Epstein-Barr virus (EBV) reactivation is a frequent event after allogeneic stem cell transplantation (SCT) and quantitatively predicts EBV-lymphoproliferative disease following T-cell--depleted SCT

Mechanistic Understanding of EBV+Lymphoproliferative Disease Development After Transplantation

Posttransplant lymphoproliferative disorders (PTLDs) are among the most common malignant complications after transplantation, leading to a drastic reduction in patient survival rates. The majority of PTLDs are tightly linked to Epstein-Barr virus (EBV+PTLDs) and are the result of an uncontrolled proliferation of EBV-infected cells. However, although EBV infections are a common finding in transplant recipients, most patients with high EBV loads will never develop EBV+PTLD. Natural killer cells and EBV-specific CD8+ T lymphocytes are critical for controlling EBV-infected cells, and the impairment of these cytotoxic immune responses facilitates the unfettered proliferation of EBV-infected cells. Recent years have seen a considerable increase in available literature aiming to describe novel risk factors associated with the development of EBV+PTLD, which may critically relate to the strength of EBV-specific natural killer cell and EBV-CD8+ T lymphocyte responses. The accumulation of risk factors and the increased risk of developing EBV+PTLD go hand in hand. On the one hand, most of these risk factors, such as the level of immunosuppression or the EBV donor and recipient serologic mismatch, and distinct genetic risk factors are host related and affect cytotoxic EBV-specific immune responses. On the other hand, there is growing evidence that distinct EBV variants may have an increased malignant potential and are thus more likely to induce EBV+PTLD. Here, we aim to review, from a mechanistic point of view, the risk factors for EBV+PTLD in the host and the infecting EBV variants that may explain why only a minority of transplant recipients develop EBV+PTLD.

Cytokine-induced killer cells: new insights for therapy of hematologic malignancies

BACKGROUND

Cytokine-induced killer (CIK) cells are a novel subgroup of immune effectors, classified as one of the modified T cell-mediated arms for immunotherapy. These cells exert MHC-unrestricted cytotoxicity against both hematological and solid malignancies with low incidence of treatment-related severe complications. This study reviews the application of CIK cells in treating cases with hematologic malignancies.

MAIN BODY

CIK cells consist of CD3+/CD56+  natural killer (NK) T cells, CD3-/CD56+ NK cells, and CD3+/CD56- cytotoxic T cells. In this regard, the CD3+/CD56+  NK T cells are the primary effectors. Compared with the previously reported antitumor immune cells, CIK cells are characterized by improved in vitro proliferation and amplification, enhanced migration and invasive capacity to tumor region, more significant antitumor activity, and a broader antitumor spectrum. CIK cells can also induce death in tumor cells via numerous pathways and mechanisms. Hence, CIKs-based therapy has been used in various clinical trials and has shown efficacy with a very low graft versus host disease (GVHD) against several cancers, such as hematologic malignancies, even in relapsing cases, or cases not responding to other therapies. Despite the high content of T cells, CIK cells induce low alloreactivity and, thus, pose a restricted threat of GVHD induction even in MHC-mismatched transplantation cases. Phase 1 and 2 clinical trials of CIK cell therapy have also highlighted satisfactory therapeutic advantages against hematologic cancers, indicating the safety of CIK cells even in haploidentical transplantation settings.

CONCLUSION

CIK cells have shown promising results in the treatment of hematologic malignancies, especially in combination with other antitumor strategies. However, the existing controversies in achieving desired clinical responses underscore the importance of future studies.

Advances and prospect in herpesviruses infections after haematopoietic cell transplantation: closer to the finish line?

BACKGROUND

Herpesviruses represent common and significant infectious complications after allogeneic haematopoietic cell transplantation (HCT). In the last decade, major advances in the prevention and treatment of these infections were accomplished.

OBJECTIVES

The aim of this paper is to review the recent advances in the prophylaxis and treatment of herpesvirus infections after allogeneic HCT, to assess the persisting challenges, and to offer future directions for the prevention and management of these infections.

SOURCES

We searched PubMed for relevant literature regarding specific herpesviruses complicating allogeneic HCT through March 2024.

CONTENT

The largest advances in this past decade were witnessed for cytomegalovirus (CMV) with the advent of letermovir for primary prophylaxis and the development of maribavir as an option for refractory and/or resistant CMV infections in transplant recipients. For varicella zoster virus, prevention of reactivation with the recombinant zoster vaccine offers an additional prophylactic intervention. Pritelivir is being explored for the treatment of drug-resistant or refractory Herpes simplex virus infections. Although rituximab is now an established option for preemptive therapy for Epstein-Barr virus, Human Herpesvirus-6 remains the most elusive virus of the herpesvirus family, with a lack of evidence supporting the benefit of any agent for prophylaxis or for optimal preemptive therapy.

IMPLICATIONS

Although considerable advances have been achieved for the treatment and prevention of herpes virus infections, most notably with CMV, the coming years should hold additional opportunities to tame the beast in these herpesviruses postallogeneic HCT, with the advent of new antivirals, cell-mediated immunity testing, and cytotoxic T lymphocytes infusions.

Update: The molecular spectrum of virus-associated high-grade B-cell non-Hodgkin lymphomas

The vast spectrum of aggressive B-cell non-Hodgkin neoplasms (B-NHL) encompasses several infrequent entities occurring in association with viral infections, posing diagnostic challenges for practitioners. In the emerging era of precision oncology, the molecular characterization of malignancies has acquired paramount significance. The pathophysiological comprehension of specific entities and the identification of targeted therapeutic options have seen rapid development. However, owing to their rarity, not all entities have undergone exhaustive molecular characterization. Considerable heterogeneity exists in the extant body of work, both in terms of employed methodologies and the scale of cases studied. Presently, therapeutic strategies are predominantly derived from observations in diffuse large B-cell lymphoma (DLBCL), the most prevalent subset of aggressive B-NHL. Ongoing investigations into the molecular profiles of these uncommon virus-associated entities are progressively facilitating a clearer distinction from DLBCL, ultimately paving the way towards individualized therapeutic approaches. This review consolidates the current molecular insights into aggressive and virus-associated B-NHL, taking into consideration the recently updated 5th edition of the WHO classification of hematolymphoid tumors (WHO-5HAEM) and the International Consensus Classification (ICC). Additionally, potential therapeutically targetable susceptibilities are highlighted, offering a comprehensive overview of the present scientific landscape in the field.

Clinical characteristics and outcomes of Epstein-Barr virus viral load after allogeneic hematopoietic stem cell transplantation

Epstein-Barr virus (EBV) reactivation can occur following allogenic hematopoietic stem cell transplantation (allo-HSCT). However, the clinical characteristics and outcomes of EBV-viral load are not well known. Thus, we retrospectively analyzed the clinical features and prognostic impact of the EBV viral load in 121 allo-HSCT recipients from our hospital. EBV DNA quantification was performed in whole blood after transplantation. Patients were grouped based on whether EBV DNA quantification reached > 1000 copies/mL during follow-up (N = 50) or not (N = 71). Patients with EBV > 1000 EBV copies/mL were relatively more common in the groups with graft versus host disease (GVHD) prophylaxis including ATG, haploidentical donor type, peripheral blood as a donor source, and acute GVHD II-IV. The 20-month OS and DFS were not significantly different between patients with < 1000 EBV copies/mL and patients with > 1000 EBV copies/mL (20-month OS, 56.0% vs. 60.6%; p = 0.503, 20-month DFS, 50.0% vs. 57.7%; p = 0.179). Immunosuppressant (ISS) dose reduction was achieved after the maximum increase in EBV in 41/50 (82%) patients. Additionally, 30/50 (60%) patients achieved a 50% dose reduction or no restarting of ISS within 3 months of the maximum EBV increase. Among cases wherein EBV DNA quantification reached > 1000 copies/mL, those that achieved rapid dose reduction of ISS tended to have longer overall survival ("not reached" vs 5.4 months, p < 0.001) and disease-free survival (88.4 months vs 5.3 months, p < 0.001) than those in patients who did not. Our data highlight the importance of rapid ISS reduction in post-transplant EBV reactivation.

