Abstract 3881: Discovery of highly potent, selective and efficacious STAT3 PROTAC degraders capable of achieving long-lasting tumor regression

Abstract STAT3 (signal transducer and activator of transcription 3) is a transcription factor and a promising therapeutic targets for cancer and other human diseases. We have previously reported the discovery of SD-36 and SD-91 as potent, selective and highly efficacious STAT3 degraders. In the present study, we report the discovery and extensive evaluation of new, highly potent, selective and efficacious new STAT3 degraders. In direct comparison, these compounds are 50-times more potent than SD-36 in inducing STAT3 degradation in cells and demonstrates 500-fold degradation selectivity over other STAT members. Proteomic analysis showed that our best lead compound (UM-STAT3-1218) only reduces the levels of STAT3 protein in cells over other 6, 700 proteins. (UM-STAT3-1218) achieves low nanomolar IC50 values in leukemia and lymphoma cancer cell lines with activated STAT3. A single intravenous dose of (UM-STAT3-1218) at 3 mg/kg reduces the STAT3 protein for 4 days in xenograft tumor and native tissues, without reducing another other STAT members. Impressively, a single dose of (UM-STAT3-1218) at 3 mg/kg achieves complete and long-lasting tumor regression in multiple xenograft tumor models without any signs of toxicity. Taken together, (UM-STAT3-1218) is a highly promising STAT3 degrader for the treatment of the treatment of human cancers and other human diseases in which STAT3 plays a key role. Citation Format: Haibin Zhou, Dimin Wu, Longchuan Bai, Ranjan K. Acharyya, Hoda Metwally, Donna McEachern, Bo Wen, Duxin Sun, Shaomeng Wang. Discovery of highly potent, selective and efficacious STAT3 PROTAC degraders capable of achieving long-lasting tumor regression abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 3881.