Evaluation of Safety, Tolerability, Pharmacokinetics, Drug-Drug and Food Interactions of Single and Multiple Doses of S-648414 in Healthy Adults

Study Overview
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Brief Summary
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The primary objective of Part 1 of the study is to evaluate the safety and tolerability of S-648414 after administration of a single oral dose of S-648414 in healthy adult study participants. The primary objective of Part 2 is to evaluate the safety and tolerability of S-648414 after administration of multiple oral doses of S-648414 in healthy adult study participants. The primary objectives of Part 3 are evaluate the safety and tolerability of S-648414 after administration of multiple oral doses of S-648414 in healthy adult study participants, and to evaluate the effect of S-648414 on the pharmacokinetics (PK) of dolutegravir and the effect of dolutegravir on the PK of S-648414 in healthy adult study participants.

Detailed Description
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Amendment 2 of the study Protocol added a third part (Part 3) to the study. The revised Official Title for the Protocol is: A Phase 1, Randomized, Double-Blind, Single-Ascending-Dose, and Food Effect Study to Assess the Safety, Tolerability, Ventricular Repolarization, and Pharmacokinetics of S-648414 in Healthy Adult Study Participants (Part 1); A Phase 1, Randomized, Double-Blind, Multiple-Ascending-Dose Study to Assess the Safety, Tolerability, and Pharmacokinetics of S-648414 and A Drug-Drug Interaction Study with the CYP3A Substrate, Midazolam, in Healthy Adult Study Participants (Part 2); and A Phase 1 Open-Label Study to Assess the Effect of S-648414 on the Pharmacokinetics of Dolutegravir and the Effect of Dolutegravir on the Pharmacokinetics of S-648414 in Healthy Adult Study Participants (Part 3)

Official Title
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A Phase 1, Randomized, Double-Blind, Single-Ascending-Dose, and Food Effect Study to Assess the Safety, Tolerability, Ventricular Repolarization, and Pharmacokinetics of S-648414 in Healthy Adult Study Participants (Part 1); A Phase 1, Randomized, Double-Blind, Multiple-Ascending-Dose Study to Assess the Safety, Tolerability, and Pharmacokinetics of S-648414 and A Drug-Drug Interaction Study With the CYP3A Substrate, Midazolam, in Healthy Adult Study Participants (Part 2)

Conditions
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Healthy Volunteer

Intervention / Treatment
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* Drug: S-648414
* Drug: Placebo
* Drug: Midazolam
* Drug: Dolutegravir


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Male or female adults ≥ 18 years in USA or ≥ 20 years in Japan to ≤ 55 years of age, at the time of signing the informed consent form (ICF). a) Specific to Japan sites: enrollment in Part 3 (Group I and J) will consist of only White or Black or African American race. Capable of giving signed informed consent Body mass index (BMI) ≥ 18.5 to < 32.0 kg/m² at the Screening visit． Considered medically healthy as determined by the investigator or subinvestigator (suitably qualified), based on medical history and clinical evaluations including physical examination, clinical laboratory tests, vital sign measurements, and 12-lead electrocardiogram (ECG) at Screening and at upon admission to the Clinical Research Unit (CRU) and prior to administration of study intervention on Day 1. Female study participants must not be a woman of childbearing potential and must either be postmenopausal (defined as no menses for 12 months without an alternative medical cause; follicle-stimulating hormone (FSH) to be tested for confirmation at Screening) or premenopausal with 1 of the following documented: hysterectomy, tubal ligation, bilateral salpingectomy, or bilateral oophorectomy. Male study participants must agree to use contraception during the treatment period and for at least 3 months after the last dose of study intervention. Exclusion Criteria: Considered by the investigator or subinvestigator (suitably qualified) to be ineligible for the study due to a history of or current condition of significant metabolic or endocrine, hepatic, renal, hematological, pulmonary, cardiovascular, gastrointestinal (GI), urological, immunological, neurological, or psychiatric disorders with clinical manifestations. History or presence of cancer in last 5 years except for non-melanoma skin cancers. Risk factors for: Torsades de Pointes (eg, heart failure, cardiomyopathy, or family history of Long QT Syndrome or Brugada