High incidence of human herpesvirus 6 infection with a high viral load in cord blood stem cell transplant recipients

Effects of human herpesvirus 6B reactivation on cognitive function in cord blood transplant recipients: a prospective multicenter study

This prospective multicenter study aimed to determine the effects of human herpesvirus-6B (HHV-6B) reactivation on central nervous system (CNS) function in cord blood transplant (CBT) recipients. Our focus was to track HHV-6B reactivation and evaluate its association with delirium and cognitive function, specifically in the domains of verbal memory, attention/processing speed, and quality of life (QOL). A cohort of 38 patients participated in this study. Of the 37 patients evaluated, seven (18.9%) developed delirium, with six of these cases emerging after HHV-6B reactivation (median lag, 7 days). Evaluation of verbal memory showed that the final trial score for unrelated words at 70 days after transplantation was significantly lower than that before preconditioning (P = 0.004) among patients (n = 15) who experienced higher-level HHV-6B reactivation (median or higher maximum plasma HHV-6 DNA load for participating patients). Patients without higher-level reactivation did not show significant declines in verbal memory scores. QOL was assessed using the 36-item Short-Form Health Survey, and the social functioning score 1 year post-transplantation was significantly lower in patients who experienced higher-level HHV-6B reactivation than in those who did not. Our findings suggest that higher-level HHV-6B reactivation can detrimentally affect certain cognitive functions in CBT recipients.

Immunology of cord blood T-cells favors augmented disease response during clinical pediatric stem cell transplantation for acute leukemia

Allogeneic hematopoietic stem cell transplantation (HSCT) has been an important and efficacious treatment for acute leukemia in children for over 60 years. It works primarily through the graft-vs.-leukemia (GVL) effect, in which donor T-cells and other immune cells act to eliminate residual leukemia. Cord blood is an alternative source of stem cells for transplantation, with distinct biological and immunological characteristics. Retrospective clinical studies report superior relapse rates with cord blood transplantation (CBT), when compared to other stem cell sources, particularly for patients with high-risk leukemia. Xenograft models also support the superiority of cord blood T-cells in eradicating malignancy, when compared to those derived from peripheral blood. Conversely, CBT has historically been associated with an increased risk of transplant-related mortality (TRM) and morbidity, particularly from infection. Here we discuss clinical aspects of CBT, the unique immunology of cord blood T-cells, their role in the GVL effect and future methods to maximize their utility in cellular therapies for leukemia, honing and harnessing their antitumor properties whilst managing the risks of TRM.

Human herpesvirus-6 in hematopoietic stem cell transplant recipients: a prospective cohort study in Egypt

BACKGROUND

Immunocompromised patients face reactivation of latent viruses that increase the risk of morbidity.

AIM

The study aimed to detect human herpes virus 6 (HHV-6) reactivation among allogeneic (allo) and autologous (auto) hematopoietic stem cell transplant (HSCT) recipients and to correlate potentially attributed clinical manifestations to HHV-6 DNA plasma level.

METHODS

A prospective study included all (forty) patients undergoing allo and auto-HSCT from Jan 2020 till June 2022. Plasma samples were collected for HHV-6 serology, and for HHV-6 quantitative PCR at post-transplantation weeks 2, 4, 6. Demographic and clinical data were recorded.

RESULTS

Out of 40 peripheral blood stem cell transplant (PBSCT) recipients, 34 (85%) were HHV-6 IgG positive pre-HSCT. Of which, fourteen patients (14/34, 41.2%) showed positive HHV-6 DNaemia. HHV-6 DNAemia (15/40, 37.5%) was significantly higher among allo (8/12, 66.7%) versus auto (7/28, 25%) HSCT recipients (p = 0.030). Patients with HHV-6 DNAemia developed fever, delayed engraftment and bone marrow suppression in 6/15, 40%, thrombocytopenia (5/15, 33.3%), rash and pneumonitis (2/15, 13.3%), acute GVHD (aGVHD) (1/15, 6.7%). HHV-6 DNAemia ranged from 101 to 102,000 copies/mL. Univariate analysis identified conditioning with busulfan-cyclophosphamide as a significant risk (p = 0.043), while receiving BEAM protocol was a protective factor (p = 0.045). In multivariate analysis, receiving BEAM protocol retained significance (p = 0.040).

CONCLUSION

Frequent HHV-6 reactivation was detected after HSCT, especially in allo-HSCT recipients with clinical manifestations which could not be otherwise explained. To our best knowledge this is the first study of HHV6 reactivation in HSCT recipients from Egypt. Raising awareness for HHV-6 reactivation manifestations and screening in HSCT recipients could be lifesaving.

HHV-6 Encephalitis After Chimeric Antigen Receptor T-cell Therapy (CAR-T): 2 Case Reports and a Brief Review of the Literature

Human herpesvirus 6 (HHV-6) reactivation can occur in patients who are highly immunosuppressed, including those who have undergone hematopoietic stem cell transplantation (HSCT). HHV-6 encephalitis is a severe manifestation that is well described in the HSCT population. Chimeric antigen receptor T-cell (CAR-T) therapy is a novel cancer-directed immunotherapy that results in severe immunosuppression. Patients undergoing CAR-T therapy may be at risk for HHV-6 encephalitis, which can be difficult to distinguish from a common adverse effect of CAR-T therapy, neurotoxicity. Herein, we describe 2 patients diagnosed with HHV-6 encephalitis after CAR-T therapy and discuss the diagnostic approach and differential diagnosis for altered mental status after CAR-T therapy. Diagnosing HHV-6 encephalitis can be difficult in this patient population as altered mental status is common after CAR-T therapy and may be attributed to CAR-T-associated neurotoxicity.

