Natural Killer Cell Lymphoma Research Articles

Modeling NK-cell lymphoma in mice reveals its cell-of-origin and microenvironmental changes and identifies therapeutic targets

Extranodal NK/T-cell lymphoma (ENKTCL) is an Epstein-Barr virus (EBV)-related neoplasm preferentially involving the upper aerodigestive tract. Here we show that NK-cell-specific Trp53 disruption in mice leads to the development of NK-cell lymphomas after long latency, which involve not only the hematopoietic system but also the salivary glands. Before tumor onset, Trp53 knockout causes extensive gene expression changes, resulting in immature NK-cell expansion, exclusively in the salivary glands. Both human and murine NK-cell lymphomas express tissue-resident markers, suggesting tissue-resident NK cells as their cell-of-origin. Murine NK-cell lymphomas show recurrent Myc amplifications and upregulation of MYC target gene signatures. EBV-encoded latent membrane protein 1 expression accelerates NK-cell lymphomagenesis and causes diverse microenvironmental changes, particularly myeloid propagation, through interferon-γ signaling. In turn, myeloid cells support tumor cells via CXCL16-CXCR6 signaling and its inhibition is effective against NK-cell tumors in vivo. Remarkably, KLRG1-expressing cells expand in the tumor and are capable of repopulating tumors in secondary recipients. Furthermore, targeting KLRG1 alone or combined with MYC inhibition using an eIF4 inhibitor is effective against NK-cell tumors. Therefore, our observations provide insights into the pathogenesis and highlight potential therapeutic targets, including CXCL16, KLRG1, and MYC, in ENKTCL, which can help improve its diagnostic and therapeutic strategies.

Impact of prior cancer history on the prognosis of extranodal NK/T-cell lymphoma.

Our goal was to assess the impact of prior cancer history on the prognosis of extranodal NK/T-cell lymphoma (ENKTCL). We searched the SEER database to retrospectively enroll patients with ENKTCL. The effects of cancer history on overall survival (OS) and disease-specific survival (DSS) were analyzed using the Cox model. A total of 691 patients were included, of whom 54 (7.8%) had prior histories of cancer. The most common solid malignancy was bone/soft tissue sarcoma. Most secondary ENKTCL cases occurred within 5-9 years following the first cancer diagnosis. Radiotherapy and chemotherapy had been administered to 45 and 40 patients, respectively, to treat their previous malignancies. Prior cancer history had little impact on DSS; however, the presence of prior solid cancer history, latency period of 10+ years, and prior administration of radiotherapy or chemotherapy significantly decreased OS. Prior cancer history had no effect on DSS, but survival compromised OS under specific circumstances.

Evaluating early response assessment in extranodal natural killer/T-cell lymphoma by analyzing ΔSUVlbm between baseline and interim 18F-FDG PET/CT scans

To determine the optimal variation in SUVlbm via 18F-FDG PET/CT imaging between the baseline and interim stages, and assess early response among patients with extranodal natural killer/T-cell lymphoma (ENKTCL) of 5-DS score ≥ 4, 20 patients after four cycles of chemotherapy were retrospectively enrolled and received re-biopsy targeting PET-positive residual masses. The optimal cutoff value for evaluating early response assessment was 66.75% for ΔSUVlbm%, with the area under curve of 0.985. All patients with a 5-DS score of 4 exhibited negative results upon re-biopsy. During follow-up, the median PFS of patients characterized by ΔSUVlbm% ≥66.75% and <66.75% were unreached and 10 months, respectively. Utilizing ΔSUVlbm% between baseline and interim 18F-FDG PET/CT scans can effectively identify a subset of patients who were visually analyzed as false positives(5-DS ≥ 4), which was confirmed by interim biopsy results, thus serving as a crucial indicator for early assessment of treatment outcomes in patients with ENKTCL.

