Mebendazole is safe at high doses and shows broad, reproducible anticancer activity in preclinical models, but clinical evidence of benefit in human cancer patients remains limited to isolated case reports of tumor regression and a single small combination trial showing a 33% response rate in pediatric brain tumors, with the only randomized trial failing to meet its efficacy endpoint. [In total, only 6 trials reported data from human clinical trials]
Disclaimer: This article is for informational and educational purposes only. We are not medical professionals and do not provide medical advice. Neither fenbendazole nor mebendazole is approved by the FDA for cancer treatment. Always consult your physician or oncologist before considering changes to your treatment plan.
Abstract
Mebendazole, a well-established benzimidazole anthelmintic, has been extensively investigated for anticancer repurposing across approximately 80 studies spanning preclinical experiments, clinical trials, case reports, and reviews. Preclinical evidence is consistently positive: mebendazole inhibits tumor growth and extends survival in animal models of glioblastoma (survival extended up to 63%) [1], medulloblastoma (100–150% survival improvement) [2], triple-negative breast cancer (prevention of lung and liver metastases) [3], thyroid cancer (tumor regression and metastasis prevention) [4], ovarian cancer [5], melanoma [6], hepatoblastoma [7], and multiple myeloma [8], among others. These effects operate through multiple mechanisms including microtubule disruption, kinase inhibition (notably MAPK14 [9] and VEGFR2 [2]), Hedgehog pathway suppression [10, 11], HIF inhibition [12], and immune modulation [13, 14]. Mebendazole synergizes preclinically with cisplatin [5], radiation therapy [15, 16], trametinib [17], gefitinib [18], and other standard agents, suggesting its greatest potential lies in combination regimens.
Clinical evidence in humans, however, remains limited and largely inconclusive. Across six prospective trials enrolling a total of approximately 161 patients, mebendazole was consistently safe and well tolerated at high oral doses [19–21]. The only randomized trial, in recurrent glioblastoma, failed to meet its prespecified 9-month overall survival benchmark of 55% in either arm [21]. Single-agent mebendazole produced no antitumor responses in refractory gastrointestinal cancer [22] or pediatric brain tumors [20]. The most encouraging clinical signal came from a small pediatric high-grade glioma trial combining mebendazole with bevacizumab and irinotecan, which yielded a 33% overall response rate including one complete response sustained for 10 months [23]. Individual case reports have described tumor regressions in metastatic colon cancer [24] and prolonged disease stabilization in adrenocortical carcinoma [25], but these remain anecdotal. The gap between preclinical promise and clinical results is likely attributable to poor and variable oral bioavailability—only a minority of patients achieved target serum concentrations [22] —and to patient selection factors such as poor performance status [21]. Formulation advances including solid dispersions [26] and nanostructured carriers [27] have shown severalfold bioavailability improvements in preclinical testing. At present, mebendazole’s demonstrated benefits for cancer in humans are limited to its established safety profile and isolated case-level tumor responses; definitive evidence of clinical anticancer efficacy awaits well-designed combination trials with optimized drug formulations and pharmacokinetic monitoring.
Paper search
We performed a semantic search across over 138 million academic papers. We retrieved 500 of the most relevant papers. 80 were used in this paper.