Post-transplant cyclophosphamide versus anti-thymocyte globulin after reduced intensity peripheral blood allogeneic cell transplantation in recipients of matched sibling or 10/10 HLA matched unrelated donors: final analysis of a randomized, open-label, multicenter, phase 2 trial

The use of post-transplantation cyclophosphamide (PTCy) for graft-versus-host disease (GVHD) prophylaxis is not established after reduced intensity conditioning (RIC) hematopoietic stem cell transplantation (HSCT) from fully matched donors. This was a randomized, open-label, multicenter, phase 2 trial. All patients received a RIC regimen with fludarabine, intravenous busulfan for 2 days (Flu-Bu2), and a peripheral blood stem cell (PBSC) graft from a matched related or 10/10 HLA-matched unrelated donor. Patients were randomly assigned to receive anti-thymocyte globulin (ATG) 5 mg/kg plus standard GVHD prophylaxis or PTCy 50 mg/kg/d at days +3 and +4 plus standard GVHD prophylaxis. The primary endpoint was the composite endpoint of GVHD- and relapse-free survival (GRFS) at 12 months after HSCT. Eighty-nine patients were randomly assigned to receive either PTCy or control prophylaxis with ATG. At 12 months, disease-free survival was 65.9% in the PTCy group and 67.6% in the ATG group (P = 0.99). Cumulative incidence of relapse, non-relapse mortality, and overall survival were also comparable in the two groups. GRFS at 12 months was 54.5% in the PTCy group versus 43.2% in the ATG group (P = 0.27). The median time to neutrophil and platelet count recovery was significantly longer in the PTCy group compared to the ATG group. Except for day +30, where EORTC QLQ-C30 scores were significantly lower in the PTCy compared to the ATG group, the evolution with time was not different between the two groups. Although the primary objective was not met, PTCy is effective for GVHD prophylaxis in patients receiving Flu-Bu2 conditioning with a PBSC graft from a fully matched donor and was well tolerated in term of adverse events and quality of life. This trial was registered at clinicaltrials.gov: NCT02876679.

Viral meningoencephalitis in pediatric solid organ or hematopoietic cell transplant recipients: a diagnostic and therapeutic approach

Neurologic complications, both infectious and non-infectious, are frequent among hematopoietic cell transplant (HCT) and solid organ transplant (SOT) recipients. Up to 46% of HCT and 50% of SOT recipients experience a neurological complication, including cerebrovascular accidents, drug toxicities, as well as infections. Defects in innate, adaptive, and humoral immune function among transplant recipients predispose to opportunistic infections, including central nervous system (CNS) disease. CNS infections remain uncommon overall amongst HCT and SOT recipients, compromising approximately 1% of total cases among adult patients. Given the relatively lower number of pediatric transplant recipients, the incidence of CNS disease amongst in this population remains unknown. Although infections comprise a small percentage of the neurological complications that occur post-transplant, the associated morbidity and mortality in an immunosuppressed state makes it imperative to promptly evaluate and aggressively treat a pediatric transplant patient with suspicion for viral meningoencephalitis. This manuscript guides the reader through a broad infectious and non-infectious diagnostic differential in a transplant recipient presenting with altered mentation and fever and thereafter, elaborates on diagnostics and management of viral meningoencephalitis. Hypothetical SOT and HCT patient cases have also been constructed to illustrate the diagnostic and management process in select viral etiologies. Given the unique risk for various opportunistic viral infections resulting in CNS disease among transplant recipients, the manuscript will provide a contemporary review of the epidemiology, risk factors, diagnosis, and management of viral meningoencephalitis in these patients.

Pre-Emptive Use of Rituximab in Epstein-Barr Virus Reactivation: Incidence, Predictive Factors, Monitoring, and Outcomes

Post-transplant lymphoproliferative disease (PTLD) is a fatal complication of hematopoietic cell transplantation (HCT) associated with the Epstein-Barr virus (EBV). Multiple factors such as transplant type, graft-versus-host disease (GVHD), human leukocyte antigens (HLA) mismatch, patient age, and T-lymphocyte-depleting treatments increase the risk of PTLD. EBV reactivation in hematopoietic cell transplant recipients is monitored through periodic quantitative polymerase chain reaction (Q-PCR) tests. However, substantial uncertainty persists regarding the clinically significant EBV levels for these patients. Guidelines recommend initiating EBV monitoring no later than four weeks post-HCT and conducting it weekly. Pre-emptive therapies, such as the reduction of immunosuppressive therapy and the administration of rituximab to treat EBV viral loads are also suggested. In this study, we investigated the occurrence of EBV-PTLD in 546 HCT recipients, focusing on the clinical manifestations and risk factors associated with the disease. We managed to identify 67,150 viral genomic copies/mL as the cutoff point for predicting PTLD, with 80% sensitivity and specificity. Among our cohort, only 1% of the patients presented PTLD. Anti-thymocyte globulin (ATG) and GVHD were independently associated with lower survival rates and higher treatment-related mortality. According to our findings, prophylactic measures including regular monitoring, pre-emptive therapy, and supportive treatment against infections can be effective in preventing EBV-related complications. This study also recommends conducting EBV monitoring at regular intervals, initiating pre-emptive therapy when viral load increases, and identifying factors that increase the risk of PTLD. Our study stresses the importance of frequent and careful follow-ups of post-transplant complications and early intervention in order to improve survival rates and reduce mortality.

Screening and Management of PTLD

Posttransplant lymphoproliferative disorder (PTLD) represents a heterogeneous group of lymphoproliferative diseases occurring in the setting of immunosuppression following hematopoietic stem cells transplant and solid organ transplantation. Despite its overall low incidence, PTLD is a serious complication following transplantation, with a mortality rate as high as 50% in transplant recipients. Therefore, it is important to establish for each transplant recipient a personalized risk evaluation for the development of PTLD based on the determination of Epstein-Barr virus serostatus and viral load following the initiation of immunosuppression. Due to the dynamic progression of PTLD, reflected in the diverse pathological features, different therapeutic approaches have been used to treat this disorder. Moreover, new therapeutic strategies based on the administration of virus-specific cytotoxic T cells have been developed. In this review, we summarize the available data on screening and treatment to suggest a strategy to identify transplant recipients at a higher risk for PTLD development and to review the current therapeutic options for PTLD.

NLRP3 and cancer: Pathogenesis and therapeutic opportunities

More than a decade ago IL-1 blockade was suggested as an add-on therapy for the treatment of cancer. This proposal was based on the overall safety record of anti-IL-1 biologics and the anti-tumor properties of IL-1 blockade in animal models of cancer. Today, a new frontier in IL-1 activity regulation has developed with several orally active NLRP3 inhibitors currently in clinical trials, including cancer. Despite an increasing body of evidence suggesting a role of NLRP3 and IL-1-mediated inflammation driving cancer initiation, immunosuppression, growth, and metastasis, NLRP3 activation in cancer remains controversial. In this review, we discuss the recent advances in the understanding of NLRP3 activation in cancer. Further, we discuss the current opportunities for NLRP3 inhibition in cancer intervention with novel small molecules.

Aplastic Anemia with Epstein-Barr Virus Reactivation after Anti-thymocyte Globulin Therapy

Lymphoproliferative disorders and Epstein-Barr virus reactivation (EBV-LPDs) have various forms of onset, ranging from infectious mononucleosis-like syndrome (IM-like) to lymphoma, although whether or not IM-like progresses to lymphoma remains unclear. A 61-year-old man was diagnosed with aplastic anemia (AA). Polyclonal atypical B-lymphocytes were observed in the peripheral blood, and IM-like was diagnosed. Atypical lymphocytes disappeared, but a gastrointestinal examination revealed diffuse large B-cell lymphoma (DLBCL). Rituximab was initiated but later discontinued because of severe acute respiratory syndrome coronavirus 2 infection. Pancytopenia due to AA exacerbation recurred. The patient ultimately died of multiple organ failure due to bacterial infection.

[Dynamic monitoring of plasma Epstein-Barr Virus DNA load can predict the occurrence of lymphoproliferative disorders after haploidentical hematopoietic stem cell transplantation]

Objective: To determine the optimal cutoff value of Epstein-Barr virus (EBV) DNA load that can assist in the diagnosis of post-transplant lymphoproliferative disease (PTLD) after haploidentical hematopoietic stem cell transplantation (haplo-HSCT) . Methods: The data of patients with EBV infection after haplo-HSCT from January to December 2016 were retrospectively analyzed. Through constructing the receiver operating characteristic (ROC) curve and calculating the Youden index to determine the cutoff value of EBV-DNA load and its duration of diagnostic significance for PTLD. Results: A total of 94 patients were included, of whom 20 (21.3% ) developed PTLD, with a median onset time of 56 (40-309) d after transplantation. The median EBV value at the time of diagnosis of PTLD was 70,400 (1,710-1,370,000) copies/ml, and the median duration of EBV viremia was 23.5 (4-490) d. Binary logistic regression was used to analyze the peak EBV-DNA load (the EBV-DNA load at the time of diagnosis in the PTLD group) and duration of EBV viremia between the PTLD and non-PTLD groups. The results showed that the difference between the two groups was statistically significant (P=0.018 and P=0.001) . The ROC curve was constructed to calculate the Youden index, and it was concluded that the EBV-DNA load ≥ 41 850 copies/ml after allogeneic hematopoietic stem cell transplantation had diagnostic significance for PTLD (AUC=0.847) , and the sensitivity and specificity were 0.611 and 0.932, respectively. The duration of EBV viremia of ≥20.5 d had diagnostic significance for PTLD (AUC=0.833) , with a sensitivity and specificity of 0.778 and 0.795, respectively. Conclusion: Dynamic monitoring of EBV load in high-risk patients with PTLD after haplo-HSCT and attention to its duration have important clinical significance, which can help clinically predict the occurrence of PTLD in advance and take early intervention measures.

