological malignancies.

Identification of 1-(3-(6,7-dimethoxyquinazolin-4-yloxy)phenyl)-3-(5-(1,1,1-trifluoro-2-methylpropan-2-yl)isoxazol-3-yl)urea hydrochloride (CEP-32496), a highly potent and orally efficacious inhibitor of V-RAF murine sarcoma viral oncogene homologue B1 (BRAF) V600E.

The Ras/RAF/MEK/ERK mitogen-activated protein kinase (MAPK) signaling pathway plays a central role in the regulation of cell growth, differentiation, and survival. Expression of mutant BRAF(V600E) results in constitutive activation of the MAPK pathway, which can lead to uncontrolled cellular growth. Herein, we describe an SAR optimization campaign around a series of quinazoline derived BRAF(V600E) inhibitors. In particular, the bioisosteric replacement of a metabolically sensitive tert-butyl group with fluorinated alkyl moieties is described. This effort led directly to the identification of a clinical candidate, compound 40 (CEP-32496). Compound 40 exhibits high potency against several BRAF(V600E)-dependent cell lines and selective cytotoxicity for tumor cell lines expressing mutant BRAF(V600E) versus those containing wild-type BRAF. Compound 40 also exhibits an excellent PK profile across multiple preclinical species. In addition, significant oral efficacy was observed in a 14-day BRAF(V600E)-dependent human Colo-205 tumor xenograft mouse model, upon dosing at 30 and 100 mg/kg BID.

Novel series of pyrrolotriazine analogs as highly potent pan-Aurora kinase inhibitors.

The synthesis and SAR for a novel series of pyrrolotriazines as pan-Aurora kinase inhibitors are described. Optimization of the cyclopropane carboxamide terminus of lead compound 1 resulted in analogs with high cellular activity and improved rat PK profiles. Notably, compound 17l demonstrated tumor growth inhibition in a mouse xenograft model.

4-Quinazolinyloxy-diaryl ureas as novel BRAFV600E inhibitors.

Aryl phenyl ureas with a 4-quinazolinoxy substituent at the meta-position of the phenyl ring are potent inhibitors of mutant and wild type BRAF kinase. Compound 7 (1-(5-tert-butylisoxazol-3-yl)-3-(3-(6,7-dimethoxyquinazolin-4-yloxy)phenyl)urea hydrochloride) exhibits good pharmacokinetic properties in rat and mouse and is efficacious in a mouse tumor xenograft model following oral dosing.

Studies toward the total synthesis of sorangiolides and their analogues. A convergent stereoselective synthesis of the macrocyclic lactone precursors.

Stereoselective synthesis of the fully protected 18-membered macrocyclic lactones as the immediate precursors of the natural products, sorangiolides A and B, is described. The key steps used in the synthesis include the sp3-hybridized carbon-carbon Fu cross coupling, the stereoselective Evans' aldol reaction with 1,5-anti induction, the 1,3-diastereoselective syn reduction of a beta-hydroxyketone intermediate, and Mukaiyama macrolactonization reactions.

Synthesis of the next-generation therapeutic antibodies that combine cell targeting and antibody-catalyzed prodrug activation.

An obstacle in the utilization of catalytic Abs for selective prodrug activation in cancer therapy has been systemic tumor targeting. Here we report the generation of catalytic Abs that effectively target tumor cells with undiminished prodrug activation capability. Ab conjugates were prepared by covalent conjugation of an integrin alpha(v)beta(3)-targeting antagonist to catalytic Ab 38C2 through either sulfide groups of cysteine residues generated by reduction of the disulfide bridges in the hinge region or surface lysine residues not involved in the catalytic activity. Using flow cytometry, the Ab conjugates were shown to bind efficiently to integrin alpha(v)beta(3)-expressing human breast cancer cells. The Ab conjugates also retained the retro-aldol activity of their parental catalytic Ab 38C2, as measured by methodol and doxorubicin (dox) prodrug activation. Complementing these Ab conjugates, an evolved set of dox prodrugs was designed and synthesized. Dox prodrugs that showed higher stability and lower toxicity were evaluated both in the presence and absence of the integrin alpha(v)beta(3)-targeting 38C2 conjugates for cell-killing efficacy by using human breast cancer cells. Our study reveals that cell targeting and prodrug activation capabilities can be efficiently combined for selective chemotherapy with novel dox prodrugs.

A bidirectional approach to the synthesis of a complete library of adjacent-bis-THF annonaceous acetogenins.

Thirty-six stereoisomers of bifunctional adjacent bis-THF (tetrahydrofuran) lactones have been synthesized, which can afford a complete library of the adjacent bis-THF Annonaceous acetogenins. The bis-THF lactones were synthesized, starting from the enantioselectively pure 8,9:12,13-(E,E and Z,E)-16-benzyloxy-5-hydroxy-hexadeca-1,4-olide, in a highly distereoselective manner using oxidative reactions, including rhenium(VII) oxides-mediated oxidative cyclization, Shi's asymmetric epoxidation, and Sharpless asymmetric dihydroxylation reactions. Using the nonsymmetrical bis-THF lactones, syntheses of two nonnatural acetogenins were achieved.

Synthetic studies on borrelidin: enantioselective synthesis of the C1-C12 fragment.

[structure: see text] An efficient, enantioselective synthesis of the C1-C12 fragment 2 of borrelidin is presented. Construction of the "skipped" polymethylene chain of 2 was accomplished by iteration of Myers' alkylation, while formation of the C3 stereocenter was achieved by Roush's asymmetric allylboration methodology.