The macrocyclic peptide cyclotheonamide A (CtA), isolated from the marine sponge Theonella sp., represents an unusual class of serine protease inhibitor. A complex of this inhibitor with human a-thrombin, a protease central to the bioregulation of thrombosis and hemostasis, was studied by x-ray crystallography. This work (2.3-A resolution) confirms the structure of CtA and reveals intimate details about its molecular recognition within the enzyme active site. Interactions due to the "Pro-Arg motif" (Arg occupancy of the SI specificity pocket; formation of a hydrogen-bonded two-strand antiparallel 3-sheet with Ser214-Gly216) and the a-keto amide group of CtA are primarily responsible for binding to thrombin, with the a-keto amide serving as a transition-state analogue. A special interaction with the "insertion loop" of thrombin (Tyr6OA-Thr60I) is manifested through engagement of the hydroxyphenyl group of CtA with Trp6OD as part of an "aromatic stacking chain." Biochemical inhibition data (K, values at 37C) were obtained for CtA with thrombin and a diverse collection of serine proteases. Thus, CtA is just a moderate inhibitor of human ae-thrombin (K, = 0.18 ,IM) but a potent inhibitor of trypsin (Kj = 0.023 IAM) and streptokinase (K, = 0.035 ,AM). The relative lack of potency of CtA as a thrombin inhibitor is discussed with respect to certain structural features of the enzyme complex. We also report the total synthesis of CtA, by a convergent [2 + 3] fragmentcondensation approach, to serve the preparation of cyclotheonamide analogues for structure-function studies.

Single-agent osimertinib is the standard of care for the firstline treatment of advancedEGFRþ NSCLC and remained the only marketed third-generation EGFR tyrosine kinase inhibitor (TKI) until March 2020 when almonertinib (HS-10296) was approved in the People's Republic of China for the treatment of advanced EGFR T790Mþ NSCLC based on a phase 2 expansion study of a phase 1/2 trial. In this review, we profiled many of the third-generation EGFR TKIs in latestage clinical development (e.g., almonertinib, lazertinib, alflutinib 1 , rezivertinib, ASK120069, SH-1028, D-0316, and abivertinib) based on their interim results from phase 1 and phase 2 trials, and included the designs of the phase 3 trials and their chemical structures when publicly available. We also listed other third-generation EGFR TKIs in pipeline development based on the search of clinical trial registration websites. In addition, we summarized the results of clinical trials that previously reported third-generation EGFR TKIs (rociletinib, olmutinib, nazartinib, mavelertinib), including phase 3 results of rociletinib and naquotinib. We further profiled combination clinical trial design of the thirdgeneration EGFR TKIs including FLAURA2 (NCT04035486), MARIPOSA (NCT04487080), ACROSS1 (NCT04500704), and ACROSS2 (NCT04500717) that if positive can potentially usher in the next standard of care for advanced EGFRþ NSCLC.

Certain leukocytes release serine proteases that sustain inflammatory processes and cause disease conditions, such as asthma and chronic obstructive pulmonary disease. We identified ␤-ketophosphonate 1 (JNJ-10311795; RWJ-355871) as a novel, potent dual inhibitor of neutrophil cathepsin G (K i ‫؍‬ 38 nM) and mast cell chymase (K i ‫؍‬ 2.3 nM). The x-ray crystal structures of 1 complexed with human cathepsin G (1.85 Å) and human chymase (1.90 Å) reveal the molecular basis of the dual inhibition. Ligand 1 occupies the S 1 and S 2 subsites of cathepsin G and chymase similarly, with the 2-naphthyl in S 1 , the 1-naphthyl in S 2 , and the phosphonate group in a complex network of hydrogen bonds. Surprisingly, however, the carboxamido-N-(naphthalene-2-carboxyl)piperidine group is found to bind in two distinct conformations. In cathepsin G, this group occupies the hydrophobic S 3 /S 4 subsites, whereas in chymase, it does not; rather, it folds onto the 1-naphthyl group of the inhibitor itself. Compound 1 exhibited noteworthy antiinflammatory activity in rats for glycogen-induced peritonitis and lipopolysaccharide-induced airway inflammation. In addition to a marked reduction in neutrophil influx, 1 reversed increases in inflammatory mediators interleukin-1␣, interleukin-1␤, tissue necrosis factor-␣, and monocyte chemotactic protein-1 in the glycogen model and reversed increases in airway nitric oxide levels in the lipopolysaccharide model. These findings demonstrate that it is possible to inhibit both cathepsin G and chymase with a single molecule and suggest an exciting opportunity in the treatment of asthma and chronic obstructive pulmonary disease.

