Human herpesvirus 6 reactivation in unmanipulated haploidentical hematopoietic stem cell transplantation predicts the occurrence of grade II to IV acute graft‐versus‐host disease

Abstract Background Human herpesvirus 6 (HHV‐6) reactivation is relatively common after allogeneic hematopoietic stem cell transplantation (allo‐HSCT). However, the incidence of HHV‐6 reactivation and the clinical outcomes following unmanipulated haploidentical HSCT (haplo‐HSCT) remain unknown. Method We prospectively monitored blood HHV‐6 DNA using real‐time quantitative polymerase chain reaction weekly until day 100 post unmanipulated haplo‐HSCT in patients with hematological malignancies. Results From November 2016 to March 2017, 102 patients (58 male and 44 female, median age 25(2‐58) years old) were enrolled. Within 100 days post‐transplantation, 27 patients (27/136, 19.9%) developed HHV‐6 viremia with a median onset time of 14 (7‐98) days. The cumulative incidence of HHV‐6 reactivation on day 100 post‐HSCT was 25.5 ± 4.3% in haplo‐HSCT. The median HHV‐6 copy number was 1.45 × 10 3 (5.48 × 10 2 ‐2.00 × 10 4 ) copies/ml. The HHV‐6 viremia duration time was 7 days in 23 patients, 14 days in one patient and 21 days in one patient. In multivariate analysis, prior HHV‐6 reactivation was an independent risk factor for grade 2‐4 graft‐versus‐host disease (GVHD). But it did not influence the overall survival (OS)(HR 1.624, 95%CI 0.768‐3.432, P = .204), disease‐free survival (DFS) (HR 1.640, 95%CI 0.799‐3.367, P = .177) and non‐relapse mortality (NRM) (HR 1.644, 95%CI 0.670‐4.038, P = .278). Conclusion The reactivation of HHV‐6 after unmanipulated haploidentical transplantation predicts the occurrence of grade 2‐4 a‐GVHD, but it may not influence the overall survival (OS), disease‐free survival (DFS) and non‐relapse mortality (NRM).