Cytomegalovirus and Glioblastoma: A Review of the Biological Associations and Therapeutic Strategies

Clinical research framework proposal for ketogenic metabolic therapy in glioblastoma

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, with a universally lethal prognosis despite maximal standard therapies. Here, we present a consensus treatment protocol based on the metabolic requirements of GBM cells for the two major fermentable fuels: glucose and glutamine. Glucose is a source of carbon and ATP synthesis for tumor growth through glycolysis, while glutamine provides nitrogen, carbon, and ATP synthesis through glutaminolysis. As no tumor can grow without anabolic substrates or energy, the simultaneous targeting of glycolysis and glutaminolysis is expected to reduce the proliferation of most if not all GBM cells. Ketogenic metabolic therapy (KMT) leverages diet-drug combinations that inhibit glycolysis, glutaminolysis, and growth signaling while shifting energy metabolism to therapeutic ketosis. The glucose-ketone index (GKI) is a standardized biomarker for assessing biological compliance, ideally via real-time monitoring. KMT aims to increase substrate competition and normalize the tumor microenvironment through GKI-adjusted ketogenic diets, calorie restriction, and fasting, while also targeting glycolytic and glutaminolytic flux using specific metabolic inhibitors. Non-fermentable fuels, such as ketone bodies, fatty acids, or lactate, are comparatively less efficient in supporting the long-term bioenergetic and biosynthetic demands of cancer cell proliferation. The proposed strategy may be implemented as a synergistic metabolic priming baseline in GBM as well as other tumors driven by glycolysis and glutaminolysis, regardless of their residual mitochondrial function. Suggested best practices are provided to guide future KMT research in metabolic oncology, offering a shared, evidence-driven framework for observational and interventional studies.

Chemical Complementarity of Blood-Sourced, Breast Cancer-Related TCR CDR3s and the CMV UL29 and IE1 Antigens is Associated with Worse Overall Survival

Cytomegalovirus (CMV) infection is common and becomes a particular concern in immunocompromised patients. Understanding the potential role CMV plays in breast cancer patients' disease progression is important for providing more patient-specific treatments. In this study, we analyzed whether a breast cancer patient's blood-sourced T-cell receptor (TCR) complementarity determining-3 (CDR3) amino acid (AA) sequences could provide an indication of the impact of a systemic CMV infection. Specifically, we assessed the chemical complementarity of patient TCR CDR3 AAs and CMV antigens to determine whether patients with greater complementarity also represented different survival probabilities. Initially, we examined five distinct CMV antigens, of which two, IE1 and UL29, represented TCR (TRA+ RB)-CDR3-CMV antigen complementarity scores (CSs) whereby cases representing the upper 50th percentile of CSs had a worse overall survival (log-rank p = 5.034E-3, for IE1). Then, an analysis of CSs representing previously identified, TCR IE1 epitopes indicated that greater TRB CDR3-IE1 epitope complementarities represented a worse OS (log-rank p = 0.0111). These results raise the question of whether a systemic, anti-CMV response leads to increased systemic inflammation, which is either directly or indirectly supportive of tumor growth; or are patients succumbing to a direct impact of CMV functions on tumor growth or metastasis?

Transient MRI changes and neurological deterioration in glioblastoma upon SARS-CoV-2 infection

PURPOSE

Little is known about the effect of SARS-CoV-2 infection on glioblastoma (GBM) growth, metabolism, and prognosis. Immunological changes within GBM tissue are potentially symptomatic, underlining the urgent need for a better understanding of this phenomenon. To date, the complex underlying biology has not been fully elucidated. A decisive role of the tumor microenvironment (TME) and the components of the immune system acting within it is assumed.

METHODS

Immunohistochemical staining of SARS-CoV-2 spike protein and immune cell infiltration of TME was performed on the tumor tissue of one patient. This patient developed hemiparesis 14 days after symptomatic SARS-CoV-2 infection, leading to tumor diagnosis. Subsequently and after biopsy, there was an unexpectedly good response to chemotherapy only. In looking for further evidence of the potential of SARS-CoV-2 to influence the course of GBM, two additional adult patients that had transient MRI changes and neurological deterioration following SARS-CoV-2 infection were evaluated.

