Drug Repurposing in Cancer Therapy: A Review of Therapeutic Potential Across Diverse Drug Classes

ABSTRACT Cancer remains one of the leading causes of morbidity and mortality worldwide, highlighting the need for new, safe, and cost‐effective therapies. Drug repurposing—identifying new anticancer uses for existing drugs with established safety profiles—offers a promising strategy to accelerate drug development while reducing cost, time, and risk. This review comprehensively explores the principles, methodologies, advantages, and limitations of drug repurposing in oncology. It examines multiple drug classes with demonstrated anticancer potential, including nonsteroidal anti‐inflammatory drugs, antidiabetic agents, antiparasitic and antiviral drugs, antibiotics, antiepileptics, anaesthetics, neuroleptics, and cardiovascular medications. Mechanistic insights are discussed with emphasis on key cancer hallmarks such as apoptosis induction, proliferation inhibition, angiogenesis suppression, and tumor metabolism disruption. Preclinical and clinical evidence, along with examples of successfully repurposed agents, illustrate the translational and therapeutic relevance of this approach. By leveraging drugs with known pharmacological and safety profiles, drug repurposing accelerates clinical translation, reduces development costs, and expands therapeutic options for cancer patients. This strategy complements conventional therapies, addresses unmet clinical needs, and enhances treatment outcomes, establishing drug repurposing as a practical and patient‐centered paradigm in modern oncology.