Activity of pembrolizumab in relapsed/refractory NK/T-cell lymphoma

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

ABSTRACT

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.

Real-World Multicenter Study of PD-1 Blockade in HIV-Associated Classical Hodgkin Lymphoma Across the United States

BACKGROUND

Despite a higher risk of classical Hodgkin lymphoma (cHL) in people with HIV and the demonstrated safety and efficacy of PD-1 blockade in cHL, there are limited data on the use of these agents in HIV-associated cHL (HIV-cHL).

PATIENTS/METHODS

We retrospectively identified patients with HIV-cHL from the "Cancer Therapy using Checkpoint inhibitors in People with HIV-International (CATCH-IT)" database who received nivolumab or pembrolizumab, alone or in combination with other agents, and reviewed records for demographics, disease characteristics, immune-mediated adverse events (imAEs), and treatment outcomes. Changes in CD4+ T-cell counts with treatment were measured via Wilcoxon signed-rank tests. Overall response rate (ORR) was defined as the proportion of patients with partial or complete response (PR/CR) per 2014 Lugano classification.

RESULTS

We identified 23 patients with HIV-cHL who received a median of 6 cycles of PD-1 blockade: 1 as 1st-line, 6 as 2nd-line, and 16 as ≥3rd-line therapy. Seventeen (74%) patients received monotherapy, 5 (22%) received nivolumab plus brentuximab vedotin, and 1 received nivolumab plus ifosfamide, carboplatin, and etoposide. The median baseline CD4+ T-cell count was 155 cells/µL, which increased to 310 cells/µL at end-of-treatment (P = .009). Three patients had grade 3 imAEs; none required treatment discontinuation. The ORR was 83% with median duration of response of 19.7 months. The median progression-free survival was 21.2 months and did not differ between patients with <200 versus ≥200 CD4+ cells/µL (P = .95).

CONCLUSION

Our findings support the use of PD-1 blockade in HIV-cHL for the same indications as the general population with cHL.

Increased coexpression of PD-L1 and IDO1 is associated with poor overall survival in patients with NK/T-cell lymphoma

Immunotherapy with programmed cell death 1 ligand 1 (PD-L1) blockade was effective in patients with NK/T-cell lymphoma. In addition to PD-L1, indoleamine 2,3-dioxygenase-1 (IDO1) is one of the most promising immunotherapeutic targets. High proportions of PD-L1 and IDO1 proteins were observed by immunohistochemistry (IHC) from 230 newly diagnosed patients with NK/T lymphoma with tissue samples from three cancer centers and were associated with poor overall survival (OS) in patients with NK/T lymphoma. Importantly, the coexpression of PD-L1 and IDO1 was related to poor OS and short restricted mean survival time in patients with NK/T lymphoma and was an independent prognostic factor in the training cohorts, and which was also validated in 58 NK/T lymphoma patients (GSE90597). Moreover, a nomogram model constructed with PD-L1 and IDO1 expression together with age could provide concise and precise predictions of OS rates and median survival time. The high-risk group in the nomogram model had a positive correlation with CD4 + T-cell infiltration in the validation cohort, as did the immunosuppressive factor level. Therefore, high PD-L1 and IDO1 expression was associated with poor OS in patients with NK/T lymphoma. PD-L1 and IDO1 might be potential targets for future immune checkpoint blockade (ICB) therapy for NK/T lymphoma.

Optimization of immune checkpoint inhibitor treatment planning for relapsed or refractory extranodal NK/T cell lymphoma