RESULTS

In the patient for whom neurological deterioration in the course of SARS-CoV-2 led to GBM diagnosis, immunohistochemistry revealed virus-specific protein accumulation in the tumor cells, microglial activation, and the formation of T-cell nodules. In the other two patients, the findings were compatible with symptomatic pseudoprogression that occurred in a temporal relationship with SARS-CoV-2 infection.

CONCLUSION

The results indicate a possible association between clinically relevant changes in GBM biology and SARS-CoV-2 infection, with histological confirmation of SARS-CoV-2-associated changes within the tumor tissue. The exact pathomechanism and underlying inflammatory pathways require further investigation.

Early growth response 1 transcription factor and its context-dependent functions in glioblastoma

Glioblastoma is the most aggressive form of primary brain tumour in adults. This tumour employs numerous transcription factors to advance and sustain its progression. Current evidence suggest that early growth response 1 (EGR1) plays a dual role as both an oncogene and a tumour suppressor in glioblastoma. Early growth response 1 expression is prevalent in glioblastoma, affecting over 80% of cases. Early growth response 1 regulatory roles extend to angiogenesis, cell adhesion, and resistance to chemotherapy, notably influencing pathways like hypoxia-inducible factor 1α and vascular endothelial growth factor A. Early growth response 1 can also induce cell adhesion, migration, chemoresistance against temozolomide, stemness, and self-renewal in glioblastoma cells. Despite its oncogenic functions, EGR1 can also suppress tumours by upregulating non-steroidal anti-inflammatory drug-activated gene 1 and phosphatase and tensin homolog deleted on chromosome ten, and inhibiting invasion and metastasis. Additionally, EGR1 may have hypothetical implications in the viral hit-and-run theory, particularly regarding cytomegalovirus infection. The key findings of this review are the context- dependent nature of EGR1's actions and its potential as a prognostic marker in glioblastoma. Further research is needed to understand EGR1's role fully and exploit its potential in clinics.

Cytomegalovirus in Adenoma and Carcinoma Lesions: Detecting Mono-Infection and Co-Infection in Salivary Glands

Salivary glands' neoplasms are hard to diagnose and present a complex etiology. However, several viruses have been detected in these neoplasms, such as HCMV, which can play a role in certain cancers through oncomodulation. The co-infections between HCMV with betaherpesviruses (HHV-6 and HHV-7) and polyomaviruses (JCV and BKV) has been investigated. The aim of the current study is to describe the frequency of HCMV and co-infections in patients presenting neoplastic and non-neoplastic lesions, including in the salivary gland. Multiplex quantitative polymerase chain reaction was used for betaherpesvirus and polyomavirus quantification purposes after DNA extraction. In total, 50.7% of the 67 analyzed samples were mucocele, 40.3% were adenoma pleomorphic, and 8.9% were mucoepidermoid carcinoma. Overall, 20.9% of samples presented triple-infections with HCMV/HHV-6/HHV-7, whereas 9.0% were co-infections with HCMV/HHV-6 and HCMV/HHV-7. The largest number of co-infections was detected in pleomorphic adenoma cases. All samples tested negative for polyomaviruses, such as BKV and JCV. It was possible to conclude that HCMV can be abundant in salivary gland lesions. A high viral load can be useful to help better understand the etiological role played by viruses in these lesions. A lack of JCV and BKV in the samples analyzed herein does not rule out the involvement of these viruses in one or more salivary gland lesion subtypes.

