IMPT Versus IMRT for Diffuse Intrinsic Pontine Glioma

• Written informed consent must be obtained before initiation of any study-related procedures.
• Male or female participants aged ≥3 years and ≤18 years.
• Histologically confirmed grade IV diffuse midline glioma by biopsy.
• Eastern Cooperative Oncology Group (ECOG) performance status of 0-2.
• No prior systemic anticancer therapy for the current locally advanced disease.

• Adequate organ function, meeting all of the following criteria:

  1. Absolute neutrophil count (ANC) ≥1.5 × 10\^9/L;
  2. Platelet count ≥75 × 10\^9/L;
  3. Hemoglobin ≥9 g/dL (90 g/L) or ≥5.6 mmol/L;
  4. Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) ≤2.5 × upper limit of normal (ULN);
  5. Serum creatinine ≤1.5 × ULN and creatinine clearance ≥60 mL/min. For participants \<18 years of age, the Schwartz formula is recommended for estimation of creatinine clearance;
  6. Adequate coagulation function; isolated laboratory abnormalities may be considered acceptable if judged by the investigator to be not clinically significant;
  7. Cardiac enzyme profile abnormalities may be considered acceptable if judged by the investigator to be not clinically significant;
  8. No severe symptoms of increased intracranial pressure, such as persistent vomiting or disturbance of consciousness, or such symptoms must be stable after dehydration therapy.

Exclusion Criteria:

• Previous cranial radiotherapy.
• Estimated life expectancy of less than 3 months.
• Presence of other central nervous system tumors, such as metastatic tumors, or other malignancies, except for curatively resected basal cell carcinoma of the skin or papillary thyroid carcinoma.
• Current participation in another interventional clinical study.
• Contraindications to radiotherapy.
• Untreated active hepatitis B virus (HBV) infection, defined as hepatitis B surface antigen (HBsAg) positivity with an HBV-DNA level above the upper limit of normal of the laboratory at the participating study center.

Participants with hepatitis B may nevertheless be eligible under either of the following conditions:

1. HBV viral load \<1,000 copies/mL (200 IU/mL) before the first study treatment; anti-HBV therapy should be administered throughout the study treatment period to prevent HBV reactivation;

2. Participants who are anti-HBc positive, HBsAg negative, anti-HBs negative, and have an undetectable HBV viral load do not require prophylactic anti-HBV therapy but must be closely monitored for HBV reactivation.

   • Active hepatitis C virus (HCV) infection, defined as HCV antibody positivity with an HCV-RNA level above the lower limit of detection.
   • Any severe or uncontrolled systemic disease, including:

(1) Clinically significant and uncontrolled abnormalities in cardiac rhythm, conduction, or morphology on resting electrocardiogram, such as complete left bundle branch block, second-degree or higher atrioventricular block, ventricular arrhythmia, or atrial fibrillation; (2) History of noninfectious pneumonitis requiring corticosteroid treatment within 1 year before the first study treatment, or current clinically active interstitial lung disease; (3) Active tuberculosis.

• Any medical history, evidence of disease, treatment, or laboratory abnormality that may interfere with the study results or prevent the participant from fully participating in the study, or any other condition that, in the investigator's judgment, makes the participant unsuitable for enrollment because of potential risks.