HLA-E-restricted immune responses are crucial for the control of EBV infections and the prevention of PTLD

Primary Epstein-Barr virus (EBV) infections may cause infectious mononucleosis (IM), whereas EBV reactivations in solid organ and hematopoietic stem cell transplant recipients are associated with posttransplantation lymphoproliferative disorders (PTLDs). It is still unclear why only a minority of primary EBV-infected individuals develop IM, and why only some patients progress to EBV+PTLD after transplantation. We now investigated whether nonclassic human leukocyte antigen E (HLA-E)-restricted immune responses have a significant impact on the development of EBV diseases in the individual host. On the basis of a large study cohort of 1404 patients and controls as well as on functional natural killer (NK) and CD8+ T-cell analyses, we could demonstrate that the highly expressed HLA-E∗0103/0103 genotype is protective against IM, due to the induction of potent EBV BZLF1-specific HLA-E-restricted CD8+ T-cell responses, which efficiently prevent the in vitro viral dissemination. Furthermore, we provide evidence that the risk of symptomatic EBV reactivations in immunocompetent individuals as well as in immunocompromised transplant recipients depends on variations in the inhibitory NKG2A/LMP-1/HLA-E axis. We show that EBV strains encoding for the specific LMP-1 peptide variants GGDPHLPTL or GGDPPLPTL, presented by HLA-E, elicit strong inhibitory NKG2A+ NK and CD8+ T-cell responses. The presence of EBV strains encoding for both peptides was highly associated with symptomatic EBV reactivations. The further progression to EBV+PTLD was highly associated with the presence of both peptide-encoding EBV strains and the expression of HLA-E∗0103/0103 in the host. Thus, HLA-E-restricted immune responses and the NKG2A/LMP-1/HLA-E axis are novel predictive markers for EBV+PTLD in transplant recipients and should be considered for future EBV vaccine design.

Metagenomic next-generation sequencing for pleural effusions induced by viral pleurisy: A case report

BACKGROUND

Viral pleurisy is a viral infected disease with exudative pleural effusions. It is one of the causes for pleural effusions. Because of the difficult etiology diagnosis, clinically pleural effusions tend to be misdiagnosed as tuberculous pleurisy or idiopathic pleural effusion. Here, we report a case of pleural effusion secondary to viral pleurisy which is driven by infection with epstein-barr virus. Viral infection was identified by metagenomic next-generation sequencing (mNGS).

CASE SUMMARY

A 40-year-old male with a history of dermatomyositis, rheumatoid arthritis, and secondary interstitial pneumonia was administered with long-term oral prednisone. He presented with fever and chest pain after exposure to cold, accompanied by generalized sore and weakness, night sweat, occasional cough, and few sputums. The computed tomography scan showed bilateral pleural effusions and atelectasis of the partial right lower lobe was revealed. The pleural fluids were found to be yellow and slightly turbid after pleural catheterization. Thoracoscopy showed fibrous adhesion and auto-pleurodesis. Combining the results in pleural fluid analysis and mNGS, the patient was diagnosed as viral pleuritis. After receiving Aciclovir, the symptoms and signs of the patient were relieved.

CONCLUSION

Viral infection should be considered in cases of idiopathic pleural effusion unexplained by routine examination. mNGS is helpful for diagnosis.

Diagnostic Value of Whole-Blood and Plasma Samples in Epstein-Barr Virus Infections

Epstein-Barr virus (EBV) is an oncogenic virus classified by the World Health Organization as a class 1 carcinogen. Post-transplant lymphoproliferative disorders are believed to be strongly related to an EBV infection. Monitoring of EBV DNAemia is recommended to assess the risk of reactivation of latent infection and to assess the effectiveness of therapy. Currently, various types of clinical specimens are used for this purpose. The aim of the study was to assess a reliable method of EBV viral load investigation depending on the clinical material used: whole blood or plasma samples. We found that of 134 EBV-DNA-positive whole-blood samples derived from 51 patients (mostly hemato-oncology or post-transplantation), only 43 (32.1%) were plasma-positive. Of these, 37 (86.0%) had lower plasma DNAemia compared to the corresponding whole-blood samples. We conclude that whole-blood samples have a higher sensitivity than plasma samples in EBV DNA detection. The clinical utility of the tests is unclear, but our results suggest that either whole blood or plasma should be used consistently for EBV viral load monitoring.

Rituximab Toxicity after Preemptive or Therapeutic Administration for Post-Transplant Lymphoproliferative Disorder

Rituximab is commonly used as prevention, preemption, or therapeutically for post-transplant lymphoproliferative disorder (PTLD) after hematopoietic cell transplantation (HCT). Although it is generally assumed that rituximab toxicity (ie, infections resulting from hypogammaglobulinemia and neutropenia) is negligible in relation to mortality due to PTLD, limited evidence supports the validity of this assumption. We sought to determine the impact of rituximab on immunoglobulin levels, neutrophil count, infection density, and mortality outcomes. This study retrospectively analyzed 349 HCT recipients, 289 of whom did not receive rituximab and 60 of whom received rituximab preemptively or therapeutically at a median of 55 days post-transplantation. IgM, IgG, and IgA levels at 6 months and 12 months post-transplantation were lower in patients who received rituximab compared with those who did not (significant at P < .05 for IgM and IgA at 6 months and for IgM and IgG at 12 months). Rituximab recipients also had a higher incidence of severe neutropenia (<.5/nl) between 3 and 24 months (subhazard ratio [SHR], 2.3; P = .020). Regarding non-Epstein-Barr viral infections/PTLD, the rituximab group had a higher infection density between 3 and 24 months compared with the no-rituximab group (3.8 versus 1.6 infections per 365 days at risk; incidence rate ratio, 2.2; P < .001). The rituximab group also had a higher incidence of fatal infections (SHR, 3.1; P = .026), higher nonrelapse mortality (SHR, 2.4; P = .006), and higher overall mortality (hazard ratio, 1.7; P = .033). There were no significant between-group differences in the incidence of clinically significant graft-versus-host disease, graft failure, or relapse. Based on this study, rituximab given for PTLD is associated with substantial morbidity and mortality. Whether the benefit of preemptive rituximab outweighs the risk remains to be determined. © 2022 American Society for Transplantation and Cellular Therapy. Published by Elsevier Inc.

Machine learning algorithm as a prognostic tool for Epstein-Barr virus reactivation after haploidentical hematopoietic stem cell transplantation

Epstein-Barr virus (EBV) reactivation is one of the most important infections after hematopoietic stem cell transplantation (HSCT) using haplo-identical related donors (HID). We aimed to establish a comprehensive model with machine learning, which could predict EBV reactivation after HID HSCT with anti-thymocyte globulin (ATG) for graft-versus-host disease (GVHD) prophylaxis. We enrolled 470 consecutive acute leukemia patients, 60% of them (n = 282) randomly selected as a training cohort, the remaining 40% (n = 188) as a validation cohort. The equation was as follows: Probability (EBV reactivation) =   1 1       +       e x p ( - Y ) , where Y = 0.0250 × (age) - 0.3614 × (gender) + 0.0668 × (underlying disease) - 0.6297 × (disease status before HSCT) - 0.0726 × (disease risk index) - 0.0118 × (hematopoietic cell transplantation-specific comorbidity index [HCT-CI] score) + 1.2037 × (human leukocyte antigen disparity) + 0.5347 × (EBV serostatus) + 0.1605 × (conditioning regimen) - 0.2270 × (donor/recipient gender matched) + 0.2304 × (donor/recipient relation) - 0.0170 × (mononuclear cell counts in graft) + 0.0395 × (CD34+ cell count in graft) - 2.4510. The threshold of probability was 0.4623, which separated patients into low- and high-risk groups. The 1-year cumulative incidence of EBV reactivation in the low- and high-risk groups was 11.0% versus 24.5% (P < .001), 10.7% versus 19.3% (P = .046), and 11.4% versus 31.6% (P = .001), respectively, in total, training and validation cohorts. The model could also predict relapse and survival after HID HSCT. We established a comprehensive model that could predict EBV reactivation in HID HSCT recipients using ATG for GVHD prophylaxis.