Elevation of HHV-6 viral load mimicking HHV-6 reactivation after second umbilical cord blood transplantation in chromosomally integrated human herpesvirus-6

Human herpesvirus-6 (HHV-6) reactivation is an important complication in patients receiving umbilical cord blood transplantation (CBT). Chromosomally integrated human herpesvirus-6 (ciHHV-6) is a condition in which the complete HHV-6 genome is integrated into the host germline genome and is transmitted in a Mendelian manner. The influence of ciHHV-6 in recipients or donors in cases of CBT is unknown. We report the first case with ciHHV-6 that received CBT twice for acute lymphoblastic T-cell leukemia. HHV-6 DNA in peripheral blood leukocytes (PBLs) was examined over time through two CBTs. After the first CBT, the HHV-6 viral load was significantly reduced by conversion to PBLs derived from the first donor. During the second CBT, an increase in HHV-6 DNA in PBLs and plasma were observed. However, HHV-6 mRNA was not detected in either the sample before 2nd CBT or at the time of HHV-6 DNA elevation. It is considered that the HHV-6 DNA detected in PBLs and plasma samples might be the HHV-6 genome released due to tissue damage. This case suggests that physicians should be aware of HHV-6 DNA variability during allogeneic hematopoietic stem cell transplantation in ciHHV-6 patients.

High Incidence of Herpes Zoster After Cord Blood Hematopoietic Cell Transplant Despite Longer Duration of Antiviral Prophylaxis

BACKGROUND

Cord blood transplant (CBT) recipients have a high incidence of herpes zoster (HZ) in the context of short-term peritransplant antiviral prophylaxis. In 2009, international guidelines recommended HZ prophylaxis for at least 1 year after hematopoietic cell transplant. The impact of longer-term antiviral prophylaxis on HZ incidence after CBT is unknown.

METHODS

We retrospectively analyzed varicella zoster virus (VZV)-seropositive CBT recipients who were transplanted between 2006 and 2016. We abstracted HZ events and other variables for up to 5 years post-CBT. We calculated the cumulative incidence of HZ and used Cox proportional hazards regression to identify variables associated with HZ.

RESULTS

The study cohort consisted of 227 patients. Among 1-year survivors, 91% were still receiving prophylaxis, for a median duration of 20.6 months. HZ occurred in 44 patients (19%) at a median of 23.6 months. The cumulative incidence of HZ by 1 year after CBT was 1.8% (95% confidence interval [CI], .1%-4%), but increased to 26% (95% CI, 19%-33%) by 5 years. In a multivariable analysis, acute graft-vs-host disease was associated with increased risk, whereas antiviral prophylaxis was associated with reduced risk for HZ (adjusted hazard ratio, 0.19 [95% CI, .09-.4]). There was no association between CD4+ T-cell counts at 1 year post-CBT and subsequent risk for HZ.

CONCLUSIONS

We found a high incidence of HZ after CBT despite antiviral prophylaxis for > 1 year. Based on these findings, we suggest longer duration of prophylaxis for HZ after CBT. Compliance with antiviral prophylaxis, VZV-specific immune monitoring, and vaccination to mitigate HZ after CBT also require further study.

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

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 × 10³ (5.48 × 10² -2.00 × 10⁴ ) 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).

Reducing infectious complications after allogeneic stem cell transplant

INTRODUCTION

Infections remain a significant problem, in patients undergoing an allogeneic hematopoietic stem-cell transplant (HSCT) and efforts have been made over the years, to reduce the incidence, morbidity and mortality of infectious complications.

AREAS COVERED

This manuscript is focused on the epidemiology, risk factors and prevention of infections after allogeneic HSCT. A systematic literature review was performed using the PubMed database, between November 2019 and January 2020, with the following MeSH terms: stem-cell transplantation, infection, fungal, bacterial, viral, prophylaxis, vaccines, prevention. The authors reviewed all the publications, and following a common revision, a summary report was made and results were divided in three sections: bacterial, fungal and viral infections.

EXPERT OPINION

Different infections occur in the early, intermediate and late post-transplant period, due to distinct risk factors. Improved diagnostic techniques, pre-emtive therapy and better prophylaxis of immunologic complications, have reduced the morbidity and mortality of infections. The role of the gut microbiota is under careful scrutiny and may further help us to identify high-risk patients.

Cooperative activation of the human herpesvirus 6B U79/80 early gene promoter by immediate-early proteins IE1B and IE2B

The human herpesvirus 6B (HHV-6B) U79/80 gene belongs to the early gene class and appears as early as 3 hr postinfection. It is one of the most abundantly expressed transcripts and a useful diagnostic marker for viral reactivation. However, the expression mechanisms of the U79/80 gene remain unclear. To identify the viral factor(s) that activates the U79/80 promoter along with other HHV-6B core early gene promoters, p41, DNA polymerase, and U41, we examined the activities of U79/80 and other early gene promoters. In HHV-6B-infected MT-4 cells, U79/80 promoter activity was the highest among early gene promoters. In addition, we identified that HHV-6B immediate-early (IE)2B protein is one of the viral proteins involved in the activation of the U79/80 and other early gene promoters. Although the IE2B could independently activate these early gene promoters, the presence of IE1B significantly augmented the activities of early gene promoters. We also found that IE2B bound three human cytomegalovirus IE2-binding consensus, cis repression signal (CRS), within the U79/80 promoter. Moreover, the U79/80 promoter was activated by cellular factors, which are highly expressed in MT-4 cells, instead of HeLa cells because it was upregulated by mock infection and in the absence of IE2B. These results suggested that the activation mechanism of the U79/80 gene differs from other HHV-6B core early genes, apparently supporting its rapid and abundant expression. Therefore, the U79/80 early gene is an actually suitable biomarker of HHV-6B reactivation.

