Therapeutic approaches to Epstein-Barr virus cancers

Metabolic regulation of the tumour and its microenvironment: The role of Epstein-Barr virus

The Epstein-Barr virus (EBV), the first identified human tumour virus, infects over 95% of the individuals globally and has the potential to induce different types of cancers. It is increasingly recognised that EBV infection not only alters cellular metabolism, contributing to neoplastic transformation, but also utilises several non-cell autonomous mechanisms to shape the metabolic milieu in the tumour microenvironment (TME) and its constituent stromal and immune cells. In this review, we explore how EBV modulates metabolism to shape the interactions between cancer cells, stromal cells, and immune cells within a hypoxic and acidic TME. We highlight how metabolites resulting from EBV infection act as paracrine factors to regulate the TME, and how targeting them can disrupt barriers to immunotherapy.

Association of Epstein-Barr Virus and its clinical relevance in Human Papillomavirus-negative oral squamous cell carcinoma: A cohort study from South India

OBJECTIVE

The study assessed the prevalence and clinical implications of Epstein Barr Virus (EBV)-positive but Human Papillomavirus (HPV)-negative oral squamous cell carcinoma (OSCC) in a tertiary care hospital setting. The overall goal was to elucidate the potential impact of EBV on OSCC disease progression and prognosis.

DESIGN

A total of 134 surgically resected and histopathologically confirmed OSCC tumor biopsies were collected from a tertiary care hospital. Tumor samples were analyzed for HPV and EBV using conventional and nested PCR. Clinical and demographic data, including age, sex, risk factors, tumor stage, and survival outcomes, were collected and analyzed to assess associations between EBV status and disease characteristics.

RESULTS

All the tumor samples tested negative for HPV. However, EBV was detected in 74 cases (55.3 %) using nested PCR which was confirmed by sanger sequencing. EBV prevalence was higher in males (62.1 %), and the left buccal mucosa was the most affected site, accounting for 34 % of cases. Although statistically not significant, 63.5 % (n = 47) of the EBV positive subjects had a history of consuming both tobacco and alcohol. Of these 20 subjects showing recurrence, 35 % (n = 7) were EBV positive suggesting poor prognosis for EBV positive OSCC subjects.

CONCLUSION

This study highlights a significant prevalence of EBV in HPV-negative OSCC cases, suggesting a potential oncogenic role for EBV in OSCC progression, particularly in patients with established lifestyle risk factors. These findings underscore the need for further research into EBV's molecular mechanisms in OSCC and its utility as a biomarker for prognosis and therapeutic targeting. The results advocate for region-specific strategies to better understand and manage EBV-associated OSCC, offering potential pathways to improve outcomes in high-risk populations.

Multiple sclerosis and infection: history, EBV, and the search for mechanism

SUMMARYInfection has long been hypothesized as the cause of multiple sclerosis (MS), and recent evidence for Epstein-Barr virus (EBV) as the trigger of MS is clear and compelling. This clarity contrasts with yet uncertain viral mechanisms and their relation to MS neuroinflammation and demyelination. As long as this disparity persists, it will invigorate virologists, molecular biologists, immunologists, and clinicians to ascertain how EBV potentiates MS onset, and possibly the disease's chronic activity and progression. Such efforts should take advantage of the diverse body of basic and clinical research conducted over nearly two centuries since the first clinical descriptions of MS plaques. Defining the contribution of EBV to the complex and multifactorial pathology of MS will also require suitable experimental models and techniques. Such efforts will broaden our understanding of virus-driven neuroinflammation and specifically inform the development of EBV-targeted therapies for MS management and, ultimately, prevention.

