This study was divided into three parts: single and multiple dosing and food effect study, which were designed to evaluate the safety and tolerability of TQH3906 capsules administered in single or multiple dose escalation in healthy adult subjects.

Inclusion Criteria:

• Healthy subjects aged 18-55 years (including 18 and 55 years), regardless of gender.
• Males weighing ≥ 50 kg, females weighing ≥ 45 kg, with a body mass index (BMI) of 19-26 kg/m2 (included).
• Be in good health with no abnormalities of clinical significance according to medical history, clinical symptoms, vital signs, physical examination, 12-lead electrocardiogram, chest radiographs, abdominal ultrasound, and laboratory tests
• Have a full understanding of the study, participate in the trial voluntarily, and have signed a written informed consent form.
• Subjects (including partners) are willing to voluntarily use appropriate and effective contraception from screening until 3 months after the last dose of study drug.

Exclusion Criteria:

• Pregnant, lactating women.

• Previous history or current cardiac, endocrine, metabolic, renal, hepatic, gastrointestinal, dermatologic, infectious, hematologic, neurologic, or psychiatric disorders/abnormalities, or related chronic illnesses, or acute illnesses, which the investigator assesses as contraindicated for participation in the trial.

• Have a QTc > 450 ms in males and > 470 ms in females at screening, or whose Electrocardiograph (ECG) is unsuitable for Concentration QT (C-QT) measurement (at the discretion of the investigator).

• The presence of risk factors and history of tip-twist ventricular tachycardia including, but not limited to: unexplained syncope, long QT syndrome, heart failure, or clinically significant abnormal laboratory tests (including hypokalemia, hypercalcemia, or hypomagnesemia) identified at Screening.

• Presence of abnormal serum virology at screening;

  1. Active hepatitis, or hepatitis B surface antigen (HBsAg) positive, or Hepatitis C virus (HCV) antibody positive;
  2. Positive for Human immunodeficiency virus (HIV) antibody at the screening stage, or previous history of HIV infection;
  3. Positive antibodies to Treponema pallidum in screening.

• Presence of active tuberculosis during the Screening Period, or being a close household contact of a patient with untreated active tuberculosis, or having a positive tuberculosis interferon gamma release assay (TB-IGRA) by laboratory examination.

• A history of severe bacterial, fungal or viral infection requiring hospitalization for intravenous antibiotic or antiviral medication within 2 months prior to randomization.

• Live vaccination within 4 weeks prior to randomization or planning to receive a live vaccine during the study.

• The presence of clinically significant infections during the Screening Period, including but not limited to upper respiratory tract infections, lower respiratory tract infections, herpes simplex, herpes zoster, and requiring treatment with antibiotics or antiviral medications.

• A history of severe herpes zoster or herpes simplex infection including, but not limited to, herpes encephalitis, disseminated herpes simplex, and herpes zoster pandemic.

• Use of any systemic cytotoxic or systemic immunosuppressive drug within 6 months prior to randomization, or use of any topical cytotoxic or topical immunosuppressive drug within 4 weeks or 5 half-lives (whichever is longer) prior to randomization.

• Receipt of a biologic or other clinical trial drug within 3 months or 5 half-lives, whichever is longer, prior to randomization.

• Has undergone surgery within 4 weeks prior to randomization or is scheduled to undergo surgery during the study.

• Who has lost or donated more than 400 mL of blood within 4 weeks prior to randomization.

• Who have taken any prescription, over-the-counter, and herbal medications, except vitamin products, within 4 weeks prior to randomization.

• Persons with potential blood collection difficulties and a history of needle and blood sickness.

• Allergy to any of the known components of TQH3906 or any previous history of severe drug allergy.

• History of substance abuse or positive urine drug screen.

• Who have smoked more than 5 cigarettes/day or used an equivalent amount of nicotine or nicotine-containing products in the 3 months prior to randomization, or who are unable to discontinue the use of any tobacco-based products during the trial.

• Those who have chronic alcohol abuse or who have consumed more than 14 units of alcohol per week (1 unit = 360 mL of beer or 45 mL of spirits of 40% alcohol by volume or 150 mL of wine) in the 3 months prior to screening or who are unable to abstain from alcohol for the duration of the trial, or who have a positive breath test for alcohol.

• Have any other valid medical, psychiatric, or social reason that, in the opinion of the investigator, precludes participation in this study.