The goal of this observational study is to learn if interferon-gamma monoclonal antibody combined with dexamethasone works to treat adults with refractory secondary hemophagocytic lymphohistiocytosis (HLH). The main questions it aims to answer are:

How well does this treatment help patients recover from refractory secondary HLH? How safe is this treatment for these patients? Participants will receive interferon-gamma monoclonal antibody and dexamethasone as part of their clinical care. Researchers will monitor participants with regular blood tests, physical exams, and safety checks for up to 8 weeks of treatment. They will collect information about how participants respond to treatment and any side effects that occur.

This study will include about 22 adult participants at Huadong Hospital Affiliated to Fudan University.

Inclusion Criteria:

• Age ≥ 18 years
• Confirmed diagnosis of secondary hemophagocytic lymphohistiocytosis (HLH) according to HLH-2004 criteria
• Refractory HLH defined as inadequate response or progression after at least 2 weeks of standard first-line or second-line therapy
• Able to provide written informed consent

Exclusion Criteria:

• Active infection with mycobacteria, histoplasma, CMV, herpes zoster, or HIV
• Left ventricular ejection fraction < 50%
• Concurrent use of other anti-neoplastic or investigational agents
• Other uncontrolled infections judged by the investigator
• Psychiatric disorders or poor protocol compliance

This study will enroll adult participants aged 18 years and older with a confirmed diagnosis of refractory secondary hemophagocytic lymphohistiocytosis (HLH) based on the HLH-2004 diagnostic criteria. Participants must have demonstrated inadequate response or disease progression following standard first-line or second-line HLH-directed therapy. All participants must be able to provide written informed consent prior to any study-related procedures.

1 year after completion of this study