Letermovir Prophylaxis for CMV Infection in Haplo-HSCT Recipients: Single-center Data in China

Letermovir Prophylaxis for Cytomegalovirus Infection in Haploidentical Allogeneic Hematopoietic Cell Transplant Recipients: Single-center Real-world Data in China

In the 30 years of fighting CMV infection, the mortality rate among HSCT patients has significantly reduced. Now, the focus is on improving the prognosis of HSCT patients and preventing CMV infection. The emergence of letermovir has provided a new opportunity in this regard. Letermovir, the only drug approved for CMV infection prevention in HSCT patients, works by inhibiting the CMV DNA terminase complex. Phase III studies have shown that letermovir significantly reduces CMV infection and all-cause mortality after HSCT, without increasing myelosuppression or nephrotoxicity. Real-world studies have further confirmed its efficacy in reducing CMV infection rates and antiviral use. Letermovir's global success has not yet been fully realized in China, where it is still in its early stages of use.

Letermovir achieved excellent therapeutic outcomes globally but is still developing in China. It received an implied license for clinical trials in June 2020, followed by marketing applications in November 2020. In December 2021, it was approved by the China National Medical Products Administration (NMPA) for preventing CMV infection and disease in CMV seropositive adult recipients undergoing allogeneic hematopoietic stem cell transplantation (HSCT). Letermovir's commercial launch in China is expected in August 2022. Given that over 90% of the Chinese population is CMV seropositive, determining whether CMV prevention is necessary based solely on serology is insufficient. The growing use of haploidentical stem cell transplantation (haplo-SCT) in China, particularly using the Beijing protocol for GVHD prevention, increases CMV risk. However, limited data exists on the efficacy of CMV prophylaxis for haplo-SCT patients in China. A real-life study assessing the efficacy, resistance, and tolerability of letermovir in this patient group is essential to guide CMV management strategies, particularly for high-risk CMV R+ haploidentical transplant recipients. This prospective study aims to evaluate letermovir's real-life impact on efficacy, resistance, tolerability, and CMV-related morbidity and mortality in China.

Inclusion Criteria:

• Haplo-SCT candidate (adult) who has decided to primary transplant and is willing to participate in the study.
• The haplo-SCT candidate (adult) should be CMV seropositive recipients.

Exclusion Criteria:

• CMV-seronegative patient receiving a negative CMV donor graft.
• Patients having active CMV DNAemia at the time of letermovir initiation.
• Patient having signed the informed consent but not grafted.
• Patient recruited in a clinical study on an anti-CMV trial.