BCR signaling is required for posttransplant lymphoproliferative disease in immunodeficient mice receiving human B cells.

Posttransplant lymphoproliferative disease (PTLD) is a major therapeutic challenge that has been difficult to study using human cells because of a lack of suitable models for mechanistic characterization. Here, we show that ex vivo-differentiated B cells isolated from a subset of healthy donors can elicit pathologies similar to PTLD when transferred into immunodeficient mice. The primary driver of PTLD-like pathologies were IgM-producing plasmablasts with Epstein-Barr virus (EBV) genomes that expressed genes commonly associated with EBV latency. We show that a small subset of EBV+ peripheral blood-derived B cells expressing self-reactive, nonmutated B cell receptors (BCRs) expand rapidly in culture in the absence of BCR stimulation. Furthermore, we found that in vitro and in vivo expansion of EBV+ plasmablasts required BCR signaling. Last, treatment of immunodeficient mice with the BCR pathway inhibitor, ibrutinib, delays onset of PTLD-like pathologies in vivo. These data have implications for the diagnosis and care of transplant recipients who are at risk of developing PTLD.

Analysis and Development of Antigen-specific T Cells Derived from Peripheral Blood Mononuclear Cells of Healthy Donors.

BACKGROUND/AIM: Adoptive cell therapy using antigen-specific T cells is a promising treatment modality for cancer patients. Various methods to isolate specific T cells and identify corresponding T cell receptor (TCR) sequences are known. This study aimed to identify antigen-specific TCR from T cells isolated using carboxyfluorescein succinimidyl ester (CFSE), which marks proliferating activated T cells. MATERIALS AND METHODS: CFSE stained healthy donor peripheral blood mononuclear cells (PBMCs) were treated with cytomegalovirus (CMV) or Epstein-Barr virus (EBV) peptides for seven days. Then, proliferating T cells with decreased CFSE staining were isolated and single cell VDJ sequencing was performed on isolated T cells to identify antigen-specific TCRs. RESULTS: As antigen-specific TCR candidates, ten TCR clones were selected for the CMV antigen and five for the EBV antigen. The reactivity of ten CMV TCR-transduced T cells and one EBV TCR-transduced T cell toward T2 cells pulsed with CMV or EBV peptide was confirmed via NFAT-luciferase, IFN-γ ELISA, and cytotoxicity assays. CONCLUSION: Identification of antigen-specific TCRs with CFSE staining is a valid method for the development of effective immunotherapy. The identified CMV- or EBV-specific TCRs can be used for adoptive cell therapy to treat cancer.

Post-transplant lymphoproliferative disorders following kidney transplantation: A literature review with updates on risk factors, prognostic indices, screening strategies, treatment and analysis of donor type.

Post-transplant lymphoproliferative disorders (PTLD) is a devastating complication of kidney transplantation with an insidious presentation and potential to disseminate aggressively. This review delineates the risk factors, prognostic indexes, screening, current management algorithm and promising treatment strategies for PTLD. Kidneys from both extended criteria donors (ECD) and living donors (LD) are being increasingly used to expand the donor pool. This review also delineates whether PTLD outcomes vary based on these donor sources. While Epstein-Barr virus (EBV) is a well-known risk factor for PTLD development, the use of T-cell depleting induction agents has been increasingly implicated in aggressive, monomorphic forms of PTLD. Research regarding maintenance therapy is sparse. The international prognostic index seems to be the most validate prognostic tool. Screening for PTLD is controversial, as annual PET-CT is most sensitive but costly, while targeted monitoring of EBV-seronegative patients was more economically feasible, is recommended by the American Society of Transplantation, but is limited to a subset of the population. Other screening strategies such as using Immunoglobulin/T-cell receptor require further validation. A risk-stratified approach is taken in the treatment of PTLD. The first step is the reduction of immunosuppressants, after which rituximab and chemotherapy may be introduced if unsuccessful. Some novel treatments have also shown potential benefit in studies: brentuximab vedotin, chimeric antigen receptor T-cell therapy and EBV-specific cytotoxic T lymphocytes. Analysis of LD v DD recipients show no significant difference in incidence and mortality of PTLD but did reveal a shortened time to development of PTLD from transplant. Analysis of SCD vs ECD recipients show a higher incidence of PTLD in the ECD group, which might be attributed to longer time on dialysis for these patients, age, and the pro-inflammatory nature of these organs. However, incidence of PTLD overall is still extremely low. Efforts should be focused on optimising recipients instead. Minimising the use of T-cell depleting therapy while encouraging research on the effect of new immunosuppressants on PTLD, screening for EBV status are essential, while enabling shared decision-making during counselling when choosing kidney donor types and individualised risk tailoring are strongly advocated.