Make Sure You Have a Safety Net: Updates in the Prevention and Management of Infectious Complications in Stem Cell Transplant Recipients

Hematopoietic stem cell transplant recipients are at increased risk of infection and immune dysregulation due to reception of cytotoxic chemotherapy; development of graft versus host disease, which necessitates treatment with immunosuppressive medications; and placement of invasive catheters. The prevention and management of infections in these vulnerable hosts is of utmost importance and a key “safety net” in stem cell transplantation. In this review, we provide updates on the prevention and management of CMV infection; invasive fungal infections; bacterial infections; Clostridium difficile infection; and EBV, HHV-6, adenovirus and BK infections. We discuss novel drugs, such as letermovir, isavuconazole, meropenem-vaborbactam and bezlotoxumab; weigh the pros and cons of using fluoroquinolone prophylaxis during neutropenia after stem cell transplantation; and provide updates on important viral infections after hematopoietic stem cell transplant (HSCT). Optimizing the prevention and management of infectious diseases by using the best available evidence will contribute to better outcomes for stem cell transplant recipients, and provide the best possible “safety net” for these immunocompromised hosts.

Work-up for Fever During Neutropenia for Both the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient

Fever is a common complication in patients with underlying neutropenia and is associated with significant mortality in neutropenic patients with acute myelogenous leukemia or hematopoietic cell transplant. Fever may be the only sign of infection and requires further clinical assessment, including a history, a physical examination, and additional laboratory and radiographic testing. National and international guidelines recommend initiation of empiric antimicrobial therapy in patients with fever during neutropenia. Stepwise escalation of antibacterial therapy, followed by antifungal therapy for patients with persistent fever, generally is recommended. Consideration should also be given to de-escalation of antimicrobial therapy in the appropriate clinical settings.

Clinical practice recommendations for the diagnosis and management of human herpesvirus-6B encephalitis after allogeneic hematopoietic stem cell transplantation: the Japan Society for Hematopoietic Cell Transplantation

Reactivation of human herpesvirus (HHV)-6B is relatively common after allogeneic hematopoietic stem cell transplantation (HSCT) and HHV-6B diseases may consequently develop. Among them, HHV-6B encephalitis is a serious and often fatal complication. The aim of these clinical practice recommendations is to provide diagnostic and therapeutic guidance for HHV-6B encephalitis after allogeneic HSCT. In this evidence-based review, we critically evaluated data from the published literature. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assist in generating recommendations. We have summarized the findings that contribute to decision-making and we have provided our recommendations. In cases where rigorous clinical data are unavailable, recommendations have been developed in discussions with physicians who have relevant expertize.

Clinical Relevance of Immunobiology in Umbilical Cord Blood Transplantation

Umbilical cord blood transplantation (UCBT) has been an important donor source for allogeneic hematopoietic stem cell transplantation, especially for patients who lack suitable matched donors. UCBT provides unique practical advantages, such as lower risks of graft-versus-host-disease (GVHD), permissive HLA mismatch, and ease of procurement. However, there are clinical challenges in UCBT, including high infection rates and treatment-related mortality in selected patient groups. These clinical advantages and challenges are tightly linked with cell-type specific immune reconstitution (IR). Here, we will review IR, focusing on T and NK cells, and the impact of IR on clinical outcomes. Better understanding of the immune biology in UCBT will allow us to further advance this field with improved clinical practice.

Human Herpesvirus 6 Reactivation Evaluated by Digital Polymerase Chain Reaction and Its Association With Dynamics of CD134-Positive T Cells After Allogeneic Hematopoietic Stem Cell Transplantation

Background

Human herpesvirus 6 (HHV-6) causes life-threatening central nervous system disorders after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Recent studies implicated CD134 as a specific receptor of HHV-6B and demonstrated that its expression levels in CD4-positive T cells after allo-HSCT could be related to the reactivation of HHV-6. We prospectively evaluated the relationship between HHV-6 reactivation and CD134+ T cells in the recipients of allo-HSCT.

Methods

HHV-6 viral load in plasma was quantitatively measured weekly after allo-HSCT by digital polymerase chain reaction in 34 patients. The ratio of CD134 in CD4+ T cells (CD134/CD4 ratio) was serially measured by flow cytometry before and after transplantation.

Results

HHV-6 reactivation was detected in 23 patients (68%). The CD134/CD4 ratio before conditioning was significantly higher in patients with HHV-6 reactivation than in those without (median, 3.8% vs 1.5%, P < .01). In multivariate analysis, a higher CD134/CD4 ratio before conditioning was significantly associated with the incidence of HHV-6 reactivation (odds ratio, 10.5 [95% confidence interval, 1.3–85.1], P = .03).

Conclusions

A higher CD134/CD4 ratio before conditioning was associated with a higher risk of HHV-6 reactivation, suggesting that the rate may be a promising marker for predicting HHV-6 reactivation after allo-HSCT.

