e18533 Background: Post transplant cyclophosphamide (PTCY) has been shown to be an effective treatment for prevention of graft versus host disease (GVHD). However, this increased immune suppression rates may increase the risk of CMV reactivation. There is limited published data addressing CMV reactivation in this patient population. Additionally there is no data on the efficacy of prophylactic letermovir in the patients who have received PTCY. In this study we analyzed the incidence of CMV reactivation in patients treated with PTCY and those not treated with PTCY, as well as the efficacy of letermovir in preventing CMV reactivation in the PTCY population. Methods: We conducted a retrospective review of MUD, MRD, and haploidentical stem cell transplant patients at our institution from 1/1/2014 until 12/10/2018. We analyzed the incidence of CMV reactivation (PCR > 137 DNA IU/ml), peak of CMV PCR titer and time to reactivation within the first 100 days post-transplant. Results: There were 150 patients with at least 60 days of follow-up that were included in this study. These patients were split into three groups: No post-transplant cyclophosphamide (NPTCY) (N = 64), received post-transplant cyclophosphamide (PTCY) (N = 70), and received PTCY and letermovir prophylaxis. (L-PTCY) (N = 15). The incidence of CMV reactivation was increased in the PTCY patients when compared to the NPTCY (44% vs 29%). In the NPTCY patients the donor (D) serostatus increased the risk of CMV reactivation (Recipient (R)+ D+ 73% vs R+D-36%) conversely in the PTCY group the donor CMV status did not influence reactivation rates (R+D+ 52% vs R+D- 81%). The CMV reactivation rate in the L-PTCY patients was lower when compared to the PTCY patients (21% vs 44%), additionally the L-PTCY patients had much lower peak CMV titers compared to PTCY group (445 vs 2112 IU/ml). Conclusions: This study demonstrates that there is an increased incidence of CMV reactivation in patients who receive PTCY. Additionally, the donor CMV serostatus does not appear to influence the incidence of CMV reactivation in patients receiving post-transplant CY. Although the number of patients in the L-PTCY group is small, it does appear to be an effective prophylactic treatment in patients receiving PTCY.
The potential association of CMV-specific CD8+ T lymphocyte reconstitution with the risk of CMV reactivation and persistency in post allogeneic stem cell transplant patients