Role of IL-27 in Epstein-Barr virus infection revealed by IL-27RA deficiency.

Epstein-Barr virus (EBV) infection can engender severe B cell lymphoproliferative diseases1,2. The primary infection is often asymptomatic or causes infectious mononucleosis (IM), a self-limiting lymphoproliferative disorder3. Selective vulnerability to EBV has been reported in association with inherited mutations impairing T cell immunity to EBV4. Here we report biallelic loss-of-function variants in IL27RA that underlie an acute and severe primary EBV infection with a nevertheless favourable outcome requiring a minimal treatment. One mutant allele (rs201107107) was enriched in the Finnish population (minor allele frequency = 0.0068) and carried a high risk of severe infectious mononucleosis when homozygous. IL27RA encodes the IL-27 receptor alpha subunit5,6. In the absence of IL-27RA, phosphorylation of STAT1 and STAT3 by IL-27 is abolished in T cells. In in vitro studies, IL-27 exerts a synergistic effect on T-cell-receptor-dependent T cell proliferation7 that is deficient in cells from the patients, leading to impaired expansion of potent anti-EBV effector cytotoxic CD8+ T cells. IL-27 is produced by EBV-infected B lymphocytes and an IL-27RA-IL-27 autocrine loop is required for the maintenance of EBV-transformed B cells. This potentially explains the eventual favourable outcome of the EBV-induced viral disease in patients with IL-27RA deficiency. Furthermore, we identified neutralizing anti-IL-27 autoantibodies in most individuals who developed sporadic infectious mononucleosis and chronic EBV infection. These results demonstrate the critical role of IL-27RA-IL-27 in immunity to EBV, but also the hijacking of this defence by EBV to promote the expansion of infected transformed B cells.

Post cross-linked ROS-responsive poly(ß-amino ester)-plasmid polyplex NPs for gene therapy of EBV-associated nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is one of the most common tumors in South China and Southeast Asia and is thought to be associated with Epstein-Barr virus (EBV) infection. Downregulation of latent membrane protein 1 (LMP1) encoded by EBV can reduce the expression of NF-κB and PI3K, induce apoptosis, and inhibit the growth of EBV-related NPC. For targeted cleavage of the Lmp1 oncogene via the CRISPR/Cas9 gene editing system, a post cross-linked ROS-responsive poly(ß-amino ester) (PBAE) polymeric vector was developed for the delivery of CRISPR/Cas9 plasmids both in vitro and in vivo. After composition optimization, the resultant polymer-plasmid polyplex nanoparticles (NPs) showed a diameter of ∼230 nm and a zeta potential of 22.3 mV with good stability. Compared with the non-cross-linked system, the cross-linked NPs exhibited efficient and quick cell uptake, higher transfection efficiency in EBV-positive C666-1 cells (53.5% vs. 40.6%), more efficient gene editing ability against the Mucin2 model gene (Muc2) (17.9% vs. 15.4%) and Lmp1 (8.5% vs. 5.6%), and lower intracellular reactive oxygen species (ROS) levels. The NPs achieved good tumor penetration and tumor growth inhibition in the C666-1 xenograft tumor model via Lmp1 cleavage, indicating their potential for gene therapy of EBV-related NPC.

Targeting Epstein-Barr virus in multiple sclerosis: when and how?