Lymphocyte Area Under the Curve as a Predictive Factor for Viral Infection after Allogenic Hematopoietic Stem Cell Transplantation

Viral infection is a serious complication that can greatly affect patient mortality and morbidity after allogenic hematopoietic stem cell transplantation (allo-HSCT). For the early identification of patients at high risk for viral infection, we evaluated the impact of lymphocyte area under the curve (AUC) value as a new predictive factor for early immune reconstitution after allo-HSCT against viral infection. This study included 286 patients who underwent their first allo-HSCT at Kyoto University Hospital between 2005 and 2017. Lymphocyte AUC from day 0 to day +15 was calculated in the analysis of human herpesvirus 6 (HHV-6), and lymphocyte AUC from day 0 to day +30 was calculated in the analysis of other viruses (cytomegalovirus [CMV], adenovirus, BK virus, JC virus, and varicella zoster virus). The risk factors for each viral reactivation/infection were assessed by multivariate analysis. The median age at transplantation was 51years (range, 17 to 68 years). The median lymphocyte AUC was 63/μL (range, 0 to 5620/μL) at day +15 and 3880 (range, 0 to 118,260/μL) at day +30. An increase in lymphocyte AUC was significantly associated with a high frequency of HHV-6 reactivation (P = .033) and a low frequency of CMV antigenemia (P = .014). No apparent association was found between lymphocyte AUC and reactivation/infection of other viruses. Aplastic anemia as a primary disease (hazard ratio [HR], 5.34; P < .001) and cord blood as a donor source (HR, 3.05; P = .006) were other risk factors for HHV-6 reactivation. Other risk factors for CMV antigenemia included the occurrence of acute graft-versus-host disease (HR 2.21; P < .001) and recipient age (HR 1.55; P = .017). Higher lymphocyte AUC at day +30 was significantly associated with low treatment-related mortality (HR, .47; P = .045). Lymphocyte AUC may be a good predictive factor for immune reconstitution against CMV reactivation. It also provides valuable information for predicting HHV-6 reactivation and treatment-related mortality.

Analysis of five cases of human herpesvirus-6 myelitis among 121 cord blood transplantations

Reports of myelitis associated with human herpesvirus-6 (HHV-6) following allogeneic transplantation are rare. Of 121 cases of cord blood transplantation (CBT) performed at Nagano Red Cross Hospital, five cases (4.1%) of HHV-6 myelitis developed at around the time of engraftment. The major symptom identified in all five patients was superficial pain or pruritus linked to segmental levels of the spinal cord. Other identified symptoms were fever or low-grade fever in all five patients, autonomic nerve disorder in four patients, bladder and rectal disturbance in two patients, and extrapyramidal disorder in two patients. These symptoms were experienced primarily 16-39 days after CBT. HHV-6 PCR tests were all positive for cerebrospinal fluid and for plasma. Of the four cases tested by magnetic resonance imaging (MRI), three showed spinal cord abnormality. Antiviral therapy using foscarnet or ganciclovir was effective in every case. Although one case treated from 12 days after onset experienced long-term pain resembling postherpetic neuralgia, symptoms in the four cases were completely relieved after antiviral therapy. In summary, the major symptoms of HHV-6 myelitis were superficial pain linked to segmental levels of the spinal cord. Prognosis may be improved by early initiation of antiviral therapy.

Consolidation of molecular testing in clinical virology

INTRODUCTION

The development of quantitative methods for the detection of viral nucleic acids have significantly improved our ability to manage disease progression and to assess the efficacy of antiviral treatment. Moreover, major advances in molecular technologies during the last decade have allowed the identification of new host genetic markers associated with antiviral drug response but have also strongly revolutionized the way we see and perform virus diagnostics in the coming years. Areas covered: In this review, we describe the history and development of virology diagnostic methods, dedicating particular emphasis on the gradual evolution and recent advances toward the introduction of multiparametric platforms for the syndromic diagnosis. In parallel, we outline the consolidation of viral genome quantification practice in different clinical settings. Expert commentary: More rapid, accurate and affordable molecular technology can be predictable with particular emphasis on emerging techniques (next generation sequencing, digital PCR, point of care testing and syndromic diagnosis) to simplify viral diagnosis in the next future.

Infections of the Central Nervous System after Unrelated Donor Umbilical Cord Blood Transplantation or Human Leukocyte Antigen-Matched Sibling Transplantation

We analyzed the incidence, clinical characteristics, prognostic factors, and outcome of central nervous system (CNS) infections in consecutive patients with receiving umbilical cord blood transplantation (UCBT) (n = 343) or HLA-matched sibling donor stem cell transplantation (MST) (n = 366). Thirty-four CNS infections were documented at a median time of 116 days after transplantation (range, 7 to 1161). The cumulative incidence (CI) risk of developing a CNS infection was .6% at day +30, 2.3% at day +90, and 4.9% at 5 years. The 5-year CI of CNS infection was 8.2% after UCBT and 1.7% after MST (P < .001). The causative micro-organisms of CNS infections were fungi (35%), virus (32%), Toxoplasma spp. (12%), and bacteria (12%). Fungal infections occurred in 11 patients after UCBT and 1 after MST and were due to Aspergillus spp. (n = 8), Cryptococcus neoformans (n = 2), Scedosporium prolificans (n = 1), and Mucor (n = 1). Except for 1 patient, all died from CNS fungal infection. Viral infections occurred in 9 patients after UCBT and 1 after MST and were due to human herpes virus 6 (n = 7), cytomegalovirus (n = 2), and varicella zoster virus (n = 1). CNS toxoplasmosis was diagnosed in 3 patients after UCBT and 1 after MST. Other pathogens were Staphylococcus spp, Nocardia spp, Streptococcus pneumoniae, and Mycobacterium tuberculosis. Twenty of the 34 patients (59%) died from the CNS infection. In multivariable analysis, UCBT and disease stage beyond first complete remission were independently associated with the risk of developing CNS infections. The 5-year overall survival was 19% in patients who developed a CNS and 39% for those who did not (P = .006). In conclusion, our study showed that CNS infections are a significant clinical problem after stem cell transplantation associated with poor survival. They were more frequent after UCBT compared to MST.

Human Herpesvirus 6 replication predicts Cytomegalovirus reactivation after allogeneic stem cell transplantation from haploidentical donor

BACKGROUND AND OBJECTIVES

Since HHV-6 reactivation after transplant has been reported to increase the risk of CMV infection, we tested this hypothesis in the HLA-haploidentical hematopoietic stem cell transplantation setting.

