Real-world Clinical Outcomes of Ivermectin and Mebendazole in Cancer Patients: Results from a Prospective Observational Cohort

Abstract

Background/Aim: Drug repurposing offers a pathway to identify accessible, low-toxicity cancer therapies. Ivermectin and mebendazole demonstrate multi-target anticancer activity in preclinical models. This study evaluates real-world patient-reported outcomes, safety, and adherence in patients with cancer using this combination. Patients and Methods: We analyzed a prospective observational cohort of 197 patients with cancer prescribed ivermectin and mebendazole off-label via a U.S. telemedicine platform. Participants received compounded capsules (25 mg ivermectin, 250 mg mebendazole). Data were collected through standardized digital surveys at baseline and 6-month follow-up. A total of 122 participants (61.9%) completed follow-up. Primary outcomes included self-reported cancer status, adherence, and adverse events. Confidence intervals were calculated using the Wilson method, with dose-stratified analyses using Chi-square tests. Results: The cohort had a mean age of 67 years with balanced sex distribution and diverse malignancies, most commonly prostate (27.9%) and breast (18.3%). Median time since diagnosis was 1.2 years, with 37.1% reporting active progression at baseline. At six months, adherence was high, with 86.9% completing the initial prescription and 66.4% remaining on therapy. The Clinical Benefit Ratio (CBR) was 84.4% (95% confidence interval=77.0-89.8%). At follow-up, 48.4% of participants reported tumor regression or no evidence of disease (32.8% NED; 15.6% regression), while 36.1% reported stable disease and 15.6% reported progression. Side effects, reported by 25.4%, were dosedependent and predominantly mild and primarily gastrointestinal, with 93.6% continuing therapy after adjustment. Concurrent therapies reported included chemotherapy (27.9%), radiation (21.3%), surgery (19.7%), supplements (49.2%), and dietary modification (37.7%). Conclusion: In this prospective real-world cohort of patients with cancer, ivermectin and mebendazole were associated with high rates of self-reported clinical benefit and favorable tolerability. These findings are hypothesis-generating and support the need for randomized controlled trials.