Fenbendazole as an Anticancer Agent? A Case Series of Self-Administration in Three Patients.

Background: Fenbendazole (FBZ), an inexpensive and widely accessible antiparasitic drug used in veterinary medicine, has garnered growing interest for its potential as an anticancer therapy. Preclinical studies suggest that FBZ exerts its anticancer effects through a wide variety of mechanisms. While FBZ has shown promise both in vitro and in vivo studies, clinical evidence supporting its use and efficacy in treating metastatic cancer is currently limited. Case Presentations: This report highlights 3 cases of patients with advanced cancer - including breast, prostate, and melanoma. Two patients achieved complete remission, and one achieved near-complete remission after incorporating FBZ into their treatment regimens alongside other therapies (excluding chemotherapy). All three patients tolerated FBZ without any reported adverse effects, and remission was sustained during follow-up periods ranging from 11 months to nearly 3 years. Conclusion: FBZ demonstrates potential as a novel promising therapeutic option for repurposing in oncology. Its ability to contribute to tumor regression and achieve disease remission warrants further clinical research to establish its efficacy and optimize its use.