Researchers at Baylor College of Medicine reported preclinical evidence that an experimental compound, CS18, can resensitize cancer drug-resistant tumors to existing therapies. The compound targets a molecular control point—TopBP1, a Topoisomerase IIβ-binding protein 1—and in laboratory and animal models increased the effectiveness of established anticancer regimens. The study adds mechanistic detail to the ongoing search for drug resistance vulnerabilities beyond classic target mutation strategies, and it positions TopBP1 as a candidate node for combination oncology programs if translational milestones follow.