TDRL-551 is a potent replication protein A (RPA) inhibitor ( IC 50 =18 µM). TDRL-551 inhibits RPA-DNA interaction and increases the efficacy of Platinum (Pt)-based chemotherapy in lung and ovarian cancer . RPA plays essential roles in both nucleotide excision repair (NER) and homologous recombination (HR), along with its role in DNA replication and DNA damage checkpoint activation.