USP5 inhibition enables potential therapy for t(8;21) AML through ubiquitin-mediated AML1-ETO degradation in patient-derived xenografts.

The AML1-ETO (AE) fusion protein is a key target for treating t(8;21) acute myeloid leukemia (AML). In this investigation, we identified ubiquitin-specific protease 5 (USP5) as the deubiquitinating enzyme of AE. USP5 knockdown decreased AML cell growth and induced differentiation both in vitro and in vivo. In addition, we developed a high-throughput screening (HTS) method and identified a potent, selective USP5 inhibitor, WCY-8-67. This lead compound was identified as a selective USP5 inhibitor by targeting the ubiquitin-associated domain 2 (UBA2) region. It also induced aggregation and precipitation of the target protein, which led to USP5 dysfunction. WCY-8-67 exhibited excellent in vivo bioavailability and tolerability, and it effectively inhibited the growth of AML cells in animal models. In addition, in a patient-derived xenograft (PDX) model, this compound, when combined with 5-azacytidine (5-Aza), improved therapeutic effects. This study presents promising targeted therapeutic possibilities for the treatment of t(8;21) AML that require further study.