Benzimidazole and Salicylanilide Antiparasitic Drugs as Repurposed Anti-Cancer Agents in Helminth-Associated Malignancies: A Mechanistic and Clinical Evidence Synthesis

Background: Benzimidazole anthelmintics (mebendazole, albendazole, fenbendazole) and the structurally and mechanistically distinct salicylanilide antitapeworm agent niclosamide share mechanistic properties that have attracted interest for oncological repurposing. Three cancers within this research programme — Opisthorchis viverrini-associated cholangiocarcinoma (CCA), Schistosoma haematobium-associated bladder squamous cell carcinoma (SCC), and Strongyloides/HTLV-1-associated adult T-cell leukaemia/lymphoma (ATL) — arise in settings of chronic helminth-driven inflammation and represent high-unmet-need cancers where novel affordable agents are warranted. Objective: To synthesise the mechanistic and clinical evidence for benzimidazole anti-cancer repurposing, assess its specific relevance to the three programme cancers, and propose a priority trial design. Methods: Narrative evidence synthesis drawing on PubMed-indexed cell line, animal model, case report, and clinical trial data identified through systematic web searches (June 2026). Evidence tier labels are applied per finding. Results: Mebendazole has the broadest evidence base: it disrupts microtubule polymerisation, inhibits...