Syndrome) Unexplained syncope, sick sinus syndrome, second- or third-degree atrioventricular (AV) block, myocardial infarction, pulmonary congestion, cardiac arrhythmia, angina, prolonged QT interval, or conduction abnormalities History of GI surgery or disease including, but not limited to, gastric band/gastric resection and/or intestinal resection and/or duodenal disease (ie, celiac disease) that may result in clinically significant malabsorption (except for an appendectomy). History of hypersensitivity or severe side effects induced by a drug. Any condition requiring medication and/or other treatment, such as dietary restriction and physical therapy. History of significant multiple and/or severe allergic symptoms including food allergy (NOTE: Study participants with seasonal allergies may participate unless they have ongoing symptoms). Used drugs or substances known to be inducers or inhibitors of cytochrome P450 enzymes and/or P-glycoprotein within 28 days prior to admission to the CRU. Used prescription or over-the-counter (OTC) drugs, antacids, proton pump inhibitors, H2 antagonists, Chinese herbal medicines, oral cannabidiol, vitamins, minerals, herbal, and dietary supplements within 14 days prior to admission to the CRU. Refuses to abstain from ingesting caffeine- or xanthine-containing products/medications (eg, coffee, tea, cola drinks, other caffeinated beverages, or chocolate) from 24 hours prior to admission to the CRU or refuses to refrain from consuming such products throughout the study (including Follow-up period). Consumed alcohol or used alcohol-containing products within 72 hours prior to admission to the CRU or refuses to refrain from consuming such products throughout the study (including Follow-up period). History of recreational drug use in the previous 6 months, or has a history of problematic alcohol use (defined as study participants who regularly consume excessive amounts of alcohol, defined as > 3 glasses of alcoholic beverages per day (1 glass is approximately equivalent to: beer [284 mL/10 ounces (oz.)], wine [125 mL/4 oz.] or distilled spirits [25 mL/1 oz.]). A positive drug or alcohol screen at the Screening visit or upon admission to the CRU. Used tobacco- or nicotine-containing products (including cigarette, pipe, cigar, chewing, nicotine patch, nicotine gum, or Vaping product) within 6 months prior to admission to the CRU or refuses to refrain from using tobacco- or nicotine-containing products throughout the study (including Follow-up period). Consumed grapefruit, grapefruit juice, Seville orange juice, orange juice, apple juice, vegetables from the mustard green family (eg, kale, broccoli, watercress, collard greens, kohlrabi, Brussels sprouts, mustard greens), or charbroiled meats within 7 days prior to admission to the CRU or refuses to refrain from consuming such products throughout the study (including Follow-up period). A corrected QT (QTc) interval of > 450 msec for males and > 470 msec for females (Fridericia's method) at the Screening visit or upon admission to the CRU. Systolic blood pressure is outside the range of 90 to 140 mm Hg, diastolic blood pressure is outside the range of 50 to 90 mm Hg, or pulse rate is outside the range of 40 to 100 beats per minute (bpm) or considered ineligible by the investigator or subinvestigator at the Screening visit or upon admission to the CRU. Total bilirubin, alanine aminotransferase (ALT), or aspartate aminotransferase (AST) values are greater than the upper limit of normal (ULN), or estimated glomerular filtration rate (eGFR) < 90 mL/min/1.73 m² at Screening or upon admission to the CRU. A positive serological test for untreated syphilis, positive hepatitis B surface antigen, positive hepatitis C virus antibody, or positive human immunodeficiency virus (HIV) antigen/antibody result at the Screening visit. Participated in any other investigational trials or has been exposed to other investigational drugs within 28 days or 5 half-lives of the previously administered investigational drug (date derived from last study procedure [blood collection or dosing] of previous trial), whichever is longer, prior to admission to the CRU. Previously received S-648414. Poor venous access. Donated blood or had significant blood loss within 56 days of study admission to the CRU or donated plasma within 7 days prior to until admission to the CRU. Considered inappropriate for participation in the study for any reason by the investigator or subinvestigator.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Sequential Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Placebo Comparator: Part 1: Placebo<br>Participants received a single oral dose of matching placebo in a fasted state on Day 1. | Drug: Placebo<br>* Tablet for oral administration<br>|