A novel anti-CD47 antibody with therapeutic potential for NK/T-cell lymphoma

ABSTRACT NK/T-cell lymphoma (NKTCL) is a rare type of non-Hodgkin lymphoma (NHL). Although L-asparaginase-based chemotherapy has significantly improved survival in early-stage patients, the prognosis is poor in advanced and relapsed or refractory patients. CD47 is a promising target for cancer immunotherapy. However, the expression of CD47 in NKTCL and the antitumor effect and mechanism of the anti-CD47 monoclonal antibody (mAb) AK117 in NKTCL remain unclear. Firstly, the expression level of CD47 protein in NKTCL cells was detected by immunoblot and flow cytometry. Secondly, in order to validate the role of CD47 downregulation in the proliferation, apoptosis, and cell cycle of NKTCL cells, we used shRNA transfection to knock down CD47 expression. We determined the effect of knocking down CD47 and the novel anti‐CD47 antibody AK117 on the phagocytosis of NKYS and YTS cells by M2 macrophages in vitro. Finally, we assessed the ability of AK117 to inhibit tumor growth in an NKTCL xenograft model in which YTS cells were engrafted in SCID mice. The results showed that CD47 is relatively highly expressed in NKTCL cells. CD47 knockdown in NKTCL promoted phagocytosis by M2 macrophages in an in vitro coculture assay. The study also demonstrated that anti-CD47 mAb AK117 promoted phagocytosis of NKTCL cells by M2 macrophages. In addition, in vivo experiments showed that the anti-CD47 mAb AK117 significantly inhibited the growth of subcutaneous xenograft tumors in SCID mice compared to the control antibody IgG. Our results indicate that targeting CD47 monoclonal antibodies is a potential therapeutic strategy for NKTCL.

Feline eosinophilic sclerosing fibroplasia associated with T-/natural killer-cell lymphoma.

Feline eosinophilic sclerosing fibroplasia (FESF) is a proliferative, inflammatory disease of the gastrointestinal tract and other sites, uncommonly diagnosed in the cat. This entity of uncertain etiology typically presents as a progressive mass lesion, mimicking a neoplastic process. In this case series, we present 17 cases of FESF associated with intralesional lymphoma. Histologic and immunohistochemical characterization of this unique lymphoma revealed that the neoplastic lymphocytes were immunopositive for CD56 and/ or CD3, suggesting a natural killer cell, natural killer T-cell, or T-cell origin. This case series represents the first description of this lymphoma subtype, for which the term eosinophilic sclerosing lymphoma is proposed.

CD98hc promotes drug resistance in extranodal natural killer/T cell lymphoma through tumor cell-derived small extracellular vesicles.

Extranodal natural killer/T cell lymphoma (ENKTL) shows a high rate of recurrence after chemoradiotherapy. Drug resistance can be mediated by the cargo of small extracellular vesicles (sEVs). Here, we show that high abundance of the transmembrane glycoprotein CD98hc in tumor cells and serum sEVs was associated with ENKTL progression and drug resistance. Mechanistically, PEGylated-asparaginase (PEG-asp) treatment, a common therapy against ENKTL, promoted the translocation of the transcription factor ATF4 to the nucleus, where it was stabilized by USP1 and subsequently increased CD98hc expression. CD98hc delivered in tumor cell-derived sEVs increased tumor cell proliferation and drug resistance in a cultured human NK lymphoma cell line, animal models, and samples from patients with refractory/relapse ENKTL. Moreover, inhibiting both USP1 and EV secretion synergistically enhanced the cytotoxicity of PEG-asp. These data suggest that targeting CD98hc in the treatment of ENKTL may be beneficial in overcoming drug resistance.

Resistance mechanisms and potential therapeutic strategies in relapsed or refractory natural killer/T cell lymphoma.

Natural killer/T cell lymphoma (NKTCL) is a malignant tumor originating from NK or T cells, characterized by its highly aggressive and heterogeneous nature. NKTCL is predominantly associated with Epstein-Barr virus infection, disproportionately affecting Asian and Latin American populations. Owing to the application of asparaginase and immunotherapy, clinical outcomes have improved significantly. However, for patients in whom first-line treatment fails, the prognosis is exceedingly poor. Overexpression of multidrug resistance genes, abnormal signaling pathways, epigenetic modifications and active Epstein-Barr virus infection may be responsible for resistance. This review summarized the mechanisms of resistance for NKTCL and proposed potential therapeutic approaches.

