Incidence and Impact of Non-CMV Herpes Viral Infection in Haploidentical and Matched Sibling Donors Receiving Post-Transplant Cyclophosphamide (PTCy): A CIBMTR Analysis

Single-center studies have reported increased risk of CMV infection in patients undergoing allogeneic transplant using haploidentical graft with post-transplant cyclophosphamide (HaploCy), however limited data exists regarding the impact of this transplant platform on the incidence of non-CMV herpes viruses (NCHV) infection (viremia/disease). Furthermore, it is unclear if the donor type or altered immune reconstitution resulting from the use of PTCy contributes to this infection risk. To study this, patients reported to the CIBMTR with AML/ALL/MDS transplanted between 2012 and 2017 receiving HaploCy (n = 757), matched-sibling donors receiving PTCy (SibCy, n=403), or matched sibling with calcineurin inhibitor and methotrexate/mycophenolate mofetil (SibCNI, n=1605) with either marrow or peripheral blood grafts were examined (Table 1). Too few matched unrelated donors (MUD) receiving PTCY reported to CIBMTR resulted in exclusion of MUD transplants. The cumulative incidence of NCHV in the HaploCy, SibCy and SibCNI were 6.9% (99% CI, 4.7-9.4), 3.2% (1.3-5.9), and 1.7% (1-2.6) respectively by day 30 [p Our results suggest that HaploCY is associated with an increased incidence of NCHV infection and HHV-6 viremia predominates. The SibCy cohort experienced an increased incidence of NCHV infections as well. However, only in the HaploCy group is this independently associated with increased TRM and decreased survival. Improved surveillance and preemptive treatment may mitigate the mortality associated with NCHV infections in HaploCy recipients.