This is a randomized, double-blind, placebo-controlled, multiple ascending-dose study to evaluate the safety, tolerability and pharmacokinetics characteristics of VV261 tablets in healthy adults.

This study is a randomized, double-blind, placebo-controlled trial designed to enroll a total of 16 participants. It initially comprises two dose groups administered sequentially from the low-dose group to the high-dose group, with eight participants in each group randomly assigned to either the investigational drug or placebo. The dose escalation levels were set at 600 mg and 900 mg, administered three times daily (with an 8-hour interval) for 7.5 consecutive days, followed by a final dose on the morning of day 8, totaling 22 doses.

Inclusion Criteria:

1. Aged 18 to 45 years old, males or females;
2. Males weight no less than 50 kg, females weight no less than 45 kg, with body mass index of 19 to 26 kg/m^2;
3. Vital signs examination, physical examination, laboratory examination ,electrocardiogram examination chest CT and B-ultrasound of liver, gallbladder, pancreas, spleen, kidney and thyroid results are normal or considered abnormal without clinical significance by the investigator;
4. Participants who are willing to take proper contraceptive methods during the study and within 3 months after the the last administration;
5. Participants who are able to understand and follow the study protocol and instructions; participants who have voluntarily decided to participate in this study, and sign the informed consent form.

Exclusion Criteria:

1. Participants with hypersensitivity to preparation or any of the excipients;
2. Participants with allergic constitution (such as asthma, urticaria, eczematous dermatitis and other allergic diseases), or have a history of drug or food allergy;
3. Participants with central nervous system, cardiovascular system, gastrointestinal, respiratory system, urinary, hematologic, or metabolic disorders that require medical intervention or other diseases (such as psychiatric history) that are not suitable for clinical trials;participants with a history of gastrointestinal conditions that may impair drug absorption (e.g., gastrectomy or small intestine resection, atrophic gastritis, gastrointestinal ulcers or perforations/fistulas, gastrointestinal bleeding, or obstruction);participants with previous surgery that may significantly affect the body's metabolic process or safety evaluation of the study drug (such as liver, gallbladder, kidney, splenectomy, gastrointestinal resection or excessive blood loss that affects drug absorption, distribution, metabolism)
4. Participants with a history of diseases affecting bone marrow hematopoietic function or reducing immunological function (including leukemia, myelodysplastic syndrome, aplastic anemia, systemic lupus erythematosus, rheumatoid arthritis, etc.) or treatment history (tumor chemotherapy or radiotherapy, use of immunosuppressants, etc.);
5. Participants with a history of spleen diseases;
6. If any of the following parameters were considered abnormal with clinical significance: white blood cell count, red blood cell count, platelet count, reticulocyte count, and absolute neutrophil count;
7. If any of the following parameters were considered abnormal with clinical significance: total bilirubin, alkaline phosphatase, alanine aminotransferase, and aspartate aminotransferase;
8. Participants who have received blood transfusion or used blood products within 3 months before screening or who have lost more than ≥400 mL of blood due to other reasons (excluding menstruation);
9. Participants who have participated in clinical trials and received drugs within 3 months before screening;
10. Participants who have taken any prescription drugs, over-the-counter drugs, Chinese herbal medicines or health products within 2 weeks before screening;
11. Participants who have received vaccination within the first 2 weeks before screening, or planned to receive any vaccine during the trial or within 1 week after the end of the study;
12. Participants with a history of drug abuse within 1 year before screening or positive urine drug screening within 1 year before screening results (morphine, tetrahydrocannabinol, methamphetamine, dimethylene diphenazine , ketamine, and cocaine);
13. Participants who drink more than 14 standard units or at least twice a day per week within one year before screening,(one standard unit equals 200 mL of beer with 5% alcohol or 25 mL of white wine with 40% alcohol content or 85 mL of red wine with 12% alcohol) or participants with breath alcohol test >0 mg/100 mL;
14. Participants who smok more than 5 cigarettes a day within one year before screening;
15. Participants who can't quit smoking or drinking during the trial period;
16. Participants who are positive for hepatitis B virus surface antigen, hepatitis C virus antibody, treponema pallidum antibody or human immunodeficiency virus antibody (Anti-HIV);
17. Participants who cannot tolerate blood collection with intravenous indwelling needles or blood fainting;
18. Participants with lactose intolerance or cannot comply with a uniform diet (such as special dietary requirements, intolerance of standard meals, etc.), Participants who have consumed excessive amounts of strong tea, coffee or caffeinated beverages in the 3 months before screening;
19. Participants with difficulty in swallowing tablets;
20. Pregnant or lactating women; participants whose spouses or partners intend to become pregnant, plan sperm or oocyte donation within 3 months after the last dose, or decline to use acceptable effective contraception；
21. The investigator believes that there are other unsuitable factors to participate this trial.