Clinical Research Directory

Inclusion Criteria: 1. Diagnosis and Grouping Criteria for LCH: Pathological confirmation of LCH via lesion biopsy, with positive immunohistochemistry for CD1a and/or CD207 (Langerin). Diagnostic and grouping criteria adhere to the 2009 standards established by the International Organization Cell Association and the CCHG-LCH-2019 research protocol by the Chinese Children's Histiocyte Group (CCHG). Disease assessment and treatment efficacy are evaluated based on the criteria set by the Society of Tissue and Cell Biology and the CCHG-LCH-2019 protocol. Treatment efficacy is categorized as: (1) No Active Disease (NAD); (2) Active Disease Better (AD-B); (3) Active Disease Stable (AD-S); (4) Active Disease Intermedia (AD-I); (5) Active Disease Worse (AD-W); (6) Relapse: Recurrence of new lesions after achieving NAD, AD-B, or AD-S, following maintenance treatment for over 3 months; (7) Refractory Disease: For SS-LCH patients, if the evaluation after first-line treatment results in AD-I or AD-W, and second-line treatment with cladribine or clofarabine still yields AD-I or AD-W; or MS-LCH patients with AD-I or AD-W after first-line treatment. Treatment responses are classified into three categories: favorable response (NAD and AD-B), moderate response (AD-I and AD-S), and adverse response (disease progression or relapse). The overall response rate (ORR) is defined as the percentage of patients achieving a favorable response (NAD or AD-B) at the evaluation time point among all enrolled patients. 2. Refractory or Recurrent LCH Criteria: Cases must meet at least one of the criteria for refractory or recurrent LCH. 3. Age Criteria: Initially, patients aged 6-17 years were included; subsequently, the age range was expanded to 1-17 years. 4. Informed Consent: All patients or their legal guardians must provide signed informed consent. 5. Performance Status: ECOG Performance Status (PS) score of 0-1; alternatively, a Karnofsky/Lansky Performance Status Scale score ≥ 50%. 6. Expected Survival: Minimum expected survival time of ≥ 6 months. 7. Organ Function Requirements: 1. Cardiac Function: Left ventricular ejection fraction ≥ 50% on echocardiography, with no significant abnormalities on electrocardiogram. 2. Renal Function: Serum creatinine ≤ 2.0 × ULN. 3. Hepatic Function: ALT and AST ≤ 5.0 × ULN; total bilirubin ≤ 2.5 × ULN (≤ 3.0 × ULN for Gilbert syndrome). For patients with histiocytosis-related liver disease, abnormal bilirubin, AST, ALT, and albumin levels are permissible. 4. Bone Marrow Function: Absolute neutrophil count (ANC) ≥ 1.0 × 10\^9/L, hemoglobin ≥ 80 g/L (red blood cell transfusion allowed), and platelets ≥ 75 × 10\^9/L (transfusion-independent, defined as no platelet transfusion within 7 days prior to enrollment). 5. Oxygenation Status: Blood oxygen saturation \> 91% in room air. Exclusion Criteria: 1. Prior use of monoclonal antibodies or targeted therapies similar to anti-PD-1 or anti-PD-L1 agents. 2. Concurrent participation in other clinical trials. 3. Persistent treatment-related toxicity \> Grade 1 (per CTCAE V5.0 criteria), excluding alopecia and neurotoxicity. 4. Known hypersensitivity to the active ingredients or excipients of trametinib and/or Adebrelimab. 5. History of autoimmune diseases, including but not limited to systemic lupus erythematosus, psoriasis, rheumatoid arthritis, inflammatory bowel disease, or Hashimoto's thyroiditis. 6. History of or current active tuberculosis infection. 7. Active infections requiring systemic treatment. 8. Severe comorbid conditions, including but not limited to uncontrolled diabetes or active peptic ulcer disease. 9. Positive serology for HIV, TP, HCV antibodies, HBV Ag, or HBV DNA copy number exceeding the upper limit of normal. 10. Thyroid dysfunction (abnormal FT3, FT4, T3, or T4 levels). 11. Administration of live or attenuated vaccines within 4 weeks prior to treatment initiation, during treatment, or within 5 months after the last dose. 12. Any condition deemed by the investigator to render the patient unsuitable for the study. 13. Inability or unwillingness to comply with the study protocol due to personal reasons.