PURPOSE OF REVIEW: Epidemiological evidence implicates Epstein-Barr virus (EBV) as the cause of multiple sclerosis (MS). However, its biological role in the pathogenesis of MS is uncertain. The article provides an overview of the role of EBV in the pathogenesis of MS and makes a case for targeting EBV as a treatment strategy for MS. RECENT FINDINGS: EBV potentially triggers autoimmunity via molecular mimicry or immune dysregulation. Another hypothesis, supported by immunological and virological data, indicates that active EBV infection via latent-lytic infection cycling within the central nervous system or periphery drives MS disease activity. This supports testing small molecule anti-EBV agents targeting both latent and lytic infection, central nervous system-penetrant B-cell therapies and EBV-targeted immunotherapies in MS. Immunotherapies may include EBV-specific cytotoxic or chimeric antigen receptors T-cells, therapeutic EBV vaccines and immune reconstitution therapies to boost endogenous EBV-targeted cytotoxic T-cell responses. SUMMARY: EBV is the probable cause of MS and is likely to be driving MS disease activity via latent-lytic infection cycling. There is evidence that all licensed MS disease-modifying therapies target EBV, and there is a compelling case for testing other anti-EBV strategies as potential treatments for MS.

Epstein Barr virus-directed T-cell therapy for refractory EBV-PTLD in a toddler post Orthotopic heart transplantation.

Epstein-Barr Virus (EBV) is a ubiquitous herpes type virus that is associated with post-transplant lymphoproliferative disorder (PTLD). Usual management includes reduction or cessation of immunosuppression and in some cases chemotherapy including rituximab. However, limited therapies are available if PTLD is refractory to rituximab. Several clinical trials have investigated the use of EBV-directed T cells in rituximab-refractory patients; however, data regarding response is scarce and inconclusive. Herein, we describe a patient with EBV-PTLD refractory to rituximab after orthotopic heart transplantation (OHT) requiring EBV-directed T-cell therapy. This article aims to highlight the unique and aggressive clinical presentation and progression of PTLD with utilization of EBV-directed T-cell therapy for management and associated pitfalls.

Precise CRISPR-Cas9 gene repair in autologous memory T cells to treat familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis (FHL) is an inherited, often fatal immune deficiency characterized by severe systemic hyperinflammation. Although allogeneic bone marrow transplantation can be curative, more effective therapies are urgently needed. FHL is caused by inactivating mutations in proteins that regulate cellular immunity. Here, we used an adeno-associated virus-based CRISPR-Cas9 system with an inhibitor of nonhomologous end joining to repair such mutations in potentially long-lived T cells ex vivo. Repaired CD8 memory T cells efficiently cured lethal hyperinflammation in a mouse model of Epstein-Barr virus-triggered FHL2, a subtype caused by perforin-1 (Prf1) deficiency. Furthermore, repair of PRF1 and Munc13-4 (UNC13D)-whose deficiency causes the FHL subtype FHL3-in mutant memory T cells from two critically ill patients with FHL restored T cell cytotoxicity. These results provide a starting point for the treatment of genetic T cell immune dysregulation syndromes with repaired autologous T cells.

Infectious Mononucleosis: An Updated Review.

