Comparing the Efficacy of Different Durations of Maribavir Treatment Regimens in Allo-HSCT

Inclusion Criteria: 1. First allogeneic hematopoietic stem cell transplantation; 2. Age ≥ 18 years; 3. Confirmed refractory CMV infection; Refractory CMV infection is defined as fulfillment of any one of the following criteria: * Persistent or increasing CMV viremia despite ≥2 weeks of appropriate antiviral therapy-specifically, CMV DNA levels remain unchanged (i.e., change ≤ log₁₀) or increase (i.e., change \> log₁₀)-concomitant with lack of clinical improvement or ongoing disease progression; * Drug-resistant CMV infection-defined as detection of specific CMV gene mutations associated with reduced susceptibility to one or more anti-CMV agents, in patients who otherwise meet the criteria for refractory CMV infection; * Intolerance to anti-CMV therapy-defined as inability to continue antiviral treatment due to severe adverse effects, such as clinically significant bone marrow suppression or renal impairment; 4. Provision of written informed consent and willingness to participate in this clinical study. Exclusion Criteria: 1. Known allergic constitution, particularly hypersensitivity to any component of maribavir; 2. Active hepatitis B infection, defined as HBV DNA level ≥ 1 × 10³ IU/mL; 3. Confirmed HIV infection; 4. Severe impairment of major organ function, including but not limited to respiratory failure, cardiac failure, decompensated hepatic insufficiency, or renal insufficiency; 5. Central nervous system CMV infection; 6. History of substance use disorder or chronic alcoholism that may compromise the validity or interpretation of trial outcomes; 7. Presence of a psychiatric disorder or cognitive impairment precluding the provision of informed consent; 8. Any other condition deemed by the investigator to render the participant unsuitable for enrollment in this clinical trial.