Recent Advances in Adult Post-Transplant Lymphoproliferative Disorder

PTLD is a rare but severe complication of hematopoietic or solid organ transplant recipients, with variable incidence and timing of occurrence depending on different patient-, therapy-, and transplant-related factors. The pathogenesis of PTLD is complex, with most cases of early PLTD having a strong association with Epstein-Barr virus (EBV) infection and the iatrogenic, immunosuppression-related decrease in T-cell immune surveillance. Without appropriate T-cell response, EBV-infected B cells persist and proliferate, resulting in malignant transformation. Classification is based on the histologic subtype and ranges from nondestructive hyperplasias to monoclonal aggressive lymphomas, with the most common subtype being diffuse large B-cell lymphoma-like PTLD. Management focuses on prevention of PTLD development, as well as therapy for active disease. Treatment is largely based on the histologic subtype. However, given lack of clinical trials providing evidence-based data on PLTD therapy-related outcomes, there are no specific management guidelines. In this review, we discuss the pathogenesis, histologic classification, and risk factors of PTLD. We further focus on common preventive and frontline treatment modalities, as well as describe the application of novel therapies for PLTD and elaborate on potential challenges in therapy.

Reconstitution of EBV-directed T cell immunity by adoptive transfer of peptide-stimulated T cells in a patient after allogeneic stem cell transplantation for AITL

Reconstitution of the T cell repertoire after allogeneic stem cell transplantation is a long and often incomplete process. As a result, reactivation of Epstein-Barr virus (EBV) is a frequent complication that may be treated by adoptive transfer of donor-derived EBV-specific T cells. We generated donor-derived EBV-specific T cells by stimulation with peptides representing defined epitopes covering multiple HLA restrictions. T cells were adoptively transferred to a patient who had developed persisting high titers of EBV after allogeneic stem cell transplantation for angioimmunoblastic T-cell lymphoma (AITL). T cell receptor beta (TCRβ) deep sequencing showed that the T cell repertoire of the patient early after transplantation (day 60) was strongly reduced and only very low numbers of EBV-specific T cells were detectable. Manufacturing and in vitro expansion of donor-derived EBV-specific T cells resulted in enrichment of EBV epitope-specific, HLA-restricted T cells. Monitoring of T cell clonotypes at a molecular level after adoptive transfer revealed that the dominant TCR sequences from peptide-stimulated T cells persisted long-term and established an EBV-specific TCR clonotype repertoire in the host, with many of the EBV-specific TCRs present in the donor. This reconstituted repertoire was associated with immunological control of EBV and with lack of further AITL relapse.

A characteristic feature of all herpesviruses is their persistence in the host’s body after primary infection. Hence, the host’s immune system is confronted with the problem to control these viruses life-long. When the immune system is severely compromised, for example after stem cell transplantation from a foreign (allogeneic) donor, these viruses can reappear, as they persist in the host’s body life-long after primary infection. Epstein-Barr virus (EBV) is a herpesvirus that can cause life-threatening complications after stem cell transplantation and only reinforcement of the host’s immune system can reestablish control over the virus. Here we show that ex vivo manufactured EBV-specific T cells can reestablish long-term control of EBV and that these cells persist in the host’s body over months. These results give us a better understanding of viral immune reconstitution post-transplant and of clinically-relevant T cell populations against EBV.

Cytomegalovirus and other herpesviruses after hematopoietic cell and solid organ transplantation: From antiviral drugs to virus-specific T cells

Herpesviruses can either cause primary infection or may get reactivated after both hematopoietic cell and solid organ transplantations. In general, viral infections increase post-transplant morbidity and mortality. Prophylactic, preemptive, or therapeutically administered antiviral drugs may be associated with serious side effects and may induce viral resistance. Virus-specific T cells represent a valuable addition to antiviral treatment, with high rates of response and minimal side effects. Even low numbers of virus-specific T cells manufactured by direct selection methods can reconstitute virus-specific immunity after transplantation and control viral replication. Virus-specific T cells belong to the advanced therapy medicinal products, and their production is regulated by appropriate legislation; also, strict safety regulations are required to minimize their side effects.

Viral infections in lung transplantation

Viral infections account for up to 30% of all infectious complications in lung transplant recipients, remaining a significant cause of morbidity and even mortality. Impact of viral infections is not only due to the direct effects of viral replication, but also to immunologically-mediated lung injury that may lead to acute rejection and chronic lung allograft dysfunction. This has particularly been seen in infections caused by herpesviruses and respiratory viruses. The implementation of universal preventive measures against cytomegalovirus (CMV) and influenza (by means of antiviral prophylaxis and vaccination, respectively) and administration of early antiviral treatment have reduced the burden of these diseases and potentially their role in affecting allograft outcomes. New antivirals against CMV for prophylaxis and for treatment of antiviral-resistant CMV infection are currently being evaluated in transplant recipients, and may continue to improve the management of CMV in lung transplant recipients. However, new therapeutic and preventive strategies are highly needed for other viruses such as respiratory syncytial virus (RSV) or parainfluenza virus (PIV), including new antivirals and vaccines. This is particularly important in the advent of the COVID-19 pandemic, for which several unanswered questions remain, in particular on the best antiviral and immunomodulatory regimen for decreasing mortality specifically in lung transplant recipients. In conclusion, the appropriate management of viral complications after transplantation remain an essential step to continue improving survival and quality of life of lung transplant recipients.

A Case of Central Nervous System Post-Transplant Lymphoproliferative Disorder Following Haploidentical Stem Cell Transplantation in a Patient With Acute Lymphoblastic Leukemia

We present a differential diagnosis of an intracranial lesion following haploidentical stem cell transplantation (haplo-SCT) in a female patient with acute lymphoblastic leukemia (ALL). This patient received an anti-CD19-chimeric antigen receptor (CAR) T-cell therapy for refractory B-cell ALL and obtained minimal residual disease (MRD)-positive (0.03%) complete remission (CR). Then the patient received a bridging therapy of haplo-SCT. After bridging therapy, the patient maintained MRD-negative and full donor chimerism in bone marrow (BM) and was negative for Epstein–Barr virus (EBV)-DNA copy in peripheral blood. At 91 days after haplo-SCT, the patient presented with dizziness and fatigue and magnetic resonance imaging (MRI) demonstrated an intracranial lesion. The diagnosis of isolated extramedullary relapse (IEMR) was temporarily considered. Then next-generation sequencing (NGS) identified positive EBV-DNA in the cerebrospinal fluid, although EBV-DNA in the peripheral blood was negative. Furthermore, the positive EBV-DNA by NGS and complete donor chimerism in the brain tissue confirmed the diagnosis of central nervous system post-transplant lymphoproliferative disorder (CNS-PTLD). However, the EBV-encoded small RNAs (EBERs) in situ hybridization was sparsely positive. The patient was subsequently treated with anti-CD22-CAR T cells in combination with Zanubrutinib, but the disease progressed quickly and died. Donor chimerism examination of focal biopsy provides important evidence for diagnosing PTLD. Furthermore, NGS detection of EBV-DNA in local lesions is more valuable for diagnosing PTLD than detection of EBV-DNA in the peripheral blood.

Trial registration: The patient was enrolled in a clinical trial of ChiCTR1800019622 and ChiCTR1800019298.

Newer developments in viral hepatitis: Looking beyond hepatotropic viruses

Viral hepatitis in the entirety of its clinical spectrum is vast and most discussion are often restricted to hepatotropic viral infections, including hepatitis virus (A to E). With the advent of more advanced diagnostic techniques, it has now become possible to diagnose patients with non-hepatotropic viral infection in patients with hepatitis. Majority of these viruses belong to the Herpes family, with characteristic feature of latency. With the increase in the rate of liver transplantation globally, especially for the indication of acute hepatitis, it becomes even more relevant to identify non hepatotropic viral infection as the primary hepatic insult. Immunosuppression post-transplant is an established cause of reactivation of a number of viral infections that could then indirectly cause hepatic injury. Antiviral agents may be utilized for treatment of most of these infections, although data supporting their role is derived primarily from case reports. There are no current guidelines to manage patients suspected to have viral hepatitis secondary to non-hepatotropic viral infection, a gap that needs to be addressed. In this review article, the authors analyze the common non hepatotropic viral infections contributing to viral hepatitis, with emphasis on recent advances on diagnosis, management and role of liver transplantation.