STUDY DESIGN

From February 2011 to October 2015, 75 patients received hematopoietic stem cell transplantation using a T-cell replete graft from a HLA-haploidentical donor at our Institution.

RESULTS

Interestingly, 87% of HHV-6 reactivations were followed by a CMV reactivation, at a median of 15days between the two viruses. Incidence of CMV reactivation was 14.5-fold higher in those patients with prior HHV-6 reactivation vs. those without it (p-value<0.001).

CONCLUSION

The present results suggest that HHV-6 can be considered as a predicting indicator of cellular immunosuppression preceding the onset of CMV infection.

Early human herpes virus type 6 reactivation in umbilical cord blood allogeneic stem cell transplantation

Human herpes virus type 6 can reactivate in patients after allogeneic stem cell transplantation and has been associated with serious sequelae such as delayed engraftment and an increased risk of developing acute graft-versus-host disease (GVHD). This study investigated human herpes virus type 6 (HHV-6) reactivation within 60 days of transplantation in stem cell transplants utilizing single umbilical cord blood, double umbilical cord blood, or umbilical cord blood plus haploidentical stem cells. Of 92 patients, 60 (65%) had HHV-6 reactivation. Reactivation was not significantly influenced by any patient characteristics, disease characteristics, or by stem cell source (umbilical cord blood only versus haploidentical plus umbilical cord blood). We did not observe any impact of HHV-6 reactivation on neutrophil or platelet count recovery or on relapse-free survival. HHV-6 reactivation was associated with subsequent development of prerelapse acute GVHD (HR = 3.00; 95% CI, 1.4 to 6.4; p = 0.004).

Human herpesvirus-6 viremia is not associated with poor clinical outcomes in children following allogeneic hematopoietic cell transplantation

HHV-6 is an evolving pathogen in the field of AlloHCT. However, the impact of HHV-6 on AlloHCT outcomes remains to be elucidated. We studied the incidence and clinical impact of HHV-6 viremia in children following AlloHCT. One hundred consecutive children were monitored weekly by plasma PCR for the first 180 days following AlloHCT for HHV-6, CMV, EBV, and ADV. HHV-6 viremia was defined as plasma PCR >1000 viral copies/mL. The median age was nine yr. Following AlloHCT, 19% (95% CI 11.3-26.7%) of patients had HHV-6 viremia, with the highest incidence of reactivation (14/19, 73%) occurring during day +15-day +98. The proportion of platelet engraftment by day +180 was lower in patients with HHV-6 viremia (58%) than in those without HHV-6 viremia (82%), p = 0.028. Delay in neutrophil and platelet engraftment was not associated with HHV-6 viremia in multivariate analysis. Similarly, HHV-6 viremia was not associated with TRM in multivariate analysis (p = 0.15). In summary, HHV-6 viremia is prevalent in pediatric AlloHCT recipients. Based on our study results, we recommend that HHV-6 PCR should only be performed on clinical suspicion.

Human Herpesvirus-6 Pneumonitis around the Engraftment of Cord Blood Transplantation following Foscarnet Prophylaxis in a Patient with Acute Leukemia

Human herpesvirus-6 (HHV-6) reactivation is sometimes observed in immunocompromised patients, especially after allogeneic stem cell transplantation. The complications of HHV-6 reactivation in this setting are mainly recognized as HHV-6 encephalitis. We herein report the case of a patient who developed HHV-6 pneumonitis after cord blood transplantation (CBT). A 35-year-old male underwent CBT for T-cell/myeloid mixed phenotype acute leukemia and achieved neutrophil engraftment on day 31. He had received foscarnet as prophylaxis for HHV-6 reactivation. A computed tomography (CT) scan to evaluate the leukemic tumor showed bilateral interstitial pneumonitis on day 33, although he had no respiratory symptoms. The findings of the CT scan were consistent with those of HHV-6 pneumonitis that were reported previously. HHV-6 DNA, but no other pathogens, was detected in his bronchoalveolar lavage (BAL) fluid. The patient was successfully treated with a therapeutic dose of foscarnet. This case indicates that performing a CT scan around the time of neutrophil engraftment can play an important role in detecting the early phase of HHV-6 pneumonia, and BAL should be considered if features consistent with HHV-6 pneumonitis are observed in patients with a risk of HHV-6 reactivation.

Child and adult forms of human herpesvirus 6 encephalitis: looking back, looking forward

PURPOSE OF REVIEW

This review evaluates publications on human herpesvirus 6 (HHV-6) encephalitis recognizing firstly that HHV-6A and HHV-6B are separate species with differing properties, and secondly the phenomenon of chromosomal integration; this occurs in a minority of persons and the complete viral genome of either HHV-6A or HHV-6B is present in every nucleated cell in the body. Although chromosomal integration has not been associated with disease, the resulting very high level of viral DNA in human tissues and blood has sometimes been wrongly misinterpreted as active infection.

RECENT FINDINGS

No disease has been linked to HHV-6A, whereas HHV-6B may cause encephalitis. Encephalitis due to primary HHV-6B infection in young children is commonly reported from Japan, but very rarely elsewhere in the world, suggesting a genetic predisposition. Reports of HHV-6A or HHV-6B encephalitis in immunocompetent older children/adults are most likely due to chromosomal integration and not active infection. HHV-6B reactivation is well established as causing limbic encephalitis after haematopoietic stem cell transplantation, particularly after receipt of cord blood; the outcome is poor and preventive strategies are ineffective.