| Experimental: Part 1: 10 mg S-648414<br>Participants received a single oral dose of 10 mg S-648414 in a fasted state on Day 1. | Drug: S-648414<br>* Tablet for oral administration<br>|
| Experimental: Part 1: 30 mg S-648414<br>Participants received a single oral dose of 30 mg S-648414 in a fasted state on Day 1. | Drug: S-648414<br>* Tablet for oral administration<br>|
| Experimental: Part 1: 100 mg S-648414<br>Participants received a single oral dose of 100 mg S-648414 in a fasted state on Day 1 followed by a single dose of S-648414 in a fed state (after a high-fat meal) on Day 14. | Drug: S-648414<br>* Tablet for oral administration<br>|
| Experimental: Part 1: 250 mg S-648414<br>Participants received a single oral dose of 250 mg S-648414 in a fasted state on Day 1. | Drug: S-648414<br>* Tablet for oral administration<br>|
| Experimental: Part 1: 500 mg S-648414<br>Participants received a single oral dose of 500 mg S-648414 in a fasted state on Day 1. | Drug: S-648414<br>* Tablet for oral administration<br>|
| Experimental: Part 1: 1000 mg S-648414<br>Participants received a single oral dose of 1000 mg S-648414 in a fasted state on Day 1. | Drug: S-648414<br>* Tablet for oral administration<br>|
| Placebo Comparator: Part 2: Placebo + Midazolam<br>Participants received matching placebo once a day on Days 1 to 14 and a single oral dose of 5 mg midazolam alone on Day -2 and co-administered with the placebo dose on Day 14. | Drug: Placebo<br>* Tablet for oral administration<br>Drug: Midazolam<br>* Solution for oral administration<br>* Other names: Versed;|
| Experimental: Part 2: 50 mg S-648414 + Midazolam<br>Participants received 50 mg S-648414 once a day on Days 1 to 14 and a single oral dose of 5 mg midazolam alone on Day -2 and co-administered with the S-648414 dose on Day 14. | Drug: S-648414<br>* Tablet for oral administration<br>Drug: Midazolam<br>* Solution for oral administration<br>* Other names: Versed;|
| Experimental: Part 2: 30 mg S-648414 + Midazolam<br>Participants received 30 mg S-648414 once a day on Days 1 to 14 and a single oral dose of 5 mg midazolam alone on Day -2 and co-administered with the S-648414 dose on Day 14. | Drug: S-648414<br>* Tablet for oral administration<br>Drug: Midazolam<br>* Solution for oral administration<br>* Other names: Versed;|
| Experimental: Part 3: 100 mg S-648414 + Dolutegravir<br>Participants received 50 mg dolutegravir orally once a day on Days 1 to 7, 100 mg S-648414 orally once a day on Days 15 to 21, and 50 mg dolutegravir co-administered with 100 mg S-648414 orally once a day on Days 22 to 28. | Drug: S-648414<br>* Tablet for oral administration<br>Drug: Dolutegravir<br>* Tablet for oral administration<br>* Other names: TIVICAY;|
| Experimental: Part 3: 200 mg S-648414 + Dolutegravir<br>Participants received 50 mg dolutegravir orally once a day on Days 1 to 7, 200 mg S-648414 orally once a day on Days 15 to 21, and 50 mg dolutegravir co-administered with 200 mg S-648414 orally once a day on Days 22 to 28. | Drug: S-648414<br>* Tablet for oral administration<br>Drug: Dolutegravir<br>* Tablet for oral administration<br>* Other names: TIVICAY;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Part 1: Number of Participants With Treatment-emergent Adverse Events (TEAEs) | A TEAE is any event not present before exposure to study drug or any event already present that worsens after exposure to study drug. A serious adverse event is any untoward medical occurrence that resulted in death, was life-threatening, required or prolonged inpatient hospitalization, resulted in persistent disability/incapacity, was a congenital anomaly/birth defect, or other event that may have jeopardized the participant or required intervention to prevent one of the outcomes above. The investigator assessed the intensity of each AE according to the following: Grade 1 (Mild): No or minimal interference with usual activities. Grade 2 (Moderate): More than minimal interference with usual activities, intervention indicated. Grade 3 (Severe): Inability to perform usual activities, intervention or hospitalization indicated. Grade 4 (Potentially life-threatening): Inability to perform self-care, intervention indicated to prevent permanent impairment, disability, or death. | From dosing on Day 1 or Day 14 up to 10 days post dose | 
