Synthetic BZLF1-targeted transcriptional activator for efficient lytic induction therapy against EBV-associated epithelial cancers.

The unique virus-cell interaction in Epstein-Barr virus (EBV)-associated malignancies implies targeting the viral latent-lytic switch is a promising therapeutic strategy. However, the lack of specific and efficient therapeutic agents to induce lytic cycle in these cancers is a major challenge facing clinical implementation. We develop a synthetic transcriptional activator that specifically activates endogenous BZLF1 and efficiently induces lytic reactivation in EBV-positive cancer cells. A lipid nanoparticle encapsulating nucleoside-modified mRNA which encodes a BZLF1-specific transcriptional activator (mTZ3-LNP) is synthesized for EBV-targeted therapy. Compared with conventional chemical inducers, mTZ3-LNP more efficiently activates EBV lytic gene expression in EBV-associated epithelial cancers. Here we show the potency and safety of treatment with mTZ3-LNP to suppress tumor growth in EBV-positive cancer models. The combination of mTZ3-LNP and ganciclovir yields highly selective cytotoxic effects of mRNA-based lytic induction therapy against EBV-positive tumor cells, indicating the potential of mRNA nanomedicine in the treatment of EBV-associated epithelial cancers.

Significant response to pembrolizumab plus lenvatinib in Epstein-Barr-virus-associated intrahepatic cholangiocarcinoma: a case report.

BACKGROUND: The prognosis for advanced intrahepatic cholangiocarcinoma (iCCA) is poor, and there remains an urgent need to develop efficient systemic therapy. The efficacy of Pembrolizumab immunotherapy combined with lenvatinibin in iCCA is still unclear. The role of Epstein-Barr-virus (EBV) as a biomarker in iCCA for response to immunotherapy needs further exploration. CASE PRESENTATION: We report a case of a 60-year-old female with EBV-associated advanced iCCA (EBVaiCCA) who progressed after first-line therapy. She accomplished an available response to the combination therapy of pembrolizumab with lenvatinib, with overall survival of 20 months. CONCLUSIONS: As far as we know, this is the first case report about the application of Pembrolizumab with lenvatinib for EBVaiCCA patients. This case indicates that the combination of immunotherapy and antiangiogenic therapy provides a glimmer of hope for advanced EBVaiCCA patients.

Transcriptome analysis of Burkitt lymphoma cells treated with anti-convulsant drugs that are inhibitors of Epstein-Barr virus lytic reactivation.

Herpesviruses have two distinct life cycle stages, latency and lytic replication. Epstein-Barr virus (EBV), a gamma-herpesvirus, establishes latency in vivo and in cultured cells. Cell lines harboring latent EBV can be induced into the lytic cycle by treatment with chemical inducing agents. In the Burkitt lymphoma cell line HH514-16 the viral lytic cycle is triggered by butyrate, a histone deacetylase (HDAC) inhibitor. Butyrate also alters expression of thousands of cellular genes. However, valproic acid (VPA), another HDAC inhibitor with global effects on cellular gene expression blocks EBV lytic gene expression in Burkitt lymphoma cell lines. Valpromide (VPM), an amide derivative of VPA, is not an HDAC inhibitor, but like VPA blocks induction of the EBV lytic cycle. VPA and VPM are the first examples of inhibitors of initial stages of lytic reactivation. We compared the effects of VPA and VPM, alone and in combination with butyrate, on host cellular gene expression using whole transcriptome analysis (RNA-seq). Gene expression was analyzed 6 h after addition of the compounds, a time before the first EBV lytic transcripts are detected. The results address two alternative, yet possibly complementary, mechanisms for regulation of EBV lytic reactivation. First, cellular genes that were up- or down-regulated by butyrate, but no longer altered in the presence of VPA or VPM, represent genes that correlated with EBV lytic reactivation. Second, genes regulated similarly by VPA and VPM in the absence and presence of butyrate are candidates for suppressors of EBV reactivation. Two genes upregulated by the lytic cycle inhibitors, CHAC1 and SLC7A11, are related to redox status and the iron-dependent cell death pathway ferroptosis. This study generates new hypotheses for control of the latency to lytic cycle switch of EBV and provides the first description of effects of the anti-convulsant drug VPM on global human cellular gene expression.

[L-DEP regimen salvage therapy for refractory primary hemophagocytic lymphohistiocytosis triggered by Epstein-Barr virus infection in 4 children].

