Deuterium modification of tyrosine kinase inhibitors contributes to reversing ferroptosis resistance through upregulation of aldehyde oxidase 1 in hepatocellular carcinoma

The susceptibility to ferroptosis partially determines the efficacy of tyrosine kinase inhibitors (TKIs) in hepatocellular carcinoma (HCC), exposing a mechanistic vulnerability that can be therapeutically exploited. The development of deuterated compounds is a promising strategy for the improvement of anti-tumor efficacy. Here, we identified HCC with higher level of ferroptosis-resistance exhibited insensitive to TKIs, which could be reversed by deuterated TKIs. Aldehyde oxidase 1 (AOX1) was screened as a critical gene mediating the responsiveness to deuterated TKIs-induced ferroptosis in HCC. The presence of a pyridyl tri-deuterated methanamide contributed to the upregulation of AOX1 in a structure-dependent manner, thereby promoting ferroptosis. Mechanistically, AOX1 inhibited sirtuin 6-mediated deacetylation of H3K9 and H3K56, leading to transcriptional activation of acyl-CoA synthetase long chain family member 5, which resulted in poly-unsaturated fatty acids hyperaccumulation-induced ferroptosis. Additionally, HCC with lower AOX1 expression conferred better efficacy to deuterated TKIs. In patient cohorts with HCC, those with lower AOX1 expression exhibited a more pronounced therapeutic response to deuterated sorafenib. Overall, the present study elucidates the mechanism by which deuterated TKIs reverse TKI resistance by promoting ferroptosis and suggests that AOX1 could serve as a biomarker to guide clinical decision-making for deuterated TKI treatment in HCC.