Drug Repurposing in Cancer Therapy: A Systematic Review

Abstract

Cancer is the second leading cause of death globally. Despite the intensive research, the success rate for new anticancer drug development remains below 10%, rendering conventional therapies alone insufficient to reduce cancer burden and mortality. Drug re-purposing offers an alternative way of identifying new therapeutic uses for approved drugs. This approach offers a shorter development timeline, lower costs, and a higher likelihood of clinical success. This systematic review aims to summarize all drugs repurposed against cancer to date comprehensively. Following PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines, we reviewed 45 publications indexed in PubMed from January 2015 to December 2024. Studies focusing on drug re-purposing in oncology were included. Data were extracted on drug name, original therapeutic class, responsive cancer types, and mechanisms of action. Additionally, annual publication trends were analyzed, and findings were presented in an accessible tabular format. A total of 181 repurposed drugs, belonging to approximately 35 distinct pharmacological classes, were identified as having anticancer activity against 28 different cancer types. With few exceptions, the annual number of publications on cancer drug re-purposing increased over the decade. Each repurposed drug is summarized by its original use, responsive cancers, and the underlying mechanism of action. This study also analyzes the distribution of cancers addressed by this approach. Finally, the study discusses current challenges and prospects for re-purposing drugs as standard cancer therapy.