Effectiveness of Pucotenlimab Combined With Standard Chemotherapy Regimen

Inclusion Criteria:

1. Age: 1-18 years old;

2. ECOG PS score: 0-1 points;

3. Pathologically confirmed newly diagnosed children or adolescents with intermediateto high-risk rhabdomyosarcoma;

4. Patients evaluated by surgery as having a high degree of difficulty;

5. Must have at least one measurable lesion defined by RECIST or WHO criteria;

6. Expected survival time ≥ 6 months;

7. Cardiac function:

8. Echocardiography shows LVEF ≥ 50%;

9. EKG indicates no evidence of myocardial ischemia;

10. No history of arrhythmia requiring pharmacological intervention beforeenrollment;

11. No history of severe immune-related adverse events (CTCAE V4.03 G3 or G4);

12. For patients with known non-involvement of the bone marrow (BM):

13. Absolute neutrophil count (ANC) ≥ 1.0 × 109/L;

14. Platelet count ≥ 100.0 × 109/L;

15. Hemoglobin ≥ 90 g/L;

16. Liver and kidney functions need to meet the following criteria:

17. Total bilirubin (conjugated + unconjugated) ≤ 2.5 × upper limit of normal (ULN)corresponding to age, patients with confirmed Gilbert's syndrome may beenrolled based on the investigator's discretion;

18. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤ 2.5 ×ULN;

19. Estimated glomerular filtration rate ≥ 30 mL/min/1.73 m2 or serum creatinine (Cr) ≤ 1.5 × ULN;

20. Able to comply with outpatient treatment, laboratory monitoring, and necessaryclinical visits during the study;

21. The parents/guardians of the child or adolescent participants have the ability tounderstand, consent to, and sign the informed consent form (ICF) and applicablechild consent forms before initiating any protocol-related procedures; theparticipants have the ability to express their consent (if applicable) with theconsent of their parents/guardians.

Exclusion Criteria:

1. Received anti-PD-1 or anti-PD-L1 monoclonal antibodies or targeted drugs related tothese pathways;

2. Received chemotherapy, radiotherapy, or other treatments;

3. Previous surgical treatment (excluding biopsy);

4. Known allergy to PD-1 monoclonal antibodies or any of their excipients; knownhistory of allergic diseases or severe allergies;

5. Having other malignant tumor diseases besides the tumor being treated in this study,excluding: malignant tumors that have been cured and have not recurred within 3years before enrollment, completely resected basal cell and squamous cell skincancers, completely resected carcinoma in situ of any type;

6. Active central nervous system metastases (whether treated or not), includingsymptomatic brain metastases, meningeal metastases, or spinal cord compression, etc.Excluding: asymptomatic brain metastases without progression within at least 4 weeksafter radiotherapy and/or without neurological symptoms or signs after surgicalresection, without the need for dexamethasone or mannitol treatment.

7. Uncontrolled pleural effusion, pericardial effusion, or ascites requiring repeateddrainage;

8. Previous treatment toxicity still > Grade 1 (CTCAE V4.03 criteria), excludingalopecia and neurotoxicity;

9. History of mental disorders;

10. History of drug abuse or substance abuse upon inquiry;

11. History of idiopathic pulmonary fibrosis or idiopathic pneumonitis;

12. Comorbidities requiring immunosuppressive drug treatment, or comorbidities requiringsystemic or local use of corticosteroids at immunosuppressive doses (prednisone > 10mg/day or equivalent doses of similar drugs).

13. History of autoimmune diseases, including but not limited to systemic lupuserythematosus, psoriasis, rheumatoid arthritis, inflammatory bowel disease,Hashimoto's thyroiditis, etc. Excluding: Type I diabetes, hypothyroidismcontrollable only through hormone replacement therapy, dermatological diseases thatdo not require systemic treatment (such as vitiligo, psoriasis), controlled celiacdisease, or diseases that are not expected to recur without external stimuli;

14. Previous or current active tuberculosis infection;

15. Active infections requiring systemic treatment;

16. Uncontrolled hypertension (systolic blood pressure ≥ 140 mmHg and/or diastolic bloodpressure ≥ 90 mmHg) or pulmonary hypertension or unstable angina pectoris;myocardial infarction or bypass surgery, stenting within 6 months beforeadministration; history of chronic heart failure satisfying New York HeartAssociation (NYHA) Class 3-4; clinically significant valvular heart disease; severearrhythmias requiring treatment (excluding atrial fibrillation, paroxysmalsupraventricular tachycardia), including QTc interval ≥ 450 ms for males and ≥ 470ms for females (calculated using the Fridericia formula); cerebrovascular accident (CVA) or transient ischemic attack (TIA) within 6 months before administration;

17. Concurrent severe medical conditions, including but not limited to: uncontrolleddiabetes, active peptic ulcer, active bleeding, etc.;

18. Positive Anti-HIV, TP-Ab, HCV-Ab; HBV-Ag positive with HBV DNA copy number > upperlimit of normal value of the testing unit;

19. Abnormal thyroid function test results (FT3, FT4, T3, T4);

20. Expected to receive live or attenuated vaccines within 4 weeks beforeadministration, during treatment, or within 5 months after the last dose;

21. Participated in another clinical trial and received experimental drug treatmentwithin 30 days before administration;