Clinical utility of measuring Epstein–Barr virus-specific cell-mediated immunity after HSCT in addition to virological monitoring: results from a prospective study

Clinical value of plasma and peripheral blood mononuclear cells Epstein–Barr Virus DNA dynamics on prognosis of allogeneic stem cell transplantation

The application of intracellular and extracellular Epstein–Barr virus (EBV) DNA in allogeneic hematopoietic stem cell transplantation (allo-HSCT) has been poorly characterized. We conducted a combined prospective-retrospective study of 300 patients who underwent allo-HSCT between 2016 to 2019 in our center and monitored for EBV DNA within the first year after HSCT. Combining the optimal cut-off value of EBV DNA load (7.3×10⁴ copies/10⁶ cells) in peripheral blood mononuclear cells (PBMCs) and qualitative detection in plasma (400 copies/mL) allowed for the better differentiation of EBV-related posttransplant lymphoproliferative disorders (EBV-PTLD), with increased sensitivity (100%) and specificity (86%), and provided the effective risk stratification of EBV DNA level according to their impact on transplant outcomes. By multivariate analysis, patients with intermediate-level of EBV DNA load (low EBV DNA load in PBMCs or high load in PBMCs but negative in plasma) was associated with superior overall survival (HR 1.92, 95% CI 1.03-3.57, p=0.039) and lower transplant-related mortality (HR 3.35, 95% CI 1.31-8.58, p=0.012) compared to those with high-level (high load in PBMCs and positive in plasma). Notably, high EBV-level group had poor reconstitution of CD4+ and CD8+T cells, and both low and high EBV-level groups showed abnormally increase in IL-10 level within one year. Additionally, patients with peak EBV DNA load in PBMCs during 3-12 months had a higher incidence of chronic graft versus host disease (GVHD) than those within 3 months post transplantation (17.4% vs 13.7%, p=0.029). Collectively, EBV DNA in PBMCs can synergistically predict the risk of EBV-PTLD and GVHD. The intermediate-level of EBV DNA presented in plasma and PBMCs might contribute to a better reconstitution of T cells associated with favorable prognosis of allo-HSCT.

Association Between Cytomegalovirus and Epstein-Barr Virus Co-Reactivation and Hematopoietic Stem Cell Transplantation

The co-reactivation of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) in patients undergoing hematopoietic stem cell transplantation (HSCT) has been found. Research has shown that the reactivation of CMV or EBV is closely related to poor HSCT outcomes. In this study, we describe the clinical characteristics of HSCT patients with co-reactivation of CMV and EBV. We retrospectively reviewed the medical records of 327 patients who underwent HSCT at the Peking University People’s Hospital Institute of Hematology. Co-reactivation of CMV and EBV was observed in a total of 75 patients (22.9%) who also had a higher incidence of hemorrhagic cystitis (P=0.000). HSCT patients with CMV and co-reactivation of CMV and EBV had a significantly lower 1-year overall survival (OS; P=0.050). Further, COX regression analysis showed that viral infection was a risk factor for 1-year OS (HR, 12.625 for co-reactivation vs. no reactivation, p=0.021, and HR 13.580 for CMV reactivation vs. no reactivation, P=0.013). In conclusion, the patients with CMV reactivation had poorer outcome after HSCT regardless of EBV reactivation.

Risk factors evaluation of post-transplant lymphoproliferative disorders after allogeneic haematopoietic stem cell transplantation with comparison between paediatric and adult

To describe the clincopathological features and evaluate risk factors of post-transplant lymphoproliferative disorder (PTLD) after allogeneic haematopoietic stem cell transplants (allo-HSCT), with comparison between paediatric and adult .Clinicopathological features of 81 cases of PTLD after allo-HSCT were analysed by histopatholgy, immunohistochemistry and in situ hybridisatioin.The cases included 58 males and 23 females with a median age of 26.7 years (range 6-55 years) and the PTLDs developed 1-60 months post-transplant (mean 5.9 months). The histological types indicated 10 cases of non-destructive PTLD, including 4 of plasmacytic hyperplasia, 5 of infectious mononucleosis and 1 of florid follicular hyperplasia. Fifty-six cases were polymorphic PTLD, and 15 were monomorphic PTLD, including thirteen of diffuse large B cell lymphoma, 1 of extranodal nasal type natural killer (NK)/T cell lymphoma and 1 of plasmablastic lymphoma. Foci and sheets of necrosis were observed in 31 cases. The infected ratio of Epstein-Barr virus (EBV) was 91.4%. Some cases were treated by reduction of immunosuppression, antiviral therapy, donor lymphocyte infusion or anti-CD20 monoclonal rituximab. Thirty-three cases died. Compared with that of adult, overall survival of paediatric recipient may be better.The first half year after allo-HSCT is very important for the development of PTLD. Type of PTLD, EBV infection and graft-versus-host disease are risk factors. The prognosis of PTLD is poor, and PTLD after allo-HSCT exhibits some features different from that after solid organ transplantation and some differences existing between adult and paediatric recipients.