BACKGROUND: Infectious mononucleosis is common among adolescents and young adults. Although the majority of cases resolve spontaneously, life-threatening manifestations, and complications have been recognised. OBJECTIVE: The purpose of this article is to familiarize clinicians with the clinical manifestations, evaluation, diagnosis, and management of infectious mononucleosis. METHODS: A search was conducted in October 2022 in PubMed Clinical Queries using the key terms "infectious mononucleosis" OR "Epstein-Barr virus" OR "EBV". The search strategy included all clinical trials, observational studies, and reviews published within the past 10 years. Only papers published in the English literature were included in this review. The information retrieved from the aforementioned search was used in the compilation of the present article. RESULTS: Infectious mononucleosis, caused by Epstein-Barr virus, most commonly affects adolescents and adults aged 15 to 24 years. Epstein-Barr virus is transmitted primarily in saliva. Infectious mononucleosis is characterized by a triad of fever, tonsillar pharyngitis, and lymphadenopathy. Fatigue may be profound but tends to resolve within three months. Periorbital and/or palpebral edema, typically bilateral, occurs in one-third of patients. Splenomegaly and hepatomegaly occur in approximately 50% and 10% of cases, respectively. A skin rash, which is usually widely scattered, erythematous, and maculopapular, occurs in approximately 10 to 45% of cases. Peripheral blood leukocytosis is observed in most patients; lymphocytes make up at least 50% of the white blood cell differential count. Atypical lymphocytes constitute more than 10% of the total lymphocyte count. The classic test for infectious mononucleosis is the demonstration of heterophile antibodies. The monospot test is the most widely used method to detect the serum heterophile antibodies of infectious mononucleosis. When confirmation of the diagnosis of infectious mononucleosis is required in patients with mononucleosis-like illness and a negative mono-spot test, serologic testing for antibodies to viral capsid antigens is recommended. Infectious mononucleosis is a risk factor for chronic fatigue syndrome. Spontaneous splenic rupture occurs in 0.1 to 0.5% of patients with infectious mononucleosis and is potentially life-threatening. Treatment is mainly supportive. Reduction of activity and bed rest as tolerated are recommended. Patients should be advised to avoid contact sports or strenuous exercise for 8 weeks or while splenomegaly is still present. Most patients have an uneventful recovery. CONCLUSION: Infectious mononucleosis is generally a benign and self-limited disease. Prompt diagnosis is essential to avoid unnecessary investigations and treatments and to minimize complications. Splenic rupture is the most feared complication. As avoiding exposure to EBV is almost impossible, the most effective way to prevent EBV infection and infectious mononucleosis is the development of an effective, safe, and affordable EBV vaccine that can confer life-long immunity.

Hematopoietic Bone Marrow Transplant to Treat Systemic EBV-positive T-cell Lymphoma of Childhood.

Systemic Epstein-Barr virus-positive T-cell lymphoma of childhood (S-EBV-TCL) is a rare disease for which there is no standard of care. S-EBV-TCL is often associated with hemophagocytic lymphohistiocytosis and is generally thought of on the spectrum of EBV-related disease. For the few reported cases of cure in the literature, hematopoietic stem cell transplant has been required because it is the only treatment that has induced complete remission in patients suffering from EBV-associated T-cell or natural killer cell lymphoproliferative diseases, except hemophagocytic lymphohistiocytosis. Here, we present the case of one patient who was successfully cured with a modified regimen of dose-adjusted EPOCH (etoposide, prednisone, vincristine, cyclophosphamide, and doxorubicin), followed by hematopoietic stem cell transplant using a reduced-intensity conditioning regimen.

Recent advances in understanding the pathogenesis and biological treatment of multiple sclerosis.

Multiple sclerosis is the most common demyelinating disease that develops in genetically predisposed individuals through various immunopathological mechanisms induced by environmental factors, especially viral infections. Th1, Th17, γδ T cells, activated macrophages, MAIT cells, and proinflammatory cytokines, particularly IFN-γ, TNF, IL-17, and GM-CSF, are the principal pathological players whose activities cause damage to the white matter. Furthermore, a recently identified subset of CD4+ T cells has been found to migrate directly to the brain cortex and cause damage to neurons. In 2022, a new mechanism was discovered in addition to these processes. It was shown that molecular mimicry between the EBNA-1 antigen of the Epstein-Barr virus and the GlialCAM molecule of glial cells forms the basis that triggers the entire pathological process. EBV is a highly B cell-tropic human herpesvirus that placed B cells at the centre of our attention. As a result, we must down-regulate their numbers using anti-CD20 monoclonal antibodies to treat such patients (Tab. 1, Fig. 1, Ref. 37). Keywords: multiple sclerosis, GlialCAM, HLA-DR15, T-, B-, MAIT-cells, EBV, monoclonal antibodies.

Humoral response to Epstein-Barr virus in patients with multiple sclerosis treated with B cell depletion therapy.