Long-term survival with mixed chimerism in patients with AML and MDS transplanted after conditioning with targeted busulfan, fludarabine, and thymoglobulin

We evaluated long-term outcome in 40 patients with MDS or AML, transplanted from related or unrelated donors following conditioning with targeted busulfan (Bu, over 4 days), fludarabine (Flu, 120 [n = 23] or 250 [n = 17] mg/m²) and thymoglobulin (THY). Compared to 95 patients conditioned with Bu/Cyclophosphamide (Cy) without THY, BuFluTHY-conditioned patients had lower rates of chronic graft-vs.-host disease (GVHD). Adjusted hazard ratios (HR) for BuFlu(120)THY and BuFlu(250)THY-conditioned patients were 1.60 (95% confidence interval (CI) 0.66-3.86) and 1.87 (0.68-5.11), respectively, for relapse; 0.77 (0.30-1.99) and 1.32 (0.54-3.23) for non-relapse mortality; 0.81 (0.42-1.57) and 1.38 (0.72-2.57) for overall mortality; and 0.78 (0.30-2.05) and 1.62 (0.63-4.41) for relapse or death (failure for relapse-free survival). At one year, 45% of BuFlu(120 or 250)THY-conditioned patients had mixed CD3+ chimerism compared to 0% with BuCy (p < 0.0001). None of 7 patients with long-term mixed chimerism had chronic GVHD; two relapsed, five remained stable mixed chimeras. THY is effective in reducing chronic GVHD, and long-term mixed T-cell chimerism can be compatible with relapse-free survival. However, Thy may also be associated with an increased risk of relapse and, dose-dependent, with non-relapse mortality.

Risk factors for post-transplant Epstein-Barr virus events in pediatric recipients of hematopoietic stem cell transplants

BACKGROUND

Epstein-Barr virus (EBV) can cause severe disease following hematopoietic stem cell transplant (HSCT), including post-transplant lymphoproliferative disorder (PTLD). The objective was to analyze risk factors associated with post-transplant EBV outcomes among pediatric allogeneic HSCT recipients.

METHODS

We used data from 156 pediatric allogeneic HSCT recipients enrolled in the Canadian multicenter TREASuRE study. Cox and Prentice-Williams-Petersen models were used to analyze risk factors for post-transplant EBV events including occurrence and recurrence of EBV DNAemia, increase in EBV viral load (EBV-VL), and preemptive use of rituximab, an effective therapy against PTLD.

RESULTS

Females were at higher risk for increasing EBV-VL (adjusted hazard ratio (HR) = 2.83 [95% confidence intervals (CI): 1.33-6.03]) and rituximab use (HR = 3.08 [1.14-8.30]), but had the same EBV DNAemia occurrence (HR = 1.21 [0.74-1.99]) and recurrence risks (HR=1.05 [0.70-1.58]) compared to males. EBV DNAemia was associated with recipient pre-transplant EBV seropositivity (HR = 2.47 [1.17-5.21]) and with graft from an EBV-positive donor (HR = 3.53 [1.95-6.38]). Anti-thymocyte globulin (ATG) was strongly associated with all EBV outcomes, including the use of rituximab (HR = 5.33 [1.47-19.40]). Mycophenolate mofetil (MMF) significantly decreased the risk of all EBV events including the rituximab use (HR = 0.13 [0.03-0.63]).

CONCLUSION

This study in pediatric allogeneic HSCT patients reveals a reduced risk of all EBV outcomes with the use of MMF. Risk factors for EBV events such as EBV-VL occurrence and recurrence include EBV positivity in the donor and recipient, and use of ATG, whereas risk factors for the most severe forms of EBV outcome (EBV-VL and the use of rituximab) include female sex and ATG use.

Risk Factors for the Incidence of and the Mortality due to Post-Transplant Lymphoproliferative Disorder after Hematopoietic Cell Transplantation

Post-transplant lymphoproliferative disorder (PTLD) is a potentially serious complication that occurs following hematopoietic cell transplantation (HCT), in which B cells transformed by Epstein-Barr virus (EBV) proliferate uncontrollably. It is unknown whether risk factors for the incidence of PTLD are identical to those for mortality due to PTLD, a clinically more important outcome. We sought to determine the risk factors influencing the incidence of PTLD and those influencing mortality due to PTLD in a cohort of 1184 allogenic HCT recipients. All patients were predisposed to PTLD, because their graft-versus-host disease (GVHD) prophylaxis included antithymocyte globulin. The overall PTLD incidence was 9.0%, and mortality due to PTLD was 1.1%. In multivariate analysis, risk factors for PTLD incidence include donor+/recipient- (D+/R-) EBV serostatus (subhazard ratio [SHR], 3.3; P = .002), use of a donor other than an HLA-matched sibling donor (non-MSD) (SHR, 1.7; P = .029), receipt of total body irradiation (TBI; SHR, 3.3; P = .008), and the absence of GVHD (SHR, 3.3; P < .001). The sole risk factor for mortality due to PTLD among all patients was D+/R- serostatus (SHR, 5.8; P = .022). Risk factors for mortality due to PTLD among patients who developed PTLD were use of a bone marrow (BM) graft (compared with peripheral blood stem cells [PBSCs]; SHR, 22.8; P < .001) and extralymphatic involvement (SHR, 14.6; P < .001). Interestingly, whereas the absence of GVHD was a risk factor for PTLD incidence, there was a trend toward the presence of GVHD as a risk factor for PTLD mortality (SHR, 4.2; P = .093). Likewise, whereas use of a BM graft was a risk factor for PTLD mortality, there was a trend toward use of a PBSC graft as a risk factor for PTLD incidence (SHR, 0.44; P = .179). Some risk factors for the incidence of PTLD are identical to the risk factors for mortality due to PTLD (ie, D+/R- serostatus), whereas other risk factors are disparate. Specifically, TBI was identified as a risk factor for PTLD incidence but not for PTLD mortality; the absence of GVHD was a risk factor for PTLD incidence, whereas the presence of GVHD was possibly a risk factor for PTLD mortality; and receipt of a PBSC graft was possibly a risk factor for PTLD incidence, whereas receipt of a BM graft was a risk factor for PTLD mortality.

Outcomes of haploidentical bone marrow transplantation in patients with severe aplastic anemia-II that progressed from non-severe acquired aplastic anemia

Severe aplastic anemia II (SAA-II) progresses from non-severe aplastic anemia (NSAA). The unavailability of efficacious treatment has prompted the need for haploidentical bone marrow transplantation (haplo-BMT) in patients lacking a human leukocyte antigen (HLA)-matched donor. This study aimed to investigate the efficacy of haplo-BMT for patients with SAA-II. Twenty-two patients were included and followed up, and FLU/BU/CY/ATG was used as conditioning regimen. Among these patients, 21 were successfully engrafted, 19 of whom survived after haplo-BMT. Four patients experienced grade II-IV aGvHD, including two with grade III-IV aGvHD. Six patients experienced chronic GvHD, among whom four were mild and two were moderate. Twelve patients experienced infections during BMT. One was diagnosed with post-transplant lymphoproliferative disorder and one with probable EBV disease, and both recovered after rituximab infusion. Haplo-BMT achieved 3-year overall survival and disease-free survival rate of 86.4% ± 0.73% after a median follow-up of 42 months, indicating its effectiveness as a salvage therapy. These promising outcomes may support haplo-BMT as an alternative treatment strategy for patients with SAA-II lacking HLA-matched donors.

Vulnerability to reservoir reseeding due to high immune activation after allogeneic hematopoietic stem cell transplantation in individuals with HIV-1

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only medical intervention that has led to an HIV cure. Whereas the HIV reservoir sharply decreases after allo-HSCT, the dynamics of the T cell reconstitution has not been comprehensively described. We analyzed the activation and differentiation of CD4⁺ and CD8⁺ T cells, and the breadth and quality of HIV- and CMV-specific CD8⁺ T cell responses in 16 patients with HIV who underwent allo-HSCT (including five individuals who received cells from CCR5Δ32/Δ32 donors) to treat their underlying hematological malignancy and who remained on antiretroviral therapy (ART). We found that reconstitution of the T cell compartment after allo-HSCT was slow and heterogeneous with an initial expansion of activated CD4⁺ T cells that preceded the expansion of CD8⁺ T cells. Although HIV-specific CD8⁺ T cells disappeared immediately after allo-HSCT, weak HIV-specific CD8⁺ T cell responses were detectable several weeks after transplant and could still be detected at the time of full T cell chimerism, indicating that de novo priming, and hence antigen exposure, occurred during the time of T cell expansion. These HIV-specific T cells had limited functionality compared with CMV-specific CD8⁺ T cells and persisted years after allo-HSCT. In conclusion, immune reconstitution was slow, heterogeneous, and incomplete and coincided with de novo detection of weak HIV-specific T cell responses. The initial short phase of high T cell activation, in which HIV antigens were present, may constitute a window of vulnerability for the reseeding of viral reservoirs, emphasizing the importance of maintaining ART directly after allo-HSCT.