Objective: To analyze the efficacy and safety of the L-DEP regimen (asparaginase, liposome doxorubicin, etoposide and methylprednisolone) as a salvage therapy for the refractory primary hemophagocytic lymphohistocytosis triggered by Epstein-Barr virus infection (EBV-pHLH) in children. Methods: In this retrospective case study, clinical and laboratory data before and after L-DEP regimen of 4 children diagnosed with EBV-pHLH in Beijing Children's hospital between January 2016 and June 2022 were collected, and the efficacy and safety of L-DEP regimen for the treatment of EBV-pHLH were analyzed. Results: Among 4 patients, there were 3 females and 1 male with the age ranged from 0.8 to 7.0 years. Two of them showed compound heterozygous mutations of PRF1, one with a heterozygous mutation of UNC13D, one homozygous mutation of ITK. Before the L-DEP therapy, all of them had anemia and a soaring level of soluble CD25, 3 patients had neutropenia and thrombopenia, 3 patients had a high level of ferritin, 3 patients had hypofibrinogenemia and 1 patient had hypertriglyceridemia. After receiving 1 or 2 cycles of L-DEP treatment, three achieved remission, including complete remission (1 case) and partial remission (2 cases), and the other one had no remission. The levels of blood cell counts, soluble CD25, triglyceride, fibrinogen and albumin were recovered gradually in 3 patients who got remission. All four patients underwent hematopoietic stem cell transplantation (HSCT) after L-DEP regimen, and three survived. All patients had no severe chemotherapy related complications. The main side effects were bone marrow suppression, infection and pancreatitis, which recovered after appropriate treatments, apart from one who died from severe infection after urgent HSCT. Conclusion: L-DEP regimen could be served as an effective and safe salvage treatment for refractory pediatric EBV-pHLH, and also provide an opportunity for patients to receive HSCT.

Effect of pre-emptive rituximab on EBV DNA levels and prevention of post-transplant lymphoproliferative disorder in pediatric kidney transplant recipients: A case series from the pediatric nephrology research consortium.

BACKGROUND: There are scant data on the effect of rituximab on EBV DNA levels and prevention of post-transplant lymphoproliferative disorder (PTLD) in pediatric kidney transplant recipients with EBV DNAemia. METHODS: Kidney transplant recipients with EBV DNAemia treated with rituximab to prevent PTLD between 7/1999 and 7/2019 at five pediatric centers were included. Those with confirmed PTLD at the onset of rituximab were excluded. Primary outcomes included percentage change in EBV DNAemia and occurrence of PTLD post rituximab. RESULTS: Twenty-six pediatric kidney transplant recipients were included. Median age at transplant was 4 years (IQR 2.1-10.3). EBV DNA load monitoring by qPCR was performed at 1-3 month intervals. EBV DNAemia onset occurred at a median of 73 days post-transplant (IQR 52-307), followed by DNAemia peak at a median of 268 days (IQR 112-536). Rituximab was administered at a median of 9 days post peak (IQR 0-118). Rituximab regimens varied; median dose 375 mg/m2 (IQR 375-439) weekly for 1-4 doses per course. Following rituximab, EBV DNA load decreased to <10% of baseline at 120 days in 20/26 patients; however, only 30% achieved complete resolution at last follow-up (median 2094 days post-transplant [IQR 1538-3463]). Two (7%) developed PTLD at 915 and 1713 days post rituximab. All recipients had functioning grafts. One death occurred in a child with PTLD following remission due to unrelated reasons. CONCLUSIONS: In the largest pediatric kidney transplant recipient case series with EBV DNAemia given rituximab to prevent PTLD, rituximab achieved a short-term reduction in DNA load; however, recurrent DNAemia is common.

The Effects of Endosomal Toll-like Receptor Inhibitors in an EBV DNA-Exacerbated Inflammatory Bowel Disease Mouse Model.

