Ivermectin Combined With Immune Checkpoint Inhibition in Cancer (ICONIC)

Public awareness of ivermectin's purported anticancer properties has led to widespread off-label use. In a 2023 cross-sectional study in Loja, Ecuador, 19% of respondents reported using ivermectin as an adjunct to cancer treatment. However, clinical data remain virtually absent. To date, only one partially reported human study has investigated ivermectin in combination with anti-PD-1 therapy in patients with metastatic triple-negative breast cancer. Among the first nine treated patients, no treatment-related serious adverse events were observed, and the study remains ongoing. Despite this growing interest, ivermectin's off-label use carries risks. For instance, Gilene et al. described a case of severe neurotoxicity in a patient with metastatic osteosarcoma receiving regorafenib, likely due to a pharmacokinetic interaction through CYP3A49. Moreover, the potential impact of ivermectin on the gut microbiome-a key modulator of immune checkpoint inhibitor (ICI) immunotherapy success or failure efficacy-remains poorly understood. As antibiotic exposure has been linked to diminished immunotherapy outcomes, ivermectin's antibiotic properties raise legitimate concerns about possible microbiome disruption. However, variables such as ivermectin dose, the duration of exposure, and the type of immunotherapy are each variables that remain poorly studied. Taken together, these data underscore the urgency to prospectively evaluate ivermectin's immunologic effects in patients with cancer treated ICIs. Given ivermectin's wide availability, affordability, and public interest, rigorous clinical testing is crucial to determine whether it enhances-or potentially compromises-anticancer immunity while simultaneously assessing its safety to provide guidance for clinicians and patients. This study will investigate the safety, pharmacodynamic effects, and potential for dose-responsive immune modulation of ivermectin given concurrently with immune checkpoint inhibitor therapy in adult subjects with solid tumors.