Pembrolizumab (anti-programmed cell death-ligand 1 inhibitor) is a promising salvage therapeutic option for relapsed/refractory extranodal NK/T-cell lymphoma (R/R ENKTL). However, the appropriate duration of pembrolizumab use in R/R ENKTL patients and the optimal timing for administering pembrolizumab remain undetermined. We collected and analyzed clinical information on R/R ENKTL 58 patients who received pembrolizumab to evaluate the optimal treatment durations and clinical information for considering treatment interruption. Treatment outcomes were assessed by 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and Epstein Barr virus DNA (EBV DNA) every 3 months. Nineteen (32.8%) patients had been treated with more than three chemotherapies before pembrolizumab administration. The best response rate towards the first try of pembrolizumab was 38.9% (31.5% complete response rate (CR), 7.4% partial response (PR)). During the 41.8-month median follow-up duration, the median progression-free survival (PFS) was 3.1 months, and the median overall survival (OS) was 7.1 months. The failure group, which was characterized by Deaville score (DS) 3-4 and circulating EBV detection, or DS 5 with/without EBV detection, had the worst PFS (p < 0.001) and OS (p < 0.001), followed by the high (DS 1-2 and EBV detection, or DS 3-4 and EBV not detected) and low-risk groups (DS 1-2 and EBV not detected). Among the 21 patients who achieved the best response at the first pembolizumab try, the patients who received planned 24 cycles presented better PFS than those who received incomplete cycles (57.6 months vs 20.9 months, P-value = 0.012). Among 13 patients who received avelumab or pembrolizumab in advance, a few who responded to the second trial of pembrolizumab administration had over one year of chemotherapy vacation. Determining the discontinuation or continuation of pembrolizumab would be considered in selected cases assessed by PET-CT and EBV monitoring. Disruption of pembrolizumab treatment may be advisable for the low-risk group(DS 1-2 and EBV not detected), whereas continuation could be warranted for the high-risk group (DS 1-2 and EBV detection, or DS 3-4 and EBV not detected). Moreover, it might be critical to maintain over 24 cycles to improve the survival outcome of R/R ENKTL.

Immunotyping of peripheral blood lymphocytes by flow cytometry reveals Th cell as a potential prognostic biomarker for extranodal NK/T-cell lymphoma

This study aimed to explore the distribution, characteristics and prognostic value of baseline peripheral blood lymphocyte subsets in patients with extranodal NK/T-cell lymphoma (NKTCL). We conducted this cross-sectional study of 205 newly-diagnosed NKTCL patients receiving first-line chemotherapy and radiation at our institute between 2010 and 2020. Baseline peripheral blood lymphocytes were detected using flow cytometry, and the clinical value was analyzed. Compared with healthy controls, patients with NKTCL presented with a distinct peripheral immunity with higher levels of cytotoxic CD8+ T cells (33.230 ± 12.090% vs. 27.060 ± 4.010%, p < 0.001) and NKT cells (7.697 ± 7.219% vs. 3.550 ± 2.088%, p < 0.001) but lower proportions of suppressive regulatory T cells (Treg, 2.999 ± 1.949% vs. 3.420 ± 1.051%, p = 0.003) and CD4+ helper T cells (Th, 33.084 ± 11.361% vs. 37.650 ± 3.153%, p < 0.001). Peripheral lymphocytes were differentially distributed according to age, stage, and primary site in patients with NKTCL. The proportion of Th cells/lymphocytes was associated with tumor burden reflected by stage (p = 0.037), serum lactate dehydrogenase (p = 0.0420), primary tumor invasion (p = 0.025), and prognostic index for NK/T-cell lymphoma (PINK) score (p = 0.041). Furthermore, elevated proportions of T cells (58.9% vs. 76.4%, p = 0.005), Th cells (56.3% vs. 68.8%, p = 0.047), or Treg cells (49.5% vs. 68.9%, p = 0.040) were associated with inferior 5-year progression-free survivals (PFS) via univariable survival analysis. Multivariate cox regression revealed elevated Th cells as an independent predictor for unfavorable PFS (HR = 2.333, 95% CI, 1.030-5.288, p = 0.042) in NKTCL. These results suggested the proportion of Th cells positively correlated with tumor burden and was a potential non-invasive biomarker for inferior survival for patients with NKTCL.

Counterproductive effects of anti-CD38 and checkpoint inhibitor for the treatment of NK/T cell lymphoma

Introduction

Natural killer/T cell lymphoma (NKTL) is an aggressive malignancy associated with poor prognosis. This is largely due to limited treatment options, especially for relapsed patients. Immunotherapies like immune checkpoint inhibitors (ICI) and anti-CD38 therapies have shown promising but variable clinical efficacies. Combining these therapies has been suggested to enhance efficacy.

Methods

We conducted a case study on a relapsed NKTL patient treated sequentially with anti-CD38 followed by ICI (anti-PD1) using cytometry analyses.