USP7 Inhibitors Destabilize EBNA1 and Suppress Epstein-Barr Virus Tumorigenesis

Epstein-Barr virus (EBV) is a ubiquitous human ɣ-herpesvirus implicated in various malignancies, including Burkitt's lymphoma and gastric carcinomas. In most EBV-associated cancers, the viral genome is maintained as an extrachromosomal episome by the EBV nuclear antigen-1 (EBNA1). EBNA1 is considered to be a highly stable protein that interacts with the ubiquitin-specific protease 7 (USP7). Here, we show that pharmacological inhibitors and small interfering RNA (siRNA) targeting USP7 reduce EBNA1 protein levels in a proteosome-dependent manner. Proteomic analysis revealed that USP7 inhibitor GNE6776 altered the EBNA1 protein interactome, including disrupting USP7 association with EBNA1. GNE6776 also inhibited EBNA1 binding to EBV oriP DNA and reduced viral episome copy number. Transcriptomic studies revealed that USP7 inhibition affected chromosome segregation and mitotic cell division pathways in EBV+ cells. Finally, we show that GNE6776 selectively inhibited EBV+ gastric and lymphoid cell proliferation in cell culture and slowed EBV+ tumor growth in mouse xenograft models. These findings suggest that USP7 inhibitors perturb EBNA1 stability and function and may be exploited to treat EBV latent infection and tumorigenesis.

Possible viral agents to consider in the differential diagnosis of blepharoconjunctivitis

BACKGROUND

Blepharoconjunctivitis poses a diagnostic challenge due to its diverse etiology, including viral infections. Blepharoconjunctivits can be acute or chronic, self-limiting, or needing medical therapy.

AIM

To review possible viral agents crucial for accurate differential diagnosis in cases of blepharoconjunctivitis.

METHODS

The PubMed database was searched for records relating to viral blepharoconjunctivitis. The search string generated was "("virally"[All Fields] OR "virals"[All Fields] OR "virology"[MeSH Terms] OR "virology"[All Fields] OR "viral"[All Fields]) AND "Blepharoconjunctivitis"[All Fields]".

RESULTS

A total of 24 publications were generated from the search string. Reference lists from each relevant article were also searched for more information and included in this review. Viral etiologies such as adenovirus, herpes simplex virus (HSV), varicella-zoster virus (VZV), and Epstein-Barr virus (EBV) are frequently implicated. Adenoviral infections manifest with follicular conjunctivitis and preauricular lymphadenopathy, often presenting as epidemic keratoconjunctivitis. HSV and VZV infections can result in herpetic keratitis and may exhibit characteristic dendritic corneal ulcers. EBV, although less common, can cause unilateral or bilateral follicular conjunctivitis, particularly in immunocompromised individuals. Other potential viral agents, such as enteroviruses and molluscum contagiosum virus, should also be considered, especially in pediatric cases.

CONCLUSION

Prompt recognition of these viral etiologies is essential for appropriate management and prevention of complications. Thus, a thorough understanding of the clinical presentation, epidemiology, and diagnostic modalities is crucial for accurate identification and management of viral blepharoconjunctivitis.

Validation of a robust and rapid liquid chromatography tandem mass spectrometric method for the quantitative analysis of VK-2019, a selective EBNA1 inhibitor

EBNA1 is an Epstein Barr virus (EBV) protein expressed in all EBV-associated cancers. EBNA1 plays a critical role in the replication and maintenance of EBV episomes in latently infected cells. VK-2019 was developed as a highly specific inhibitor of EBNA1 DNA binding activity and is currently in phase 1 development as a treatment for EBV-associated carcinomas. A sensitive and reliable method was developed to quantify VK-2019 in human plasma using liquid chromatography with tandem mass spectrometry to perform detailed pharmacokinetic studies. VK-2019 was extracted from plasma using protein precipitation with acetonitrile. Separation of VK-2019, two purported metabolites, and the internal standard, VK-2019-d6, was achieved with a Zorbax XDB C18 column using a gradient flow over 6 min. VK-2019 was detected using a SCIEX 4500 triple quadrupole mass spectrometer operating in positive electrospray ionization mode. The assay range was 0.5-500 ng/mL and proved to be accurate and precise. Dilutions of 1:10 were accurately quantified. VK-2019 was stable in plasma at -70°C for approximately 18 months. The method was applied to assess the total plasma concentrations of VK-2019 in a patient who received a single and multiple oral daily doses of 120 mg.

EBNA1 Inhibitors Block Proliferation of Spontaneous Lymphoblastoid Cell Lines From Patients With Multiple Sclerosis and Healthy Controls

BACKGROUND AND OBJECTIVES

Epstein-Barr virus (EBV) is a ubiquitous herpesvirus that establishes lifelong latency in memory B cells and has been identified as a major risk factor of multiple sclerosis (MS). B cell depletion therapies have disease-modifying benefit in MS. However, it is unclear whether this benefit is partly attributable to the elimination of EBV+ B cells. Currently, there are no EBV-specific antiviral therapies available for targeting EBV latent infection in MS and limited experimental models to study EBV in MS.