Epstein-Barr virus (EBV), a Herpesviridae family member, is associated with an increased risk of autoimmune disease development in the host. We previously demonstrated that EBV DNA elevates levels of the pro-inflammatory cytokine IL-17A and that inhibiting Toll-like receptor (TLR) 3, 7, or 9 reduces its levels. Moreover, this DNA exacerbated colitis in a mouse model of inflammatory bowel disease (IBD). In the study at hand, we examined whether inhibition of TLR3, 7, or 9 alleviates this exacerbation. Mice were fed 1.5% dextran sulfate sodium (DSS) water and administered EBV DNA. Then, they were treated with a TLR3, 7, or 9 inhibitor or left untreated. We also assessed the additive impact of combined inhibition of all three receptors. Mice that received DSS, EBV DNA, and each inhibitor alone, or a combination of inhibitors, showed significant improvement. They also had a decrease in the numbers of the pathogenic colonic IL-17A+IFN-γ+ foci. Inhibition of all three endosomal TLR receptors offered no additive benefit over administering a single inhibitor. Therefore, inhibition of endosomal TLRs reduces EBV DNA exacerbation of mouse colitis, offering a potential approach for managing IBD patients infected with EBV.

Secondary hemophagocytic lymphohistiocytosis in pediatric patients with visceral leishmaniasis and Epstein-Barr virus infection.

Visceral leishmaniasis-associated hemophagocytic lymphohistiocytosis (VL-HLH) is indistinguishable from those of HLH of other etiologies due to the overlap symptoms, posing a serious threat to life. In this study, we aimed to provide insights for early diagnosis and improve outcomes in pediatric patients with VL-HLH. We retrospectively analyzed the clinical and laboratory data of 10 pediatric patients with VL-HLH and 58 pediatric patients with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH). The median time from symptom onset to cytopenia in patients with VL-HLH and EBV-HLH was 11 days (interquartile range, 7-15 days) and five days (interquartile range, 3.75-9.25 days) (P = 0.005). Both groups showed liver injury and increased lactate dehydrogenase levels; however the levels of aspartate aminotransferase, alanine aminotransferase, direct bilirubin, and lactate dehydrogenase in patients with VL-HLH were significantly lower than those in patients with EBV-HLH (P < 0.05). The fibrinogen and triglyceride levels were almost normal in VL-HLH patients but were significantly altered in EBV-HLH cases ( P < 0.05). The positive rate of first bone marrow microscopy examination, anti-rK39 IgG detection, and blood metagenomic next-generation sequencing was 50%, 100%, and 100%, respectively. After VL diagnosis, eight patients were treated with sodium stibogluconate and two were treated with liposomal amphotericin B. All the patients with VL-HLH recovered. Our study demonstrates that regular triglyceride and fibrinogen levels in pediatric patients with VL-HLH may help in differential diagnosis from EBV-HLH. VL-HLH is milder than EBV-HLH, with less severe liver injury and inflammatory responses, and timely treatment with antileishmanial agents is essential to improve the outcomes of pediatric patients with VL-HLH.

Epstein-Barr virus reactivation and disease flare of systemic lupus erythematosus.

SLE affects females rather than males with a ratio of about 9:1. Owing to the high morbidity with multiple organ involvement, SLE flare-up remains a challenge for women's health. In an accumulation of the past 70 years of studies globally, EBV has been found to be strongly associated with SLE. In the past two decades, EBV reactivation has been proven as prevalent in SLE patients as well as being strongly associated with higher SLE activity and higher prevalence of SLE flare. Hence, strategies to control EBV reactivation in SLE including pharmacological (such as Tenofovir prodrugs TDF and TAF) and non-pharmacological approaches are being developed. The heterogeneity of SLE constitutes clinical challenges, suggesting a stratification of SLE into subgroups based on EBV reactivation or non-reactivation is reasonable. Future-wise, adding anti-EBV reactivation medication to current immunosuppressants for the subgroup of SLE patients with EBV reactivation could be beneficial to achieve long-term remission of SLE.

Diagnosis of an immunocompetent adult with acute headache and fever as Epstein-Barr virus encephalitis by mNGS of cerebrospinal fluid.

Complicated case with fever or headache of unknown origin is currently one of the main challenges in clinical diagnosis. A retrospective analysis was conducted on a 27-year-old female patient hospitalized with headache and fever, and the pathogen species were ultimately determined by metagenomic next-generation sequencing (mNGS) of cerebrospinal fluid (CSF). The culture results of CSF showed no bacterial or fungal growth. CSF cytology showed a significant increase in nucleated cells. Pathogenic index (corresponded to human gamma herpesvirus 4) of the microorganism after correcting for human background was 12846.77 with a host index (human resource) of 27822.48 by mNGS of CSF. The patient improved through antiviral treatment with ganciclovir. Epstein-Barr virus encephalitis is rare in immunocompetent adults, which can easily cause misdiagnosis and should be paid attention to. mNGS of CSF has significant advantages in the diagnosis of Epstein-Barr virus encephalitis.

