Andrew C. Ivy announced this claim at a press conference in Chicago in 1951, presenting 22 case observations in which he reported that a majority of patients showed favorable objective responses (Ivy, Science 1951, PMID 14866224). He supported the claim using what he called “enzyme analysis,” a non-standard methodology that was not independently reproducible. The American Medical Association’s status report six months later (JAMA 1951, PMID 14873580) reviewed the same 22 cases and found the data too incomplete and uncontrolled to support the claim, noting that several patients Ivy had counted as improved had died of cancer. The National Cancer Institute later reviewed 504 cases submitted by the Durovic brothers and also concluded that Krebiozen did not demonstrate antitumor activity. No independently controlled trial ever confirmed efficacy.