The main purpose of this study is to determine the effect of itraconazole on the amount of GLPG3667 that gets into the blood when the 2 drugs are administered together compared to when GLPG3667 is administered alone.

Inclusion Criteria:

• Male or female between 18 and 55 years of age (extremes included), on the date of signing the informed consent form (ICF). Female subjects should be of non-childbearing potential, defined as permanently surgically sterile (bilateral oophorectomy, i.e. surgical removal of ovaries, bilateral salpingectomy or hysterectomy, i.e. surgical removal of uterus), or with no menses for 12 or more months without an alternative medical cause AND a follicle-stimulating hormone (FSH) level in the postmenopausal range. For surgical sterilization, documented confirmation will be requested.
• A body mass index between 18.0 and 30.0 kg/m2, inclusive.
• Judged to be in good health by the investigator based upon the results of a medical history, physical examination, vital signs, 12-lead electrocardiogram (ECG), and fasting clinical laboratory safety tests. Neutrophil, lymphocyte, and platelet counts must be above the lower limit of normal range. Total bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) must be within normal ranges. Other clinical laboratory safety test results must be within the normal ranges or test results that are outside the normal ranges need to be considered not clinically significant in the opinion of the investigator.

This list only contains the key inclusion criteria.

Exclusion Criteria:

• Known hypersensitivity to ingredients of GLPG3667 and/or itraconazole, or history of a significant allergic reaction to ingredients of GLPG3667 and/or itraconazole, as determined by the investigator.
• Treatment with any medication (including over-the-counter (OTC) and/or prescription medication, dietary supplements, nutraceuticals, vitamins and/or herbal supplements, and hormonal replacement therapy) except occasional paracetamol (maximum dose of 2 g/day and maximum of 10 g/2 weeks) in the last 2 weeks or 5 half-lives of the drug, whichever is longer, prior to the first dosing.

This list only contains the key exclusion criteria.