The Screening And Evaluation Of Druggability Of A New Kind Of Dual PI3K/mTOR Inhibitors

Along with the social structure of population aging and the envirnmental factor,the incidence of malignant tumors has increased,and it has become an important killer for public health.The research and development of small molecule kinase inhibitors has become an important method for the treatment of malignant tumors.All pharmaceutical companies in the world have a portfolio in the development of small molecule inhibitors targeting kinases,and it has become the focus of research in the industry.On the basis of the role of PI3K/AKT/mTOR signaling pathway in the progress of malignant tumors,we focused on the research of PI3K/mTOR dual inhibitors.NVP-BEZ235 was used as a reference compound,and several compounds in the existing library were screened in the cellular assay,10 compounds equivalent to NVP-BEZ235 at the cellular level.After preliminary in vivo rat pharmacokinetic screening,Compound 39 and Compound 11 were obtained.The druggability of the two compounds were evaluated in the next step.Compound 39 has a good in vitro activity on enzyme of PI3K/mTOR and common human malignant tumor cell lines,and also it exhibits good in vivo efficacy in the CDX model in nude mouse.Compound 39 has excellent pharmacokinetic properties in rats/dogs,and it does not inhibit hERG and CYPs,so the cardiovascular risk and DDI risk was excluded.So Compound 39 has good druggability.In the subsequent PK/PD study in nude mouse,a high proportion metabolite,Compound 45(oxidative metabolites of Compound 39),was found in the plasma of nude mice.After the quantitative study,the plasma drug concentration of Compound 45 in mouse was much higher than that of Compound 39.In the in vitro enzyme assay,Compound 45 showed better activity against PI3K/mTOR than Compound 39.In the liver microsomal metabolic stability tests of different species,it was found that Compound 39 converted into Compound 45 only in mouse liver microsome and was not produced in that of human and dog.In conjunction with the above information,we decided to evaluate the druggability of Compound 45.Compound 45 had excellent cellular activity,which is significantly superior to NVP-BEZ235,but the oral bioavailability of Compound 45 is very low and its bioavailability cannot be improved by improving the pre-formulation.Therefore,a phosphate ester prodrug of Compound 45 was synthesized,which is Compound 46.The solubility of Compound 46 was increased 1000 fold compared with Compound 45.In the rat PK study,Compound 46 was converted into Compound 45 rapidly and completely,it showed good property for a prodrug.However,the oral bioavailability of Compound 45 was not improved via dosing Compound 46.After tested in CaCO-2 assay,it was shown that Compound 45 is a low-permeability Compound and it is likely to be the P-gp substrate,and therefore it was unlikely to be developed into an oral drugs.Compound 46 can be developed in intravenous administration,and it will be further studied as an i.v.candidate in the preclinical development.In order to find an oral candidate in the project,a comprehensive evaluation of Compound 11 were performed.The results showed that Compound 11 has good in vitro enzyme activity on PI3K and mTOR,and it had also good activity on the cellular level,which was equivalent to NVP-BEZ235 or better than it,Compound 11 was showed good efficacy in the CDX model.Compound 11 has good pharmacokinetic properties in rats and dogs and it showed good oral drug properties.At the same time,the metabolite of Compound 11 was explored,it was found that Compound 11 metabolizes into a metabolite,namely Compound 47,in mice.Fortunately,Compound 47 did not had activity against PI3K and mTOR,so it was not an active metabolite.In the stability of liver microsome in multiple species,Compound 47 was only found in mice,cynomolgus monkeys and human liver microsome,indicating that mice and cynomolgus monkeys are related species for human in the toxicological study,and the two species need to be considered in following toxicological studies.In summary,Compound 11 is worthy for the further preclinical development.In summary,through the screening of the compounds,the evaluation of druggability,and the research of the metabolites,two compound with good preclinical druggability for different routes of administration were found,they were Compounds 46 for intravenous and Compound 11 for Oral administration.They were could be further explored in the following preclinical development.During the research process of the above two compounds,we explored the strategy of investigating the metabolic characteristics of compounds at an early stage,particularly based on the differences characteristic for the same metabolites in multiply species,which provided more information for R&D.At the same time,through the analysis of low bioavailability drugs,the analysis strategy and solution for the low BA compounds have been identified,including prodrug strategies.