BACKGROUND: B cell depletion therapy is highly effective in relapsing-remitting multiple sclerosis (RRMS). However, the precise underlying mechanisms of action for its biological effects in MS have still not been clarified. Epstein-Barr virus (EBV) is a known risk factor for MS and seems to be a prerequisite for disease development. EBV resides latently in the memory B cells, and may not only increase the risk of developing MS, but also contribute to disease activity and disability progression. Therefore, the effects of B cell depletion in MS could be associated with the depletion of EBV-infected cells and the altered immune response to the virus. In this study, we investigate the impact of B cell depletion on the humoral immune response specific to EBV in patients with MS. METHODS: Newly diagnosed, treatment-naïve patients with RRMS were followed up to 18 months after initiation of B-cell depletion therapy in the Overlord-MS study, a phase III trial (NCT04578639). We analyzed serum sampled before treatment and after 3, 6, 12 and 18 months for immunoglobulin γ (IgG) against Epstein-Barr nuclear antigen 1 (EBNA1) and Epstein-Barr viral capsid antigen (VCA). We analyzed antibodies to cytomegalovirus (CMV) and total IgG in serum, as controls for viral and overall humoral immunity. The risk allele, HLA-DRB1*15:01, and the protective allele, HLA-A*02:01, were determined in all participants. In addition, polymerase chain reaction (PCR) for circulating EBV-DNA was performed in the first 156 samples drawn. The associations between time on B cell-depletion therapy and serum anti-EBV antibody levels were estimated using linear mixed-effects models. RESULTS: A total of 290 serum samples from 99 patients were available for analysis. After 6, 12 and 18 months, the EBNA1 IgG levels decreased by 12.7 % (95 % CI -18.8 to -6.60, p < 0.001), 12.1 % (95 % CI -19.8 to -3.7, p = 0.006) and 14.6 % (95 % CI to -25.3 to -2.4, p = 0.02) respectively, compared to baseline level. Carriers of the HLA-DRB1*15:01 allele had higher EBNA1 IgG levels at baseline (p = 0.02). The VCA IgG levels significantly increased by 13.7 % (95 % CI 9.4 to 18.1, p < 0.001) after 3 months, compared to baseline, and persisted at this level throughout the follow-up. CMV IgG levels decreased, but to a lesser extent than the decrease of EBNA1 IgG, and total IgG levels decreased during therapy. Circulating EBV-DNA was found in only three of 156 samples from 64 patients. CONCLUSIONS: EBNA1 IgG levels decreased, while VCA IgG levels increased, during B cell depletion therapy. This supports the hypothesis that the mechanism of action for B cell depletion therapy might be mediated by effects on EBV infection, which, in turn, mitigate immune cross-reactivity and disease perpetuation.

mRNA-based Vaccines Targeting the T-cell Epitope-rich Domain of Epstein Barr Virus Latent Proteins Elicit Robust Anti-Tumor Immunity in Mice.

Epstein-Barr virus (EBV) is associated with various malignancies and infects >90% of the global population. EBV latent proteins are expressed in numerous EBV-associated cancers and contribute to carcinogenesis, making them critical therapeutic targets for these cancers. Thus, this study aims to develop mRNA-based therapeutic vaccines that express the T-cell-epitope-rich domain of truncated latent proteins of EBV, including truncatedlatent membrane protein 2A (Trunc-LMP2A), truncated EBV nuclear antigen 1 (Trunc-EBNA1), and Trunc-EBNA3A. The vaccines effectively activate both cellular and humoral immunity in mice and show promising results in suppressing tumor progression and improving survival time in tumor-bearing mice. Furthermore, it is observed that the truncated forms of the antigens, Trunc-LMP2A, Trunc-EBNA1, and Trunc-EBNA3A, are more effective than full-length antigens in activating antigen-specific immune responses. In summary, the findings demonstrate the effectiveness of mRNA-based therapeutic vaccines targeting the T-cell-epitope-rich domain of EBV latent proteins and providing new treatment options for EBV-associated cancers.

Dynamic single-cell mapping unveils Epstein‒Barr virus-imprinted T-cell exhaustion and on-treatment response.