Allogeneic Stem Cell Transplantation Platforms With Ex Vivo and In Vivo Immune Manipulations: Count and Adjust

Various allogeneic (allo) stem cell transplantation platforms have been developed over the last 2 decades. In this review we focus on the impact of in vivo and ex vivo graft manipulation on immune reconstitution and clinical outcome. Strategies include anti-thymocyte globulin- and post-transplantation cyclophosphamide-based regimens, as well as graft engineering, such as CD34 selection and CD19/αβT cell depletion. Differences in duration of immune suppression, reconstituting immune repertoires, and associated graft-versus-leukemia effects and toxicities mediated through viral reactivations are highlighted. In addition, we discuss the impact of different reconstituting repertoires on donor lymphocyte infusions and post allo pharmacological interventions to enhance tumor control. We advocate for precisely counting all graft ingredients and therapeutic drug monitoring during conditioning in the peripheral blood, and for adjusting dosing accordingly on an individual basis. In addition, we propose novel trial designs to better assess the impact of variations in transplantation platforms in order to better learn from our diversity of "counts" and potential "adjustments." This will, in the future, allow daily clinical practice, strategic choices, and future trial designs to be based on data guided decisions, rather than relying on dogma and habits.

[EBV and immunodeficiency]

Epstein-Barr virus (EBV), discovered in 1964, is a double-stranded DNA virus belonging to the Herpesviridae family. EBV has a lymphoid tropism with transforming capacities using different oncogenic viral proteins. This virus has two replication cycles: a lytic cycle mainly occuring during primary infection and a latent cycle allowing viral persistence into host memory B cells. More than 90% of adults are seropositive for EBV worldwide, with a past history of asymptomatic or mild primary infection. EBV infection can sometimes cause life-threatening complications such as hemophagocytic lymphohistiocytosis, and lead to the development of lymphoproliferative disorders or cancers. Risk factors associated with these phenotypes have been recently described through the study of monogenic primary immune deficiencies with EBV susceptibility. We here review the virological and immunological aspects of EBV infection and EBV-related complications with an overview of current available treatments.

Considerations for Child Cancer Survivors and Immunocompromised Children to Prevent Secondary HPV-associated Cancers

Survivors of childhood cancer and other immunocompromised children are at high risk for the development of secondary human papillomavirus (HPV)-associated cancers. In this overview, the authors examine the epidemiology of vaccine efficacy, the natural history of HPV infections, and accelerated HPV-associated cancer development in these populations. The authors highlight the opportunities for preventive care and future research directives.

Factors Associated with Post-Transplant Active Epstein-Barr Virus Infection and Lymphoproliferative Disease in Hematopoietic Stem Cell Transplant Recipients: A Systematic Review and Meta-Analysis

This systematic review was undertaken to identify risk factors associated with post-transplant Epstein-Barr virus (EBV) active infection and post-transplant lymphoproliferative disease (PTLD) in pediatric and adult recipients of hematopoietic stem cell transplants (HSCT). A literature search was conducted in PubMed and EMBASE to identify studies published until 30 June 2020. Descriptive information was extracted for each individual study, and data were compiled for individual risk factors, including, when possible, relative risks with 95% confidence intervals and/or p-values. Meta-analyses were planned when possible. The methodological quality and potential for bias of included studies were also evaluated. Of the 3362 titles retrieved, 77 were included (62 for EBV infection and 22 for PTLD). The overall quality of the studies was strong. Several risk factors were explored in these studies, but few statistically significant associations were identified. The use of anti-thymocyte globulin (ATG) was identified as the most important risk factor positively associated with post-transplant active EBV infection and with PTLD. The pooled relative risks obtained using the random-effect model were 5.26 (95% CI: 2.92-9.45) and 4.17 (95% CI: 2.61-6.68) for the association between ATG and post-transplant EBV infection and PTLD, respectively. Other risk factors for EBV and PTLD were found in the included studies, such as graft-versus-host disease, type of conditioning regimen or type of donor, but results are conflicting. In conclusion, the results of this systematic review indicate that ATG increases the risk of EBV infection and PTLD, but the link with all other factors is either nonexistent or much less convincing.

The association of Epstein-Barr virus infection with CXCR3+ B-cell development in multiple sclerosis: impact of immunotherapies

Epstein–Barr virus (EBV) infection of B cells is associated with increased multiple sclerosis (MS) susceptibility. Recently, we found that CXCR3‐expressing B cells preferentially infiltrate the CNS of MS patients. In chronic virus‐infected mice, these types of B cells are sustained and show increased antiviral responsiveness. How EBV persistence in B cells influences their development remains unclear. First, we analyzed ex vivo B‐cell subsets from MS patients who received autologous bone marrow transplantation (n = 9), which is often accompanied by EBV reactivation. The frequencies of nonclass‐switched and class‐switched memory B cells were reduced at 3–7 months, while only class‐switched B cells returned back to baseline at 24–36 months posttransplantation. At these time points, EBV DNA load positively correlated to the frequency of CXCR3⁺, and not CXCR4⁺ or CXCR5⁺, class‐switched B cells. Second, for CXCR3⁺ memory B cells trapped within the blood of MS patients treated with natalizumab (anti‐VLA‐4 antibody n = 15), latent EBV infection corresponded to enhanced in vitro formation of anti‐EBNA1 IgG‐secreting plasma cells under GC‐like conditions. These findings imply that EBV persistence in B cells potentiates brain‐homing and antibody‐producing CXCR3⁺ subsets in MS.

Cytomegalovirus and Epstein-Barr Infections: Prevalence and Impact on Patients with Hematological Diseases

Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) infections are widely distributed throughout the world. EBV is linked to various hematological and autoimmune disorders whereas CMV might play important role in the progression of chronic hematological diseases, such as hemoglobinopathies, lymphomas, myelomas, hemophilia, and aplastic and sickle cell anemia. Both viruses produce a viral homolog of human interleukin-10 that can cause general suppression of immune response, increasing susceptibility to other infections. These viruses can remain latent in the host cells and be reactivated when the host immune system is compromised. Studies showing the impact of CMV and EBV infections on hematological disorders are scarce and unclear in the context of coinfection. This review intends to present the biology, prevalence, and impact of CMV and EBV infections in patients with hematological diseases.

Transfusion-related Epstein-Barr virus (EBV) infection: A multicenter prospective cohort study among pediatric recipients of hematopoietic stem cell transplants (TREASuRE study)

BACKGROUND

Epstein-Barr virus (EBV) is carried in the blood of most adults, and transfusion-related infections have been reported. EBV is particularly deleterious in immunosuppressed transplant patients. The aim was to determine if EBV transmission occurred through leukodepleted blood product transfusion in pediatric recipients of hematopoietic stem cell transplants (HSCT).

STUDY DESIGN AND METHODS

This prospective Canadian multi-center cohort study includes 156 allogeneic HSCT pediatric recipients. The association between EBV and transfusion was analyzed using Cox regressions. EBV infection, defined by a PCR+ test in the blood of seronegative recipients of an EBV-negative graft, was monitored in order to correlate the recipient EBV strain with that of the blood donors. EBV genotypes were determined by PCR amplification followed by DNA sequencing at two loci (EBNA3b and LMP1).

RESULTS

No statistically significant associations were found between transfusions and EBV. One case of post-transplant EBV infection was identified among the 21 EBV-seronegative recipients receiving an EBV-negative graft. A total of 22 blood donors were retraced to determine whether the recipient's EBV strain matched that of a donor. One donor strain showed 100% sequence homology at the EBNA3b locus, but differed by one or two point mutations and by a 132-bp deletion at the LMP1 locus. The blood donor in question was alone among the 22 donors to show amplifiable virus in plasma. Blood from this donor readily produced an immortalized lymphoblastoid cell line in culture.

CONCLUSION

While considered a rare event, EBV transmission through transfusion may occur in the context of severe immunosuppression.

