Targeting ALDH7A1 with covalent inhibitors reveals new chemical space for prostate cancer therapy

: Prostate cancer (PCa) remains a major global health burden. Although androgen deprivation and receptor-targeted therapies initially benefit patients, resistance often leads to metastatic castration-resistant prostate cancer, with limited treatment options. Aldehyde dehydrogenase 7A1 (ALDH7A1) is an emerging oncogenic driver of PCa, but selective inhibitors are lacking. Here, we report irreversible ALDH7A1 inhibitors targeting the catalytic Cys330, identified from a library of 3-bromo-4,5-dihydroisoxazole derivatives. These compounds show minimal inhibition of ALDH4A1 and GAPDH, supporting selectivity for ALDH7A1. Compounds 3b and 4b reduced DU145 cell viability (low μM IC50), impaired migration, and altered the cell cycle. No significant effects were observed in LNCaP cells (low ALDH7A1 expression) or Hs27 fibroblasts. Treatment of DU145 cells resulted in the inhibition of intracellular ALDH activity and accumulation of malondialdehyde, consistent with increased oxidative stress. These findings validate ALDH7A1 as a druggable target and introduce a new chemical space for selective covalent ALDH inhibitors in oncology.