Results and Discussion

Our analysis showed an expected depletion of peripheral CD38+ B cells following anti-CD38 treatment. Further analysis indicated that circulating anti-CD38 retained their function for up to 13 weeks post-administration. Anti-PD1 treatment triggered re-activation and upregulation of CD38 on the T cells. Consequently, these anti-PD1-activated T cells were depleted by residual circulating anti-CD38, rendering the ICI treatment ineffective. Finally, a meta-analysis confirmed this counterproductive effect, showing a reduced efficacy in patients undergoing combination therapy. In conclusion, our findings demonstrate that sequential anti-CD38 followed by anti-PD1 therapy leads to a counterproductive outcome in NKTL patients. This suggests that the treatment sequence is antithetic and warrants re-evaluation for optimizing cancer immunotherapy strategies.

Pembrolizumab for Patients with Relapsed or Refractory Extranodal NK/T-Cell Lymphoma in Korea

PURPOSE

Programmed death-1 blockade with pembrolizumab has shown promising activity in relapsed/refractory (R/R) extranodal natural killer/T-cell lymphoma (NKTCL), but studies are limited, with small patient numbers.

MATERIALS AND METHODS

Thirteen institutes involved with the Consortium for Improving Survival of Lymphoma, a Korean lymphoma study group, collected the clinical data of 59 patients treated with pembrolizumab as salvage therapy between 2016 and 2022.

RESULTS

The median age of the patients was 60 years (range, 22 to 87 years), and 76.3% had advanced Ann Abor stage disease. Pembrolizumab was given to 35.6%, 40.7%, and 23.7% of the patients as second-, third-, and fourth- or higher-line chemotherapy, respectively. The overall response rate was 40.7%, with 28.8% having complete response. The estimated 2-year progression-free survival (PFS) and overall survival rates for all patients were 21.5% and 28.7%, respectively; for responders, the rates were 53.0% and 60.7%, respectively. Although not statistically significant, Eastern Cooperative Oncology Group performance status ≥ 2 (hazard ratio [HR], 1.91; 95% confidence interval [95% CI], 0.93 to 3.94; p=0.078) and stage III or IV disease (HR, 2.59; 95% CI, 0.96 to 6.96; p=0.060) were associated with a trend toward shorter PFS in multivariate analysis. Grade 3 or 4 adverse events (AEs) were noted in 12 patients (20.3%); neutropenia (10.2%), fatigue (6.8%), and pneumonitis (5.1%) were most common AEs.

CONCLUSION

In conclusion, while pembrolizumab had a modest effect on patients with R/R NKTCL, it may be a useful salvage therapy for patients with localized disease and good performance status.

TIGIT is Frequently Expressed in the Tumor Microenvironment of Select Lymphomas: Implications for Targeted Therapy

Immune checkpoint inhibitors against Programmed Cell Death Protein 1/Programmed Cell (PD-1/PD-L1) and CTLA-4/B7 axes have had limited success in hematologic malignancies, requiring the need to explore alternative targets such as T-cell immunoreceptor with Ig and ITIM domains (TIGIT)/CD155 to improve durable clinical responses. We undertook this study to investigate the expression profile of TIGIT such that the potential efficacy of TIGIT blockade could be mapped among lymphoma subtypes. We validated an immunohistochemical assay for TIGIT and evaluated its expression in lymphoma and tumor microenvironment (TME) cells in 661 lymphoma/leukemia biopsies. Multiplex immunofluorescence was used for correlation with normal TME cell subsets. Tumor or TME TIGIT-positivity was defined as moderate to strong membrane staining in at least 10% of tumor or TME cells, respectively. TME TIGIT expression was correlated with overall survival and progression-free survival and comparison with PD-L1 expression. In most cases, lymphoma cells were TIGIT-negative except for angioimmunoblastic and peripheral T-cell lymphomas, which showed 91% and 47% positivity, respectively. A high proportion of small B-cell lymphoma and anaplastic large cell lymphoma cases had TIGIT-positive TME cells. Chronic lymphocytic leukemia/small lymphocytic lymphoma patients with TIGIT-negative TME cells showed significantly shorter overall survival ( P =0.04). No other statistically significant differences were found. When TIGIT was expressed in TME cells, there were a comparable number of TIGIT-positive only and dual TIGIT/PD-L1 positive cases except for more TIGIT-positive only cases in CLL/SLL. TIGIT expression shows distinctive profiles among lymphoma subtypes. Chronic lymphocytic leukemia/small lymphocytic lymphoma and anaplastic large cell lymphoma demonstrated high TME TIGIT expression compared with PD-L1, with a high proportion of dual TIGIT and PD-L1-positivity. Our results are likely to contribute to the design and correlative study of therapeutic response in clinical trials targeting TIGIT alone or in combination with PD1/PDL1.

