A Phase 1, Open-Label, Two-Stage, Food Effect Study to Assess the Safety, Tolerability, and Pharmacokinetics of EI-1071 Under Fasted or Fed Conditions in Healthy Volunteers

1. Male or non-lactating and non-pregnant female, aged 18 to 55 years old at the Screening Visit.

2. Body mass index (BMI) ranging from 18.0 to 30.0 kg/m2 and body weight ≥ 50 kilograms at the Screening Visit.

   Note: Participants who will participate in four periods in stage 1 (Dose Levels 1 and 2) must weigh greater than 60 kg at screening.

3. Able to speak, read, and understand the language of the ICF, the nature of the study, and any potential risk associated with the IP and willing to provide written informed consent, to communicate with the Investigator, and to comply with all study visits, procedures, requirements, and restrictions.
4. Mentally and physically healthy according to medical history, physical examination, vital signs, laboratory tests, and 12-lead ECG as determined by the Investigator.

5. Reproductive and Contraceptive Status Requirements

   • Female participants: Must not be pregnant, nor breastfeeding
   • Female participants with childbearing potential must have a negative result of serum pregnancy test at the Screening Visit; and must not plan to become pregnant during the study until 5 half-lives of EI-1071+ 30 days after the last administration of EI-1071

   • - A female is considered to be of childbearing potential unless she:

     • has had a hysterectomy, bilateral salpingectomy, or bilateral oophorectomy documented in medical history
     • has been amenorrhoeic for consecutive ≥ 12 months (including no irregular menses or spotting) in the absence of any medication which induces a menopausal state and has documented ovarian insufficiency by follicle stimulating hormone [FSH] levels within the institutional laboratory postmenopausal range).
   • Female participants with childbearing potential and male participants with reproductive potential must agree to refrain from unprotected sex and use two methods of medically acceptable contraception (e.g., barrier contraceptives [male condom, female condom, or diaphragm plus spermicide], non-hormonal intrauterine device [IUD]) or abstain from sexual intercourse from the Screening Visit until 5 half-lives of EI-1071 + 30 days after the last dose of EI-1071 for female participants, and until 5 half-lives of EI-1071 + 90 days after the last dose of EI-1071 for male participants.
6. Male participants must agree to refrain from sperm donation, and female participants must agree to refrain from ova donation from Study Day -1 until 5 half-lives of EI-1071 + 90 days after the last dose of the IP.

Note: For participants who consent to CBSF sampling in Stage 2, the absence of tumor, hemorrhage (including asymptomatic), or any clinically significant findings have to be evaluated and confirmed by the Investigator based on the brain CT scan prior to CBSF sampling.

Exclusion Criteria:

1. History of allergy or hypersensitivity or clinically significant idiosyncratic reaction to EI-1071 or any component of this formulation (e.g., hydroxypropyl methylcellulose acetate succinate).
2. Current or historical evidence of any clinically significant gastrointestinal, cardiovascular, hepatic, renal, hematological, endocrine, neurological, immunodeficiency, pulmonary, or other disorder, disease, or condition, that in the opinion of the Investigator, may increase the risk of IP or affect drug absorption, distribution, metabolism, or excretion.
3. History of neoplastic or malignant disease (except for localized skin cancer without metastases).
4. Known history of gastrointestinal surgery unless determined as non-clinically significant by the Investigator. Participants with a history of appendectomy or hemorrhoidectomy may be included at the discretion of the Investigator.
5. A clinically significant vital signs abnormality, as judged by the Investigator. This includes, but is not limited to, the following (values obtained in the supine position with rest for at least 5 minutes before blood pressure assessment): systolic blood pressure \< 90 or > 150 mmHg, diastolic blood pressure \< 50 or > 95 mmHg, or heart rate \< 45 or > 100 beats per minute. One repeat measurement is allowed for eligibility purposes at the Screening Visit and on Day -1.
6. Significantly abnormal 12-lead ECG or QT prolongation (e.g., QTcF > 450 ms) at the Screening Visit, deemed unsuitable for participation in the trial as judged by the Investigator.
7. Positive for human immunodeficiency virus (HIV) antibody, hepatitis B surface antigen (HBsAg), or hepatitis C virus (HCV) antibody as defined by serology tests at the Screening Visit.
8. Positive for amphetamine (AMP), cocaine (COC), opiates (morphine), and cannabinoid (THC) as defined by urine tests at the Screening Visit or Check-in Visit.
9. Positive serum alcohol test result, defined as a result above the laboratory-defined lower limit of quantification (or detection) at Screening Visit or Check-in Visit.
10. Onset of influenza-like symptoms as defined by: fever (temperature ≥ 38℃), dry cough, headache, fatigue, respiratory sputum production, dysgeusia, anosmia, shortness of breath, muscle and joint pain, or sore throat within 1 week prior to the Screening Visit.
11. Receipt of vaccination within 30 days prior to the first administration of the IPs or plan to receive vaccination during the study.
12. Use of any prescription or over-the-counter (OTC) medication, including oral contraceptives, oral multivitamins, herbal and/or dietary supplements within 30 days prior to the first administration of the IP (except topical agents without systemic absorption, as determined by the Investigator).
13. Administration of any investigational drug other than EI-1071 within 30 days or 5 elimination half-lives of such investigational drug, whichever is longer, prior to the first administration of the IP; or planned administration of another investigational drug or procedure during the study.
14. Consumption of products containing caffeine/methylxanthines, poppy seeds, and/or alcohol within 48 hours before the first administration of the IPs and products containing grapefruit and/or pomelo (shown to inhibit cytochrome P450 [CYP] 3A4 activity) or St John's wort (Hypericum perforatum; shown to induce CYP3A4 activity) within 14 days prior to the first administration of the IP.
15. Receipt of any blood, plasma, or platelet transfusions within 3 months prior to the first administration of the IP.
16. Blood donation or blood loss of more than 250 mL within 3 months prior to the first administration of the IP.
17. Use of any tobacco- or nicotine-containing products within 3 months prior to the first administration of the IP or during the study.
18. History of regular alcohol consumption within 3 months of Day 1, defined as an average intake of > 15 alcoholic drinks per week in males and > 8 alcoholic drinks per week in females. One drink (14 g alcohol) is equivalent to 150 mL of wine, 360 mL of beer, or 45 mL of 80 proof distilled spirits. Participants who have consumed any alcohol products within 48 hours prior to the first administration of the IP will not be enrolled in the study.
19. History of addiction to or abuse of illicit drug(s), prescription medicine(s), or alcohol within the past 2 years prior to the Screening Visit.
20. Participant who is considered unfit to participate in the clinical study based on the judgment of the Investigator.