| Part 2: Number of Participants With Treatment-emergent Adverse Events | A TEAE is any event not present before exposure to study drug or any event already present that worsens after exposure to study drug. A serious adverse event is any untoward medical occurrence that resulted in death, was life-threatening, required or prolonged inpatient hospitalization, resulted in persistent disability/incapacity, was a congenital anomaly/birth defect, or other event that may have jeopardized the participant or required intervention to prevent one of the outcomes above. The investigator assessed the intensity of each AE according to the following: Grade 1 (Mild): No or minimal interference with usual activities. Grade 2 (Moderate): More than minimal interference with usual activities, intervention indicated. Grade 3 (Severe): Inability to perform usual activities, intervention or hospitalization indicated. Grade 4 (Potentially life-threatening): Inability to perform self-care, intervention indicated to prevent permanent impairment, disability, or death. | From the first dose up to 10 days after end of dosing (25 days); A TEAE was summarized to a given treatment if the event onset/worsening occurred any time after the dose of that treatment and before the dose of the next treatment. | 
| Part 3: Number of Participants With Treatment-emergent Adverse Events | A TEAE is any event not present before exposure to study drug or any event already present that worsens after exposure to study drug. A serious adverse event is any untoward medical occurrence that resulted in death, was life-threatening, required or prolonged inpatient hospitalization, resulted in persistent disability/incapacity, was a congenital anomaly/birth defect, or other event that may have jeopardized the participant or required intervention to prevent one of the outcomes above. The investigator assessed the intensity of each AE according to the following: Grade 1 (Mild): No or minimal interference with usual activities. Grade 2 (Moderate): More than minimal interference with usual activities, intervention indicated. Grade 3 (Severe): Inability to perform usual activities, intervention or hospitalization indicated. Grade 4 (Potentially life-threatening): Inability to perform self-care, intervention indicated to prevent permanent impairment, disability, or death. | From the first dose up to Day 36; A TEAE was summarized to a given treatment if the event onset/worsening occurred any time after the dose of that treatment and before the dose of the next treatment. | 
| Part 3: Maximum Plasma Concentration (Cmax) of S-648414 | The effect of dolutegravir on the pharmacokinetics (PK) of S-648414 was assessed after administration of multiple oral doses of S-648414 alone (Day 21) and after administration of multiple oral doses of S-648414 co-administered with dolutegravir (Day 28). | Day 21 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 hours postdose. Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 3: Time to Maximum Plasma Concentration (Tmax) of S-648414 | The effect of dolutegravir on the pharmacokinetics (PK) of S-648414 was assessed after administration of multiple oral doses of S-648414 alone (Day 21) and after administration of multiple oral doses of S-648414 co-administered with dolutegravir (Day 28). | Day 21 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 hours postdose. Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 3: Plasma Concentration of S-648414 at the End of the Dosing Interval τ (Cτ) | The effect of dolutegravir on the pharmacokinetics (PK) of S-648414 was assessed after administration of multiple oral doses of S-648414 alone (Day 21) and after administration of multiple oral doses of S-648414 co-administered with dolutegravir (Day 28). | Day 22 and Day 29 (24 hours post-dosing on Days 21 and 28) | 
| Part 3: Area Under the Concentration-time Curve Over the Dosing Interval τ (AUC0-τ) for S-648414 | The effect of dolutegravir on the pharmacokinetics (PK) of S-648414 was assessed after administration of multiple oral doses of S-648414 alone (Day 21) and after administration of multiple oral doses of S-648414 co-administered with dolutegravir (Day 28). Area under the concentration-time curve over the dosing interval τ (24 hours) was calculated by the linear up/log down trapezoidal method. | Day 21 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 hours postdose. Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 3: Apparent Total Clearance (CL/F) of S-648414 | The effect of dolutegravir on the pharmacokinetics (PK) of S-648414 was assessed after administration of multiple oral doses of S-648414 alone (Day 21) and after administration of multiple oral doses of S-648414 co-administered with dolutegravir (Day 28). Apparent total clearance was calculated as CL/F = Dose/AUC0-τ | Day 21 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8 and 12 hours postdose. Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 3: Maximum Plasma Concentration (Cmax) of Dolutegravir | The effect of S-648414 on the PK of dolutegravir was assessed after administration of multiple oral doses of dolutegravir alone and after administration of multiple oral doses of S-648414 co-administered with dolutegravir. | Day 7 and Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12 and 24 hours postdose. | 