A Mechanism-Based Targeted Screen To Identify Epstein-Barr Virus-Directed Antiviral Agents

Epstein-Barr virus (EBV) is one of nine human herpesviruses that persist latently to establish permanent residence in their hosts. Periodic activation into the lytic/replicative phase allows such viruses to propagate and spread, but can also cause disease in the host. This lytic phase is also essential for EBV to cause infectious mononucleosis and cancers, including B lymphocyte-derived Burkitt lymphoma and immunocompromise-associated lymphoproliferative diseases/lymphomas as well as epithelial cell-derived nasopharyngeal cell carcinoma. In the absence of anti-EBV agents, however, therapeutic options for EBV-related diseases are limited. In earlier work, we discovered that through the activities of the viral protein kinase conserved across herpesviruses and two cellular proteins, ATM and KAP1, a lytic cycle amplification loop is established, and disruption of this loop disables the EBV lytic cascade. We therefore devised a high-throughput screening assay, screened a small-molecule-compound library, and identified 17 candidates that impair the release of lytically replicated EBV. The identified compounds will (i) serve as lead compounds or may be modified to inhibit EBV and potentially other herpesviruses, and (ii) be developed into anticancer agents, as functions of KAP1 and ATM are tightly linked to cancer. Importantly, our screening strategy may also be used to screen additional compound libraries for antiherpesviral and anticancer drugs.IMPORTANCE Epstein-Barr virus, which is nearly ubiquitous in humans, is causal to infectious mononucleosis, chronic active EBV infection, and lymphoid and epithelial cancers. However, EBV-specific antiviral agents are not yet available. To aid in the identification of compounds that may be developed as antivirals, we pursued a mechanism-based approach. Since many of these diseases rely on EBV's lytic phase, we developed a high-throughput assay that is able to measure a key step that is essential for successful completion of EBV's lytic cascade. We used this assay to screen a library of small-molecule compounds and identified inhibitors that may be pursued for their anti-EBV and possibly even antiherpesviral potential, as this key mechanism appears to be common to several human herpesviruses. Given the prominent role of this mechanism in both herpesvirus biology and cancer, our screening assay may be used as a platform to identify both antiherpesviral and anticancer drugs.

Epstein-Barr Virus and Monoclonal Gammopathy of Clinical Significance in Autologous Stem Cell Transplantation for Multiple Sclerosis

INTRODUCTION

Autologous hematopoietic stem cell transplantation (AHSCT) with anti-thymocyte globulin (ATG) conditioning as treatment of active multiple sclerosis (MS) is rapidly increasing across Europe (EBMT registry data 2017). Clinically significant Epstein-Barr virus reactivation (EBV-R) following AHSCT with ATG for severe autoimmune conditions is an underrecognized complication relative to T-cell deplete transplants performed for hematological diseases. This retrospective study reports EBV-R associated significant clinical sequelae in MS patients undergoing AHSCT with rabbit ATG.

METHODS

Retrospective data were analyzed for 36 consecutive MS-AHSCT patients at Kings College Hospital, London. All patients routinely underwent weekly EBV DNA polymerase chain reaction monitoring and serum electrophoresis for monoclonal gammopathy (MG or M-protein). EBV-R with rising Epstein-Barr viral load, M-protein, and associated clinical sequelae were captured from clinical records.

RESULTS

All patients had evidence of rising EBV DNA-emia, including 7 who were lost to long-term follow-up, with a number of them developing high EBV viral load and associated lymphoproliferative disorder (LPD). Nearly 72% (n = 18/29) developed de novo MG, some with significant neurological consequences with high M-protein and EBV-R. Six patients required anti-CD20 therapy (rituximab) with complete resolution of EBV related symptoms. Receiver operating characteristics estimated a peak EBV viremia of >500 000 DNA copies/mL correlated with high sensitivity (85.5%) and specificity (82.5%) (area under the curve: 0.87; P = .004) in predicting EBV-R related significant clinical events.

CONCLUSION

Symptomatic EBV reactivation increases risk of neurological sequelae and LPD in MS-AHSCT. We recommend regular monitoring for EBV and serum electrophoresis for MG in MS patients in the first 3 months post-AHSCT.

Persistent Challenges of Interassay Variability in Transplant Viral Load Testing

While quantification of viruses that cause important infections in transplant recipients has been the standard of care for years, important challenges related to standardization remain. The issues are wide ranging, and until they are adequately addressed, the full impact of viral load testing regarding clinical management decisions will not be realized. This review focuses on a broad array of problems, including the lack of available FDA-approved/cleared tests, limited uptake of international standards, accurate quantification of secondary standards, specific assay characteristics, and commutability. Though some of these topics are nuanced, taken together they greatly influence the clinical utility of testing. For example, it has not been possible to define thresholds that predict the risk of developing disease and determine significant changes in serial viral load values for a given patient. Moreover, the utility of international guidelines may be limited due to the lack of a standardized assay. By summarizing the issues, the hope is that commercial companies, regulatory agencies, and professional societies can come together to advance the field and solve these problems.

Management of PTLD After Hematopoietic Stem Cell Transplantation: Immunological Perspectives

Post-transplant lymphoproliferative disorders (PTLDs) are life-threatening complications of iatrogenic immune impairment after allogeneic hematopoietic stem cell transplantation (HSCT). In the pediatric setting, the majority of PTLDs are related to the Epstein-Barr virus (EBV) infection, and present as B-cell lymphoproliferations. Although considered rare events, PTLDs have been increasingly observed with the widening application of HSCT from alternative sources, including cord blood and HLA-haploidentical stem cell grafts, and the use of novel agents for the prevention and treatment of rejection and graft-vs.-host disease. The higher frequency initially paralleled a poor outcome, due to limited therapeutic options, and scarcity of controlled trials in a rare disease context. In the last 2 decades, insight into the relationship between EBV and the immune system, and advances in early diagnosis, monitoring and treatment have changed the approach to the management of PTLDs after HSCT, and significantly ameliorated the prognosis. In this review, we summarize literature on the impact of combined viro-immunologic assessment on PTLD management, describe the various strategies for PTLD prevention and preemptive/curative treatment, and discuss the potential of novel immune-based therapies in the containment of this malignant complication.

Post Transplant Lymphoproliferative Disorder risk factors in children: Analysis of a 23-year single-institutional experience

INTRODUCTION

PTLD is the most frequent malignancy following SOT in children and the second most common SOT complication in adults. However, factors determining outcomes in children are poorly understood due to its relative rarity.

METHODS

This study was performed at the University of Florida. Univariate and multivariate analyses were used to identify prognostic factors in pediatric patients diagnosed with PTLD.

RESULTS

We reviewed records of 54 pediatric (younger than 18 years old at diagnosis) patients diagnosed with PTLD from 1994 to 2017. The median follow-up was 28.8 months. The estimated 5-year survival rate was 87.6% (95% CI 74.3-94.2%). Univariate analysis showed that organ transplanted (specifically heart transplant), poor response to initial treatment, allograft rejection, and low Karnofsky score were statistically significant for negative prognostic factors in determining survival. Multivariate analysis determined progression in response to initial treatment and presence of allograft rejection as statistically significant prognostic factors affecting overall survival. We found no statistically significant impact of EBV serological status on PTLD prognosis.

CONCLUSIONS

Disease progression and allograft rejection were strong negative prognostic indicators in our study cohort. Close attention to graft status and development of therapies that protect the graft from rejection while bolstering anti-EBV immunity will be essential to further improving PTLD outcomes in children.

Viral opportunistic infections in Mauritian cynomolgus macaques undergoing allogeneic stem cell transplantation mirror human transplant infectious disease complications

Allogeneic hematopoietic stem cell transplantation (HSCT) and xenotransplantation are accompanied by viral reactivations and virus-associated complications resulting from immune deficiency. Here, in a Mauritian cynomolgus macaque model of fully MHC-matched allogeneic HSCT, we report reactivations of cynomolgus polyomavirus, lymphocryptovirus, and cytomegalovirus, macaque viruses analogous to HSCT-associated human counterparts BK virus, Epstein-Barr virus, and human cytomegalovirus. Viral replication in recipient macaques resulted in characteristic disease manifestations observed in HSCT patients, such as polyomavirus-associated hemorrhagic cystitis and tubulointerstitial nephritis or lymphocryptovirus-associated post-transplant lymphoproliferative disorder. However, in most cases, the reconstituted immune system, alone or in combination with short-term pharmacological intervention, exerted control over viral replication, suggesting engraftment of functional donor-derived immunity. Indeed, the donor-derived reconstituted immune systems of two long-term engrafted HSCT recipient macaques responded to live attenuated yellow fever 17D vaccine (YFV 17D) indistinguishably from untransplanted controls, mounting 17D-targeted neutralizing antibody responses and clearing YFV 17D within 14 days. Together, these data demonstrate that this macaque model of allogeneic HSCT recapitulates clinical situations of opportunistic viral infections in transplant patients and provides a pre-clinical model to test novel prophylactic and therapeutic modalities.

