Discovery of TK-642 as a highly potent,selective,orally bioavailable pyrazolopyrazine-based allosteric SHP2 inhibitor

Src homology-2-containing protein tyrosine phosphatase 2(SHP2)is a promising therapeutic target for cancer therapy.In this work,we presented the structure-guided design of 5,6-fused bicyclic allosteric SHP2 inhibitors,leading to the identification of pyrazolopyrazine-based TK-642 as a highly potent,selective,orally bioavailable allosteric SHP2 inhibitor(SHP2WT IC_(50)=2.7 nmol/L)with favorable pharmacokinetic profiles(F=42.5%;t_(1/2)=2.47 h).Both dual inhibition biochemical assay and docking analysis indicated that TK-642 likely bound to the“tunnel”allosteric site of SHP2.TK-642 could effectively suppress cell proliferation(KYSE-520 cells IC_(50)=5.73μmol/L)and induce apoptosis in esophageal cancer cells by targeting the SHP2-mediated AKT and ERK signaling pathways.Additionally,oral administration of TK-642 also demonstrated effective anti-tumor effects in the KYSE-520 xenograft mouse model,with a T/C value of 83.69%.Collectively,TK-642 may warrant further investigation as a promising lead compound for the treatment of esophageal cancer.

A multifunctional cross-validation high-throughput screening protocol enabling the discovery of new SHP2 inhibitors

The protein tyrosine phosphatase Src homology phosphotyrosyl phosphatase 2(SHP2) is implicated in various cancers, and targeting SHP2 has become a promising therapeutic approach. We herein described a robust cross-validation high-throughput screening protocol that combined the fluorescence-based enzyme assay and the conformation-dependent thermal shift assay for the discovery of SHP2 inhibitors. The established method can effectively exclude the false positive SHP2 inhibitors with fluorescence interference and was also successfully employed to identify new protein tyrosine phosphatase domain of SHP2(SHP2-PTP) and allosteric inhibitors. Of note, this protocol showed potential for identifying SHP2 inhibitors against cancer-associated SHP2 mutation SHP2-E76 A. After initial screening of our in-house compound library(w2300 compounds), we identified 4 new SHP2-PTP inhibitors(0.17%hit rate) and 28 novel allosteric SHP2 inhibitors(1.22% hit rate), of which SYK-85 and WS-635 effectively inhibited SHP2-PTP(SYK-85: IC_(50) Z 0.32 mmol/L;WS-635: IC_(50) Z 4.13 mmol/L) and thus represent novel scaffolds for designing new SHP2-PTP inhibitors. TK-147, an allosteric inhibitor, inhibited SHP2 potently(IC_(50) Z 0.25 mmol/L). In structure, TK-147 could be regarded as a bioisostere of the well characterized SHP2 inhibitor SHP-099, highlighting the essential structural elements for allosteric inhibition of SHP2. The principle underlying the cross-validation protocol is potentially feasible to identify allosteric inhibitors or those inactivating mutants of other proteins.

Harnessing the cyclization strategy for new drug discovery

The design of new ligands with high affinity and specificity against the targets of interest has been a central focus in drug discovery.As one of the most commonly used methods in drug discovery,the cyclization represents a feasible strategy to identify new lead compounds by increasing structural novelty,scaffold diversity and complexity.Such strategy could also be potentially used for the follow-on drug discovery without patent infringement.In recent years,the cyclization strategy has witnessed great success in the discovery of new lead compounds against different targets for treating various diseases.Herein,we first briefly summarize the use of the cyclization strategy in the discovery of new small-molecule lead compounds,including the proteolysis targeting chimeras(PROTAC)molecules.Particularly,we focus on four main strategies including fused ring cyclization,chain cyclization,spirocyclization and macrocyclization and highlight the use of the cyclization strategy in lead generation.Finally,the challenges including the synthetic intractability,relatively poor pharmacokinetics(PK)profiles and the absence of the structural information for rational structure-based cyclization are also briefly discussed.We hope this review,not exhaustive,could provide a timely overview on the cyclization strategy for the discovery of new lead compounds.

BrΦnsted acid-promoted ‘on-water’ C(sp^3)-H functionalization fot the synthesis of isoindolinone/[1,2,4]triazolo[1,5-a]pyrimidine derivatives targeting the SKP2-CKS1 interaction

The isoindolinone and biaryl scaffolds are prevalent in natural products and drug molecules,which have showed broad and interesting biological activities.The efficient construction of such hybridized molecules and biological evaluation are of great interest to medicinal chemistry community.In this communication,we report an efficient BrΦnsted acid-promoted C(sp^3)-H functionalization approach that enables the rapid construction of biologically important isoindolinone/[1,2,4]triazolo[1,5-a]pyrimidine hybrids from 5-methyl-7-(2,4,6-trimethoxyphenyl)-[1,2,4]triazolo[1,5-a]pyrimidine,2-formylbenzoic acid and various anilines.The title compounds were generated in high to excellent yields(up to 96%)regardless of the electronic nature and steric effects of the substituents.In this reaction,an isoindolinone scaffold,one C-C single bond,and two C-N bonds were formed simultaneously with high atom economy.In this work,we have envisioned that the methyl group linked to the electron-deficient Nheterocycles could be used as a new synthetic handle for late-state diversification and may have broad applications in the field of organic and medicinal chemistry.Besides,the title compounds have exhibited promising activity against the SKP2-CKS1 interaction.