We have explored the structure-activity relationship (SAR) surrounding the clinically efficacious antiepileptic drug topiramate (1), a unique sugar sulfamate anticonvulsant that was discovered in our laboratories. Systematic structural modification of the parent compound was directed to identifying potent anticonvulsants with a long duration of action and a favorable neurotoxicity index. In this context, we have probed the pharmacological importance of several molecular features: (1) the sulfamate group (6-8, 22-25, 27, 84), (2) the linker between the sulfamate group and the pyran ring (9, 10, 21a,b), (3) the substituents on the 2,3- (58-60, 85, 86) and 4, 5-fused (30-38, 43, 45-47, 52, 53) 1,3-dioxolane rings, (4) the constitution of the 4,5-fused 1,3-dioxolane ring (2, 54, 55, 63-68, 76, 77, 80, 83a-r, 84-87, 90a, 91a, 93a), (5) the ring oxygen atoms (95, 96, 100-102, 104, 105), and (6) the absolute stereochemistry (106 and 107). We established the C1 configuration as R for the predominant alcohol diastereomer from the highly selective addition of methylmagnesium bromide to aldehyde 15 (16:1 ratio) by single-crystal X-ray analysis of the major diastereomer of sulfamate 21a. Details for the stereoselective syntheses of the hydrindane carbocyclic analogues 95, 96, 100, and 104 are presented. We also report the synthesis of cyclic imidosulfites 90a and 93a, and imidosulfate 91a, which are rare examples in the class of such five-membered-ring sulfur species. Imidosulfite 93a required the preparation and use of the novel sulfur dichloride reagent, BocN=SCl2. Our SAR investigation led to the impressive 4,5-cyclic sulfate analogue 2 (RWJ-37947), which exhibits potent anticonvulsant activity in the maximal electroshock seizure (MES) test (ca. 8 times greater than 1 in mice at 4 h, ED50 = 6.3 mg/kg; ca. 15 times greater than 1 in rats at 8 h, ED50 = 1.0 mg/kg) with a long duration of action (>24 h in mice and rats, po) and very low neurotoxicity (TD50 value of >1000 mg/kg at 2 h, po in mice). Cyclic sulfate 2, like topiramate and phenytoin, did not interfere with seizures induced by pentylenetetrazole, bicucculine, picrotoxin, and strychnine; also, 2 was not active in diverse in vitro receptor binding and uptake assays. However, 2 turned out to be a potent inhibitor of carbonic anhydrase from different rat tissue sources (e. g., IC50 of 84 nM for the blood enzyme and 21 nM for the brain enzyme). An examination of several analogues of 2 (83a-r, 85-87, 90a, 91a, 93a) indicated that potent anticonvulsant activity is associated with relatively small alkyl substituents on nitrogen (Me/H, 83a; Me/Me, 83m; Et/H, 83b; allyl/H, 83e; c-Pr/H, 83j; c-Bu/H, 83k) and with limited changes in the cyclic sulfate group, such as 4,5-cyclic sulfite 87a/b. The potent anticonvulsants 83a and 83j had greatly diminished carbonic anhydrase inhibitory activity; thus, inhibition of this enzyme may not be a significant factor in the anticonvulsant activity. The alpha-L-sorbopyranoses 67, 68, and 80, which mainly possess a skew conformation (ref 29...

The serine protease cathepsin G (EC 3.4.21.20; Cat G), which is stored in the azurophilic granules of neutrophils (polymorphonuclear leukocytes) and released on degranulation, has been implicated in various pathological conditions associated with inflammation. By employing high-throughput screening, we identified beta-ketophosphonic acid 1 as a moderate inhibitor of Cat G (IC(50) = 4.1 microM). We were fortunate to obtain a cocrystal of 1 with Cat G and solve its structure by X-ray crystallography (3.5 A). Structural details from the X-ray analysis of 1.Cat G served as a platform for optimization of this lead compound by structure-based drug design. With the aid of molecular modeling, substituents were attached to the 3-position of the 2-naphthyl ring of 1, which occupies the S1 pocket of Cat G, to provide an extension into the hydrophobic S3 region. Thus, we arrived at analogue 7 with an 80-fold potency improvement over 1 (IC(50) = 53 nM). From these results, it is evident that the beta-ketophosphonic acid unit can form the basis for a novel class of serine protease inhibitors.