Antibodies are proteins made to attach to a chosen target. In prion disease the target is the normal cellular prion protein, and the idea is that binding it could stop it being converted into the abnormal form. The Atlas entry for this approach is PRN100, a humanised version of a mouse antibody called ICSM18, developed at the MRC Prion Unit in London.
In 2022 the unit reported PRN100 given to six patients as infusions every two weeks, under compassionate use and not in a trial. No serious adverse events were reported. Survival looked similar to historical controls, and the numbers were too small to judge benefit. The CJD Foundation lists PRN100 as not currently enrolling, and the Prion Alliance noted in July 2026 that the two active PrP-lowering trials use a siRNA and an antisense oligonucleotide. For the wider picture see therapies and PrP-lowering.