Study 11 — ClinicalTrials.gov Audit: Helminth Serology Absent from All ICI Trials in Helminth-Endemic Regions

Study 11 of the Hidden Infections research series. Evidence tier: STRONG. Chronic helminth infection drives Th2/Treg immune polarisation — the environment that reduces CD8+ cytotoxic T lymphocyte efficacy and may attenuate immune checkpoint inhibitor (ICI) response. Parasite-associated cancers (cholangiocarcinoma, bladder SCC, endemic Burkitt lymphoma) are treated with checkpoint inhibitors in trials enrolling substantially from helminth-endemic regions. This systematic ClinicalTrials.gov audit examines 200 registered ICI trials in those cancer types to determine whether any collected helminth serology data at baseline. Key finding: Zero of 200 trials collected helminth serology as an inclusion criterion, exclusion criterion, stratification variable, or exploratory endpoint. The TOPAZ-1 Asia subgroup HR of 0.72 versus global HR 0.80 for durvalumab is consistent with — but untestable as — a helminth effect, because baseline serology was never collected. Group C: Pharmacovigilance and surveillance. CC0 public domain. AI-assisted draft pre-print.