Blockade of CD300A enhances the ability of human NK cells to lyse hematologic malignancies

OBJECTIVE

The human cluster of differentiation (CD)300A, a type-I transmembrane protein with immunoreceptor tyrosine-based inhibitory motifs, was investigated as a potential immune checkpoint for human natural killer (NK) cells targeting hematologic malignancies (HMs).

METHODS

We implemented a stimulation system involving the CD300A ligand, phosphatidylserine (PS), exposed to the outer surface of malignant cells. Additionally, we utilized CD300A overexpression, a CD300A blocking system, and a xenotransplantation model to evaluate the impact of CD300A on NK cell efficacy against HMs in in vitro and in vivo settings. Furthermore, we explored the association between CD300A and HM progression in patients.

RESULTS

Our findings indicated that PS hampers the function of NK cells. Increased CD300A expression inhibited HM lysis by NK cells. CD300A overexpression shortened the survival of HM-xenografted mice by impairing transplanted NK cells. Blocking PS-CD300A signals with antibodies significantly amplified the expression of lysis function-related proteins and effector cytokines in NK cells, thereby augmenting the ability to lyse HMs. Clinically, heightened CD300A expression correlated with shorter survival and an "exhausted" phenotype of intratumoral NK cells in patients with HMs or solid tumors.

CONCLUSIONS

These results propose CD300A as a potential target for invigorating NK cell-based treatments against HMs.

Tislelizumab and radiation therapy in low-risk early-stage extranodal natural killer/T-cell lymphoma, nasal type: a phase II study protocol

Low-risk early-stage extranodal natural killer/T-cell lymphoma, nasal type has a favorable outcome with radiation therapy alone, and the addition of chemotherapy shows no survival benefit. Nonetheless, a proportion of patients will relapse or progress, with a dismal outcome, highlighting the need for a novel therapeutic strategy. Promising preliminary findings indicate the efficacy of PD-1/PD-L1 inhibitors in extranodal natural killer/T-cell lymphoma, nasal type, with good toxicity profiles. Here we describe the design of a phase II study (CLCG-NKT-2101), which is evaluating the safety and efficacy of adding anti-PD-1 antibody to the current radiation therapy regimen in low-risk early-stage extranodal natural killer/T-cell lymphoma, nasal type patients. Tislelizumab will be added in an inductive and concurrent way to radiation therapy. The primary end point will be the complete response rate after induction immunotherapy. Clinical trial registration: ClinicalTrials.gov (NCT05149170).

Therapeutic challenges in peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is a rare and heterogeneous group of hematological malignancies. Compared to our knowledge of B-cell tumors, our understanding of T-cell leukemia and lymphoma remains less advanced, and a significant number of patients are diagnosed with advanced stages of the disease. Unfortunately, the development of drug resistance in tumors leads to relapsed or refractory peripheral T-Cell Lymphomas (r/r PTCL), resulting in highly unsatisfactory treatment outcomes for these patients. This review provides an overview of potential mechanisms contributing to PTCL treatment resistance, encompassing aspects such as tumor heterogeneity, tumor microenvironment, and abnormal signaling pathways in PTCL development. The existing drugs aimed at overcoming PTCL resistance and their potential resistance mechanisms are also discussed. Furthermore, a summary of ongoing clinical trials related to PTCL is presented, with the aim of aiding clinicians in making informed treatment decisions.

