A Phase 1 Double-blind, Randomised, Placebo Controlled Study Evaluating the Safety, Tolerability, and Pharmacokinetics of Single Ascending Doses of S1-221 Following Oral Administration

Inclusion criteria

• Provision of signed and dated participant informed consent form (PICF) and willing and able to follow all study procedures and requirements for the duration of the study.
• Healthy adult males and females aged 18 to 65 years, inclusive, at Screening.
• Body mass index (BMI) of 18 to 32.0 kg/m2, inclusive, and body weight ≥50.0 kg, at Screening.
• Considered healthy, as determined by no clinically significant findings from medical history or physical examination at Screening and Day -1, in the opinion of the Investigator.
• Vital signs after 5 minutes resting in supine position within the following ranges (assessment may be repeated once per schedule time point, at the discretion of the Investigator, to obtain a clinically reliable result):
• Systolic blood pressure: 90 to 140 mmHg inclusive;
• Diastolic blood pressure: 40 to 90 mmHg inclusive;
• Heart rate: 40 to 100 bpm inclusive.
• Standard 12-lead ECG with parameters (average of triplicate readings) after 10 minutes in supine position within the following ranges (assessment may be repeated once per schedule time point, at the discretion of the Investigator, to obtain a clinically reliable result):
• QRS \<120 msec;
• QT \<500 msec;
• QTc ≤450 msec (both genders);
• PR interval ≥120 to ≤220 msec.
• Screening and Day -1 (and Day 14 for Parts B and C) safety laboratory test values within normal ranges. Out of normal range values may be accepted by the Investigator if not considered clinically significant, with the exception of the following:
• ALT or AST \>1.5 x upper limit of normal (ULN);
• Total, indirect, or direct bilirubin \>1.5 x ULN. Participants with Gilbert's syndrome with indirect bilirubin outside of the normal range will not be excluded from the study;
• Abnormal kidney function, as assessed by estimated glomerular filtration rate (eGFR) calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI);
• Creatinine \>1.2 x ULN;
• Haemoglobin \<100.0 g/L in females or \<115 g/L in males; or white blood cells \<3.5 x 109/L or \>11.5 x 109/L;
• HbA1c ≥6.5% (participant must be non-diabetic). In Parts B and C, any laboratory abnormalities noted prior to the crossover repeat dosing will be discussed with the medical monitor and Sponsor to determine whether repeat dosing may proceed as planned.
• Negative tests for HBsAg, HBcAb, anti-HCV, and HIV antibodies at Screening.
• Women of childbearing potential (WOCBP) must have a negative pregnancy test at Screening and Day -1 (and Day 14 for Parts B and C). Note: Definition of child-bearing potential is fertile and following menarche until becoming post-menopausal, unless permanently sterile. Permanent sterilisation methods include hysterectomy, bilateral salpingectomy and bilateral oophorectomy. A post-menopausal state is defined as no menses for 12 months without an alternative medical cause and follicle-stimulating hormone (FSH) documented in the post- menopausal range (≥40 IU/L).
• WOCBP must agree to the use adequate contraception from Screening through 60 days following the last dose of study drug. Additionally, they should avoid egg/ova donation throughout the study and for 60 days after the last dose of the study drug.
• Male participants must agree to use adequate contraception from Screening through 95 days following the last dose of study drug. Male participants with female partners that are surgically sterile or post-menopausal (defined as being amenorrhoeic for at least 12 months without an alternative medical cause) may also be included and will not be required to use above-described methods of contraception. Male partners with potentially post-menopausal females who are under the age of 55 years must use condoms unless their partner's postmenopausal status has been confirmed by FSH level \>40mIU/mL. Male participants who have undergone vasectomy and have had testing to confirm azoospermia 90 days after procedure may also be included. The use of condom by male participant will be required if vasectomy is the chosen highly effective method of contraception. Male participants must also agree not to donate sperm throughout the study and for 95 days following the last dose of study drug.
• Non-smoker, ex-smoker, or smoker willing to refrain from use of tobacco/nicotine-containing products, e.g., cigarettes, vaporizers, cigars, pipe tobacco, smokeless tobacco, nicotine gum, lozenges, patches, on more than 5 occasions within 1 month prior to the Screening visit and for the duration of the study. Note: a cotinine level or other observations that, in the opinion of the Investigator, suggest heavy use of tobacco will be exclusionary.
• Willing to refrain from consumption of alcohol as follows:
• Part A: for at least 48 hours prior to Screening and Day -1, then from Day 1 through End of Study (EOS).
• Parts B and C: for at least 48 hours prior to Screening, Day -1, and Day 14, and from Day -1 through Day 7 visit, and from Day 14 through EOS (consumption of alcohol is permitted from Day 8 through Day 13).
• Willing to withhold cannabinoids (including CBD and THC) and cannabis (including hemp) products for 60 days prior to administration of the first dose of study drug and throughout the study.
• Willing to refrain from consumption of food or beverages containing xanthine derivatives or xanthine-related compounds (e.g., coffee, black/green tea, chocolate) or energy drinks from 48 hours prior to each clinic admission and each follow-up visit.
• Willing to defer blood donations to a blood service for minimum of 30 days following the last dose of study drug.
• Willing to comply with the study-specified diet while confined in the CRU. Participants in Part B (Food Effect Cohort) must agree to complete consumption of a standardised high-fat, high-calorie breakfast during the fed period on Day 15.
• Willing to not operate a motor vehicle or heavy machinery for 7 days following administration of study drug.
• In the opinion of the Investigator, is willing and able to comply with and understand study requirements and be available for the required study visits.