Tabelecleucel for allogeneic haematopoietic stem-cell or solid organ transplant recipients with Epstein-Barr virus-positive post-transplant lymphoproliferative disease after failure of rituximab or rituximab and chemotherapy (ALLELE): a phase 3, multicentre, open-label trial.

BACKGROUND: Survival in Epstein-Barr virus (EBV)-positive post-transplant lymphoproliferative disease following haematopoietic stem-cell transplant (HSCT) or solid organ transplant (SOT) is poor after failure of initial therapy, indicating an urgent need for therapies for this ultra-rare disease. With recent EU marketing authorisation, tabelecleucel is the first off-the-shelf, allogeneic, EBV-specific T-cell immunotherapy to receive approval for treatment of relapsed or refractory EBV-positive post-transplant lymphoproliferative disease. We aimed to determine the clinical benefit of tabelecleucel in patients with relapsed or refractory EBV-positive post-transplant lymphoproliferative disease following HSCT or SOT. METHODS: In this global, multicentre, open-label, phase 3 trial, eligible patients (of any age) had biopsy-proven EBV-positive post-transplant lymphoproliferative disease, disease that was relapsed or refractory to rituximab after HSCT and rituximab with or without chemotherapy after SOT, and partially HLA-matched and appropriately HLA-restricted tabelecleucel available. Patients received tabelecleucel administered intravenously at 2 × 106 cells per kg on days 1, 8, and 15 in 35-day cycles and are assessed for up to 5 years for survival post-treatment initiation. The primary endpoint was objective response rate. All patients who received at least one dose of tabelecleucel were included in safety and efficacy analyses. This trial is registered with ClinicalTrials.gov, NCT03394365, and is ongoing. FINDINGS: From June 27, 2018, to Nov 5, 2021, 63 patients were enrolled, of whom 43 (24 [56%] male and 19 [44%] female) were included, 14 had prior HSCT, 29 had SOT. Seven (50%, 95% CI 23-77) of 14 participants in the HSCT group and 15 (52%, 33-71) of 29 participants in the SOT group had an objective response, with a median follow-up of 14·1 months (IQR 5·7-23·9) and 6·0 months (1·8-18·4), respectively. The most common grade 3 or 4 treatment-emergent adverse events were disease progression (in four [29%] of 14 in HSCT and eight [28%] of 29 in SOT) and decreased neutrophil count (in four [29%] of 14 in HSCT and four [14%] of 29 in SOT). Treatment-emergent serious adverse events were reported in 23 (53%) of 43 patients and fatal treatment-emergent adverse events in five (12%); no fatal treatment-emergent adverse event was treatment-related. There were no reports of tumour flare reaction, cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, transmission of infectious diseases, marrow rejection, or infusion reactions. No events of graft-versus-host disease or SOT rejection were reported as related to tabelecleucel. INTERPRETATION: Tabelecleucel provides clinical benefit in patients with relapsed or refractory EBV-positive post-transplant lymphoproliferative disease, for whom there are no other approved therapies, without evidence of safety concerns seen with other adoptive T-cell therapies. These data represent a potentially transformative and accessible treatment advance for patients with relapsed or refractory disease with few treatment options. FUNDING: Atara Biotherapeutics.

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.

Durable immunity to EBV after rituximab and third-party LMP-specific T cells: a Children's Oncology Group study.

ABSTRACT: Posttransplant lymphoproliferative disease (PTLD) in pediatric solid organ transplant (SOT) recipients is characterized by uncontrolled proliferation of Epstein-Barr virus-infected (EBV+) B cells due to decreased immune function. This study evaluated the feasibility, safety, clinical and immunobiological outcomes in pediatric SOT recipients with PTLD treated with rituximab and third-party latent membrane protein-specific T cells (LMP-TCs). Newly diagnosed (ND) patients without complete response to rituximab and all patients with relapsed/refractory (R/R) disease received LMP-TCs. Suitable LMP-TC products were available for all eligible subjects. Thirteen of 15 patients who received LMP-TCs were treated within the prescribed 14-day time frame. LMP-TC therapy was generally well tolerated. Notable adverse events included 3 episodes of rejection in cardiac transplant recipients during LMP-TC therapy attributed to subtherapeutic immunosuppression and 1 episode of grade 3 cytokine release syndrome. Clinical outcomes were associated with disease severity. Overall response rate (ORR) after LMP-TC cycle 1 was 70% (7/10) for the ND cohort and 20% (1/5) for the R/R cohort. For all cohorts combined, the best ORR for LMP-TC cycles 1 and 2 was 53% and the 2-year overall survival was 70.7%. vßT-cell receptor sequencing showed persistence of adoptively transferred third-party LMP-TCs for up to 8 months in the ND cohort. This study establishes the feasibility of administering novel T-cell therapies in a cooperative group clinical trial and demonstrates the potential for positive outcomes without chemotherapy for ND patients with PTLD. This trial was registered at www.clinicaltrials.gov as #NCT02900976 and at the Children's Oncology Group as ANHL1522.