Use of PD-1 blockade in refractory/relapsed natural killer T-cell lymphomas: a systematic review and synthesis of case reports

Natural killer/T-cell lymphoma (NK/T-cellL) is an aggressive non-Hodgkin's lymphoma with limited treatment options for patients who experience disease progression or recurrence after second-line treatment. The use of new therapies, such as pembrolizumab, which involves immune checkpoint blockade mechanisms, is proposed. This systematic review followed the MOSE guidelines and searched PUBMED/MEDLINE, EMBASE, and Scopus databases. Fourteen articles were found, reporting on the use of pembrolizumab anti PD-1 in NK/T-cellL patients. The objective response rate was 84.50%, with disease-free survival ranging from two to 48 months. The complete response rate was 61.6%, and the quality of the reported studies was evaluated to be of high and moderate confidence bias levels in case reports and high bias in clinical trials. Pembrolizumab and others anti PD-1 are treatment options for refractory/recurrent NK/T-cellL, regardless of PD-L1 expression, with good short- and long-term results and low adverse events.

Comparative analysis of upper aerodigestive tract and non-upper aerodigestive tract in NK/T-cell lymphoma

OBJECTIVE

Nasal or extranasal natural killer/T-cell lymphoma (NKTCL) is a very rare aggressive lymphoma, but it is increasingly diagnosed. To evaluate some specificity by comparative analysis between primary upper aerodigestive tract (UAT) and non-upper aerodigestive tract (NUAT)NKTCL.

METHODS

A retrospective analysis was performed on NKTCL patients from January 2013 to November 2022 in our cancer center.

RESULTS

The majority of the lesions were UAT-NKTCL 70 cases (92.1%), the primary NUAT occurred in 6 cases. Patients in the UAT group were mainly in the early stage and in the low and medium risk, while those in the NUAT group were late stage and in high risk (p = 0.000). The expressions of CD3 and TIA-1 in UAT group were higher than those in NUAT group (p = 0.031, p = 0.003), while CD7 was dominant in NUAT group (p = 0.009). For early stage NKTCL, multivariate analysis suggested that gender and PINK score were independent factors affecting PFS and OS (p < 0.05). The 3 year OS rate in initial CR group was 90.1% versus 46.4% in non-CR group (p = 0.000). In advanced stage, KI67% and bone marrow involvement were independent factors affecting OS (p = 0.022, p = 0.038).

CONCLUSION

It was difficult to distinguish between UAT and NUAT-NKTCL from histopathology. NUAT-NKTCL patients did have advanced stage and poor outcome. The prognostic value of PINK score and bone marrow involvement was proposed. We aimed to improve initial CR rates, as well as to find new predictive models to predict the whole population.

Single-Cell Analysis Reveals Malignant Cells Reshape the Cellular Landscape and Foster an Immunosuppressive Microenvironment of Extranodal NK/T-Cell Lymphoma

Extranodal natural killer/T-cell lymphoma (NKTCL) is an aggressive type of lymphoma associated with Epstein-Barr virus (EBV) and characterized by heterogeneous tumor behaviors. To better understand the origins of the heterogeneity, this study utilizes single-cell RNA sequencing (scRNA-seq) analysis to profile the tumor microenvironment (TME) of NKTCL at the single-cell level. Together with in vitro and in vivo models, the study identifies a subset of LMP1+ malignant NK cells contributing to the tumorigenesis and development of heterogeneous malignant cells in NKTCL. Furthermore, malignant NK cells interact with various immunocytes via chemokines and their receptors, secrete substantial DPP4 that impairs the chemotaxis of immunocytes and regulates their infiltration. They also exhibit an immunosuppressive effect on T cells, which is further boosted by LMP1. Moreover, high transcription of EBV-encoded genes and low infiltration of tumor-associated macrophages (TAMs) are favorable prognostic indicators for NKTCL in multiple patient cohorts. This study for the first time deciphers the heterogeneous composition of NKTCL TME at single-cell resolution, highlighting the crucial role of malignant NK cells with EBV-encoded LMP1 in reshaping the cellular landscape and fostering an immunosuppressive microenvironment. These findings provide insights into understanding the pathogenic mechanisms of NKTCL and developing novel therapeutic strategies against NKTCL.

