Study to evaluate the safety, tolerability, and effect of the body and food on RO7308480 following oral administration in healthy participants

INTERVENTION: Part 1: RO7308480‐SAD Cohorts: Participants will receive a single dose of RO7308480 capsule, orally, under fasted conditions on Day 1 in cohort 1. The dose will be escalated in subsequent cohorts in six steps as per the Sponsor’s clinical pharmacologist and Principal Investigator’s judgment Part 1: Placebo‐SAD Cohorts: Participants will receive a single dose of RO7308480 matching placebo capsule, orally, under fasted conditions on Day 1 of the SAD stage Part 2: Food Effect Assessment (FE)‐Fasted Period: Participants will receive a single dose of RO7308480 capsule, orally, under fasted conditions on Day 1 of the FEC‐fasted period Part 2: FE‐Fed Period: Participants will receive a single dose of RO7308480 capsule, orally, 30 minutes after a standardized high fat, high‐calorie breakfast on Day 1 of the FE‐fed period This study consists of two parts, Part 1, and Part 2. Participants will be assigned to either Part 1 or Part 2. Part 1 Participants may be asked to be in the study for about 8 weeks in Part 1. This includes: 1. A screening visit within 28 days before treatment administration where tests will be done to check if the participants are eligible to take part in the study 2. An inpatient stay at the clinic for 8 days and 7 nights (from 2 days before until 6 days after treatment) 3. Six walk‐in visits on Days 7, 8, 10, 12, 14, and 28 after treatment. Part 1 or the “single‐ascending dose” stage will evaluate the safety, tolerability, and pharmacokinetics of RO7308480. Participants will be divided into seven different groups, with each group receiving a higher dose level than the preceding CONDITION: Safety, tolerability, pharmacokinetics, and food effects of single‐ascending oral doses of RO7308480 in healthy participants ; Not Applicable SECONDARY OUTCOME: ; Measured from blood samples using a specific and validated liquid chromatography‐mass spectrometry/mass spectrometry (LC‐MS/MS) method:; 1. Part 1: Maximum observed plasma concentration (Cmax) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 hours (h) thereafter up to Day 14 in SAD stage; 2. Part 1: Time to maximum observed concentration (Tmax) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 3. Part 1: Area under the plasma concentration‐time curve from time zero up to the last measurable concentration (AUClast) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 4. Part 1: Area under the plasma concentration‐time curve from time zero up to 24 h (AUC0‐24h) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 5. Part 1: Area under the plasma concentration‐time curve from time zero extrapolated to infinity (AUCinf) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 6. Part 1: Area under the plasma concentration‐time curve from zero up to a given time (AUC0‐t) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 7. Part 1: Terminal rate constant (?z) calculated by linear regression of the log‐transformed terminal part of the concentration‐time curve of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 8. Part 1: Apparent terminal half‐life (t1/2), computed as log (2) per ?z (ln(2)/?z) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 9. Part 1: Apparent clearance (CL/F) calculated from Dose/AUCinf of RO7308480 measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in SAD stage; 10. Part 1: Cumulative amount excreted (Ae) unchanged into urine of RO7308480 and its metabolites, as appropriate, measured using urine samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 6 in Part 1 (SAD) only; 11. Part 1: Fraction of dose excreted (Fe) unchanged in urine of RO7308480 and its metabolites, as appropriate, measured using urine samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 6 in Part 1 (SAD) only; 12. Part 1: Calculated renal clearance (CLR), computed as Ae/AUC of RO7308480 measured using urine samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 6 in Part 1 (SAD) only; 13. Part 2: Maximum observed plasma concentration (Cmax) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 14. Part 2: Time to maximum observed concentration (Tmax) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 15. Part 2: Area under the plasma concentration‐time curve from time zero up to the last measurable concentration (AUClast) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 16. Part 2: Area under the plasma concentration‐time curve from time zero up to 24 h (AUC0‐24h) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 17. Part 2: Area under the plasma concentration‐time curve from time zero extrapolated to infinity (AUCinf) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 18. Part 2: Area under the plasma concentration‐time curve from zero up to a given time (AUC0‐t) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 19. Part 2: Terminal rate constant (?z) calculated by linear regression of the log‐transformed terminal part of the concentration‐time curve of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 20. Part 2: Apparent terminal half‐life (t1/2), computed as log (2) per ?z (ln(2)/?z) of RO7308480 and its metabolites, as appropriate, measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 in FE (fed and fasted state) stage; 21. Part 2: Apparent clearance (CL/F) calculated from Dose/AUCinf of RO7308480 measured using blood samples at pre‐dose and multiple time‐points post‐dose on Day 1 and every 12 h thereafter up to Day 14 FE (fed and fasted state) stage; INCLUSION CRITERIA: 1. 18 to 55 years of age inclusive, at the time of signing the informed consent 2. Male and female participants who are overtly healthy (defined by the absence of evidence of any active or chronic disease) as determined by medical evaluation 3. Participants able to communicate with the study staff 4. Body mass index (BMI) of 18 to 30 kg/m² inclusive PRIMARY OUTCOME: ; 1. Part 1 and 2: Percentage of participants with adverse event (AEs), recorded by non‐leading verbal questioning of the participant, from screening up to Day 14 and 28 days after study drug administration (up to approximately 6 months) in single‐ascending dose (SAD) and food effect assessment (FE) stages, respectively; 2. Part 1 and 2: Percentage of participants with the severity of AEs as assessed by the investigator (mild, moderate, or severe) from screening up to Day 14 and 28 days after study drug administration (up to approximately 6 months) in SAD and FE stages, respectively; 3. Part 1 and 2: Percentage of participants with clinically significant changes in vital signs values measured using body temperature (tympanic), pulse rate, respiratory rate, and blood pressure from screening up to Day 14 and 28 days after study drug administration (up to approximately 6 months) in SAD and FE stages, respectively; 4. Part 1 and 2: Percentage of participants with clinically significant changes in physical findings measured by assessment of cardiovascular, respiratory, gastrointestinal, dermatological, neurological, and musculoskeletal systems in addition to head, eyes, ears, nose, throat, neck, and lymph nodes from screening up to Day 14 and 28 days after study drug administration (up to approximately 6 months) in SAD and FE stages, respectively; 5. Part 1 and 2: Percentage of participants with clinically significant changes in neurological findings assessed using measurement of motor and sensory skills, functioning of cranial nerves (including pupillary responses), coordination, gait, reflexes, and mental status from screening up to Day 14 and 28 days after study drug administration (up to approximately 6 months) in SAD and FE stages, respectively; 6. Part 1 and 2: Percentage of participants with clinically significant changes in electrocardiogram (ECG) parameters measured using 12‐lead ECG and Holter ECG (only in Part 1) from screening up to Day 14 and 28 days after study drug administration (up to approximately 6 months) in SAD and FE stages, respectively; 7. Part 1 and 2: Percentage of participants with significant changes in clinical laboratory results measured using blood or urine samples collected from screening up to Day 14 and 28 days after study drug administration (up to approximately 6 months) in SAD and FE stages, respectively;