This is a 3-part study. Parts 1 and 2 are randomized, double-blind, placebo-controlled investigations of single ascending doses (SAD) (Part 1) and multiple ascending doses (MAD) (Part 2) of orally administered BLU-808 in healthy adult participants. Part 2 will also include an evaluation of the effect of multiple doses of BLU-808 on the single-dose pharmacokinetics (PK) of midazolam. Part 3 is an open-label, 2-sequence, 2-period, food effect (FE) study in healthy adult participants.

Key Inclusion Criteria:

• Continuous non-smoker who has not used nicotine- and tobacco-containing products for at least 3 months prior to the first dosing based on subject self-reporting.
• Medically healthy with no clinically significant medical history, physical examination, clinical laboratory profiles, or vital signs, as deemed by the Principal Investigator (PI) or designee.
• No clinically significant cardiac history as judged by the PI or designee at the screening visit and check-in.

Key Exclusion Criteria:

• Participant is mentally or legally incapacitated or has significant emotional problems at the time of the screening visit or expected during the conduct of the study.
• Participant has history or presence of clinically significant medical or psychiatric condition or disease in the opinion of the PI, designee, or Sponsor.
• Participant has history or presence of alcohol or drug abuse within the past 2 years prior to the first dosing.
• Participant has positive results at the screening visit for human immunodeficiency virus (HIV), hepatitis B surface antigen (HBsAg), or hepatitis C virus (HCV).
• Participant has been on a diet incompatible with the on-study diet (that is, unusual meal habits and special diet requirements or unwillingness to eat the food provided in the trial), in the opinion of the PI or designee, within the 30 days prior to the first dosing and throughout the study.
• Participant has participated in another clinical study within 30 days prior to the first dosing. The 30-day window will be derived from the date of the last dosing in the previous study to the first dosing of the current study.
• Participant has positive coronavirus disease 2019 (COVID-19) results at first check-in.

Note: Other protocol-specified inclusion and exclusion criteria may apply.

Parts 1 and 2 are double-blind and placebo-controlled. Part 3 is open-label.