LMP1 enhances aerobic glycolysis in natural killer/T cell lymphoma

Natural killer/T cell lymphoma (NKTCL) exhibits highly aggressive clinical behavior, and the outcomes for relapsed/refractory patients are still poor. Recently, the mechanism underlying the effect of Epstein-Barr virus (EBV) infection, which has not been fully defined in NKTCL, has attracted great attention. We explored how LMP1 promoted aerobic glycolysis via metabolic sequencing combined with mRNA sequencing and immunoprecipitation coupled to mass spectrometry. Experimental assays were used to determine the effects of LMP1 and its downstream pathway on the function and glucose metabolism of NKTCL cells. The correlations between LMP1 expression in patients and their clinical features, treatment response, and prognosis were analyzed. Results show that LMP1 enhances NKTCL cell proliferation in vitro and in vivo, inhibits apoptosis, and decreases gemcitabine sensitivity. In addition, LMP1 also enhances aerobic glycolysis in NKTCL cells, as indicated by increases in glucose uptake, lactate production, and extracellular acidification rate. Clinically, LMP1 expression is correlated with risk stratification, treatment response, and prognosis, and higher LMP1 expression indicates greater SUVmax for NKTCL patients. Mechanistically, LMP1 competitively binds to TRAF3 to promote cell proliferation and aerobic glycolysis by regulating the noncanonical NF-κB pathway. The application of an NF-κB pathway inhibitor or reactivation of the NF-κB pathway affects aerobic glycolysis and the biological function of NKTCL cells. In summary, this study is the first to describe and define in detail how LMP1 affects glucose metabolism in NKTCL and might provide a novel perspective for further treatment.

Clinical Impact of Microbiome Characteristics in Treatment-Naïve Extranodal NK/T-Cell Lymphoma Patients.

Extranodal NK/T-cell lymphoma (ENKTL) predominantly manifests in East Asia and Latin America. Despite shared intrinsic factors, such as ethnic and genetic backgrounds, the progression of ENKTL can be influenced by extrinsic factors related to changing lifestyle patterns. This study collected stool samples from newly diagnosed (ND)-ENKTL patients (n=40) and conducted whole genome shotgun sequencing. ND-ENKTL revealed reduced alpha diversity in ND-ENKTL compared to healthy controls (HCs) (p=0.008), with Enterobacteriaceae abundance significantly contributing to the beta diversity difference between ENKTL and HCs (p<0.001). Functional analysis indicated upregulated aerobic metabolism and degradation of aromatic compounds in ND-ENKTL. Enterobacteriaceae were associated not only with clinical data explaining disease status (serum CRP, stage, prognosis index of natural killer cell lymphoma (PINK), and PINK-E) but also with clinical outcomes (early relapse and short progression-free survival). The relative abundance of Enterobacteriaceae at the family level was similar between ENKTL and diffuse large B-cell lymphoma (DLBCL) (p=0.140). However, the ENKTL exhibited a higher abundance of Escherichia, in contrast to the prevalence of Enterobacter and Citrobacter in DLBCL. Linear regression analysis demonstrated a significant association between Escherichia abundance and PD-L1 levels in tissue samples (p=0.025), whereas no correlation with PD-L1 was observed for Enterobacteriaceae at the family level (p=0.571). ND-ENKTL exhibited an abundance of Enterobacteriaceae and a dominant presence of Escherichia. These microbial characteristics correlated with disease status, treatment outcomes, and PD-L1 expression, suggesting the potential of the ENKTL microbiome as a biomarker and cause of lymphomagenesis, which warrants further exploration.

Primary intestinal T-cell and natural killer-cell lymphomas: Clinicopathologic and prognostic features of 79 cases in South China.

Primary intestinal T-cell and natural killer-cell lymphomas (PITNKLs) are aggressive and make pathologic diagnoses in biopsy specimens challenging. We analyzed different subtypes' clinicopathologic features and treatment outcomes. Seventy-nine PITNKL cases were characterized by clinical, morphologic, and immunohistochemical features. Among 79 cases of PITNKLs from 2008 to 2017 in our institution, 40 (50.63%) were extranodal NK/T-cell lymphoma, nasal type (ENKTL); 32 (40.51%) monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL); 6 (7.59%) intestinal T-cell lymphoma, not otherwise specified; and 1 (1.27%) indolent T-cell lymphoma of the gastrointestinal tract. Small intestine (n = 47) was the most common site. Monomorphic epitheliotropic intestinal T-cell lymphoma showed distinctive clinicopathologic features from other subtypes with high expression (96.88%) of spleen tyrosine kinase (SYK) and PD-L1 (87.5%) and the poorest prognosis (P < .001). CD30 was highly expressed in ENKTL (9/17, 57.94%) and irrelevant to prognosis (P > .05). Cases of PITNKL are biologically heterogeneous; most have a dismal prognosis. SYK and PD-L1 expression might be a significant marker for MEITL and helps differential diagnosis.

