Design,Synthesis,and Biological Activity Evaluation Of Novel SOS1 Inhibitors Based On Quinazoline Scaffold

SOS1（Son of seven 1）is an important guanine nucleotide exchange factors（GEFs）that can activate rat sarcoma（Ras）proteins in cells,leading to cell proliferation.Ras has been found to play a crucial role in the occurrence and development of cancer.There are multiple mutations in Ras,with KRas mutations accounting for the majority.SOS1 inhibitors can block downstream signaling pathways by blocking the interaction between SOS1 and KRas proteins,thereby combating cancer.At present,multiple small molecule inhibitors of SOS1 have been at the forefront of research,among which Bayer’s BAY-293 has shown good results in preclinical studies.The emergence of these small molecule inhibitors that indirectly target Ras protein has brought new therapeutic strategies to Ras,a previously considered"undruggable"target.This paper takes BAY-293 as the lead and analyzes the eutectic structure of BAY-293 and SOS1:KRas protein complex.Based on reasonable drug design principles,three series of SOS1small molecule inhibitors with quinazoline as the mother nucleus were designed and synthesized.Among them,IA compounds mainly explored the effect of substituents at 6 and 7positions on the activity of quinazoline ring.Secondly,since the positive compound BAY-293is a single R configuration compound,some compounds were chiral resolution in IB compounds to prove the effect of its chiral structure on the activity.In the design of class II compounds,this paper extends the 6-position substituent of the quinazoline ring to form a morpholine ester structure,and evaluates the effects of different thiophene ring connection methods and different phenyl substitutions on the activity of the compound.In the design of Class III compounds,the influence of thiophene ring substitution on activity was explored based on the structural characteristics of the active cavity.The 22 compounds designed and synthesized in this article have not been reported in literature,and their structures have been confirmed by high-resolution mass spectrometry,nuclear magnetic resonance hydrogen spectroscopy,and nuclear magnetic resonance carbon spectroscopy.This paper systematically evaluated the activity of the compounds designed and synthesized.Firstly,an in vitro SOS1 protein inhibition experiment was conducted at 500n M.In IA class compounds,it was found that the 6-position substitution of the quinoline ring is crucial for the activity of the compound,and the presence or absence of the 7-position substitution has no significant impact on the activity results of the compound.The single R configuration productⅠB-9 obtained after chiral resolution has obvious activity improvement(IC₅₀=8 n M).The inhibitory activity of class II compounds did not significantly increase after extending position 6 to form morpholine esters.The inhibitory rate of compound II-3 with the best activity was 82.1±0.6%,which may be due to the rigidity of morpholine esters hindering the hydrogen bonding interaction between the compounds and proteins.In addition,the substituents on the benzene ring require appropriate chain lengths to produce good hydrogen bonding interactions.In Class III compounds,the substitution strategy for the thiophene ring did not meet expectations,and the activity of this series of compounds significantly decreased.Except for compound III-4,which had an inhibition rate of 71.2%±2.1,the inhibition rates of III-1～3 did not reach 30%.Subsequently,this article tested the antiproliferative activity of compounds with superior activity on human chronic myeloid leukemia cell line（K562）.Among them,the cell activities of IA-4,IB-9,and II-6 were all less than 3μM.Compound IB-9(IC₅₀=1.20μM)Shown in comparison to BAY-293(IC₅₀=1.09μM)Equivalent anti cell proliferation activity.In order to further discuss the selectivity of the compound,this article tested the anti proliferative effect of the compound on the EGFR wild-type cell line（NCI-H838）,but no significant inhibitory effect was found,proving the selectivity of the compound towards SOS1.This paper systematically designed,synthesized,and evaluated the in vitro biological activity of SOS1 small molecule inhibitors using quinazoline as the mother nucleus.The corresponding structure-activity relationships were elucidated,and three compounds with further research value,namelyⅠA-4,ⅠB-9,andⅡ-6,were discovered,providing a theoretical reference for the subsequent research of SOS1 inhibitors.