This is a single center, non-randomized, open label Phase 1 study to determine the PK and absolute bioavailability of BIIB122 (DNL151) in 2 conditions: following a single, oral dose of BIIB122 (DNL151) and following consecutive days of oral dosing, approximating steady state.

This clinical trial information was submitted voluntarily under the applicable law and, therefore, certain submission deadlines may not apply. (That is, clinical trial information for this applicable clinical trial was submitted under section 402(j)(4)(A) of the Public Health Service Act and 42 CFR 11.60 and is not subject to the deadlines established by sections 402(j)(2) and (3) of the Public Health Service Act or 42 CFR 11.24 and 11.44.).

Key Inclusion Criteria:

• Women of non-childbearing potential and men either with a vasectomy, using contraception, or having sex with a woman of non-childbearing potential
• Body mass index (BMI) ≥ 18 kg/m2 and ≤ 32 kg/m2
• Considered to be in good health
• Nonsmoker

Key Exclusion Criteria:

• History or presence of any condition or prior surgery that, in the opinion of the investigator, poses a significant risk to subject safety and/or achievement of study objectives