Significance of circulating Epstein-Barr virus DNA monitoring after remission in patients with extranodal natural killer T cell lymphoma

First-line sintilimab with pegaspargase, gemcitabine, and oxaliplatin in advanced extranodal natural killer/T cell lymphoma (SPIRIT): a multicentre, single-arm, phase 2 trial

BACKGROUND

Programmed cell death protein 1 (PD-1) inhibitor sintilimab is effective in relapsed and refractory extranodal natural killer/T cell lymphoma (ENKTL), nasal type. We aimed to assess the safety and activity of sintilimab plus P-GEMOX (pegaspargase, gemcitabine, and oxaliplatin) in the first-line setting for advanced ENKTL.

METHODS

The multicentre, single-arm, phase 2 trial was done at three medical centres in China. Patients aged 18-75 years with treatment-naive pathologically confirmed advanced ENKTL and an with Eastern Cooperative Oncology Group performance status score of 0-2 were eligible. Patients received intravenous sintilimab (200 mg on day 1), intramuscular pegaspargase (2000 U/m2 on day 1), intravenous gemcitabine (1 g/m2 on days 1 and 8), and intravenous oxaliplatin (130 mg/m2 on day 1) every 3 weeks for six cycles, followed by intravenous sintilimab (200 mg) every 3 weeks for up to 2 years or until disease progression or unacceptable toxicities. The primary endpoint was the complete response rate in the intention-to-treat population. The secondary endpoints were overall response rate (ORR), progression-free survival (PFS), disease-free survival (DFS), and overall survival. This trial is registered with ClinicalTrials.gov, NCT04127227. Enrolment has been completed, and follow-up is ongoing.

FINDINGS

Between Nov 29, 2019, and Sept 7, 2022, 34 eligible patients were enrolled (median age 39 years [IQR 32-55]; 25 [74%] of 34 patients were male; nine [26%] were female; and all were of Asian ethnicity). At the data cutoff (July 20, 2023), the median follow-up was 21 months (IQR 13-32). The complete response rate was 85% (29 of 34 patients, 95% CI 70-94). Five patients (15%; 95% CI 7-30) attained partial response and the ORR was 100% (34 of 34 patients). 24-month PFS was 64% (95% CI 48-86), 24-month DFS was 72% (54-95), and 36-month overall survival was 76% (52-100). The most common grade 3 or 4 treatment-related adverse events were neutropenia (17 [50%] of 34 patients), anaemia (10 [29%] patients), and hypertriglyceridemia (10 [29%] patients). Hypothyroidism was the most frequent immune-related adverse event (18 [53%]), including grade 3 hypothyroidism in one (3%) patient that caused treatment termination. No severe adverse events occurred. There were three deaths: one due to haemophagocytic syndrome, one due to disease progression, and one due to unknown cause, which were not considered to be treatment related.

INTERPRETATION

Combination of sintilimab with P-GEMOX seems to be an active and safe first-line regimen for patients with advanced ENKTL.

FUNDING

National Key Research and Development Program and National Natural Science Foundation of China, Guangzhou Science and Technology Program and the Clinical Oncology Foundation of Chinese Society of Clinical Oncology.

Contribution of the Epstein-Barr virus to the oncogenesis of mature T-cell lymphoproliferative neoplasms

EBV is a lymphotropic virus, member of the Herpesviridae family that asymptomatically infects more than 90% of the human population, establishing a latent infection in memory B cells. EBV exhibits complex survival and persistence dynamics, replicating its genome through the proliferation of infected B cells or production of the lytic virions. Many studies have documented the infection of T/NK cells by EBV in healthy individuals during and after primary infection. This feature has been confirmed in humanized mouse models. Together these results have challenged the hypothesis that the infection of T/NK cells per se by EBV could be a triggering event for lymphomagenesis. Extranodal NK/T-cell lymphoma (ENKTCL) and Epstein-Barr virus (EBV)-positive nodal T- and NK-cell lymphoma (NKTCL) are two EBV-associated lymphomas of T/NK cells. These two lymphomas display different clinical, histological and molecular features. However, they share two intriguing characteristics: the association with EBV and a geographical prevalence in East Asia and Latin America. In this review we will discuss the genetic characteristics of EBV in order to understand the possible role of this virus in the oncogenesis of ENKTCL and NKTCL. In addition, the main immunohistological, molecular, cytogenetic and epigenetic differences between ENKTCL and NKTCL will be discussed, as well as EBV differences in latency patterns and other viral molecular characteristics.

