ABSTRACT
Interleukin-2 inducible T-cell kinase (Itk) plays a role in T-cell functions, and its inhibition potentially represents an attractive intervention point to treat autoimmune and allergic diseases. Herein we describe the discovery of a series of potent and selective novel inhibitors of Itk. These inhibitors were identified by structure-based design, starting from a fragment generated de novo, the 3-aminopyrid-2-one motif. Functionalization of the 3-amino group enabled rapid enhancement of the inhibitory activity against Itk, while introduction of a substituted heteroaromatic ring in position 5 of the pyridone fragment was key to achieving optimal selectivity over related kinases. A careful analysis of the hydration patterns in the kinase active site was necessary to fully explain the observed selectivity profile. The best molecule prepared in this optimization campaign, 7v, inhibits Itk with a K(i) of 7 nM and has a good selectivity profile across kinases.
Subject(s)
Drug Design , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Protein-Tyrosine Kinases/antagonists & inhibitors , Pyridones/chemistry , Pyridones/pharmacology , Adenosine Triphosphate/metabolism , Catalytic Domain , Hydrogen Bonding , Maleimides/chemistry , Models, Molecular , Protein Kinase Inhibitors/chemical synthesis , Protein-Tyrosine Kinases/chemistry , Protein-Tyrosine Kinases/metabolism , Pyridones/chemical synthesis , Structure-Activity Relationship , Substrate SpecificityABSTRACT
DNA-damaging agents are among the most frequently used anticancer drugs. However, they provide only modest benefit in most cancers. This may be attributed to a genome maintenance network, the DNA damage response (DDR), that recognizes and repairs damaged DNA. ATR is a major regulator of the DDR and an attractive anticancer target. Herein, we describe the discovery of a series of aminopyrazines with potent and selective ATR inhibition. Compound 45 inhibits ATR with a K(i) of 6 nM, shows >600-fold selectivity over related kinases ATM or DNA-PK, and blocks ATR signaling in cells with an IC(50) of 0.42 µM. Using this compound, we show that ATR inhibition markedly enhances death induced by DNA-damaging agents in certain cancers but not normal cells. This differential response between cancer and normal cells highlights the great potential for ATR inhibition as a novel mechanism to dramatically increase the efficacy of many established drugs and ionizing radiation.
Subject(s)
Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Drug Discovery , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Protein Serine-Threonine Kinases/antagonists & inhibitors , Amino Acid Sequence , Antineoplastic Agents/chemical synthesis , Catalytic Domain , Models, Molecular , Molecular Sequence Data , Protein Kinase Inhibitors/chemical synthesis , Protein Serine-Threonine Kinases/chemistry , Pyrazines/chemical synthesis , Pyrazines/chemistry , Pyrazines/pharmacology , Structure-Activity Relationship , Substrate Specificity , Sulfones/chemistryABSTRACT
Aryl CH hydrogen bonds play an important role in the binding of several analogues of a pyrazol-3-ylquinazolin-4-ylamine inhibitor of glycogen synthase kinase 3 (GSK3). Understanding the importance of these CH...O and CH...N hydrogen bonds allowed the design of a novel quinazolin-4-ylthiazol-2-ylamine inhibitor of GSK3 with a structurally confirmed CH...O hydrogen bond to the protein.