| Part 3: Time to Maximum Plasma Concentration (Tmax) of Dolutegravir | The effect of S-648414 on the PK of dolutegravir was assessed after administration of multiple oral doses of dolutegravir alone and after administration of multiple oral doses of S-648414 co-administered with dolutegravir. | Day 7 and Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12 and 24 hours postdose. | 
| Part 3: Plasma Concentration of Dolutegravir at the End of the Dosing Interval τ (Cτ) | The effect of S-648414 on the PK of dolutegravir was assessed after administration of multiple oral doses of dolutegravir alone and after administration of multiple oral doses of S-648414 co-administered with dolutegravir. | Day 8 and Day 29 (24 hours post-dosing on Day 7 and Day 28). | 
| Part 3: Area Under the Concentration-time Curve Over the Dosing Interval τ (AUC0-τ) for Dolutegravir | The effect of S-648414 on the PK of dolutegravir was assessed after administration of multiple oral doses of dolutegravir alone and after administration of multiple oral doses of S-648414 co-administered with dolutegravir. Area under the concentration-time curve over the dosing interval τ (24 hours) was calculated by the linear up/log down trapezoidal method. | Day 7 and Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12 and 24 hours postdose. | 
| Part 3: Apparent Total Clearance (CL/F) of Dolutegravir | The effect of S-648414 on the PK of dolutegravir was assessed after administration of multiple oral doses of dolutegravir alone and after administration of multiple oral doses of S-648414 co-administered with dolutegravir. Apparent total clearance calculated as CL/F =Dose/AUC0-τ | Day 7 and Day 28 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12 and 24 hours postdose. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Part 1: Maximum Plasma Concentration (Cmax) of S-648414 |  | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Time to Maximum Plasma Concentration (Tmax) of S-648414 |  | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Area Under the Concentration-time Curve From Time Zero to the Last Quantifiable Concentration After Dosing (AUC0-last) of S-648414 | Area under the concentration-time curve from time zero to the time of the last quantifiable concentration after dosing, calculated by the linear trapezoidal method when concentrations are increasing and by the logarithmic trapezoidal method when concentrations are decreasing (linear up/log down trapezoidal method). | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Area Under the Concentration-time Curve From Time Zero to Infinity (AUC0-inf) of S-648414 | Area under the concentration-time curve extrapolated from time zero to infinity defined as AUC0-last + (Clast/λz), where Clast is the last measurable plasma concentration and λz is the plasma terminal elimination rate constant. | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Terminal Elimination Half-life (t1/2,z) of S-648414 | Terminal elimination half-life calculated as t1/2,z = (ln2)/λz, where λz is the terminal elimination rate constant. | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Terminal Elimination Rate Constant (λz) of S-648414 |  | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Mean Residence Time (MRT) of S-648414 | Mean residence time, calculated as MRT = AUMC0-inf / AUC0-inf, where AUMC0-inf is the area under the first moment curve extrapolated to infinity. | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Apparent Total Clearance (CL/F) of S-648414 | Apparent total clearance estimated according to: CL/F = Dose / AUC0-inf. | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Apparent Volume of Distribution in the Terminal Elimination Phase (Vz/F) of S-648414 | Apparent volume of distribution in the terminal elimination phase was estimated according to: Vz /F = Dose / AUC0-inf / λz. | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose, 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72 and 96 hours postdose. | 
