Cytomegalovirus Cell Mediated Immunity

The goal of this laboratory research study is to learn if interrupting a patient's letermovir dosing based on their immune system response can help HSC transplant patients avoid post-treatment CMV infections better than taking letermovir every day without interruption.

Cytomegalovirus (CMV) infection is a common complication in patients undergoing hematopoietic stem cell transplantation (SCT). Fixed-duration letermovir (LTV) prophylaxis during the first 100 days post-SCT is effective and safe in preventing this infection, although it may be associated with a delay in CMV-specific immune reconstitution. Hence, it is needed a study to evaluate whether the absence of CMV-specific immune reconstitution at the end of LTV prophylaxis is associated with the development of late infection. This could facilitate the individualization of CMV prophylaxis duration in these patients. Methods and analysis: INMUNOEND is a multicenter, prospective, observational, non-interventional study including CMV seropositive patients undergoing allo-SCT who receive LTV prophylaxis during the first 100 days post-SCT. Immunological and virological monitorization will be conducted until day +200 post-SCT. The primary outcome variable is the percentage of patients who develop clinically significant CMV infection up to day +200 post-SCT after completing LTV prophylaxis. Data collected will include: baseline characteristics of the hematological diseases and comorbidities, variables related to SCT (i.e. engrafment, graft-versus-host disease, use of letermovir and CMV replication) and variables related to CMV-specific immune reconstitution.