Phase Ib Study of Efsubaglutide Alfa Injection in Obese Adolescents

Inclusion criteria

• 1\. Informed consent must be obtained from the participant's parent or legally authorized representative and assent from the adolescent participant before any study-related procedures.
• 2\. Adolescent participants aged ≥12 years and \<18 years (at the time of informed consent).
• 3\. At screening, meet the obesity criteria defined in "WS/T586-2018 Screening for Overweight and Obesity among School-age Children and Adolescents".
• 4\. Before screening, have been on dietary and exercise control alone for at least 3 months with \<5.0% reduction in body mass index (based on self-report or report by parent or legally authorized representative).
• 5.Must be willing to follow the diet and exercise guidance and able to maintain such stable diet and exercise lifestyle during the study period.
• 6\. Female participants of childbearing potential must have a negative serum pregnancy test at screening.
• 7\. Able to understand all study procedures, willing to strictly comply with the study protocol, complete the study visits as scheduled, and finish the study.

Exclusion criteria

• 1\. Pre-pubertal participants (Tanner Stage I).
• 2\. History of severe allergic reactions or suspected allergy to study drug or its ingredients.
• 3\. Pregnant or lactating women; men or women of childbearing potential planning pregnancy or unwilling to use highly effective contraception throughout the study.
• 4\. Use of weight-affecting medications before screening.
• 5\. Known monogenic obesity, obesity caused by other diseases or medications,
• 6\. Previously diagnosed Type 1 diabetes, Type 2 diabetes, or special types of diabetes;
• 7\. history of severe hypoglycemia or recurrent symptomatic hypoglycemia (≥2 times within half a year).
• 8\. Clinically significant gastric emptying abnormalities, severe chronic gastrointestinal diseases, long-term use of medications directly affecting gastrointestinal motility, or gastrointestinal surgery within 6 months prior to screening, deemed unsuitable for the study by the investigator.
• 9\. History of malignancy within 5 years prior to screening, excluding clinically cured cervical intraepithelial neoplasia, squamous cell carcinoma, or basal cell carcinoma within 5 years.
• 10\. Major surgery within 6 months prior to screening, or planned surgery during the study that may affect study completion or compliance;
• 11\. history of bariatric surgery or planned bariatric surgery during the study (e.g., gastric bypass, gastric banding).
• 12\. History of acute or chronic pancreatitis, symptomatic gallbladder disease at screening, history of pancreatic injury, or other high-risk factors for pancreatitis; or amylase or lipase \>2.0×ULN at screening.
• 13\. Known or suspected drug/substance abuse at screening; positive HBsAg;
• 14\. Positive HCV antibody with HCV RNA above the lower limit of detection; positive HIV antibody; positive Tp-Ab.
• 15\. Currently receiving or received chronic (\>14 days) systemic glucocorticoid therapy within 3 months prior to screening, or evidence of severe active autoimmune disease that may require systemic glucocorticoid therapy within the next 12 months as judged by the investigator.
• 16\. History of hyperthyroidism or hypothyroidism, or TSH \<1.0×LLN, or TSH \>1.5×ULN, or history of medullary thyroid carcinoma.
• 17\. Serum calcitonin ≥50 ng/L (pg/mL) at screening; ALT \>3.0×ULN, or AST \>3.0×ULN, or total bilirubin \>2.0×ULN; eGFR \<60 mL/min/1.73 m² at screening; fasting triglycerides ≥5.64 mmol/L (500 mg/dL).
• 18\. Blood donation and/or blood loss ≥400 mL or bone marrow donation within 3 months prior to screening, or presence of hemoglobinopathy, hemolytic anemia, sickle cell anemia, or hemoglobin \<118 g/L (ages 12-\<13 years), \<129 g/L (males ≥13 years), or \<114 g/L (females ≥13 years).
• 19\. Participation in vaccine or medical device clinical trials within 3 months prior to screening, or any drug clinical trial within less than 3 months or 5 half-lives (whichever is longer).
• 20\. History of moderate to severe depression, anxiety disorder, or severe psychiatric illness.
• 21\. Any other condition that, in the opinion of the investigator, may affect the participant's safety or compliance with the study protocol.