Structure-Guided Optimization and Preclinical Evaluation of 6‑O‑Benzylguanine-Based Pin1 Inhibitor for Hepatocellular Carcinoma Treatment

Hepatocellular carcinoma (HCC) is a major cause of cancer-related deaths globally, and the need for effective systemic therapies for HCC is urgent. Our previous work reveals that Pin1 is a potential anti-HCC target, which regulates miRNA biogenesis and identifies API-1 as a novel Pin1 inhibitor to suppresses HCC. However, a great demand in HCC therapy as well as the limited chemical stability and pharmacokinetic feature of API-1 motivated us to find improved Pin1 inhibitors. Herein, we designed and synthesized diverse 6-O-benzylguanine derivatives and discovered API-32 as a novel Pin1 inhibitor with better stability and pharmacokinetic property over API-1. API-32 directly interacted with the Pin1 PPIase domain to inhibit Pin1 activity. API-32 significantly suppressed the cell proliferation and migration of HCC cells by blocking Pin1’s downstream signal. Moreover, API-32 exhibited an enhanced inhibitory function against the HCC tumor in mice models without obvious toxicity, making it a promising drug candidate for HCC treatment.