The purpose of this study is to determine the safety and tolerability [maximum tolerated dose
(MTD) within planned dosing range] of intravenous (IV) infusions of TPI 287 administered once
every 3 weeks for 9 weeks (for a total of 4 infusions) in patients with primary four repeat
tauopathies (4RT), corticobasal syndrome (CBS; also called corticobasal degeneration, CBD) or
progressive supranuclear palsy (PSP).