SUMMARY

Understanding the pathophysiology of HHV-6B encephalitis remains incomplete, especially regarding young children. Clinical trials of antiviral therapy are warranted for treatment and prevention of HHV-6B encephalitis after transplantation.

Analysis of human herpes virus 6 infections with a quantitative, standardized, commercial kit in pediatric stem cell transplant recipients after transplantation

BACKGROUND AND OBJECTIVES

The aim of the study was to assess the incidence and clinical relevance of active Human Herpes Virus 6 (HHV6) infections in pediatric patients after allogeneic stem cell transplantation.

DESIGN AND SETTINGS

Retrospective analysis of samples prospectively collected at Akdeniz University Medical Faculty Hospital, Antalya, Turkey, between May 2006 and July 2007 from 15 pediatric patients with allogeneic hematopoietic stem cell transplantation (HSCT).

SUBJECTS AND METHODS

A commercial quantitative real-time polymerase chain reaction kit was used to analyze plasma samples collected from 15 pediatric allogeneic HSCT recipients.

RESULTS

HHV6 DNA was found positive in 8 (53%) patients. HHV6 DNA levels above 1000 copies/mL were found only in 2 patients and they were also consecutively positive for HHV6 DNA. Age at transplantation, use of ATG, and receiving grafts other than HLA identical siblings increased the risk, with a statistically significant difference, of having HHV6 reactivation with levels exceeding 1000 copies/mL (P values, respectively, P=.03, .001, .025). Active HHV6 infections with HHV6 viremia levels higher than 1000 copies/mL were associated with subsequent delayed platelet engraftment (P=.001), acute graft versus host disease (P=.001), skin rash, and fever of unknown origin.

CONCLUSION

More than half of pediatric allogeneic HSCT patients develop active HHV6 infection, and especially in patients with high viremic loads, the infection can result in serious clinical situations. A clinically significant cutoff value for viremia seems to be necessary to predict serious clinical complications.

Human herpes virus 6 reactivation: important predictor for poor outcome after myeloablative, but not non-myeloablative allo-SCT

Hematopoietic SCT (HSCT) is often complicated by viral reactivations. In this retrospective cohort study (January 2004-August 2008), predictors for human herpes virus 6 (HHV6)-reactivation and associations between HHV6-reactivation and clinical outcomes after allogeneic HSCT were studied. HHV6 DNA load in plasma was monitored weekly by quantitative real-time PCR. Associations between the main end point HHV6-reactivation and other end points, that is, acute GVHD (aGVHD) and NRM were analyzed using Cox proportional hazard models. In total, 108 patients receiving either a myeloablative (MA; n=60) or non-myeloablative (NMA; n=48) conditioning regimen were included. Median age was 40 years (range 17-65); median follow-up was 20 months (range 3-36). In 16/60 (27%) patients with MA conditioning regimen, a HHV6 reactivation was observed (mean viral load 50 323 cp/mL) compared with 2/48 (4%) patients with a NMA conditioning regimen with low viral load (mean 1100 cp/mL). In multivariate analysis, MA conditioning was the only predictor for HHV6 reactivation (P=0.02). In addition, HHV6 reactivation was associated with grades 2-4 aGVHD (P<0.001) and NRM (P=0.03). Regular monitoring of HHV6 reactivation after HSCT might be important in MA HSCT patients to enable early initiation of antiviral treatment or to anticipate aGVHD, all of which may improve clinical outcome.

Human herpesvirus-6 encephalitis during hematopoietic stem cell transplantation leads to poor prognosis

INTRODUCTION

Indications for the application of hematopoietic stem cell transplantation (HSCT) from alternative donors have remarkably broadened in scope; however, the incidence of infections that lead to failure of HSCT, such as human herpesvirus-6 (HHV-6) encephalitis, has also increased.

METHODS

We analyzed risk factors for symptomatic HHV-6 reactivation and the development of HHV-6 encephalitis in 140 consecutive adult patients who received allogeneic HSCT at our institution. Stem cell sources for the recipients were as follows: related-donor bone marrow in 40, related-donor peripheral blood in 5, unrelated bone marrow in 67, and unrelated cord blood in 28.

RESULTS

Symptomatic HHV-6 reactivation occurred in 22 patients (16%), and 11 patients manifested encephalitis. Multivariate Cox proportional hazards regression analysis identified cord blood cell transplantation (CBT) as an independent predictor of HHV-6 reactivation (P = 0.008). Hyponatremia or hypernatremia at the time of HHV-6 reactivation was detected before the development of HHV-6 encephalitis in 2 or 4 patients, respectively. Two patients died of HHV-6 encephalitis and 6 patients died of relapse of underlying diseases. Survival analysis identified higher risk of the disease (P = 0.021) and HHV-6 encephalitis (P = 0.003) as independent risk factors for reduced overall survival.

CONCLUSION

In cases involving CBT or unrelated-donor transplantation, patients should be carefully monitored for the symptomatic reactivation of HHV-6.

