The concept of tau spreading created an opportunity for novel therapeutic strategies targeting extracellular tau. The underlying mechanisms for tau transmission and how much this process contributes to the progression of tauopathies in humans is still an open question in the field. The nature of interstitial tau and processes taking place within the brain parenchyma are extremely challenging to study. However, even without answers to the basic biological questions around tau propagation, several companies have developed therapeutic approaches focusing on preventing the cellular release, uptake, clearance or neutralization of extracellular tau. Immunotherapy is the primary approach used in the clinic to target extracellular to clear it or neutralize it in order to prevent propagation.
