At the time of writing, the most active field is tau immunotherapy, with two active vaccines (AADvac1 and ACI-35) and nine antibodies (APNmAb005, E2814, JNJ-63733657, Lu AF87908, MK-2214, PNT001, PRX005, semorinemab and bepranemab) in ongoing clinical trials. Several of the other compounds in trials have complex or incompletely defined mechanisms of action; in this diagram, these compounds are categorized according to their presumed tau-related mode of action. X indicates trials that, to our knowledge, have been halted or terminated, as detailed in the main text, although their current status is sometimes difficult to determine, ? reflects uncertainty about the current status of trials. Adapted from ref.1.