Distinct clinical features of infectious complications in adult T cell leukemia/lymphoma patients after allogeneic hematopoietic stem cell transplantation: a retrospective analysis in the Nagasaki transplant group

Although allogeneic hematopoietic stem cell transplantation (allo-SCT) is performed as a curative option in adult T cell leukemia-lymphoma (ATL) patients, its high transplantation-related mortality raises a serious issue. The clinical features of infectious complications after transplantation are not well known. To analyze the impact of infections after allo-SCT for ATL, we retrospectively compared infectious complications in 210 patients at 3 institutions in Nagasaki prefecture between 1997 and 2009. There were 91 patients with acute myeloid leukemia (AML), 51 with acute lymphoblastic leukemia/lymphoblastic lymphoma (ALL/LBL), and 68 with ATL. No patient received ganciclovir or foscarvir as prophylaxis, and most patients received antifungal prophylaxis with fluconazole or itraconazole. The cumulative incidence of cytomegalovirus (CMV) infection at 3 years was 69.2% in ATL patients versus 54.4% in AML patients (P = .0255). Cumulative infection-related mortality was significantly higher in ATL patients than in the 2 other groups (ATL versus AML, P = .0496; ATL versus ALL/LBL, P = .0075), and most death-causing pathogens were bacteria and fungus. The appearance of CMV infection was negatively associated with infectious mortality in ATL patients, but the P value for this association was near the borderline of significance (P = .0569). In multivariate analysis, transplantation using unrelated bone marrow and episodes of CMV infection were associated with worse overall survival in ATL patients, but were not in either AML or ALL/LBL patients. Collectively, the impact of infectious complications after transplantation in ATL patients was different from that in AML and ALL/LBL patients, suggesting that a more intensive strategy for infection control in ATL patients is required to reduce infectious mortality.

HHV-6 encephalitis in umbilical cord blood transplantation: a systematic review and meta-analysis

Reactivation of human herpesvirus-6 (HHV-6) frequently occurs following hematopoietic SCT (HSCT), and has been associated with clinical consequences in many patient populations. HHV-6 reactivation and HHV-6 encephalitis seem to occur more frequently in patients undergoing HSCT with cord blood (CB) as the stem cell source. We have conducted a systematic literature review and meta-analysis to investigate the clinical significance of this correlation. A systematic review of publications indexed in PubMed was performed for HSCT studies published over the past 10 years that fit inclusion criteria. Data on prevalences of HHV-6 reactivation and HHV-6 encephalitis post HSCT were abstracted from 19 papers. Meta-analyses were conducted to calculate combined prevalence estimates. The prevalences of HHV-6 reactivation and encephalitis were compared among CB vs non-CB HSCT. Prevalences of HHV-6 reactivation and HHV-6 encephalitis were significantly higher in patients receiving CB as the stem cell source than in patients receiving another stem cell source (72.0% vs 37.4%, P<0.0001; 8.3% vs 0.50%, P<0.0001, respectively). HHV-6 reactivation and HHV-6 encephalitis are significant complications in the post-HSCT setting, particularly in patients receiving CB as the stem cell source. Thus, patients undergoing umbilical CB transplantation should be closely monitored for HHV-6 reactivation.

Cord-blood hematopoietic stem cell transplant confers an increased risk for human herpesvirus-6-associated acute limbic encephalitis: a cohort analysis

Human herpesvirus-6 (HHV-6) frequently reactivates after allogeneic hematopoietic stem cell transplantation (HSCT); its most severe manifestation is the syndrome of posttransplantation acute limbic encephalitis (HHV-6-PALE). The epidemiology, risk factors, and characteristics of HHV-6-PALE after unrelated cord-blood transplantation (UCBT) are not well characterized. We analyzed 1344 patients undergoing allogeneic HSCT between March 2003 and March 2010 to identify risk factors and characteristics of HHV-6-PALE. The cohort included 1243 adult-donor HSCT and 101 UCBT recipients. All patients diagnosed with HHV-6-PALE had HHV-6 DNA in cerebrospinal fluid (CSF) specimens in addition to symptoms and studies indicating limbic encephalitis. Nineteen cases (1.4%) of HHV-6-PALE were identified during this study: 10 after UCBT (9.9%) and 9 after adult-donor HSCT (0.7%), for an incidence rate of 1.2 cases/1000 patient-days compared to 0.08 cases/1000 patient-days (P < .001), respectively. Risk factors for HHV-6-PALE on multivariable Cox modeling were UCBT (adjusted hazard ratio [aHR], 20.0; 95% confidence interval [CI], 7.3-55.0; P < .001), time-dependent acute graft-versus-host disease (aGVHD) grades II to IV (aHR, 7.5; 95% CI, 2.8-19.8; P < .001), and adult-mismatched donor (aHR, 4.3; 95% CI, 1.1-17.3; P = .04). Death from HHV-6-PALE occurred in 50% of affected patients undergoing UCBT and no recipients of adult-donor cells. Patients receiving UCBT have increased risk for HHV-6-PALE and greater morbidity from this disease.

Pre-engraftment syndrome after unrelated donor umbilical cord blood transplantation in patients with hematologic malignancies

Pre-engraftment syndrome (PES) after umbilical cord blood transplantation (CBT) remains poorly characterized, and the prognosis and appropriate management are unclear. Therefore, we retrospectively analyzed the incidence, risk factors, manifestations, and clinical outcomes of PES in CBT recipients, who had been treated for hematologic malignancies at our transplantation center. PES was defined as unexplained fever higher than 38.3°C that is not associated with documented infection and unresponsive to antimicrobial manipulations and/or unexplained erythematous skin rash occurring prior to neutrophil engraftment. A total of 81 patients (median 18 yr, range 3-48) received either myeloablative (n=72) or non-myeloablative (n=9) conditioning. Neutrophil engraftment was achieved in 69 of the 81 cases [86.2%, 95% confidence interval (CI)=78.9-94.1%], and the median time to more than 0.5 × 10(9) /L ANC was 19 d (range, 12-39). Fifty-one patients (63.0%) developed PES at a median of 7d (range 3-15) post-transplant: 46 patients had both rash and unexplained fever; one patient had unexplained fever alone; and four patients had rash only. Forty-seven patients (92.2%) received IV methylprednisolone (MP) at a median dose of 1 mg/kg (range 0.4-3). All patients treated with MP responded as evidenced by fever resolution combined with resolution of rash. All patients with PES had high serum levels of C-reactive protein (CRP), which were significantly reduced after effective steroid treatment. Univariate analysis identified myeloablative conditioning and younger age as significant risk factors for developing PES. Cumulative incidence of grade II-IV acute graft-versus-host disease (aGVHD) in the PES+ and PES- groups was 51.5% (95% CI=38.0-70.0%) and 17.0% (95% CI=6.9-41.7%), respectively. In a multivariate analysis, we found significantly increased risk of grade II-IV aGVHD among PES patients (P=0.041). However, PES was not associated with sustained donor engraftment, the day to neutrophil recovery, chronic graft-versus-host disease, transplant-related mortality at day 180, and overall survival. Despite of the inherent limitations of this small retrospective study, PES seemed to be common after CBT and associated with high incidence of aGVHD.