A glance on the role of IL-35 in systemic lupus erythematosus (SLE).

It is well known that systemic lupus erythematosus (SLE) is an auto-inflammatory disease that is characterized by chronic and widespread inflammation. The exact pathogenesis of SLE is still a matter of debate. However, it has been suggested that the binding of autoantibodies to autoantigens forms immune complexes (ICs), activators of the immune response, in SLE patients. Ultimately, all of these responses lead to an imbalance between anti-inflammatory and pro-inflammatory cytokines, resulting in cumulative inflammation. IL-35, the newest member of the IL-12 family, is an immunosuppressive and anti-inflammatory cytokine secreted mainly by regulatory cells. Structurally, IL-35 is a heterodimeric cytokine, composed of Epstein-Barr virus-induced gene 3 (EBI3) and p35. IL-35 appears to hold therapeutic and diagnostic potential in cancer and autoimmune diseases. In this review, we summarized the most recent associations between IL and 35 and SLE. Unfortunately, the comparative review of IL-35 in SLE indicates many differences and contradictions, which make it difficult to generalize the use of IL-35 in the treatment of SLE. With the available information, it is not possible to talk about targeting this cytokine for the lupus treatment. So, further studies would be needed to establish the clear and exact levels of this cytokine and its related receptors in people with lupus to provide IL-35 as a preferential therapeutic or diagnostic candidate in SLE management.

Update of Natural Products and Their Derivatives Targeting Epstein-Barr Infection.

Epstein-Barr (EBV) is a human γ-herpesvirus that undergoes both a productive (lytic) cycle and a non-productive (latent) phase. The virus establishes enduring latent infection in B lymphocytes and productive infection in the oral mucosal epithelium. Like other herpesviruses, EBV expresses its genes in a coordinated pattern during acute infection. Unlike others, it replicates its DNA during latency to maintain the viral genome in an expanding pool of B lymphocytes, which are stimulated to divide upon infection. The reactivation from the latent state is associated with a productive gene expression pattern mediated by virus-encoded transcriptional activators BZLF-1 and BRLF-1. EBV is a highly transforming virus that contributes to the development of human lymphomas. Though viral vectors and mRNA platforms have been used to develop an EBV prophylactic vaccine, currently, there are no vaccines or antiviral drugs for the prophylaxis or treatment of EBV infection and EBV-associated cancers. Natural products and bioactive compounds are widely studied for their antiviral potential and capability to modulate intracellular signaling pathways. This review was intended to collect information on plant-derived products showing their antiviral activity against EBV and evaluate their feasibility as an alternative or adjuvant therapy against EBV infections and correlated oncogenesis in humans.

Epstein-Barr Virus: Human Interactome Reveals New Molecular Insights into Viral Pathogenesis for Potential Therapeutics and Antiviral Drug Discovery.

Host-virus Protein-Protein Interactions (PPIs) play pivotal roles in biological processes crucial for viral pathogenesis and by extension, inform antiviral drug discovery and therapeutics innovations. Despite efforts to develop the Epstein-Barr virus (EBV)-host PPI network, there remain significant knowledge gaps and a limited number of interacting human proteins deciphered. Furthermore, understanding the dynamics of the EBV-host PPI network in the distinct lytic and latent viral stages remains elusive. In this study, we report a comprehensive map of the EBV-human protein interactions, encompassing 1752 human and 61 EBV proteins by integrating data from the public repository HPIDB (v3.0) as well as curated high-throughput proteomic data from the literature. To address the stage-specific nature of EBV infection, we generated two detailed subset networks representing the latent and lytic stages, comprising 747 and 481 human proteins, respectively. Functional and pathway enrichment analysis of these subsets uncovered the profound impact of EBV proteins on cancer. The identification of highly connected proteins and the characterization of intrinsically disordered and cancer-related proteins provide valuable insights into potential therapeutic targets. Moreover, the exploration of drug-protein interactions revealed notable associations between hub proteins and anticancer drugs, offering novel perspectives for controlling EBV pathogenesis. This study represents, to the best of our knowledge, the first comprehensive investigation of the two distinct stages of EBV infection using high-throughput datasets. This makes a contribution to our understanding of EBV-host interactions and provides a foundation for future drug discovery and therapeutic interventions.

