This is a two-part study designed to evaluate the safety, tolerability, pharmacokinetics (PK), and receptor occupancy (RO) of ENX-205 in healthy adult participants in a double-blind placebo-controlled, single ascending dose (SAD) study (Part 1) and an open-label, single-dose, positron emission tomography (PET) study (Part 2).

Inclusion Criteria:

• Biologically female participants who are not pregnant, lactating, or breastfeeding

  1. Of non-childbearing potential, defined as either permanently sterilized, and with a negative pregnancy test. OR
  2. Part 1 only: Of childbearing potential and willing to comply with restrictions related to birth control, and with a negative pregnancy test.

• Biologically male participants (defined as assigned male at birth), if fertile must be willing to comply with restrictions related to birth control. Moreover, male participants should refrain from sperm donation.

Exclusion Criteria:

• Unable or unwilling to comply with the requirements of the study or, in the opinion of the Investigator or Sponsor, should not participate in the study

Part 2 of this study is open-label, and as such, randomization and blinding are not applicable.