Comparative Analysis of the Clinical Manifestations of Sinonasal Natural Killer T-Cell Lymphoma and Diffuse Large B-Cell Lymphoma

Background and Objectives: Natural killer T-cell lymphoma (NKTCL) and diffuse large B-cell lymphoma (DLBCL) are the two most prevalent subtypes of lymphoma in the sinonasal region. Accurately differentiating between sinonasal DLBCL and NKTCL is crucial for determining the appropriate treatment and prognosis. The present study compared the clinical characteristics of these two conditions.Methods: We conducted a retrospective review of 173 patients diagnosed with sinonasal lymphoma at a single institute between 2004 and 2017. This review included only patients with DLBCL and NKTCL who had more than 6 months of follow-up records. We analyzed patient data encompassing clinical characteristics, pathologic findings, radiologic findings, treatment modalities, recurrence, and survival.Results: Among the patients analyzed, 117 patients were diagnosed with NKTCL and 45 with DLBCL. Endoscopic evaluation revealed a significantly higher incidence of crusting (p&lt;0.001) and necrotic lesions (p=0.001) in patients with NKTCL, whereas polypoid masses were more commonly observed in patients with DLBCL (p&lt;0.001). Computed tomography (CT) scans indicated no significant differences in bilaterality or bone destruction between the two groups. The DLBCL group exhibited a higher rate of concurrent lymph node or organ involvement than the NKTCL group (p&lt;0.001). The 5-year overall survival rate was 67.4% for DLBCL and 69.1% for NKTCL, with no significant difference between the two.Conclusion: Clinical differences exist between sinonasal DLBCL and NKTCL in terms of endoscopic and CT findings. These distinct characteristics can aid in distinguishing between the two types of sinonasal lymphoma during clinical diagnosis.

Challenges in overcoming advanced-stage or relapsed refractory extranodal NK/T-cell lymphoma: meta-analysis of individual patient data.

Extranodal NK/T-cell lymphoma (ENKTCL), a non-Hodgkin lymphoma, is known for its destructive local impact on nasal structures and systemic induction of inflammatory cytokines. Concurrent treatment with radiation and nonanthracycline- based chemotherapy has improved survival rates in patients with localized disease stages. However, survival outcomes vary significantly in advanced-stage and relapsed or refractory (R/R) cases. Therefore, we conducted a meta-analysis using random effects models to assess prognostic factors in advanced or R/R ENKTCL, employing a digital extractor on Kaplan-Meier graphs owing to the scarcity of published prospective trials for these patients. We observed that patients with advanced ENKTCL treated with Lasparaginase had a median progression-free survival (PFS) of 14.3 months and an overall survival (OS) of 19 months. In R/R ENKTCL, PFS and OS were 11.7 and 15.6 months, respectively. Additionally, OS outcomes in advanced-stage ENKTCL were better in the asparaginase group than that in the non-asparaginase group, with PEG-asparaginase showing superior results compared with that using Lasparaginase. Epstein-Barr Virus (EBV)-DNA positivity in the bloodstream prior to treatment was associated with poor outcomes in advanced-stage ENKTCL, and similar trends were observed in patients with R/R ENKTCL and post-treatment EBV viremia. Collectively, these findings suggest that chemotherapy with Lasparaginase or PEG-asparaginase can enhance survival in advanced or R/R ENKTCL. However, future strategies must be developed to effectively suppress EBV viremia and achieve a deep response toward tumor eradication.

A novel prognostic index for extranodal natural killer/T-cell lymphoma in the era of pegaspargase/L-asparaginase.

