Background

Topoisomerase 1 (TOP1) is an essential enzyme that plays a critical role in DNA transcription and replication. TOP1 inhibitors are a known class of anti-cancer agents that work to interrupt DNA replication in cancer cells, causing cell death. Since the discovery of the TOP1 inhibitor camptothecin (CPT) from plant extracts more than 60 years ago, two CPT analogs (irinotecan and topotecan) were approved by the FDA for cancer treatment. Tyrosyl-DNA phosphodiesterase 1 (TDP1) is an enzyme involved in DNA repair created when TOP1 is inhibited. As a result, targeting TDP1 is considered a potential therapeutic approach to enhance and possibly synergize the potency of TOP1 inhibitors. While TOP1 inhibitors are widely used to treat solid tumors – such as