| Part 1: Fraction of S-648414 Dose Excreted in Urine From 0 to 96 Hours Postdose (Feu0-96) | The fraction of S-648414 dose excreted in urine from 0 to 96 hours postdose was calculated as: Cumulative amount of S-648414 excreted in urine from time zero to 96 hours postdose (Aeu0-96) / Dose × 100 | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose (-12 to 0 hours), 0 to 24 hours, 24 to 48 hours, 48 to 72 hours, and 72 to 96 hours postdose | 
| Part 1: Renal Clearance (CLR) of S-648414 | Renal clearance was estimated according to: CLR = cumulative amount of S-648414 excreted in urine from time zero to 96 hours postdose (Aeu0-96) / area under the concentration-time curve from time zero to the time of the last quantifiable concentration after dosing (AUC0-last). | Day 1 and Day 14 (for participants in the 100 mg dose group only) predose (-12 to 0 hours), 0 to 24 hours, 24 to 48 hours, 48 to 72 hours, and 72 to 96 hours postdose | 
| Part 2: Maximum Plasma Concentration (Cmax) of S-648414 Following Single and Multiple-dose Administration |  | Day 1 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose; Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72, and 96 hours postdose. | 
| Part 2: Time to Maximum Plasma Concentration (Tmax) of S-648414 Following Single and Multiple-dose Administration |  | Day 1 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose; Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72, and 96 hours postdose. | 
| Part 2: Area Under the Concentration-time Curve Over the Dosing Interval τ (AUC0-τ) of S-648414 Following Single and Multiple-dose Administration | Area under the concentration-time curve over the dosing interval (24 hours) on Day 1 and Day 14, calculated by the linear up/log down trapezoidal method. | Day 1 and day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Terminal Elimination Half-life (t1/2,z) of S-648414 Following Multiple-dose Administration | Terminal elimination half-life, where t1/2,z = (ln2)/λz on Day 14. | Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72, and 96 hours postdose. | 
| Part 2: Terminal Elimination Rate Constant (λz) of S-648414 Following Multiple-dose Administration | Terminal elimination rate constant, where λz is the magnitude of the slope of the linear regression of the log concentration versus time profile during the terminal phase on Day 14. | Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72, and 96 hours postdose. | 
| Part 2: Apparent Total Clearance (CL/F) of S-648414 Following Multiple-dose Administration | Apparent total clearance estimated according to: CL/F = Dose/AUC0-τ on Day 14 | Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Apparent Volume of Distribution in the Terminal Elimination Phase (Vz/F) of S-648414 Following Multiple-dose Administration | Apparent volume of distribution in the terminal elimination phase on Day 14, estimated according to: Vz /F = Dose/AUC0-τ/λz | Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, 24, 48, 72, and 96 hours postdose. | 
| Part 2: Fraction of S-648414 Dose Excreted in Urine Over the Dosing Interval (Feu0- τ) Following Multiple-dose Administration | Fraction of dose excreted in urine over the dosing interval τ (24 hours) on Day 14 calculated as Aeu0-τ/Dose × 100, where Aeu0-τ is the amount of drug excreted in urine over the dosing interval τ (24 hours). | Day 14 0-24 hours postdose | 
| Part 2: Renal Clearance (CLR) of S-648414 Following Multiple-dose Administration | Renal clearance on Day 14, calculated as CLR = Aeu0-τ/AUC0-τ, where Aeu0-τ is the amount of drug excreted in urine over the dosing interval τ (24 hours) | Day 14 0-24 hours postdose | 
| Part 2: Maximum Plasma Concentration (Cmax) of Midazolam | The effect of S-648414 on the PK of midazolam (a cytochrome P450 3A [CYP3A] substrate) was assessed in Part 2 following 5 mg midazolam administration alone (Day -2) and co-administration with S-648414 30 or 50 mg (Day 14). | Day -2 and Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Time to Maximum Plasma Concentration of Midazolam | The effect of S-648414 on the PK of midazolam (a cytochrome P450 3A [CYP3A] substrate) was assessed in Part 2 following 5 mg midazolam administration alone (Day -2) and co-administration with S-648414 30 or 50 mg (Day 14). | Day -2 and Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Area Under the Concentration-time Curve From Time Zero to the Last Quantifiable Concentration After Dosing (AUC0-last) for Midazolam | The effect of S-648414 on the PK of midazolam (a cytochrome P450 3A [CYP3A] substrate) was assessed in Part 2 following 5 mg midazolam administration alone (Day -2) and co-administration with S-648414 30 or 50 mg (Day 