Epstein‒Barr virus (EBV)-associated gastric cancer (GC) manifests an intriguing immunotherapy response. However, the cellular basis for EBV-imprinted tumour immunity and on-treatment response remains undefined. This study aimed to finely characterize the dynamic tumour immune contexture of human EBV (+) GC treated with immunochemotherapy by longitudinal scRNA-seq and paired scTCR/BCR-seq. EBV (+) GC exhibits an inflamed-immune phenotype with increased T-cell and B-cell infiltration. Immunochemotherapy triggers clonal revival and reinvigoration of effector T cells which step to determine treatment response. Typically, an antigen-specific ISG-15+CD8+ T-cell population is highly enriched in EBV (+) GC patients, which represents a transitory exhaustion state. Importantly, baseline intratumoural ISG-15+CD8+ T cells predict immunotherapy responsiveness among GC patients. Re-emerged clonotypes of pre-existing ISG-15+CD8+ T cells could be found after treatment, which gives rise to a CXCL13-expressing effector population in responsive EBV (+) tumours. However, LAG-3 retention may render the ISG-15+CD8+ T cells into a terminal exhaustion state in non-responsive EBV (+) tumours. In accordance, anti-LAG-3 therapy could effectively reduce tumour burden in refractory EBV (+) GC patients. Our results delineate a distinct implication of EBV-imprinted on-treatment T-cell immunity in GC, which could be leveraged to optimize the rational design of precision immunotherapy.

Perspectives for immunotherapy of EBV-associated GLELC: A relatively "hot" tumor microenvironment.

BACKGROUND: Epstein-Barr virus (EBV)-associated gastric lymphoepithelioma-like carcinoma (EBVaGLELC) represents a small number of gastric cancer (GC), and research on tumor microenvironment (TME) and treatment strategy are still lacking. AIMS: Here, we aim to elucidate the immune features of this rare disease and further help to develop more effective treatment options. MATERIALS & METHODS: A retrospective analysis was conducted between 2019 to 2022 in West China Hospital to reveal the immunological characteristics of EBV-positive GLELC. The difference of immune cell subset and tumor vascular structure between gastric denocarcinoma (GAC) and EBVaGLELC will be pointed out. DISCUSSION: 13 patients with GELEC and 8 patients with GAC were retrospectively studied. The heterogeneity of the immune cell profile was then confirmed through multiplexed immunofluorescence staining (mIF), which revealed a higher proportion of CD3+ T cells, CD8+ T cells, and Treg cells in the EBV-associated GLELC group. Such a distinct TME may provide therapeutic advantages, and patients with this rare subtype of GC could be good candidates for immune checkpoint inhibitors (ICIs). Angiogenesis in EBV-positive GLELC may be less intense than that in gastric adenocarcinoma (GAC), a feature that might decrease their susceptibility to antiangiogenic therapy. Furthermore, we reported a 52-year-old male with advanced EBV-positive GLELC who showed a favorable response to the combined therapy with . A repeat evaluation showed sustained partial response (PR), and the progression-free survival (PFS) was more than 34 months until now. CONCLUSION: Compared with GAC, EBVaGLELC revealed higher T cell infiltration and less intense of angiogenesis. It displays relatively "hot" TME that may provide the rationality to treat with immunotherapy in EBV-related GLELC.

Updated guidelines for chronic active Epstein-Barr virus disease.

Chronic active Epstein-Barr virus disease (CAEBV), formerly named chronic active Epstein-Barr virus infection, is characterized by systemic inflammation and clonal proliferation of Epstein-Barr virus (EBV)-infected T or NK cells. As CAEBV is a potentially life-threatening illness, appropriate diagnosis and therapeutic interventions are necessary for favorable clinical outcomes. Substantial evidence regarding the pathogenesis and treatment of CAEBV has been accumulated since previous guidelines for the diagnosis of CAEBV were proposed. To reflect this evidence, we updated the guidelines for the diagnosis and treatment of CAEBV to improve clinical management of the disease. The details of the updated guidelines are presented in this report. Diagnosis of CAEBV now requires confirmation of a high copy number of EBV genome and EBV-infected T or NK cells. An EBV DNA load ≥ 10,000 IU/mL in whole blood is proposed as the diagnostic cutoff value for CAEBV in this updated guideline. A standard treatment approach for CAEBV has not been established, and hematopoietic stem cell transplantation (HSCT) is considered the only curative treatment. Chemotherapy can be administered to control disease activity before HSCT.

Locoregional radiotherapy improves survival outcomes in de novo metastatic nasopharyngeal carcinoma treated with chemoimmunotherapy.