Opportunistic Infections in Patients Receiving Post-Transplantation Cyclophosphamide: Impact of Haploidentical versus Unrelated Donor Allograft.

Post-transplantation cyclophosphamide (PTCy) is an effective strategy for graft-versus-host disease (GVHD) prophylaxis and is the standard of care for haploidentical hematopoietic cell transplantation (HCT). It is increasingly used for matched and mismatched unrelated donor (MUD/MMUD) HCT, but infections remain a concern. The objective of this study was to evaluate the characteristics and risk factors for infections in haploidentical and unrelated donor HCT recipients treated with PTCy-based GVHD prophylaxis. This single-center retrospective study examined 354 consecutive adults undergoing HCT with PTCy-based GVHD prophylaxis (161 MUD/MMUD; 193 haploidentical) between 2015 and 2022. Opportunistic infections (OIs), including cytomegalovirus (CMV), adenovirus (AdV), Epstein-Barr virus (EBV), and invasive fungal disease (IFD), were assessed from day 0 through day +365. The 1-year cumulative incidence functions of OIs and nonrelapse mortality (NRM) were calculated using dates of relapse and repeat HCT as competing risks. Secondary analysis evaluated risk factors for OIs and NRM using univariate and multivariable Cox regression models. Haploidentical HCT recipients had an increased risk of OIs compared to unrelated donor allograft recipients (39% for haploidentical versus 25% for MUD/MMUD; hazard ratio [HR], 1.70; 95% confidence interval [CI], 1.16 to 2.49; P = .006). On multivariable analysis, haploidentical donor (HR, 1.50; 95% CI, 1.01 to 2.23; P = .046), prior HCT (HR, 1.99; 95% CI, 1.29 to 3.09; P = .002), and diagnosis of aGVHD (HR, 1.47; 95% CI, 1.02 to 2.14; P = .041) were associated with increased risk of OIs. NRM within the first year was not significantly different between the 2 cohorts (HR, 1.11; 95% CI, .64 to 1.93; P = .70). Overall, haploidentical donor was a significant risk factor for OIs in patients receiving PTCy, although 1-year NRM was not different between haploidentical HCT and MUD/MMUD HCT recipients. CMV and AdV infections were significantly increased among haploidentical HCT recipients, whereas the incidences of EBV infection and IFD were similar in the 2 cohorts. Our findings may have implications for infection monitoring and prophylaxis in the setting of PTCy, particularly in haploidentical HCT recipients.

Outcomes for patients with EBV-positive PTLD post-allogeneic HCT after failure of rituximab-containing therapy.

Epstein-Barr virus-positive (EBV+) post-transplant lymphoproliferative disease (PTLD) is an ultra-rare and aggressive condition that may occur following allogeneic hematopoietic cell transplant (HCT) due to immunosuppression. Approximately half of EBV+ PTLD cases are relapsed or refractory (R/R) to initial rituximab-containing therapy. There are limited treatment options and no standard of care for patients with R/R EBV+ PTLD, and little is known about their treatment history and outcomes. We performed a multinational, multicenter, retrospective chart review of patients with R/R EBV+ PTLD following HCT to describe patients' demographic and disease characteristics, treatment history, and overall survival (OS) from rituximab failure. Among 81 patients who received initial treatment with rituximab as monotherapy (84.0%) or in combination with chemotherapy (16.0%), median time from HCT to PTLD diagnosis was 3.0 months and median OS was 0.7 months. Thirty-six patients received a subsequent line of treatment. The most frequent causes of death were PTLD (56.8%), graft-versus-host disease (13.5%) and treatment-related mortality (10.8%). In multivariate analysis, early PTLD onset and lack of response to initial treatment were associated with mortality. This real-world study demonstrates that the prognosis of patients with R/R EBV+ PTLD following HCT remains poor, highlighting the urgent unmet medical need in this population.