Risk factors for herpes simplex virus-1/2 viremia and clinical outcomes following unmanipulated haploidentical haematopoietic stem cell transplantation

•We investigated the risk factors for HSV-1/2 viremia and clinical outcomes after haploidentical HSCT for the first time.•HSV-1/2 viremia was associated with delayed platelet engraftment, a higher incidence of oral mucositis and severe HC.•However, HSV-1/2 viremia was not associated with NRM, LFS and OS.

BackgroundHerpes simplex virus (HSV)-1/2 can still be reactivated after allogeneic haematopoietic stem cell transplantation (allo-HSCT) even when the prophylactic acyclovir is used. However, the risk factors for HSV-1/2 viremia and the clinical outcomes following unmanipulated haploidentical HSCT remain unknown.Objectives and study designNineteen patients with HSV-1/2 viremia and fifty-seven patients without HSV-1/2 viremia which were selected using the case-pair method after undergoing haploidentical HSCT were enrolled. We analysed the risk factors for HSV-1/2 viremia and compared the clinical outcomes between the two groups.ResultsThe risk factors for HSV-1/2 viremia included HLA disparity ≥2 loci (p = 0.049) and cytomegalovirus (CMV) reactivation (p = 0.028). The incidences of platelet engraftment, oral mucositis and severe haemorrhagic cystitis (HC) in patients with and without HSV-1/2 viremia were 77% and 94% (p = 0.003), 78% and 13% (p = 0.000), and 25% and 6% (p = 0.04), respectively. Moreover, the median time to platelet engraftment in patients with and without HSV-1/2 viremia was +25 days (range, +11-+80) and +17 days (range, +8-+67) (p = 0.004), respectively. According to the multivariate analyses, HSV-1/2 viremia was associated with delayed platelet engraftment (p = 0.038), a higher incidence of oral mucositis (p = 0.000) and severe HC (p = 0.038). However, HSV-1/2 viremia was not associated with non-relapse mortality (34.0% vs. 31.5%, p = 0.26), leukaemia-free survival (60.9% vs. 57.9%, p = 0.46) and overall survival (61.2% vs. 60.7%, p = 0.37).ConclusionsBased on our study results, we recommend that HSV-1/2 PCR should be performed upon clinical suspicion of HSV-1/2 infection.