I had the honor to present as an oral presentation our work that we conducted in three Italian centers. It was a multi-center study, a retrospective one, and we decided to try to understand if the letermovir prophylaxis, that is still off-label in pediatric patients, could somehow hinder immune reconstitution. And we decided to study how the immune reconstitution after letermovir correlates to viral activation and viral infection...
I had the honor to present as an oral presentation our work that we conducted in three Italian centers. It was a multi-center study, a retrospective one, and we decided to try to understand if the letermovir prophylaxis, that is still off-label in pediatric patients, could somehow hinder immune reconstitution. And we decided to study how the immune reconstitution after letermovir correlates to viral activation and viral infection.
So we enrolled 191 pediatric patients in these three Italian centers and we extracted the two groups, two different groups of patients, matching them through a statistical method that is called the Mahalanobis distance and we matched them for CMV status pre-transplant, conditioning regimen, ATG use in GvHD prophylaxis and also in the occurrence of acute GvHD greater or equal than grade 2. So after matching we obtained two well-balanced groups, one of children receiving pre-emptive antiviral therapy and one of children receiving letermovir prophylaxis.
What we observed interestingly was that patients undergoing letermovir actually had a better immune reconstitution in terms of CD4, CD19, CD16 counts at day 60 and 100 of their transplantation and moreover they had CD8 immune reconstitution better at day 100. In terms of viral reactivation, we observed a greater number of viral reactivations in the letermovir group. This was quite surprising, but these were not CMV reactivations, but were non-CMV viruses. In terms of CMV reactivation under letermovir, we did not observe a significant number of CMV reactivations. Actually, patients under the letermovir showed CMV reactivation outside the letermovir window as was expected and as it had also been registered in literature. For multiple viral infections, there were no differences between the two groups. Moreover, the letermovir group showed a slight protective effect against relapse, even if this was a small cohort of patients and the follow-up needed to be longer for this kind of outcome.
So it’s interesting and it requires further research. And this is quite an important study because it’s a study in which for the first time we demonstrated that letermovir does not hinder immune reconstitution in pediatric patients and it is also a safe option so further studies are waranted to confirm our findings and have letermovir in clinical routine administration for all pediatric centers and not as off-label.
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