14). Area under the concentration-time curve from time zero to the time of the last quantifiable concentration after dosing, calculated by linear up/log down trapezoidal method. | Day -2 and Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Area Under the Concentration-time Curve From Time Zero to Infinity (AUC0-inf) of Midazolam | The effect of S-648414 on the PK of midazolam (a cytochrome P450 3A [CYP3A] substrate) was assessed in Part 2 following 5 mg midazolam administration alone (Day -2) and co-administration with S-648414 30 or 50 mg (Day 14). Area under the concentration-time curve extrapolated from time zero to infinity defined as AUC0-last + (Clast/λz), where Clast is the last measurable plasma concentration and λz is the plasma terminal elimination rate constant. | Day -2 and Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Terminal Elimination Half-life for Midazolam | The effect of S-648414 on the PK of midazolam (a cytochrome P450 3A [CYP3A] substrate) was assessed in Part 2 following 5 mg midazolam administration alone (Day -2) and co-administration with S-648414 30 or 50 mg (Day 14). | Day -2 and Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Terminal Elimination Rate Constant for Midazolam | The effect of S-648414 on the PK of midazolam (a cytochrome P450 3A [CYP3A] substrate) was assessed in Part 2 following 5 mg midazolam administration alone (Day -2) and co-administration with S-648414 30 or 50 mg (Day 14). | Day -2 and Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 2: Mean Residence Time for Midazolam | The effect of S-648414 on the PK of midazolam (a cytochrome P450 3A [CYP3A] substrate) was assessed in Part 2 following 5 mg midazolam administration alone (Day -2) and co-administration with S-648414 30 or 50 mg (Day 14). Mean residence time was calculated as MRT = AUMC0-inf/AUC0-inf where AUMC0-inf is the area under the first moment curve extrapolated to infinity. | Day -2 and Day 14 predose (0 hours), 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Change From Baseline in Fridericia's Corrected QT Interval (QTcF) | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. The QT interval is a measure between Q and T wave in heart's electrical cycle. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median QT in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. QT interval was corrected for heart rate using Fridericia's correction (QTcF). Baseline was defined as the average of the measured ECG intervals from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline (ΔQTcF) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline QTcF as covariate. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Parts 1: Change From Baseline in Heart Rate (HR) | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median HR in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. Baseline was defined as the average of the measured ECG values from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline in HR (ΔHR) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline HR as covariate. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Change From Baseline in PR Interval | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. The PR interval is the time from the onset of the P-wave to the start of the next QRS complex. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median PR in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. Baseline was defined as the average of the measured ECG intervals from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline in PR interval (ΔPR) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline PR as covariate. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Change From Baseline in QRS Interval | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. The QRS complex is a combination of the Q wave, R wave and S wave on an ECG tracing, and represents ventricular depolarization. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median QRS in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. Baseline was defined as the average of the measured ECG intervals from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline in QRS interval (ΔQRS) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline QRS as covariate. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Placebo-corrected Change From Baseline in Fridericia's Corrected QT Interval | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median QT in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. QT interval was corrected for heart rate using Fridericia's correction (QTcF). Baseline was defined as the average of the measured ECG intervals from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline (ΔQTcF) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline QTcF as covariate. Placebo-corrected ΔQTcF (ΔΔQTcF) was calculated as the adjusted mean ΔQTcF in the S-648414 group minus adjusted mean ΔQTcF in the placebo group at each time point. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Placebo-corrected Change From Baseline in Heart Rate | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median HR in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. Baseline was defined as the average of the measured values from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline (ΔHR) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline HR as covariate. Placebo-corrected ΔHR (ΔΔHR) was calculated as the adjusted mean ΔHR in the S-648414 group minus adjusted mean ΔHR in the placebo group at each time point. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Placebo-corrected Change From Baseline in PR Interval | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median PR interval in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. Baseline was defined as the average of the measured ECG intervals from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline (ΔPR) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline PR as covariate. Placebo-corrected ΔPR (ΔΔPR) was calculated as the adjusted mean ΔPR in the S-648414 group minus adjusted mean ΔPR in the placebo group at each time point. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Placebo-corrected Change From Baseline in QRS Duration | Continuous 12-lead digital electrocardiogram (ECG) recording was performed on Day 1. ECGs were analyzed at a blinded, central ECG laboratory. At each specified time point, ten 14-second 12-lead ECG tracings were extracted from the continuous recordings. The median QRS duration in each replicate was calculated; the mean of available medians was used as the participant's reportable value at that time point. Baseline was defined as the average of the measured ECG intervals from the 3 pre-dose time points (45, 30, and 15 minutes before dosing) on Day 1. Change from Baseline in QRS duration (ΔQRS) was calculated based on a linear mixed-effects model with time (categorical), treatment, and time-by-treatment interaction as fixed effects and Baseline QRS as covariate. Placebo-corrected ΔQRS (ΔΔQRS) was calculated as the adjusted mean ΔQRS in the S-648414 group minus adjusted mean ΔQRS in the placebo group at each time point. | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Number of Participants With Recorded Outlier Values for QTcF, HR, PR, and QRS | A participant was determined as an outlier if the following criteria (assessed separately) were met for the ECG intervals at any time point: QTcF: Treatment-emergent value of > 450 and ≤ 480 ms when not present at Baseline (new onset) Treatment-emergent value of > 480 and ≤ 500 ms when not present at Baseline (new onset) Treatment-emergent value of > 500 ms when not present at Baseline (new onset) Increase of QTcF (ΔQTcF) from Baseline of > 30 and ≤ 60 ms Increase of QTcF from Baseline > 60 ms HR: Decrease of HR from Baseline > 25% resulting in HR < 50 bpm Increase of HR from Baseline > 25% resulting in HR > 100 bpm PR: Increase of PR from Baseline > 25% resulting in PR > 200 ms QRS: Increase of QRS from Baseline > 25% resulting in QRS > 120 ms | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 
| Part 1: Number of Participants With Treatment-emergent Changes for T-wave Morphology and U-wave Presence | T-wave abnormalities were categorized as follows: Normal T wave: Any positive T wave not meeting any criterion below Flat T wave: T amplitude < 1 mm (either positive or negative) including flat isoelectric line Notched T wave (+): Presence of notch(es) of at least 0.05 mV amplitude on ascending or descending arm of the positive T wave Biphasic: T wave that contains a second component with an opposite phase that is at least 0.1 mV deep (both positive/negative and negative/positive and polyphasic T waves included) Normal T wave (-): T amplitude that is negative, without biphasic T wave or notches Notched T wave (-): Presence of notch(es) of at least 0.05 mV amplitude on descending or ascending arm of the negative T wave U waves: Presence of abnormal U waves | Day 1: Predose at 3 time points (-45, -30 and -15 minutes), and 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 12, and 24 hours postdose. | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Antiretroviral, Pharmacokinetics, S-648414, Food effect, Drug-drug interaction