Virological Markers in Epstein–Barr Virus-Associated Diseases

Epstein–Barr virus (EBV) is an oncogenic virus infecting more than 95% of the world’s population. After primary infection—responsible for infectious mononucleosis in young adults—the virus persists lifelong in the infected host, especially in memory B cells. Viral persistence is usually without clinical consequences, although it can lead to EBV-associated cancers such as lymphoma or carcinoma. Recent reports also suggest a link between EBV infection and multiple sclerosis. In the absence of vaccines, research efforts have focused on virological markers applicable in clinical practice for the management of patients with EBV-associated diseases. Nasopharyngeal carcinoma is an EBV-associated malignancy for which serological and molecular markers are widely used in clinical practice. Measuring blood EBV DNA load is additionally, useful for preventing lymphoproliferative disorders in transplant patients, with this marker also being explored in various other EBV-associated lymphomas. New technologies based on next-generation sequencing offer the opportunity to explore other biomarkers such as the EBV DNA methylome, strain diversity, or viral miRNA. Here, we review the clinical utility of different virological markers in EBV-associated diseases. Indeed, evaluating existing or new markers in EBV-associated malignancies or immune-mediated inflammatory diseases triggered by EBV infection continues to be a challenge.

Plasma EBV-DNA and peripheral blood mononuclear cell EBV-DNA have disparate clinical relevance in patients with extranodal NK/T-cell lymphoma

BACKGROUND

Extranodal NK/T-cell lymphoma (ENKTCL) is an Epstein-Barr virus (EBV)-related hematological malignancy. The presence of EBV-DNA in peripheral blood is a widely used ENKTCL tumor marker. However, there is no consensus on the preferred blood specimen type for EBV testing. Furthermore, discordance between EBV-based and imaging-based disease assessments is common, and how to interpret this discordance is important.

METHOD

We retrospectively analyzed the data of ENKTCL patients in the Affiliated Cancer Hospital of Zhengzhou university and Sun Yat-sen University Cancer Center. All EBV-DNA and imaging-based disease assessment data were collected at diagnosis, during treatment, at the end of treatment, and during follow-up. We compared matched plasma EBV-DNA and peripheral blood mononuclear cell (PBMC) EBV-DNA and matched EBV-based and imaging-based assessments to uncover their clinical relevance.

RESULT

A total of 450 patients with adequate data were included, of whom 278 had plasma EBV-DNA data, 250 had PBMC EBV-DNA data, and 78 had matched plasma and PBMC EBV-DNA data. No significant correlations were found between PBMC and plasma EBV-DNA and between PBMC EBV-DNA and imaging-based assessment, but patients with positive PBMC EBV-DNA at diagnosis or intermittently/persistently positive PBMC EBV-DNA during follow-up had poorer survival. In contrast, plasma EBV-DNA strongly correlated with lymphoma status. Detectable pre- and post-treatment plasma EBV-DNA was associated with significantly worse survival. Patients with early-stage disease who had detectable plasma EBV-DNA at the end of treatment shared similar survival to those with advanced-stage disease, even if their imaging-based assessments were negative. For disease relapse monitoring, 78 (55.7%) episodes of relapse were detected by both imaging and plasma EBV-DNA; 58 (41.4%) detected by plasma EBV-DNA earlier than imaging, with a median time of 9.3 (0.3 - 37.8) months; and only 4 (2.9%) detected by plasma EBV-DNA later than imaging. The sensitivities of plasma EBV-DNA, PET/CT, and CT/MRI were 97.1%, 76.8%, and 45.1%, respectively, and their specificities were 91.7%, 84.2%, and 96.7%, respectively. Analysis of EBV kinetic patterns in EBV+/imaging- episodes revealed that relapse occurred only in patients with intermittently/persistently positive plasma EBV-DNA. Persistent plasma EBV+ was also seen in patients after autologous hematopoietic stem cell transplantation. Occasional EBV+ was not associated with relapse.

CONCLUSION

Plasma and PBMC EBV-DNA have different clinical relevance in ENKTCL patients. PBMC EBV-DNA does not correlate with imaging-based disease assessment. PBMC or even whole blood should not be used for response evaluation and relapse monitoring. However, PBMC EBV-DNA still has prognostic value. Plasma EBV-DNA is strongly related to tumor status and is not only a prognosticator at diagnosis and end of treatment, but also a sensitive marker in relapse monitoring compared to PET/CT and CT/MRI. The specificity of plasma EBV-DNA is relatively low, but when EBV-DNA kinetic patterns are considered, it can identify at-risk patients.

Comprehensive Analysis and Summary of the Value of Immunophenotypes of Mature NK Cell Tumors for Differential Diagnosis, Treatment, and Prognosis

Background

Few studies have been performed to comprehensively analyze and summarize the immunophenotype and differential diagnosis of mature NK cell tumors, and there is often overlap between tumorigenic and reactive NK cell phenotypes. Furthermore, the impact of different phenotypes on patient prognosis has rarely been reported.