IGH Complementarity Determining Region-3-Cytomegalovirus Protein Chemical Complementarity Linked to Better Overall Survival Probabilities for Glioblastoma

Cytomegalovirus (CMV) has long been thought to have an association with glioblastoma multiforme (GBM), although the exact role of CMV and any subsequent implications for treatment have yet to be fully understood. This study addressed whether IGH complementarity determining region-3 (CDR3)-CMV protein chemical complementarity, with IGH CDR3s representing both tumor resident and blood-sourced IGH recombinations, was associated with overall survival (OS) distinctions. IGH recombination sequencing reads were obtained from (a) the Clinical Proteomic Tumor Analysis Consortium, tumor RNAseq files; and (b) the cancer genome atlas, blood exome-derived files. The Adaptive Match web tool was used to calculate chemical complementarity scores (CSs) based on hydrophobic interactions, and those scores were used to group GBM cases and assess survival probabilities. We found a higher OS probability for cases whose hydrophobic IGH CDR3-CMV protein chemical complementarity scores (Hydro CSs) were in the upper 50th percentile for several CMV proteins, including UL99 and UL123, as well as for CSs based on known B cell epitopes representing these proteins. We also identified multiple immune signature genes, including CD79A and TNFRSF17, for which higher RNA expression was associated with higher Hydro CSs. Results were consistent with the idea that stronger immunoglobulin responses to CMV are associated with better OS probabilities for GBM.

The Role of Oncogenic Viruses in the Pathogenesis of Sporadic Breast Cancer: A Comprehensive Review of the Current Literature

Breast cancer is the most common malignancy in the female sex; although recent therapies have significantly changed the natural history of this cancer, it remains a significant challenge. In the past decade, evidence has been put forward that some oncogenic viruses may play a role in the development of sporadic breast cancer; however, data are scattered and mostly reported as sparse case series or small case-control studies. In this review, we organize and report current evidence regarding the role of high-risk human papillomavirus, mouse mammary tumor virus, Epstein-Barr virus, cytomegalovirus, bovine leukemia virus, human polyomavirus 2, and Merkel cell polyomavirus in the pathogenesis of breast cancer.

Friend or Foe? Exploring the Role of Cytomegalovirus (HCMV) Infection in Head and Neck Tumors

Although not regarded as an oncogenic pathogen, the human cytomegalovirus (HCMV) has been associated with a wide array of malignancies. Conversely, a number of studies report on possible anti-tumor properties of the virus, apparently mediated via HCMV-galvanized T-cell tumor killing; these were recently being investigated in clinical trials for the purposes of anti-cancer treatment by means of dendritic cell vaccines and HCMV-specific cytotoxic T cells. In the present study, we have analyzed the relation between a complement of head-and-neck tumors and HCMV infection across 73 countries worldwide using Spearman correlation, univariate and multivariate regression analysis. Intriguingly, HCMV was found to be pro-oncogenic in patients with nasopharyngeal carcinoma; contrarywise, the virus manifested an inverse (i.e., anti-tumor) association with the tumors of the lip/oral region and the salivary glands. Although this putative protective effect was noted initially for thyroid neoplasia and hypopharyngeal tumors as well, after multivariate regression analysis the connection did not hold. There was no association between laryngeal cancer and HCMV infection. It would appear that, depending on the tissue, HCMV may exert both protective and oncogenic effects. The globally observed protective feature of the virus could potentially be utilized in future therapeutic approaches for salivary tumors and neoplasia in the lip/oral region. As correlation does not necessarily imply causation, more in-depth molecular analyses from comprehensive clinical studies are warranted to substantiate our findings.

Human Cytomegalovirus Oncoprotection across Diverse Populations, Tumor Histologies, and Age Groups: The Relevance for Prospective Vaccinal Therapy

