Reducing Post-Letermovir CMV Infection: Efficacy of an Immune-Reconstitution-Based Scoring System to Guide Prophylaxis Duration

Based on the established scoring system for cytomegalovirus-specific immune reconstitution, guide the discontinuation of letermovir after transplantation to reduce the incidence of CMV infection within one year after letermovir discontinuation.

Inclusion criteria

• (1) Recipients who meet either of the following conditions:

• CMV IgG-positive recipients undergoing HLA-haploidentical hematopoietic stem cell transplantation (HSCT).
• CMV IgG-negative recipients receiving a graft from a CMV IgG-positive donor, and who have received letermovir as CMV prophylaxis post-transplant without prior discontinuation.
• (2) Plasma CMV-DNA level below the lower limit of detection (local threshold: 400 copies/mL) within 5 days before enrollment.
• (3) Age ≥ 18 years.
• (4) Ability to provide written informed consent independently.
• (5) Negative for HIV, HBV, and HCV.
• (6) Written informed consent must be provided before initiation of any study procedure. Consent may be provided by the patient or a legally authorized representative if, in the investigator's judgment, obtaining consent directly from the patient is not in the patient's best medical interest.

Exclusion criteria

• (1) Prior clinical diagnosis of CMV infection, CMV disease, or CMV viremia before enrollment;
• (2) Received ganciclovir, valganciclovir, foscarnet, acyclovir (oral dose >3200 mg daily, or intravenous dose >25 mg/kg daily), valacyclovir (oral dose >3000 mg daily), or famciclovir (oral dose >1500 mg daily) within 7 days before enrollment;
• (3) Received the following treatments within 30 days before enrollment: cidofovir, CMV hyperimmune globulin, any experimental anti-CMV therapy or biologics;
• (4) Presence of uncontrolled infection, requirement for mechanical ventilation, or hemodynamic instability at enrollment;
• (5) Suffering from mental illness or other conditions that prevent compliance with study treatment and monitoring requirements;
• (6) Inability or unwillingness to sign the informed consent form;
• (7) Other special circumstances deemed ineligible by the investigator.