This study will evaluate the mass balance recovery and metabolite profile, and will identify metabolite structures following a single oral dose of 14C-XEN1101 in healthy adult male subjects.

Key Inclusion Criteria:

• Body mass index (BMI) of 18.0 to 32.0 kg/m2
• Must be willing and able to communicate and participate in the whole study
• Provide written informed consent
• Adhere to the specified contraception requirements

Key Exclusion Criteria:

• Subjects who have received any investigational medicinal product (IMP) in a clinical research study within 90 days
• Evidence of any current infection or an infection within 14 days before study drug administration
• History of any drug or alcohol abuse in the past 2 years
• Subjects with pregnant or lactating partners
• Radiation exposure, including that from the present study, excluding background radiation but including diagnostic x-rays and other medical exposures, exceeding 5 millisievert (mSv) in the last 12 months or 10 mSv in the last 5 years. No occupationally exposed worker, as defined in the Ionising Radiation Regulations 2017, shall participate in the study
• Participation in a clinical trial involving administration of radiolabelled compound(s) within 180 days of the planned dosing date of this study
• Clinically significant abnormal clinical chemistry, haematology, coagulation or urinalysis. Subjects with Gilbert's Syndrome will be excluded.
• Confirmed positive drugs of abuse test result
• Positive hepatitis B surface antigen (HBsAg), hepatitis C virus antibody (HCV Ab) or human immunodeficiency virus (HIV) antibody results
• History of clinically significant cardiovascular, renal, hepatic, dermatological, chronic respiratory or gastrointestinal disease, neurological or psychiatric disorder
• Donation of blood or plasma within the previous 3 months or loss of greater than 400 mL of blood