Multiomics profiling and experiments in preclinical models revealed RAD51-IN-1 as a synergistic potentiator of anlotinib sensitivity.

Anlotinib has demonstrated preliminary efficacy as a first-line maintenance therapy for ovarian cancer. However, clinical responses vary widely. To investigate resistance mechanisms and explore rational combinations, pretreatment tumors from 18 patients in clinical trial NCT04807166 underwent whole-exome and RNA sequencing and stratified into sensitive and resistant groups based on progression-free survival. VEGFR-related mutations were enriched in sensitive tumors, whereas resistant tumors showed increased activity of DNA repair pathways and Notch signaling. In vitro screening identified strong synergy between anlotinib and the RAD51 inhibitor RAD51-IN-1, which outperformed the Notch inhibitor FLI-06 in resistant patient-derived organoids. Mechanistic studies revealed that RAD51 inhibition was associated with impaired HRR and increased sensitivity to anlotinib. In vivo, combined treatment with anlotinib and RAD51-IN-1 significantly reduced tumor burden without notable toxicity. These findings suggest that RAD51-mediated HRR may contribute to anlotinib resistance and support RAD51 inhibition as a promising approach to overcome therapeutic resistance in ovarian cancer.