Interim PET/CT-adapted Use of PD-1 Inhibitor Combined With De-escalated Chemotherapy-AVD in Classic Hodgkin Lymphoma

This study enrolls newly diagnosed unfavorable stage II /stage III-IV classical Hodgkin lymphoma patients. All participants receive 2 cycles ABVD induction chemotherapy, then stratified by interim PET-CT Deauville score for differentiated treatment: standard ABVD for DS1-3, AVD plus Sintilimab for DS4, salvage chemotherapy plus autologous stem cell transplant for DS5. The primary goal is to assess 2-year progression-free survival and compare long-term survival and toxicities across subgroups, to verify whether Sintilimab addition can avoid high-dose chemo-radiotherapy for DS4 patients.

Inclusion Criteria: * Age ≥ 18 years old; * Histologically confirmed newly diagnosed classical Hodgkin lymphoma (cHL); * Eligible to receive standard frontline ABVD induction chemotherapy for 2 cycles; * Able to complete interim PET-CT (iPET2) scan after 2 cycles ABVD for Deauville score stratification; * Adequate bone marrow, hepatic and renal function to tolerate chemotherapy and immunotherapy; * Life expectancy ≥ 6 months at enrollment; * Willing to comply with scheduled treatment, imaging follow-up and laboratory tests; Exclusion Criteria: * Prior systemic anti-lymphoma therapy, including chemotherapy, radiation, anti-PD-1/PD-L1 immunotherapy or stem cell transplantation; * Severe irreversible organ dysfunction (cardiac, pulmonary, hepatic, renal) that cannot tolerate cytotoxic chemotherapy; * Known hypersensitivity to doxorubicin, bleomycin, vinblastine, dacarbazine or sintilimab; * Active severe infection (e.g., uncontrolled sepsis, active tuberculosis, HIV infection); * Pregnant or breastfeeding female patients; * Inability to complete serial PET-CT imaging due to contraindications such as severe contrast allergy