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

Evaluation of the Efficacy of a Cytomegalovirus-Specific Immune Reconstitution-Incorporated Scoring System in Guiding the Duration of Antiviral Prophylaxis to Reduce Cytomegalovirus Infection Following Letermovir Discontinuation

With the increasing use of letermovir and considering that haploidentical hematopoietic stem cell transplantation (haplo-HSCT) predominates in China alongside a high CMV seroprevalence in the population, multiple domestic centers have reported cases of CMV infection after letermovir discontinuation. Currently, there is no clear definition for the high-risk population who may benefit from extended letermovir prophylaxis. This study aims to utilize CMV-specific immune reconstitution to identify high-risk individuals for CMV infection after letermovir cessation post-transplant, thereby guiding the timing of letermovir discontinuation and balancing the risks and safety associated with prolonged prophylaxis.

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:

  1. CMV IgG-positive recipients undergoing HLA-haploidentical hematopoietic stem cell transplantation (HSCT).
  2. 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.