Methods

The degree of expression of extracellular and intracellular markers of NK cells in each group was compared by FCM, and the differences in expression of various markers among different disease groups and their impact on prognosis have been analyzed and summarized.

Results

Compared with normal NK cells, tumor cells of ANKL and ENKTL had characteristics of being more activated and progressive with larger FSC, in contrast to NK-CLPD and RNKL. Differential diagnoses with RNKL, ANKL, and ENKTL have broader FCM clues. In contrast, the phenotypes of NK-CLPD and RNKL are not significantly different, and consistent phenotypic abnormalities require ongoing monitoring to confirm malignant clones. The sensitivity of differentiating malignant NK cells from reactive NK cells by KIRs alone was poor. The clustering results showed that CD5, CD16, CD56, CD57, CD94, CD45RA, CD45RO, HLA-DR, KIRs, Granzyme B, Perforin and Ki-67 were differentially distributed in the expression of three NK cell tumors and reactive NK cell hyperplasia, so a comprehensive judgment using a wide range of antibody combinations is required in disease staging diagnosis. The tumor cell loads in BM and PB were also compared, and there was a clear correlation between the two. Moreover, the sensitivity of PB for monitoring tumor cells was up to 87.10%, suggesting that PB could be used as an alternative to BM for the diagnosis and screening of NK cell tumors. Analysis of the phenotypic impact of ENKTL patients on prognosis showed that those with CD7 and CD45RO expression had a poor prognosis, while those with positive KIRs had a better prognosis.

Conclusion

This study systematically characterized the FCM of mature NK cell tumors, emphasizing the importance and clinical value of accurate immunophenotyping in diagnosing, classifying, determining prognosis, and guiding treatment of the disease.

Towards Next Generation Biomarkers in Natural Killer/T-Cell Lymphoma

Natural killer/T-cell lymphoma (NKTCL) is an Epstein-Barr virus-associated non-Hodgkin lymphoma linked to an aggressive clinical course and poor prognosis. Despite an improvement in survival outcomes with the incorporation of novel agents including immune checkpoint inhibitors in the treatment of NKTCL, a significant proportion of patients still relapse or remain refractory to treatment. Several clinical prognostic models have been developed for NKTCL patients treated in the modern era, though the optimal approach to risk stratification remains to be determined. Novel molecular biomarkers derived from multi-omic profiling have recently been developed, with the potential to improve diagnosis, prognostication and treatment of this disease. Notably, a number of potential biomarkers have emerged from a better understanding of the tumor immune microenvironment and inflammatory responses. This includes a recently described 3'UTR structural variant in the PD-L1 gene, which confers susceptibility to checkpoint immunotherapy. In this review, we summarize the biomarker landscape of NKTCL and highlight emerging biomarkers with the potential for clinical implementation.

GM-CSF mediates immune evasion via upregulation of PD-L1 expression in extranodal natural killer/T cell lymphoma

Background

Granulocyte-macrophage colony stimulating factor (GM-CSF) is a cytokine that is used as an immunopotentiator for anti-tumor therapies in recent years. We found that some of the extranodal natural killer/T cell lymphoma (ENKTL) patients with the treatment of hGM-CSF rapidly experienced disease progression, but the underlying mechanisms remain to be elucidated. Here, we aimed to explore the mechanisms of disease progression triggered by GM-CSF in ENKTL.

Methods

The mouse models bearing EL4 cell tumors were established to investigate the effects of GM-CSF on tumor growth and T cell infiltration and function. Human ENKTL cell lines including NK-YS, SNK-6, and SNT-8 were used to explore the expression of programmed death-ligand 1 (PD-L1) induced by GM-CSF. To further study the mechanisms of disease progression of ENKTL in detail, the mutations and gene expression profile were examined by next-generation sequence (NGS) in the ENKTL patient’s tumor tissue samples.

Results

The mouse-bearing EL4 cell tumor exhibited a faster tumor growth rate and poorer survival in the treatment with GM-CSF alone than in treatment with IgG or the combination of GM-CSF and PD-1 antibody. The PD-L1 expression at mRNA and protein levels was significantly increased in ENKTL cells treated with GM-CSF. STAT5A high-frequency mutation including p.R131G, p.D475N, p.F706fs, p.V707E, and p.S710F was found in 12 ENKTL cases with baseline tissue samples. Importantly, STAT5A-V706fs mutation tumor cells exhibited increased activation of STAT5A pathway and PD-L1 overexpression in the presence of GM-CSF.