Aim: This multicenter retrospective study aimed to develop a novel prognostic system for extranodal natural killer/T-cell lymphoma (ENKTL) patients in the era of pegaspargase/L-asparaginase.Materials & methods: A total of844 newly diagnosed ENKTL patients were included.Results: Multivariable analysis confirmed that Eastern Cooperative Oncology Group performance status, lactate dehydrogenase, Chinese Southwest Oncology Group and Asia Lymphoma Study Group ENKTL (CA) system, and albumin were independent prognostic factors. By rounding up the hazard ratios from foursignificant variables, a maximum of 7 points wereassigned. The model of Huaihai Lymphoma Working Group-Natural killer/T-cell Lymphoma prognostic index (NPI) was identified with four risk groups and the 5-year overall survival was 88.2, 66.7, 54.3and 30.5%, respectively.Conclusion: Huaihai Lymphoma Working Group-NPI provides a feasible stratification system for patients with ENKTL in the era of pegaspargase/L-asparaginase.

TET2 regulates extranodal NK/T cell lymphoma progression through regulation of DNA methylation.

The biological role of Ten-11 translocation 2 (TET2) and the conversion of 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in the development of extra-nodal natural killer/T-cell lymphoma (ENKTL) remains unclear. The level of 5mC and 5hmC was detected in 112 cases of ENKTL tissue specimens by immunohistochemical (IHC) staining. Subsequently, TET2 knockdown and the overexpression cell models were constructed in ENKTL cell lines. Biochemical analyses were used to assess proliferation, apoptosis, cell cycle and monoclonal formation in cells treated or untreated with L-Ascorbic acid sodium salt (LAASS). Dot-Blots were used to detect levels of genome 5mC and 5hmC. Additionally, the ILLUMINA 850k methylation chip was used to analyze the changes of TET2 regulatory genes. RNA-Seq was used to profile differentially expressed genes regulated by TET2. The global level of 5hmC was significantly decreased, while 5mC was highly expressed in ENKTL tissue. TET2 protein expression was negatively correlated with the ratio of 5mC/5hmC (p<0.0001). The 5mC/5hmC status were related to the site of disease, clinical stage, PINK score and Ki-67 index, as well as the 5-year OS. TET2 knockdown prolonged the DNA synthesis period, increased the cloning ability of tumor cells, increased the level of 5mC and decreased the level of 5hmC in ENKTL cells. While overexpression of TET2 presented the opposite effect. Furthermore, treatment of ENKTL cells with LAASS significantly induced ENKTL cell apoptosis. These results suggest that TET2 plays an important role in ENKTL development via regulation of 5mC and 5hmC and may serve as a novel therapeutic target for ENKTL.

CDK4/6 inhibition augments anti-tumor efficacy of XPO1 inhibitor selinexor in natural killer/T-cell lymphoma

XPO1 is an attractive and promising therapeutic target frequently overexpressed in multiple hematological malignancies. The clinical use of XPO1 inhibitors in natural killer/T-cell lymphoma (NKTL) is not well documented. Here, we demonstrated that XPO1 overexpression is an indicator of poor prognosis in patients with NKTL. The compassionate use of the XPO1 inhibitor selinexor in combination with chemotherapy showed favorable clinical outcomes in three refractory/relapsed (R/R) NKTL patients. Selinexor induced complete tumor regression and prolonged survival in sensitive xenografts but not in resistant xenografts. Transcriptomic profiling analysis indicated that sensitivity to selinexor was correlated with deregulation of the cell cycle machinery, as selinexor significantly suppressed the expression of cell cycle-related genes. CDK4/6 inhibitors were identified as sensitizers that reversed selinexor resistance. Mechanistically, targeting CDK4/6 could enhance the anti-tumor efficacy of selinexor via the suppression of CDK4/6-pRb-E2F-c-Myc pathway in resistant cells, while selinexor alone could dramatically block this pathway in sensitive cells. Overall, our study provids a preclinical proof-of-concept for the use of selinexor alone or in combination with CDK4/6 inhibitors as a novel therapeutic strategy for patients with R/R NKTL.

Clinicopathological analysis of immunohistochemical CD47 and signal-regulatory protein-α expression in Extranodal Natural killer/T-cell lymphoma.