BACKGROUND: We aimed to investigate the efficacy of locoregional radiotherapy (LRRT) in patients with de novo metastatic nasopharyngeal carcinoma (dmNPC) receiving chemotherapy combined with anti-programmed cell death receptor-1 monoclonal antibodies (anti-PD-1 mAbs) as first-line treatment and identify optimal candidates for LRRT. MATERIALS AND METHODS: We enrolled patients with dmNPC receiving platinum-based palliative chemotherapy and anti-PD-1 mAbs followed or not followed by LRRT from four centers. The endpoints were progression-free survival (PFS), objective response rate (ORR), and overall survival (OS). We used the inverse probability of treatment weighting (IPTW) to balance the baseline characteristics of the LRRT and non-LRRT groups to minimize selection bias before comparative analyses. Multivariate analyses were carried out using the Cox proportional hazards model. RESULTS: We included 163 patients with dmNPC (median follow-up: 22 months). The median PFS was 20 months, and the ORR was 92.0%; the median OS was not achieved. After IPTW adjustments, patients who received LRRT had a significant survival benefit over those not receiving LRRT (median PFS: 28 versus 15 months, P < 0.001). The Epstein-Barr virus DNA (EBV DNA) level after four to six cycles of anti-PD-1 mAbs [weighted hazard ratio (HR): 2.19, 95% confidence interval (CI) 1.22-3.92, P = 0.008] and LRRT (weighted HR: 0.58, 95% CI 0.34-0.99, P = 0.04) were independent prognostic factors. Patients with undetectable EBV DNA levels after four to six cycles of anti-PD-1 mAbs (early EBV DNA clearance) benefitted from LRRT (HR: 0.41, 95% CI 0.22-0.79, P = 0.008), whereas those with detectable levels did not (HR: 1.30, 95% CI 0.59-2.87, P = 0.51). CONCLUSIONS: Palliative chemotherapy combined with anti-PD-1 mAbs followed by LRRT was associated with improved PFS in patients with dmNPC, especially for patients with early EBV DNA clearance.

[Diagnosis and management of EBV-positive lymphoproliferative disorders].

Epstein-Barr virus (EBV) has the ability to immortalize not only B cells but also T and natural killer (NK) cells. The virus may also contribute to the onset of EBV-positive lymphoproliferative disorders (EBV-LPDs) by inducing the introduction of gene mutations. It is known that B cell EBV-LPDs (B-EBV-LPDs) develop with preexisting immunodeficiency, but the onset mechanism of T cell and NK cell EBV-LPDs (T-EBV-LPDs and NK-EBV-LPDs), also known as chronic active EBV disease and associated diseases, is unclear. The diagnosis of both EBV-LPDs requires the quantitative examination of EBV-DNA in the peripheral blood. Eliminating the cause of immunodeficiency or administering rituximab is effective in treating B-EBV-LPDs, but some B-EBV-LPDs and T-EBV-LPDs/NK-EBV-LPDs are resistant to pharmacotherapy. Therefore, further research is needed to explicate the pathophysiology of EBV-LPDs and develop a drug for its treatment.

How I treat posttransplant lymphoproliferative disorder.

Posttransplant lymphoproliferative disorder (PTLD) is an important and potentially life-threatening complication of solid organ transplant and hematopoietic stem cell transplant (HSCT). Given the heterogeneity of PTLD and the risk of infectious complications in patients with immunosuppression, the treatment of this disease remains challenging. Monomorphic PTLD and lymphoma of B-cell origin account for the majority of cases. Treatment strategies for PTLD consist of response-adapted, risk-stratified methods using immunosuppression reduction, immunotherapy, and/or chemotherapy. With this approach, ∼25% of the patients do not need chemotherapy. Outcomes for patients with high risk or those who do not respond to frontline therapies remain dismal, and novel treatments are needed in this setting. PTLD is associated with Epstein-Barr virus (EBV) infection in 60% to 80% of cases, making EBV-directed therapy an attractive treatment modality. Recently, the introduction of adoptive immunotherapies has become a promising option for refractory cases; hopefully, these treatment strategies can be used as earlier lines of therapy in the future.