The complex relationship between human herpesvirus 6 and acute graft-versus-host disease

The most frequent manifestation of human herpesvirus 6 (HHV-6) reactivation after allogeneic hematopoietic stem cell transplantation (HSCT) is febrile rash, raising the question of its relationship with graft-versus-host disease (GVHD). In this retrospective analysis of 365 patients who underwent allogeneic HSCT, HHV-6 reactivation was significantly associated with cord blood transplantation (hazard ratio [HR], 3.20; P < .0001) and the use of unrelated donors (HR, 2.02; P = .008). On multivariate analysis, previous GVHD was a predictive factor for HHV-6 reactivation (HR, 1.80; P = .01), and previous HHV-6 reactivation was a predictive factor for acute GVHD (HR, 1.66; P = .03). Nineteen patients with no pathological evidence of GVHD later developed severe clinical GVHD (grade III-IV), suggesting the role of HHV-6 as a trigger for severe GVHD. Furthermore, 17 patients without histopathological GVHD demonstrated a significant lymphoid infiltrate suggesting "pure" HHV-6-related manifestations, and these patients could have been spared steroid therapy.

Human herpesvirus 6 infection after hematopoietic cell transplantation: is routine surveillance necessary?

Human herpesvirus 6 (HHV6) may be an important pathogen following allogeneic hematopoietic cell transplantation (HCT). We prospectively evaluated weekly HHV6 viremia testing after allogeneic HCT using a quantitative polymerase chain reaction (PCR)-based assay. HHV-6 viremia was detected in 46 of 82 (56%) patients at a median of 23 days post-HCT (range: day +10 to +168). More males (65% vs females 39%, P = .03) and recipients of umbilical cord blood (UCB 69% vs unrelated donor [URD], 46% vs sibling donor [20%] grafts, P = 0.01) reactivated HHV-6. Patients with HHV6 viremia had more cytomegalovirus (CMV) reactivation (26% vs 5.5%, P = .01) and unexplained fever and rash (23.9% vs 2.7%, P = .01) compared with patients without HHV6 viremia. High-level HHV6 (≥ 25,000 copies/mL) versus lower levels were associated with more culture-negative pneumonitis (72.7% vs 22.8%, P = .01). Twenty HHV6-positive patients were treated with foscarnet, ganciclovir, or cidofovir for HHV6 or other coexistent viruses. Within 2 weeks, HHV6 viremia resolved more commonly in treated (65%) than untreated patients (31%), P = .02. Survival at 3 months was similar in treated and untreated patients (90% vs 81%, P = .4). Survival at 3 and 6 months post-HCT were not affected by HHV6 positivity (3 months HHV6+ 85% vs 78%, P = .46; 6 months HHV6+ 70% vs 72%, P = .89) or by HHV6 level (3-month high level 73% vs 89%, P = .23; 6-month high level 64% vs 71%, P = .54). Neither the occurrence of HHV6, degree of viremia, nor use of antiviral drugs influenced short-term survival after HCT.

Serious infection risk and immune recovery after double-unit cord blood transplantation without antithymocyte globulin

Factors contributing to infection risk after cord blood transplantation (CBT) include the use of anti-thymocyte globulin (ATG), prolonged neutropenia, and failure to transfer immunity. In the present study, we investigated the potential of double-unit CBT without ATG to reduce the risk of infection and evaluated the nature of serious infections in the first year after CBT using this approach. Seventy-two predominantly adult patients underwent CBT for hematologic malignancies; of these, 52 patients received myeloablative conditioning, and 20 received nonmyeloablative conditioning. The peak incidences of bacterial infections (32%), fungal infections (14%), and bacterial/fungal pneumonias (10%) occurred in the first 30 days posttransplantation. Three such infections contributed to early mortality. The peak incidence of viral infections was 31-60 days posttransplantation, affecting 30% of patients. Cytomegalovirus (CMV) was the most common viral infection. CMV infections occurring before day 120 (n = 23) had no relationship with graft-versus-host disease (GVHD), whereas CMV infections occurring after day 120 (n = 5), along with all cases of Epstein-Barr virus viremia (n = 5) and adenoviral enteritis (n = 2), occurred exclusively in the context of GVHD therapy or corticosteroid use for another indication. Viral infections had the highest lethality: 2 were a direct cause of death, and 3 contributed to death. Patients exhibited steady immune recovery, achieving a median CD3(+)4(+) T cell count >200 cells/μL by day 120 post-CBT, and no infection-related deaths occurred after day 120. Our results suggest that double-unit CBT without ATG is associated with prompt T cell recovery, and, unlike in CBT incorporating ATG, infection is rarely a primary cause of death. However, CBT without ATG is associated with a significant risk of GVHD, and serious infections remain a challenge, especially in the setting of GVHD. New strategies are needed to further reduce infectious complications after CBT; these will require earlier neutrophil recovery and more effective prevention of GVHD, ideally without the profound T cell depletion associated with ATG therapy.