Discovery of Potent SOS1 PROTACs with Effective Antitumor Activities against NCI-H358 Tumor Cells In Vitro/In Vivo.

Directly targeted KRAS inhibitors are now facing resistance problems, which might be partially solved by the combination of SOS1 inhibitors with KRAS inhibitors. However, this combination may still have some resistance mitigation potential. Comparatively, SOS1 PROTAC may have promising applications in addressing the drug resistance problem by degrading the SOS1 protein. Herein, we report the discovery of novel SOS1 PROTACs and their antitumor activity both in vitro and in vivo. In vitro studies demonstrated that degrader 4 had strong inhibitory effects on the proliferation of NCI-H358 cells with IC 50 of 5 nM, together with significant degradation of SOS1 protein with DC 50 of 13 nM. In the NCI-H358 xenograft model, degrader 4 exhibited significant antitumor activities with TGI TV values of 58.8% at 30 mg/kg bid. The PK and safety profiles also supported degrader 4 for further studies as an effective tool compound.