B05 | ADENOVIRUS INFECTION IN ALLOGENEIC TRANSPLANT ADULT PATIENTS WITH POST-TRANSPLANT CYCLOPHOSPHAMIDE

Background: Post-transplant cyclophosphamide (PTCy) used for Graft-versus-Host Disease (GVHD) prophylaxis is associated with a higher risk of viral reactivations in allogeneic stem cell transplant recipients. Despite the potential impact on transplant morbidity and mortality, data of adenovirus (AdV) infection on adult population are scarce. Methods: We analyzed 757 adult pts who underwent HSCT from 2015 to 2022. All pts received PTCy in association with sirolimus (31), MMF (28) and ATG (1) as GvHD prophylaxis. PCR was used for AdV-DNA detection in biological samples. Until 2018, AdV-PCR was carried out only in case of clinical suspicion; afterwards, we chose to perform weekly monitoring on peripheral blood during the early-phase after HSCT. Results: Overall, we detected 31 cases of AdV-infection, 21 with organ involvement. Most pts (median age 47 yrs) were affected by myeloid malignancies (68%) and received a myeloablative conditioning regimen (68%). Donors were: 55% haplo, 42% matched-unrelated (MUD) and only 3% matched-related. Median time from HSCT to AdV positivity was 53 days (3-271). The virus was isolated in plasma samples (26), bone marrow aspirates (8), gut biopsy specimens (14), urine samples (7) and cerebrospinal fluid (1). We reported the following clinical manifestations: fever (4), colitis (14), cystitis (7), delayed engraftment (7) and encephalitis (1). Seven pts had concomitant severe acute GvHD (aGvHD). Overall, 21 pts received specific antiviral treatment, mainly based on intravenous immunoglobulin and cidofovir. Brincidofovir was administered as compassionate use in 6 pts. More than 75% of pts achieved complete response. At a median follow-up of 468 days after HSCT (31-2235), 26 pts solved the infection while 4 died due to infection. The overall survival (OS) was positively affected by the absence of aGvHD (95% CI, 0.57-0.04) and AdV weekly monitoring (95% CI, 0.11-0.87). Conclusions: AdV infection in HSCT recipients deserves attention as potential cause of morbidity and mortality. We reported AdV mainly in the context of haplo and MUD transplants, myeloablative conditioning regimen, severe aGvHD. In our analysis OS was positively affected by the introduction of AdV weekly monitoring which is warranted for early diagnosis and pre-emptive treatments.