The oncogenicity of the human cytomegalovirus (CMV) is currently being widely debated. Most recently, mounting clinical evidence suggests an anti-cancer effect via CMV-induced T cell-mediated tumor destruction. However, the data were mostly obtained from single-center studies and in vitro experiments. Broad geographic coverage is required to offer a global perspective. Our study examined the correlation between country-specific CMV seroprevalence (across 73 countries) and the age-standardized incidence rate (of 34 invasive tumors). The populations studied were stratified according to decadal age periods as the immunologic effects of CMV seropositivity may depend upon age at initial infection. The International Agency for Research on Cancer of the World Health Organization (IARC WHO) database was used. The multivariate linear regression analysis revealed a worldwide inverse correlation between CMV seroprevalence and the incidences of 62.8% tumors. Notably, this inverse link persists for all cancers combined (Spearman's ρ = -0.732, p < 0.001; β = -0.482, p < 0.001, adjusted R2 = 0.737). An antithetical and significant correlation was also observed in particular age groups for the vast majority of tumors. Our results corroborate the conclusions of previous studies and indicate that this oncopreventive phenomenon holds true on a global scale. It applies to a wide spectrum of cancer histologies, additionally supporting the idea of a common underlying mechanism-CMV-stimulated T cell tumor targeting. Although these results further advance the notion of CMV-based therapies, in-depth investigation of host-virus interactions is still warranted.

Glioblastoma Therapy: Past, Present and Future

Glioblastoma (GB) stands out as the most prevalent and lethal form of brain cancer. Although great efforts have been made by clinicians and researchers, no significant improvement in survival has been achieved since the Stupp protocol became the standard of care (SOC) in 2005. Despite multimodality treatments, recurrence is almost universal with survival rates under 2 years after diagnosis. Here, we discuss the recent progress in our understanding of GB pathophysiology, in particular, the importance of glioma stem cells (GSCs), the tumor microenvironment conditions, and epigenetic mechanisms involved in GB growth, aggressiveness and recurrence. The discussion on therapeutic strategies first covers the SOC treatment and targeted therapies that have been shown to interfere with different signaling pathways (pRB/CDK4/RB1/P16ink4, TP53/MDM2/P14arf, PI3k/Akt-PTEN, RAS/RAF/MEK, PARP) involved in GB tumorigenesis, pathophysiology, and treatment resistance acquisition. Below, we analyze several immunotherapeutic approaches (i.e., checkpoint inhibitors, vaccines, CAR-modified NK or T cells, oncolytic virotherapy) that have been used in an attempt to enhance the immune response against GB, and thereby avoid recidivism or increase survival of GB patients. Finally, we present treatment attempts made using nanotherapies (nanometric structures having active anti-GB agents such as antibodies, chemotherapeutic/anti-angiogenic drugs or sensitizers, radionuclides, and molecules that target GB cellular receptors or open the blood-brain barrier) and non-ionizing energies (laser interstitial thermal therapy, high/low intensity focused ultrasounds, photodynamic/sonodynamic therapies and electroporation). The aim of this review is to discuss the advances and limitations of the current therapies and to present novel approaches that are under development or following clinical trials.

Human cytomegalovirus induces significant structural and functional changes in terminally differentiated human cortical neurons

IMPORTANCE

Human cytomegalovirus (HCMV) is a highly prevalent viral pathogen that can cause serious neurological deficits in infants experiencing an in utero infection. Also, as a life-long infection, HCMV has been associated with several diseases in the adult brain. HCMV is known to infect early neural progenitor cells, but whether it also infects terminally differentiated neurons is still debated. Here, we differentiated human-induced pluripotent stem cells into neurons for 84-120 days to test the ability of HCMV to infect terminally differentiated neurons and assess the downstream functional consequences. We discovered that mature human neurons are highly permissive to HCMV infection, exhibited late replication hallmarks, and produced infectious virus. Moreover, infection in terminally differentiated neurons essentially eliminated neuron function. These results demonstrate that terminally differentiated human neurons are permissive to HCMV infection, which can significantly alter both structural and functional features of this mature neuron population.

Ganciclovir as a potential treatment for glioma: a systematic review and meta-analysis

BACKGROUND

Glioma is a challenging malignant tumor with a low survival rate and no effective treatment. Recently, ganciclovir, an antiviral drug, combined with gene therapy and its own antiviral ability, has been proposed as a potential treatment for glioma. However, there are differences in the results of various clinical trials. In this study, we conducted a systematic review and meta-analysis to evaluate the efficacy of ganciclovir in treating glioma.

