The SAD design of the study is based on the aim to study safety, tolerability and PK of selected doses of ACD856 in a limited number of healthy volunteers. ACD856 will be administered orally.

Inclusion Criteria:

• Signed and dated informed consent prior to any study-mandated procedure.´
• Willing and able to comply with study requirements.
• Healthy males and healthy women of non-childbearing potential aged ≥18 and <65 years at screening.
• BMI ≥18.0 and ≤30.0 kg/m2 at screening.
• Males and females of non-childbearing potential may be included in the study. Male subjects must be willing to use condom or be vasectomized or practice sexual abstinence to prevent pregnancy and drug exposure of a partner and refrain from donating sperm from the date of dosing until 3 months after dosing with the IMP.
• Clinically acceptable medical history, physical findings, vital signs, ECG and laboratory values at the time of screening, as judged by the Investigator.

Exclusion Criteria:

• Planned treatment or treatment with another investigational drug within 3 months prior to randomization.
• Positive screen for drugs of abuse or a positive alcohol result at screening or admission to the clinic.
• Clinically relevant findings in laboratory parameters, ECG or vital signs at screening
• Current smokers or users of nicotine products.
• History of alcohol abuse or excessive intake of alcohol.
• Presence or history of drug abuse.
• History of, or current use of, anabolic steroids.
• Excessive caffeine consumption.
• Plasma donation within one month of screening or blood donation prior to screening.