Post-allogeneic hematopoietic stem cell transplantation viral reactivations and viremias: a focused review on human herpesvirus-6, BK virus and adenovirus

Viral Encephalitis after Hematopoietic Cell Transplantation: A Systematic Review

Viral encephalitis is a rare but serious complication after hematopoietic cell transplantation (HCT). The nonspecific early signs and symptoms and rapid progression can make it difficult to diagnose and treat in a timely fashion. To better inform clinical decision making in post-HCT viral encephalitis, a systematic review of prior studies of viral encephalitis was performed, with the goal of characterizing the frequency of various infectious etiologies and their clinical course, including treatments and outcomes. A systematic review of studies of viral encephalitis was performed. Studies were included if they described a cohort of HCT recipients who were tested for at least 1 pathogen. Of 1613 unique articles initially identified, 68 met the inclusion criteria, with a total of 72,423 patients studied. A total of 778 cases of encephalitis were reported (1.1%). Human herpesvirus 6 (HHV-6) (n = 596), Epstein-Barr virus (n = 76), and cytomegalovirus (n = 33) were the most commonly reported causes of encephalitis, and HHV-6 encephalitis tended to occur the earliest, accounting for most cases prior to day +100 post-transplantation. Of 29,671 patients with available transplantation data, encephalitis was diagnosed in 282 of 4707 (6.0%) cord blood transplantation (CBT) recipients, in 372 of 24,664 (1.5%) non-CBT allogeneic HCT recipients, and in 5 of 300 (1.7%) autologous HCT recipients. Of the 282 CBT encephalitis cases, 270 (95.7%) were caused by HHV-6. Overall, 288 (37.0%) of the 778 patients with encephalitis died, and 75 deaths were attributable to encephalitis, with the time between diagnosis and death ranging from 3 to 192 days. Viral encephalitis occurs in approximately 1% of HCT recipients, and HHV-6 is the most common cause. Mortality following encephalitis in HCT recipients is high, indicating an urgent need for advancement in preventive and therapeutic strategies.

An impact of CMV and HHV-6 reactivation on the course of early period after hematopoietic stem cell transplantation in patients with hematologic malignancies

   Objective. To assess the impact of CMV and HHV-6 reactivation on the course of early post-transplant period in patients with hematologic malignancies.   Materials. Retrospective analysis of medical records of 339 patients with hematologic malignancies who received hematopoietic stem cell transplantation (HSCT) was performed, and markers of CMV and HHV-6 infections were detected (specific IgG, EIA). Blood and other materials from HSCT recipients were tested (PCR) for viral DNA in early post-transplant period (up to Day 100).

   Results. Reactivation of viral infections after HSCT was discovered in 177 patients (52,2 %): CMV-infection was detected in 23 %, HHV-6 in 17,4 %, CMV+HHV-6 in 11,6 % of HSCT recipients. CMV DNA was predominantly identified in blood, while HHV-6 DNA was more frequently discovered in GIT mucosa and bone marrow. 40 % of 99 patients with HHV-6 reactivation had concomitant CMV+HHV-6 reactivation. In this group, the clinical manifestation of infections was registered significantly more frequently. Febrile neutropenia was more frequent in HSCT recipients with CMV reactivation, sepsis and graft hypofunction were diagnosed more frequently in presence of HHV-6 and predominantly HHV-6+CMV infections. The direct correlation (using Spearman’s method) between CMV and HHV-6 reactivation and terms of leukopoiesis recovery, engraftment terms, and transplant hypofunction was revealed. An impact of herpetic infections reactivation on the graft hypofunction and late recovery of leukopoiesis was confirmed using the logistic regression; its impact on the chimerism was revealed. In 72 % of cases, the graft failure in early post-transplant period occurred in patients with herpetic infections reactivation.   Conclusion. HHV-6 and CMV reactivation in the early period after HSCT correlates with terms of leukopoiesis recovery, contributes to development of complications, and is an additional factor aggravating the course of the post-transplant period.

BKV Related Hemorrhagic Cystitis-An Insight into Risk Factors and Later Complications-An Analysis on Behalf of Polish Adult Leukemia Group

Simple Summary

Despite noticeable progress in allogeneic hematopoietic stem cell transplantation, potential viral reactivations are still one of the most challenging complications. The aim of our study was to identify predictive and risk factors associated with the occurrence of the BK virus related hemorrhagic cystitis following hematopoietic stem cell transplantation. Furthermore, we investigated the impact of various factors on the clinical course of patients after hematopoietic stem cell transplantation. We confirmed that >0.75 × 10³ BK virus copies/mL in serum at day +21 after allogeneic hematopoietic stem cell transplantation has a strong predictive ability for hemorrhagic cystitis. Thus, we believe that our findings could be helpful in establishing the predictive validity of the BK viral load measurement in polyomavirus BK-associated hemorrhagic cystitis and survival.

Abstract

BK virus reactivation increases the likelihood of hemorrhagic cystitis (HC) after allogeneic hematopoietic stem cell transplant (HCT). In this study, we aimed to identify predictive and risk factors associated with the increased occurrence of this condition following HCT. On a group of 124 patients aged ≤71 years old (median 40 years) who underwent HCT, we analyzed sex, age, time from diagnosis to transplantation, type of conditioning, donor’s relationship, age, and sex, the impact of immunosuppression with different drugs, and acute and chronic GVHD, BK viremia and viruria as potential factors increasing the risk of BK-related HC after HCT. HC occurred among 24 patients (24/124; 29.2%). A significant correlation was observed between HC incidences after HCT, BK viremia and viruria, and acute GVHD occurrence. Furthermore, the level of BKV DNA in serum at day +21 (>0.75 × 10³) significantly impacted the patients’ survival time. According to our results, the likelihood ratio of BKV-DNA on day +21 in serum is 6.25, indicating that this diagnostic test has the potential to be utilized in a clinical setting. These findings may be used as a voice in the discussion on implementing an optimal preemptive treatment in BKV reactivation after allogeneic HCT.