What doses of ivermectin were used in cancer clinical studies and how did side effects vary?
Executive summary
Clinical human data on ivermectin in cancer are scarce: registered cancer trials include a phase I/II study of oral ivermectin given intermittently with the PD‑1 antibody balstilimab (NCT05318469) — dosing schedules reported in trial summaries use ivermectin on Days 1–3, 8–10, 15–17 of each 21‑day cycle (three one‑week pulses per cycle) [1] [2]. Most published evidence remains preclinical (cell lines, animals) and reviews note few or no completed anticancer clinical trials in humans prior to these ongoing studies [3] [4] [5].
1. What trials exist and what doses/schedules do they report?
The clearest human trial signal is a U.S.‑registered phase I/II combining oral ivermectin with the PD‑1/PD‑L1 inhibitor balstilimab (ClinicalTrials.gov NCT05318469). Trial descriptions and oncology conference materials state ivermectin is given orally on Days 1–3, 8–10, and 15–17 of each 21‑day cycle alongside balstilimab or pembrolizumab on Day 1; balstilimab dosing is listed at 450 mg IV and pembrolizumab 200 mg IV in some summaries [1] [2] [6]. The ASCO abstract for a 2025 phase I/II in metastatic triple‑negative breast cancer confirms the study exists but the public abstract does not include full safety/dose‑escalation details [7].
2. How complete is the reporting on dose levels and pharmacology?
Publicly available records and reviews emphasize that human clinical reporting is limited. Reviews and older systematic overviews state there have been “no reports of clinical trials of ivermectin as an anticancer drug” in earlier literature and that clinical evidence remains sparse despite many preclinical studies [4] [3]. Conference abstracts and trial registries give schedules but often omit precise mg/kg or escalate‑to doses in their public summaries; the ClinicalTrials.gov record exists but the detailed dose‑escalation/schema information is not fully published in the sources provided [1] [8] [7].
3. What do preclinical studies show about doses and effects relevant to toxicity?
Laboratory and animal reports document anticancer activity across cell lines and in vivo models, with effective concentrations in vitro often higher than standard antiparasitic exposures; animal toxicology shows much higher LD50s than human therapeutic dosing, and one review notes healthy‑volunteer escalation up to 2 mg/kg without “serious adverse reactions” in older studies [9] [4]. These preclinical dose ranges do not translate directly into human oncology dosing and the sources warn against assuming safety at oncology‑relevant exposures without clinical trials [3] [4].
4. What have trials or clinicians reported about side effects so far?
Available trial summaries and the ASCO abstract do not publish comprehensive adverse‑event tables or comparative safety outcomes in the public sources provided [7] [1]. Media and clinician commentaries describe oncologists’ concerns about off‑label patient use and anecdotal toxicities attributed to ivermectin taken outside trials, but these are not formal trial adverse‑event reports [10]. In short: trial‑level side‑effect data are not found in the current reporting; ongoing studies are designed to assess safety but have not produced full published safety datasets in the provided sources [7] [10].
5. Competing perspectives and implicit agendas
Researchers and advocates emphasize strong preclinical rationale and low drug cost as reasons to study ivermectin in oncology [11] [12]. Regulators and many oncologists warn that preclinical promise does not equal clinical benefit and stress the ethical risk of patients foregoing proven therapies for off‑label ivermectin use; several reviews and commentaries call for rigorous trials and caution against extrapolating lab data to practice [5] [3] [10]. Some patient‑facing websites and integrative medicine outlets portray ivermectin as a hopeful repurposing candidate and highlight registered trials, reflecting an advocacy agenda for exploration despite limited clinical evidence [12].
6. Bottom line and reporting limitations
Human oncology dosing information beyond scheduled pulse regimens in ongoing trials is not publicly detailed in the supplied sources, and published safety/outcome data from these cancer trials are not available in the current reporting [1] [7] [2]. Preclinical work is abundant and supportive of further study, but clinical proof of efficacy and comprehensive toxicity profiles in cancer patients remain unreported in the cited literature [3] [4] [5]. Available sources do not mention completed randomized trials demonstrating benefit or full adverse‑event data for ivermectin as a cancer therapy [5] [4].