METHODS

We searched databases such as PubMed, EMBASE, and Cochrane Library before March 30, 2023. The search terms included glioma, ganciclovir, valganciclovir and treatment. Calculated 1, 2 and 4-year survival rate by risk difference (RD), and overall survival (OS) by odds ratio (OR).

RESULTS

Five randomized controlled trials (RCTs) with a total of 606 high-grade glioma patients were included. The results showed that ganciclovir can improve 2-yeaer (RD = 0.179, 95% CI 0.012-0.346, P = 0.036) and 4-year survival rate (RD = 0.185, 95% CI 0.069-0.3, P = 0.002) and OS (OR 2.393, 95% CI 1.212-4.728, P = 0.012) compared with the control group.

CONCLUSIONS

This meta-analysis showed that ganciclovir significantly improved the prognosis of glioma patients. Therefore, we suggest that more cases of ganciclovir as a glioma treatment can be conducted, or a large clinical trial can be designed.

Mechanism of Human Cytomegalovirus-Induced Epithelial-Mesenchymal Transition in Glioma Cells via the Upregulation of RIP2 Expression

Human cytomegalovirus (HCMV) is associated with epithelial-mesenchymal transition (EMT) in glioma cells; however, its underlying action mechanism remain ambiguous. In this study, we investigated the effects of receptor-interacting protein 2 (RIP2) and nuclear factor (NF)-κB on EMT in HCMV-infected glioma LN-18 cells. Wound healing and invasion assays were used to evaluate the migration and invasion of cells. Western blotting and immunofluorescence microscopy were used to determine the protein expression levels. We found that HCMV induced enhanced migration and invasion of LN-18 cells, activation of the RIP2/NF-κB signaling pathway, downregulation of epithelial cell marker (E-cadherin) expression, and upregulation of mesenchymal cell marker (N-cadherin and vimentin) expression. Moreover, inhibition of RIP2 or NF-κB inhibited the induction of HCMV in LN-18 cells. Therefore, HCMV induces EMT in glioma cells by promoting the activation of NF-κB signaling pathway via the upregulation of RIP2 expression.

Challenges, Recent Advances and Perspectives in the Treatment of Human Cytomegalovirus Infections

Human cytomegalovirus (HCMV) is ubiquitous worldwide and elicits global health problems. The diseases associated with HCMV are a serious threat to humans, especially for the sick, infant, elderly and immunocompromised/immunodeficient individuals. Although traditional antiviral drugs (e.g., ganciclovir, valganciclovir, cidofovir, foscarnet) can be used to treat or prevent acute HCMV infections, their efficacy is limited because of toxicity, resistance issues, side effects and other problems. Fortunately, novel drugs (e.g., letermovir and maribavir) with less toxicity and drug/cross-resistance have been approved and put on the market in recent years. The nucleic acid-based gene-targeting approaches including the external guide sequences (EGSs)-RNase, the clustered regularly interspaced short palindromic repeats (CRISPRs)/CRISPRs-associated protein 9 (Cas9) system and transcription activator-like effector nucleases (TALENs) have been investigated to remove both lytic and latent CMV in vitro and/or in vivo. Cell therapy including the adoptive T cell therapy (ACT) and immunotherapy have been tried against drug-resistant and recurrent HCMV in patients receiving hematopoietic stem cell transplantation (HSCT) or solid organ transplant (SOT), and they have also been used to treat glioblastoma (GBM) associated with HCMV infections. These newly developed antiviral strategies are expected to yield fruitful results and make a significant contribution to the treatment of HCMV infections. Despite this progress, the nucleic acid-based gene-targeting approaches are still under study for basic research, and cell therapy is adopted in a small study population size or only successful in case reports. Additionally, no current drugs have been approved to be indicated for latent infections. Therefore, the next strategy is to develop antiviral strategies to elevate efficacy against acute and/or latent infections and overcome challenges such as toxicity, resistance issues, and side effects. In this review, we would explore the challenges, recent advances and perspectives in the treatment of HCMV infections. Furthermore, the suitable therapeutic strategies as well as the possibility for compassionate use would be evaluated.