First-in-human test of ZE66-0205 in healthy adults

Inclusion Criteria:

* Written informed consent provided before any study-related activities; able to understand the nature, purpose, risks, and possible adverse effects of the study.
* Male or female, 18 to 55 years of age, inclusive, at Screening.
* Body mass index 18.0 to 32.0 kg/m², inclusive, and body weight no more than 100 kg at Screening.
* Medically healthy in the opinion of the Investigator or delegate based on medical history and absence of clinically significant abnormalities, including: no clinically relevant physical-examination findings; systolic blood pressure 90 to 160 mmHg and diastolic blood pressure 50 to 95 mmHg after at least 5 minutes of rest; pulse rate 40 to 100 beats/minute after at least 5 minutes of rest; tympanic body temperature 35.5°C to 37.7°C; and electrocardiogram without clinically significant abnormalities, including QTcF less than 450 msec for males and less than 470 msec for females.
* Female participants must be of non-childbearing potential (surgically sterilised at least 6 weeks before Screening or postmenopausal with confirmatory follicle-stimulating hormone level) or, if of childbearing potential, must have negative pregnancy tests at Screening and Day -1, agree not to become pregnant or donate ova until at least 30 days after the last dose, and use protocol-defined adequate contraception during this period unless exclusively in a same-sex relationship or abstinent as a committed lifestyle.
* Male participants must agree not to donate sperm until at least 90 days after the last dose. When engaging in sexual intercourse with a female partner who could become pregnant, the participant must use a condom together with a protocol-defined highly effective method of contraception until at least 90 days after the last dose. When engaging in sexual intercourse with a female partner who is not of childbearing potential or with a same-sex partner, the participant must use a condom until at least 5 days after the last dose.
* Suitable venous access for blood sampling.
* Willing and able to comply with all study assessments, schedule requirements, and restrictions.

Exclusion Criteria:

* History of anaphylaxis or another significant allergy that, in the opinion of the Investigator or delegate, could interfere with study participation.
* History or presence of clinically significant cardiovascular, pulmonary, hepatic, renal, hematological, gastrointestinal, endocrine, immunologic, dermatologic, psychiatric, or neurological disease or disorder, including any clinically relevant acute illness within the previous 3 months.
* Surgery or hospitalization within 3 months before Screening, or planned surgery during the study.
* History of malignant disease within the previous 10 years, except surgically resected squamous-cell or basal-cell skin carcinoma with histopathologically confirmed clear margins.
* Clinically relevant immunosuppression, including immunodeficiency conditions such as common variable hypogammaglobulinemia.
* History of risk factors for torsade de pointes, including family history of long QT syndrome or sudden cardiac death, or a known arrhythmia.
* Gastrointestinal, hepatic (including Gilbert syndrome), renal, or other condition known to interfere with absorption, distribution, metabolism, or excretion of drugs.
* Gamma-glutamyl transferase, total bilirubin, alkaline phosphatase, aspartate aminotransferase, or alanine aminotransferase greater than 1.5 times the upper limit of normal, unless an isolated elevation is considered a normal variant by the Investigator or delegate and is not accompanied by clinical signs.
* Estimated creatinine clearance below 60 mL/min using the Cockcroft-Gault formula or serum creatinine greater than 1.5 times the upper limit of normal.
* History of or positive Screening test for human immunodeficiency virus, hepatitis B surface antigen, or hepatitis C virus antibodies.
* Positive urine drug-of-abuse test, carbon monoxide breath test, or alcohol breath test at Screening or Day -1.
* Regular smoking of more than 5 cigarettes per week or equivalent, including tobacco, nicotine replacement therapy, e-cigarettes, or marijuana. Casual smokers may be eligible only if all protocol requirements are met.
* Pregnant or breastfeeding female, or female planning to breastfeed from Screening until 3 months after the last dose or 5 half-lives, whichever is longer.
* Unable to swallow oral medication.
* Use of prescription medication, including oral contraceptives, within 14 days or 5 half-lives, whichever is longer, before the first dose; or use of over-the-counter medication within 7 days or 5 half-lives, whichever is longer, before the first dose, except protocol-permitted paracetamol.
* Current infection requiring a systemically absorbed antibiotic, antifungal, antiparasitic, or antiviral medication within 10 days before the first dose.
* Receipt of an inactivated vaccination within 14 days or a live vaccination within 30 days before the first dose, or planned vaccination during the study.
* Use of systemic immunosuppressive or immunomodulating medication within 28 days or 5 half-lives, whichever is longer, before dosing or during the study.
* Blood or plasma donation within 30 days before the first dose; loss of more than 500 mL of whole blood within 30 days before the first dose; or receipt of a blood transfusion within 1 year before the first dose.
* Participation in a clinical study of an investigational drug or device within 30 days or 5 half-lives of the investigational drug, whichever is longer, before Screening.
* Any other condition or prior therapy that, in the opinion of the Investigator or delegate, makes the participant unsuitable for the study, including inability to cooperate fully or likely noncompliance with study requirements.