-Participant meets the criteria for possible or probable progressive supranuclear palsy (PSP) Richardson’s Syndrome according to the Movement Disorder Society-PSP criteria (Hoeglinger et al, 2017) -Participant completed the Treatment Period (regardless of the total number of infusions) in PSP003 (NCT04185415) -Participant can be male or female a) A male participant must agree to use contraception as detailed in the protocol during the Treatment Period and for at least 6 months after the last dose of study treatment and refrain from donating sperm during this period b) A female participant is eligible to participate if she is not pregnant, not breastfeeding, and at least one of the following conditions applies: I. Not a woman of childbearing potential (WOCBP) OR II. A WOCBP who agrees to follow the contraceptive guidance in the protocol during the Treatment Period and for at least 6 months after the last dose of study treatment. -Participant (or legal representative, as applicable and acceptable by local regulations) is capable of giving signed informed consent, which includes compliance with the requirements and restrictions listed in the ICF and in this protocol. Informed consent must be obtained before initiating any study procedures