The interaction between CD47 and signal-regulatory protein-alpha (SIRPα) inhibits phagocytosis, and their clinicopathological characteristics have been evaluated in various diseases. However, the significance of CD47 and SIRPα expression, as well as the combined effect, in Extranodal Natural killer/T-cell Lymphoma (ENKTL) remains uncertain. In total, 76 newly diagnosed ENKTL patients (mean age 49.9 years, 73.7% male) were included in this study. CD47 and SIRPα expression were examined by immunohistochemistry. Survival analyses were conducted through Kaplan-Meier curves and the Cox regression model. Seventy-one (93.4%) cases were categorized as the CD47 positive group and 59 (77.6%) cases were categorized as the SIRPα positive group. CD47-negative cases had more advanced-stage illness (P = 0.001), while SIRPα-positive cases showed significantly lower levels of high-density lipoprotein (P < 0.001). In univariable analysis, CD47, SIRPα expression, and their combination were significantly associated with prognosis (P < 0.05). In multivariable analysis, only positive SIRPα expression remained significantly associated with superior overall survival (Hazard ratio [HR] 0.446; 95% confidence interval [CI] 0.207-0.963; P = 0.004). Furthermore, SIRPα expression could re-stratify the survival of patients in ECOG (< 2), advanced CA stage, PINK (HR), CD38-positive, PD1-positive, and CD30-positive groups. SIRPα status was a potential independent prognostic factor for ENKTL. The prognostic significance of CD47 expression and the interaction between CD47 and SIRPα in ENKTL need further investigation.

METTL3 regulates M6A methylation-modified EBV-pri-miR-BART3-3p to promote NK/T cell lymphoma growth

OBJECTIVEN6-methyladenosine (M6A) is the most prevalent epigenetic alteration. Methyltransferase-like 3 (METTL3) is a key player in the control of M6A modification. Methyltransferase promote the processing of mature miRNA in an M6A-dependent manner, thereby participating in disease occurrence and development. However, the regulatory mechanism of M6A in NK/T cell lymphoma (NKTCL) remains unclear. PATIENTS AND METHODSWe determined the expression of METTL3 and its correlation with clinicopathological features using qRT-PCR and immunohistochemistry. We evaluated the effects of METTL3 on NKTCL cells using dot blot assay, CCK8 assay and subcutaneous xenograft experiment. We then applied M6A sequencing combined with gene expression omnibus data to screen candidate targets of METTL3. Finally, we investigated the regulatory mechanism of METTL3 in NKTCL by methylated RNA immunoprecipitation and RNA immunoprecipitation (RIP) assays. RESULTSWe demonstrated that METTL3 was highly expressed in NKTCL cells and tissues and indicated poor prognosis. The METTL3 expression was associated with NKTCL survival. Functionally, METTL3 promoted the proliferation capability of NKTCL cells in vitro and in vivo. Furthermore, EBV-miR-BART3-3p was identified as the downstream effector of METTL3, and silencing EBV-miR-BART3-3p inhibited the proliferation of NKTCL. Finally, we confirmed that PLCG2 as a target gene of EBVmiR-BART3-3p by relative assays. CONCLUSIONSWe identified that METTL3 is significantly up-regulated in NKTCL and promotes NKTCL development. M6A modification contributes to the progression of NKTCL via the METTL3/EBV-miR-BART3-3p/PLCG2 axis. Our study is the first to report that M6A methylation has a critical role in NKTCL oncogenesis, and could be a potential target for NKTCL treatment.

Hemophagocytic syndrome secondary to invasive NK cell leukemia and T-cell lymphoma treated with the modified MINE protocol: report of three cases and literature review

Lymphoma-associated hemophagocytic syndrome is aggressive with rapid progression, particularly in NK/T cell lymphoma. The MINE regimen is a salvage treatment for aggressive non-Hodgkin lymphoma. In our center, the modified MINE regimen was applied to treat three patients with hemophagocytic syndrome secondary to aggressive NK cell leukemia and T-cell lymphoma. The modified MINE regimen showed good efficacy against NK/T cell lymphoma, control of the inflammatory state of secondary hemophagocytic syndrome, and good tolerability.

