The purpose of this study is to assess the safety, tolerability and pharmacokinetics of repeat doses of IRL201104 given to healthy volunteers.

Inclusion Criteria:

• Healthy male and female subjects age 18 to 65 years of age, and in good health as determined by medical history, physical examination, vital signs, electrocardiogram, and laboratory tests.
• Female subjects agree to use highly effective contraception or be of non-childbearing potential.
• Written informed consent must be obtained before any assessment is performed.
• Able to communicate well with the Investigator/designee.

Exclusion Criteria:

• Any known reaction to study drug or components
• concurrent or recent infection or clinically significant conditions that may place subject at risk or interference with absorption, distribution or excretion of drugs
• No QTcF interval ≥450 milliseconds, no QRS complex ≥120 milliseconds, at Screening
• Positive test results for hepatitis B surface antigen (HBsAg), hepatitis C virus antibodies (HCVAb) or human immunodeficiency virus (HIV) 1 and/or -2 antibodies at Screening.
• Excessive use of caffeine-containing beverages
• Urinary cotinine level indicative of smoking or history or regular use of tobacco- or nicotine containing products within 6 months before screening.
• Presence or history of drug of alcohol abuse.
• Positive screen for drugs-of-abuse or cotinine.
• Blood donation in excess of 500mL within 3 months.
• Participation in another clinical study with licensed or unlicensed study drug within 3 months of first IMP administration.
• Exposure to more than 4 new chemical entities within 12 months before the first IMP administration.
• Use of live vaccine 28 days before dosing with study drug until telephone follow-up and use of killed vaccine (including COVID-19 vaccine) 14 days before dosing with study drug until telephone follow-up.