Off-Label Use of Letermovir as Preemptive Anti-Cytomegalovirus Therapy in a Pediatric Allogeneic Peripheral Blood Stem Cell Transplant

Despite the effectiveness of the currently available antiviral drugs in treating cytomegalovirus (CMV) infection, high rates of adverse effects are associated with their use. Moreover, a problem of increasing importance is the emergence of drug-resistant CMV infection. Here, we describe the first case of off-label use of letermovir (LMV) as preemptive antiviral therapy, in a pediatric allogeneic peripheral blood stem cell transplant recipient with ganciclovir-resistant CMV infection who was intolerant to foscarnet and unable to achieve viral clearance after seven doses of cidofovir. After the administration of LMV, a gradual reduction in viral load was observed and within 6 weeks of LMV treatment, after more than 6 months of positive CMV-DNAemia, the patient cleared the infection. No adverse effects associated with LMV were observed during treatment. In this pediatric study case, the off-label use of LMV for the treatment of CMV infection has been well tolerated and proved to be effective in leading to the suppression of viral replication.

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.

Supportive Care During Pediatric Hematopoietic Stem Cell Transplantation: Prevention of Infections. A Report From Workshops on Supportive Care of the Paediatric Diseases Working Party (PDWP) of the European Society for Blood and Marrow Transplantation (EBMT)

Specific protocols define eligibility, conditioning, donor selection, graft composition and prophylaxis of graft vs. host disease for children and young adults undergoing hematopoietic stem cell transplant (HSCT). However, international protocols rarely, if ever, detail supportive care, including pharmaceutical infection prophylaxis, physical protection with face masks and cohort isolation or food restrictions. Supportive care suffers from a lack of scientific evidence and implementation of practices in the transplant centers brings extensive restrictions to the child's and family's daily life after HSCT. Therefore, the Board of the Pediatric Diseases Working Party (PDWP) of the European Society for Blood and Marrow Transplantation (EBMT) held a series of dedicated workshops since 2017 with the aim of initiating the production of a set of minimal recommendations. The present paper describes the consensus reached within the field of infection prophylaxis.

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.

Evaluation of T-activated proteins as recall antigens to monitor Epstein-Barr virus and human cytomegalovirus-specific T cells in a clinical trial setting

BACKGROUND

Pools of overlapping synthetic peptides are routinely used for ex vivo monitoring of antigen-specific T-cell responses. However, it is rather unlikely that these peptides match those resulting from naturally processed antigens. T-activated proteins have been described as immunogenic and more natural stimulants, since they have to pass through antigen processing and comprise activation of all clinically relevant effector cell populations.

METHODS

We performed comparative analysis of numbers and cytokine expression pattern of CD4 and CD8 T cells after stimulation with recombinant, urea-formulated T-activated EBV-BZLF1, -EBNA3A, and HCMV-IE1, and -pp65 proteins or corresponding overlapping peptide pools. Freshly isolated and cryopreserved PBMC of 30 EBV- and 19 HCMV-seropositive and seven EBV- and HCMV-seronegative subjects were stimulated ex vivo and analysed for IFN-γ, TNF and IL-2 production by flow cytometry-based intracellular cytokine staining.

RESULTS

T-activated proteins showed a high specificity of 100% (EBV-BZLF1, HCMV-IE1, and -pp65) and 86% (EBV-EBNA3A), and a high T-cell stimulatory capacity of 73-95% and 67-95% using freshly isolated and cryopreserved PBMC, respectively. The overall CD4 T-cell response rates in both cohorts were comparable after stimulation with either T-activated protein or peptide pools with the exception of lower numbers of CD8 T cells detected after stimulation with T-activated EBV-EBNA3A- (p = 0.038) and HCMV-pp65- (p = 0.0006). Overall, the number of detectable antigen-specific T cells varied strongly between individuals. Cytokine expression patterns in response to T-activated protein and peptide pool-based stimulation were similar for CD4, but significantly different for CD8 T-cell responses.

CONCLUSION

EBV and HCMV-derived T-activated proteins represent innovative, highly specific recall antigens suitable for use in immunological endpoint assays to evaluate success or failure in immunotherapy clinical trials (e.g. to assess the risk of EBV and/or HCMV reactivation after allogenic hematopoietic stem cell transplantation). T-activated proteins could be of particular importance, if an impaired antigen processing (e.g. in a post-transplant setting) must be taken into account.