Epstein-Barr virus related post-transplant lymphoproliferative disorder prevention strategies in allogeneic hematopoietic stem cell transplantation

Epstein-Barr virus associated post-transplant lymphoproliferative disorders (EBV PTLD) are recognized as a significant cause of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplantation (alloHSCT). The number of patients at risk of developing EBV PTLD is increasing, partly as a result of highly immunosuppressive regimens, including the use of anti-thymocyte globulin (ATG). Importantly, there is heterogeneity in PTLD management strategies between alloHSCT centers worldwide. This review summarizes the different EBV PTLD prevention strategies being utilized including the alloHSCT and T-cell depletion regimes and the risk they confer; monitoring programs, including the timing and analytes used for EBV virus detection, as well as pre-emptive thresholds and therapy with rituximab. In the absence of an institution-specific policy, it is suggested that the optimal pre-emptive strategy in HSCT recipients with T-cell depleting treatments, acute graft vs host disease (GVHD) and a mismatched donor for PTLD prevention is (a) monitoring of EBV DNA post-transplant weekly using plasma or WB as analyte and (b) pre-emptively reducing immune suppression (if possible) at an EBV DNA threshold of >1000 copies/mL (plasma or WB), and treating with rituximab at a threshold of >1000 copies/mL (plasma) or >5000 copies/mL (WB). There is emerging evidence for prophylactic rituximab as a feasible and safe strategy for PTLD, particularly if pre-emptive monitoring is problematic. Future management strategies such as prophylactic EBV specific CTLs have shown promising results and as this procedure becomes less expensive and more accessible, it may become the strategy of choice for EBV PTLD prevention.

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.

Nascent Transcriptomics Reveal Cellular Prolytic Factors Upregulated Upstream of the Latent-to-Lytic Switch Protein of Epstein-Barr Virus

Lytic activation from latency is a key transition point in the life cycle of herpesviruses. Epstein-Barr virus (EBV) is a human herpesvirus that can cause lymphomas, epithelial cancers, and other diseases, most of which require the lytic cycle. While the lytic cycle of EBV can be triggered by chemicals and immunologic ligands, the lytic cascade is activated only when expression of the EBV latent-to-lytic switch protein ZEBRA is turned on. ZEBRA then transcriptionally activates other EBV genes and, together with some of those gene products, ensures completion of the lytic cycle. However, not every latently infected cell exposed to a lytic trigger turns on the expression of ZEBRA, resulting in responsive and refractory subpopulations. What governs this dichotomy? By examining the nascent transcriptome following exposure to a lytic trigger, we find that several cellular genes are transcriptionally upregulated temporally upstream of ZEBRA. These genes regulate lytic susceptibility to various degrees in latently infected cells that respond to mechanistically distinct lytic triggers. While increased expression of these cellular genes defines a prolytic state, such upregulation also runs counter to the well-known mechanism of viral-nuclease-mediated host shutoff that is activated downstream of ZEBRA. Furthermore, a subset of upregulated cellular genes is transcriptionally repressed temporally downstream of ZEBRA, indicating an additional mode of virus-mediated host shutoff through transcriptional repression. Thus, increased transcription of a set of host genes contributes to a prolytic state that allows a subpopulation of cells to support the EBV lytic cycle.IMPORTANCE Transition from latency to the lytic phase is necessary for herpesvirus-mediated pathology as well as viral spread and persistence in the population at large. Yet, viral genomes in only some cells in a population of latently infected cells respond to lytic triggers, resulting in subpopulations of responsive/lytic and refractory cells. Our investigations into this partially permissive phenotype of the herpesvirus Epstein-Barr virus (EBV) indicate that upon exposure to lytic triggers, certain cellular genes are transcriptionally upregulated, while viral latency genes are downregulated ahead of expression of the viral latent-to-lytic switch protein. These cellular genes contribute to lytic susceptibility to various degrees. Apart from indicating that there may be a cellular "prolytic" state, our findings indicate that (i) early transcriptional upregulation of cellular genes counters the well-known viral-nuclease-mediated host shutoff and (ii) subsequent transcriptional downregulation of a subset of early upregulated cellular genes is a previously undescribed mode of host shutoff.

Epstein-Barr virus reactivation after allogeneic hematopoietic stem cell transplantation: multifactorial impact on transplant outcomes

Epstein-Barr virus (EBV) reactivation after allogeneic hematopoietic cell transplantation (allo-HCT) is one of the major concerns that may lead to fatal EBV diseases. However, updated data are needed because of the remarkable evolution of the HCT protocol and donor selection. We conducted a retrospective study that enrolled 890 allo-HCT recipients. Independent risk factors for EBV reactivation were use of antithymocyte globulin, haploidentical donor, and the presence of chronic graft-versus-host disease. The cumulative incidence of EBV reactivation was 2.9%, 11.7%, 27.3%, and 41.9% for patients with 0, 1, 2, and 3 risk factors, respectively (P < 0.001). Posttransplant lymphoproliferative disorders (PTLDs) occurred in seven patients. EBV reactivation was associated with inferior survival in recipients who survived more than 2 years post-HCT (P < 0.001) but might time-dependently benefit those patients with malignancies by decreasing relapse incidence (P = 0.046). A decreased relapse incidence was observed 1 year after HCT for recipients at first or second remission (P = 0.042) and in the first year post-HCT for recipients with advanced diseases (P = 0.032). We concluded that with current management, PTLDs were efficiently controlled, but EBV reactivation still had a multifactorial impact on transplant outcomes. Multicenter prospective studies are warranted to validate these findings.

A promiscuous inflammasome sparks replication of a common tumor virus

Viruses activate inflammasomes but then subvert resulting inflammatory responses to avoid elimination. We asked whether viruses could instead use such activated or primed inflammasomes to directly aid their propagation and spread. Since herpesviruses are experts at coopting cellular functions, we investigated whether Epstein-Barr virus (EBV), an oncoherpesvirus, exploits inflammasomes to activate its replicative or lytic phase. Indeed, our experiments reveal that EBV exploits several inflammasome sensors to actually activate its replicative phase from quiescence/latency. In particular, TXNIP, a key inflammasome intermediary, causes assembly of the NLRP3 inflammasome, resulting in caspase-1-mediated depletion of the heterochromatin-inducing epigenetic repressor KAP1/TRIM28 in a subpopulation of cells. As a result, only TXNIPhiKAP1lo cells, that is, in a primed/prolytic state, turn expression of the replication/lytic/reactivation switch protein on to enter the replicative phase. Our findings 1) demonstrate that EBV dovetails its escape strategy to a key cellular danger-sensing mechanism, 2) indicate that transcription may be regulated by KAP1 abundance aside from canonical regulation through its posttranslational modification, 3) mechanistically link diabetes, which frequently activates the NLRP3 inflammasome, to deregulation of a tumor virus, and 4) demonstrate that B lymphocytes from NOMID (neonatal onset multisystem inflammatory disease) patients who have NLRP3 mutations and suffer from hyperactive innate responses are defective in controlling a herpesvirus.

Identification of the best-suited donor for generating virus-specific T cells

BACKGROUND AND OBJECTIVES

Administration of virus-specific T cells (VSTs) is a viable antiviral treatment strategy after allogeneic HSCT, even if conventional therapies fail. Third-party donors are often chosen for the generation of the VST product. The eligibility of the donor has to be tested in a rigorous donor screening procedure, since the isolation technology only targets pre-existing VSTs.

MATERIALS AND METHODS

In a period of 3 years, we performed 32 VST treatments for 28 patients. Targeting four different viruses, 284 healthy individuals underwent 417 donor screening procedures. VSTs were counted by flow cytometry detecting interferon-gamma (IFN-γ) producing T cells. Generation of the VSTs was performed from leukapheresis products in a fully automated and closed system using magnetic cell separation.

RESULTS

The mean circulating VST frequencies ranged from 0·006% to 0·328%. The average yield of viable VSTs in the product was 1·83·10₆ cells, while the average VST dose calculated for the patient's body weight was 4·63·10₄ /kg. The mean purity - percentage of VSTs within the T cells - of all T-cell products was 62·9%. Correlation was identified between the frequency of the VSTs in the peripheral blood of the donor and the VST numbers of the end product; the strongest correlation was seen for CMV.

CONCLUSION

This paper focuses on the T-cell donors, highlighting some key points on the donor selection process. Based on the findings in connection with the CMV therapies, peripheral VST seems to be the best predictor of the VST content of the final product administered to the patient.