Geographic EBV variants confound disease-specific variant interpretation and predict variable immune therapy responses

AbstractEpstein-Barr virus (EBV) is a potent carcinogen linked to hematologic and solid malignancies and causes significant global morbidity and mortality. Therapy using allogeneic EBV-specific lymphocytes shows promise in certain populations, but the impact of EBV genome variation on these strategies remains unexplored. To address this, we sequenced 217 EBV genomes, including hematologic malignancies from Guatemala, Peru, Malawi, and Taiwan, and analyzed them alongside 1307 publicly available EBV genomes from cancer, nonmalignant diseases, and healthy individuals across Africa, Asia, Europe, North America, and South America. These included, to our knowledge, the first natural killer (NK)/T-cell lymphoma (NKTCL) EBV genomes reported outside of East Asia. Our findings indicate that previously proposed EBV genome variants specific to certain cancer types are more closely tied to geographic origin than to cancer histology. This included variants previously reported to be specific to NKTCL but were prevalent in EBV genomes from other cancer types and healthy individuals in East Asia. After controlling for geographic region, we did identify multiple NKTCL-specific variants associated with a 7.8-fold to 21.9-fold increased risk. We also observed frequent variations in EBV genomes that affected peptide sequences previously reported to bind common major histocompatibility complex alleles. Finally, we found several nonsynonymous variants spanning the coding sequences of current vaccine targets BALF4, BKRF2, BLLF1, BXLF2, BZLF1, and BZLF2. These results highlight the need to consider geographic variation in EBV genomes when devising strategies for exploiting adaptive immune responses against EBV-related cancers, ensuring greater global effectiveness and equity in prevention and treatment.

P-GEMOX with sequential or sandwiched radiotherapy for early-stage extranodal natural killer/T-cell lymphoma.

7075 Background: Combined modality therapy (CMT), namely chemotherapy combined with radiotherapy, has been recommended for patients with localized extranodal natural killer/T-cell lymphoma (ENKTL). However, the optimal CMT has not been fully clarified. As chemotherapy is more easily accessible than immediate radiotherapy in the routine clinical practice, the “chemotherapy-first” CMT including sequential or sandwiched radiotherapy deserves further exploration. In addition, the optimal non-anthracycline-based regimen needs to be confirmed. Methods: The P-GEMOX regimen was administrated as follows: pegaspargase 2000 IU/m2 intramuscular on day 1, gemcitabine 1000 mg/m2 intravenous on day 1 and 8, oxaliplatin 130 mg/m2 intravenous on day 1 and was repeated every 21 days. Patients who achieved at least stable disease (SD) subsequently underwent involved field radiotherapy (IFRT). The dose of IFRT ranged from 50 to 55 Gy. Performing sequential radiotherapy (4 cycles of CT+RT) or sandwich radiotherapy (2 cycles of CT+RT+2 cycles of CT) is determined by the clinician based on the patients' conditions. The primary endpoint was the overall response rate (ORR) after 2 cycles of chemotherapy, and secondary study endpoints were CR, PFS, and OS. Safety was also evaluated. Results: From August 2020 to April 2023, thirty-seven patients (23 men, 14 women; median age: 55, 26-76 years) with stage I/II ENKTL who had received P-GEMOX were collected. 14 patients were stage IE and 23 were IIE. ALL patients completed at least 2 cycles of P-GEMOX, which resulted in 94.6% (35/37) of ORR including 30 patients with CR and 5 patients with PR. Among the patients in remission, 15 patients received sequential radiotherapy, 15 received sandwich radiotherapy, 4 were waiting for or in the process of radiotherapy, and 1 patient progressed before radiotherapy. With a median follow-up of 14.8 months (range: 2.6-38.1 months), the 3-year PFS and OS were 87.2% (95%CI 69.3%-95%) and 90.6% (95%CI 72%-97.1%), respectively. Sandwich radiotherapy had an obvious trend for longer PFS than sequential radiotherapy (18moths-PFS 100% vs. 78%; P=0.073). During the treatment, 21.6% (8/37) of the patients experienced grade 3–4 treatment-emergent adverse events (TEAEs). The most grade 3–4 hematological TEAEs were neutropenia (7/37, 18.9%) and thrombocytopenia (4/37, 10.8%). As for grade 3–4 non-hematological TEAEs, elevated aminotransferase, hyperbilirubinemia and hypofibrinogenemia were 16.2%, 10.8% and 8.1%, respectively. The adverse events of this CMT were well-tolerated and manageable. No treatment-related death occurred. Conclusions: Our study demonstrated that CMT consisted of P-GEMOX showed favorable efficacy with acceptable toxicity, and sandwich radiotherapy (CT+RT+CT) seems give more favorable PFS than sequential radiotherapy. The CMT protocol could be an effective treatment option for early-stage ENKTL patients.