What dosing regimens and routes were used for ivermectin in cancer clinical studies?
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Executive summary
Clinical testing of ivermectin in oncology remains limited but active: registered phase I/II trials administer ivermectin orally on multi-day schedules within 21‑day cycles alongside intravenous immune checkpoint inhibitors (balstilimab or pembrolizumab) [1] [2] [3]. Outside these oncology trials, human dosing experience ranges from the standard antiparasitic oral doses of 150–400 µg/kg up to reported experimental regimens including subcutaneous 1.6 mg/kg twice weekly and single‑dose escalation to 2 mg/kg in healthy volunteers—data points that inform oncology trial design but do not establish a standard anticancer dose [4] [5].
1. Clinical trials and the actual oncology schedules used
The most concrete clinical regimens for cancer come from US trials testing ivermectin with immunotherapy: Cedars‑Sinai’s trial and related reports describe oral ivermectin given on Days 1–3, 8–10 and 15–17 of each 21‑day cycle, combined with either balstilimab (450 mg IV) or pembrolizumab (200 mg IV) on Day 1 of each cycle, with treatment continued for up to about two years or until progression or toxicity [1] [2] [3].
2. Routes of administration reported in cancer and related human studies
The oncology trials use the oral route for ivermectin administration, paired with intravenous immune checkpoint inhibitors; there are no published cancer trials in the provided sources using non‑oral routes for ivermectin in cancer patients [1] [3]. However, historical and non‑oncology clinical reports show alternative routes have been used in humans: a trial for spinal injury reported subcutaneous ivermectin at 1.6 mg/kg twice weekly for 12 weeks, demonstrating that parenteral routes have precedent in clinical settings outside oncology [4].
3. Doses referenced that inform oncology dosing decisions
Standard human antiparasitic dosing is far lower than many preclinical anticancer concentrations: commonly used antiparasitic regimens are 150–200 µg/kg and up to 400 µg/kg for lymphatic filariasis, and those benchmarks underpin safety expectations when repurposing ivermectin in cancer trials [4]. Separate human studies escalated single doses to 2 mg/kg in healthy volunteers without serious adverse reactions, a finding frequently cited to justify exploring higher exposure in trials—even though that is not an established anticancer dose [5].
4. Preclinical exposure gaps and why schedules matter
Laboratory studies demonstrating anticancer activity typically use concentrations many times higher than plasma levels achieved with standard oral dosing; reviews note that the lowest in vitro anticancer concentration reported (1 µM) is tens of times above usual human plasma concentrations following approved doses, which explains why investigators test intensified or repeated oral schedules in clinics to attempt higher cumulative exposure [6] [4].
5. Safety, precedent and remaining uncertainties
Human safety data cited in the literature show tolerability for standard oral antiparasitic doses and some higher‑dose human work (up to 2 mg/kg single dose, and subcutaneous 1.6 mg/kg twice weekly in a non‑oncology trial), but the oncology trials’ oral multi‑day schedules have limited published safety or efficacy results to date, leaving a crucial evidence gap on optimal anticancer dose, pharmacokinetics in tumor tissue, and long‑term toxicity in cancer patients [5] [4] [7] [8].
6. Bottom line for what has been used in cancer clinical studies
In sum, the documented cancer trial practice to date is oral ivermectin administered intermittently across 21‑day cycles (Days 1–3, 8–10, 15–17) alongside IV checkpoint inhibitors, grounded in broader human experience with oral dosing at 150–400 µg/kg and limited higher‑dose or parenteral data (2 mg/kg single dose in healthy volunteers; 1.6 mg/kg subcutaneously twice weekly in a spinal injury trial), but definitive anticancer dosing and route optimization remain unestablished pending further clinical results [1] [3] [4] [5] [7] [8].