Conclusions

These findings demonstrate that GM-CSF potentially triggers the loss of tumor immune surveillance in ENKTL patients and promotes disease progression, which is associated with STAT5 mutations and JAK2 hyperphosphorylation and then upregulates the expression of PD-L1. These may provide new concepts for GM-CSF application and new strategies for the treatment of ENKTL.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-021-01374-y.

Survival outcomes of patients with extranodal natural-killer T-cell lymphoma: a prospective cohort study from the international T-cell Project

BACKGROUND

Extranodal natural killer (NK) T-cell lymphoma (ENKTL) is a unique clinicopathological entity, typically associated with poor survival outcomes. Most published data have come from east Asian study groups, with little information available from international cohorts. The effects of treatment advances on routine clinical practice across continental territories has not been clear. We aimed to improve understanding of the clinical characteristics and outcomes of patients with ENKTL.

METHODS

We did a substudy of patients with ENKTL from the T-cell Project, a global prospective cohort study. The T-cell Project registered consecutively diagnosed adults (>18 years) with newly diagnosed, untreated mature T-cell or NK lymphomas (WHO 2001 or 2008 classifications) from 74 centres in 13 countries (in Asia, Europe, North America, and South America). In total, 1695 patients with mature T-cell or NK lymphomas were enrolled between Oct 12, 2006 and Feb 28, 2018 in the T-cell Project. The first patient with ENKTL was enrolled on Feb 15, 2007, and the last on May 26, 2017. Data on baseline characteristics, first-line treatment, treatment response, and survival outcomes were recorded in a central database (locked March 30, 2019). The primary outcome was 5-year overall survival. The T-cell Project is registered on ClinicalTrials.gov, NCT01142674.

FINDINGS

166 patients were diagnosed with ENKTL, comprising 11% of 1553 eligible registered cases and distributed across 40 participating centres in four continents. At a median follow-up of 44 months (IQR 20-61), overall survival at 5 years was 54% (95% CI 44-63) in patients with nasal disease (n=98) and 34% (27-46) in patients with extranasal disease (n=68).

INTERPRETATION

To our knowledge, this study presents the largest international cohort of patients with ENKTL. We describe a clinically significant improvement in the survival of patients with ENKTL treated in routine clinical practice over the past decade, likely to be attributable to the increasing use of treatment protocols specific for ENKTL.

FUNDING

The Fondazione Cassa di Risparmio di Modena, the Associazione Angela Serra per la Ricerca sul Cancro, the Fondazione Italiana Linfomi, Allos Therapeutics, Spectrum Pharmaceuticals, Associazione Italiana per la Ricerca sul Cancro, and the National Cancer Institute at the National Institutes of Health.

EBV Viral Loads in Diagnosis, Monitoring, and Response Assessment

The quantification of circulating Epstein Barr virus (EBV) DNA loads has played an important role in the diagnosis and management of EBV-associated lymphoid malignancies. Viral load measurement is particularly useful for monitoring EBV-DNA in hematopoietic stem cell transplant patients, and for assessing the prognosis or response to therapy of EBV-associated intractable lymphomas like extranodal NK/T-cell lymphoma, nasal type. Cell-free EBV-DNA in plasma can be used as a biomarker for estimating the severity or prognosis of these lymphomas. In addition to plasma, whole blood has been used for the management of transplant patients. Although measuring EBV-DNA has been useful, there is a lack of standardization and the optimal specimens for measuring viral loads are unknown. This can be attributed to the different forms of EBV-DNA that exist in peripheral blood and the different pathologies that result from diverse EBV disease states. As a result, guidelines for EBV diagnosis or the initiation of treatment are unclear. However, the newly established World Health Organization standard for EBV quantification will encourage collaborative studies across institutions and countries to establish proper guidelines for EBV diagnosis and the initiation of treatment.

Molecular mechanisms of EBV-driven cell cycle progression and oncogenesis

The early stage of oncogenesis is linked to the disorder of the cell cycle. Abnormal gene expression often leads to cell cycle disorders, resulting in malignant transformation of human cells. Epstein–Barr virus (EBV) is associated with a diverse range of human neoplasms, such as malignant lymphoma, nasopharyngeal carcinoma and gastric cancer. EBV mainly infects human lymphocytes and oropharyngeal epithelial cells. EBV is latent in lymphocytes for a long period of time, is detached from the cytoplasm by circular DNA, and can integrate into the chromosome of cells. EBV expresses a variety of latent genes during latent infection. The interaction between EBV latent genes and oncogenes leads to host cell cycle disturbances, including the promotion of G₁/S phase transition and inhibition of cell apoptosis, thereby promoting the development of EBV-associated neoplasms. Molecular mechanisms of EBV-driven cell cycle progression and oncogenesis involve diverse genes and signal pathways. Here, we review the molecular mechanisms of EBV-driven cell cycle progression and promoting oncogenesis.