[Clinical characteristics and prognostic factors in patients with cerebrospinal fluid torque teno virus positivity after allogeneic hematopoietic stem cell transplantation].

Objective: To investigate the clinical characteristics and prognostic factors for patients with cerebrospinal fluid positivity for torque teno virus (TTV) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: A retrospective analysis was conducted on the patients who received allo-HSCT at Hebei Yanda Lu Daopei Hospital from 2022 to 2023 year and showed positive cerebrospinal fluid metagenomic next-generation sequencing (mNGS) results post-transplantation, with their clinical data collected accordingly. The patients were categorized into TTV-negative and TTV-positive groups based on the detection of TTV in cerebrospinal fluid. The TTV-positive group was further subdivided into low-RPM [TTV reads per million sequencing reads (TTV-RPM)<1] and high-RPM (TTV-RPM≥1) subgroups using the threshold of TTV-RPM. The patients were followed until December 9, 2025, to investigate the clinical features of cerebrospinal fluid TTV positive patients after allo-HSCT. The survival curve was drawn to compare the difference of survival rate between groups. The influencing factors of patient prognosis were analyzed using a multivariate Cox regression model. Results: A total of 134 patients were enrolled: sixty in the TTV-negative group, including 35 males and 25 females, aged [M (Q1, Q3)] 30 (14, 42) years, and 74 in the TTV-positive group, including 45 males and 29 females, aged 24 (15, 40) years. Within the TTV-positive group, 44 were classified as low-RPM subgroup and 30 as high-RPM subgroup. Baseline characteristics, including gender, age, primary disease, donor type, neutrophil engraftment time, platelet engraftment time, whether acute graft-versus-host disease (aGVHD) occurred, and other microbial infections in cerebrospinal fluid, showed no significant differences between the TTV-negative and TTV-positive groups, or between the low-RPM and high-RPM subgroups (all P>0.05). The median follow-up time was 30.0(18.0, 35.4) months, the median survival period was not reached in the low-RPM subgroup, while that in the high-RPM subgroup was 25.6 months (95%CI: 5.3-45.9), and the 3-year survival rate was lower than that in the low-RPM subgroup (41.1% vs 76.8%, P=0.014). Multivariate Cox regression analysis confirmed high TTV-RPM level (≥1) in cerebrospinal fluid as a risk factor for mortality in allo-HSCT patients (HR=2.57, 95%CI: 1.09-6.08). Conclusions: There is no difference in clinical characteristics among allo-HSCT patients with or without TTV infection or with different TTV viral loads. A high TTV-RPM value (≥1) in cerebrospinal fluid is a risk factor for mortality in allo-HSCT patients.