{"entity":{"id":"paper-cheng-melanoma-ctdna-antiparasitic-front-oncol-2026","kind":"paper","name":"Metastatic melanoma with initial ctDNA decline and radiographic response during self-directed antiparasitic use: treatment effect or spontaneous regression?","aka":[],"tldr":"A man with metastatic melanoma who refused standard treatment and took ivermectin and fenbendazole saw his tumour markers and scans improve for a while, then worsen; his oncologists judged spontaneous immune regression at least as likely as any drug effect.","summary":"A 74-year-old man with nodular melanoma and nodal and liver metastases declined guideline-directed therapy and took ivermectin and fenbendazole with lifestyle changes; his disease initially showed reduced metabolic activity and size on imaging and his tumour-informed ctDNA fell from 2.04 to 0.18 MTM/mL, then both worsened, with ctDNA rising to 0.93 MTM/mL and the dominant axillary mass growing (Cheng melanoma case report 2026). The tumour carried at least 50 mutations per megabase, placing it at the extreme immunogenic end of the spectrum, and the authors write that spontaneous immune-mediated regression is at least as plausible as any effect of the patient's interventions, that clinical evidence for efficacy is absent, and that safety counselling is needed given the drugs' reported toxicities (Cheng melanoma case report 2026).","asOf":"2026-09-24","links":[{"label":"Cheng melanoma case report 2026","url":"https://doi.org/10.3389/fonc.2026.1907192"},{"label":"PubMed","url":"https://pubmed.ncbi.nlm.nih.gov/42745863/"}],"tags":[],"related":[],"cancers":["melanoma"],"sections":[],"technologies":["fenbendazole-ivermectin-repurposing-claims"],"targets":[],"drugs":["ivermectin","fenbendazole"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"provenance":{"editedBy":"OnCo agent (Claude Fable 5.1)","editedOn":"2026-09-24","note":"Written from cached ClinicalTrials.gov v2, Europe PMC, DailyMed, Drugs@FDA and WHO eEML responses; no figure appears without its source link."},"journal":"Frontiers in Oncology","year":2026,"doi":"10.3389/fonc.2026.1907192","pmid":"42745863","authors":"Cheng R, Araujo DV.","paperType":"observational","findings":["Transient ctDNA and imaging improvement followed by progression during self-directed ivermectin and fenbendazole.","Very high tumour mutational burden made spontaneous immune regression a plausible explanation."],"whatItMeans":"Shows why single stories cannot settle the question: a melanoma this immunogenic can wax and wane on its own, and the improvement did not last.","caveats":["Single case; the patient declined immunotherapy, which such a tumour would be expected to respond to."],"changedPractice":false,"participants":1},"route":"/key-papers/paper-cheng-melanoma-ctdna-antiparasitic-front-oncol-2026/","neighbours":{"cancer":[{"id":"melanoma","kind":"cancer","name":"Melanoma","route":"/cancers/melanoma/"}],"technology":[{"id":"fenbendazole-ivermectin-repurposing-claims","kind":"technology","name":"Fenbendazole, ivermectin and other internet 'repurposed cures'","route":"/technologies/fenbendazole-ivermectin-repurposing-claims/"}],"drug":[{"id":"fenbendazole","kind":"drug","name":"Fenbendazole (veterinary anthelmintic)","route":"/drugs/fenbendazole/"},{"id":"ivermectin","kind":"drug","name":"Ivermectin","route":"/drugs/ivermectin/"}]}}