METHODS

In this study, we describe the establishment of spontaneous lymphoblastoid cell lines (SLCLs) generated ex vivo with the endogenous EBV of patients with MS and controls and treated with either an Epstein-Barr virus nuclear antigen 1 (EBNA1) inhibitor (VK-1727) or cladribine, a nucleoside analog that eliminates B cells.

RESULTS

We showed that a small molecule inhibitor of EBNA1, a critical regulator of the EBV life cycle, blocks the proliferation and metabolic activity of these SLCLs. In contrast to cladribine, a highly cytotoxic B cell depleting therapy currently used in MS, the EBNA1 inhibitor VK-1727 was cytostatic rather than cytotoxic and selective for EBV+ cells, while having no discernible effects on EBV- cells. We validate that VK-1727 reduces EBNA1 DNA binding at known viral and cellular sites by ChIP-qPCR.

DISCUSSION

This study shows that patient-derived SLCLs provide a useful tool for interrogating the role of EBV+ B cells in MS and suggests that a clinical trial testing the effect of EBNA1 inhibitors in MS may be warranted.

Human genetic and immunological determinants of SARS-CoV-2 and Epstein-Barr virus diseases in childhood: Insightful contrasts

There is growing evidence to suggest that severe disease in children infected with common viruses that are typically benign in other children can result from inborn errors of immunity or their phenocopies. Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a cytolytic respiratory RNA virus, can lead to acute hypoxemic COVID-19 pneumonia in children with inborn errors of type I interferon (IFN) immunity or autoantibodies against IFNs. These patients do not appear to be prone to severe disease during infection with Epstein-Barr virus (EBV), a leukocyte-tropic DNA virus that can establish latency. By contrast, various forms of severe EBV disease, ranging from acute hemophagocytosis to chronic or long-term illnesses, such as agammaglobulinemia and lymphoma, can manifest in children with inborn errors disrupting specific molecular bridges involved in the control of EBV-infected B cells by cytotoxic T cells. The patients with these disorders do not seem to be prone to severe COVID-19 pneumonia. These experiments of nature reveal surprising levels of redundancy of two different arms of immunity, with type I IFN being essential for host defense against SARS-CoV-2 in respiratory epithelial cells, and certain surface molecules on cytotoxic T cells essential for host defense against EBV in B lymphocytes.

Tabelecleucel: First Approval

Tabelecleucel (Ebvallo^TM) is an allogeneic Epstein-Barr virus (EBV)-specific T-cell immunotherapy that targets and eliminates EBV positive (EBV⁺) cells in a human leukocyte antigen (HLA) restricted manner. Tabelecleucel has been developed by Atara Biotherapeutics under a license from Memorial Sloan-Kettering Cancer Center (MSKCC) for the treatment of lymphoproliferative disorders (LPDs), including rituximab relapsed/refractory EBV⁺ post-transplant lymphoproliferative disease (PTLD). Tabelecleucel was granted marketing authorization under 'exceptional circumstances' on 16 December 2022 as monotherapy for the treatment of adult and paediatric patients 2 years of age and older with relapsed or refractory EBV⁺ PTLD who have received at least one prior therapy. For solid organ transplant patients, prior therapy includes chemotherapy unless chemotherapy is inappropriate. This article summarizes the milestones in the development of tabelecleucel leading to this first approval for EBV⁺ PTLD.

Epstein-Barr virus as a leading cause of multiple sclerosis: mechanisms and implications

Epidemiological studies have provided compelling evidence that multiple sclerosis (MS) is a rare complication of infection with the Epstein-Barr virus (EBV), a herpesvirus that infects more than 90% of the global population. This link was long suspected because the risk of MS increases markedly after infectious mononucleosis (symptomatic primary EBV infection) and with high titres of antibodies to specific EBV antigens. However, it was not until 2022 that a longitudinal study demonstrated that MS risk is minimal in individuals who are not infected with EBV and that it increases over 30-fold following EBV infection. Over the past few years, a number of studies have provided clues on the underlying mechanisms, which might help us to develop more targeted treatments for MS. In this Review, we discuss the evidence linking EBV to the development of MS and the mechanisms by which the virus is thought to cause the disease. Furthermore, we discuss implications for the treatment and prevention of MS, including the use of antivirals and vaccines.