Advances and challenges of immunotherapies in NK/T cell lymphomas

Natural killer (NK)/T cell lymphoma (NKTCL) is a rare subtype of Epstein-Barr virus (EBV)-associated non-Hodgkin lymphoma characterized by poor clinical outcomes. It is more common in East Asian and Latin American countries. Despite the introduction of asparaginase/pegaspargase-based chemotherapy, the prognosis of patients with advanced NKTCL needs to be improved, and few salvage treatment options are available for relapsed/refractory patients who fail chemotherapy. Although many unknowns remain, novel treatment strategies to further improve outcomes are urgently needed. Immunotherapy has emerged and shown favorable antitumor activity in NKTCL, including monoclonal antibodies targeting immune checkpoint inhibitors, other receptors on the cellular membrane, and cellular immunotherapy, which could enhance immune cells attack on tumor cells. In this review, we provide an overview of recent immunotherapy in NKTCL, focusing on programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1), cytotoxic T lymphocyte-associated protein 4 (CTLA-4), chimeric antigen receptor (CAR) T cells, EBV-specific cytotoxic T lymphocytes, immunomodulatory agents, and other targeted agents, as well as the current progress and challenges in the field.

Enhanced efficacy of combined fluzoparib and chidamide targeting in natural killer/T-cell lymphoma

The treatment of natural killer/T-cell lymphoma (NKTCL) presents an onerous challenge, and a search for new therapeutic targets is urgently needed. Poly ADP-ribose polymerase inhibitors (PARPi) were initially used to treat breast and ovarian cancers with BRCA1/2 mutations. Their excellent antitumor efficacy led to a series of clinical trials conducted in other malignancies. However, the exploration of PARPi and their potential use in combination treatments for NKTCL remains unexplored. We treated NKTCL cell lines with fluzoparib (a novel inhibitor of PARP) and chidamide (a classical inhibitor of HDACs) to explore their cytotoxic effects in vitro. Then, their antitumor efficacy in vivo was confirmed in YT-luciferin xenograft mouse models. Fluzoparib or chidamide alone inhibited NKTCL cell proliferation in a dose-dependent manner. Cotreatment with both drugs synergistically induced excessive accumulation of DNA double-strand breaks and massive apoptotic cell death by inhibiting the DNA damage repair pathway, as shown by the decreased protein levels of p-ATM, p-BRCA1, p-ATR, and Rad51. Moreover, the combination treatment apparently increased the level of intracellular reactive oxygen species (ROS) to enhance apoptosis, and pretreatment with an ROS scavenger reduced the proapoptotic effect by 30-60% in NKTCL cell lines. In vivo, this combined regimen also showed synergistic antitumor effects in xenograft mouse models. The combination of fluzoparib and chidamide showed synergistic effects against NKTCL both in vitro and in vivo and deserves further exploration in clinical trials.

Extranodal lymphoma: pathogenesis, diagnosis and treatment

Approximately 30% of lymphomas occur outside the lymph nodes, spleen, or bone marrow, and the incidence of extranodal lymphoma has been rising in the past decade. While traditional chemotherapy and radiation therapy can improve survival outcomes for certain patients, the prognosis for extranodal lymphoma patients remains unsatisfactory. Extranodal lymphomas in different anatomical sites often have distinct cellular origins, pathogenic mechanisms, and clinical manifestations, significantly influencing their diagnosis and treatment. Therefore, it is necessary to provide a comprehensive summary of the pathogenesis, diagnosis, and treatment progress of extranodal lymphoma overall and specifically for different anatomical sites. This review summarizes the current progress in the common key signaling pathways in the development of extranodal lymphomas and intervention therapy. Furthermore, it provides insights into the pathogenesis, diagnosis, and treatment strategies of common extranodal lymphomas, including gastric mucosa-associated lymphoid tissue (MALT) lymphoma, mycosis fungoides (MF), natural killer/T-cell lymphoma (nasal type, NKTCL-NT), and primary central nervous system lymphoma (PCNSL). Additionally, as PCNSL is one of the extranodal lymphomas with the worst prognosis, this review specifically summarizes prognostic indicators and discusses the challenges and opportunities related to its clinical applications. The aim of this review is to assist clinical physicians and researchers in understanding the current status of extranodal lymphomas, enabling them to make informed clinical decisions that contribute to improving patient prognosis.

Treating relapsed/refractory mature T- and NK-cell neoplasms with tislelizumab: a multicenter open-label phase 2 study

Patients with relapsed/refractory (R/R) mature T- and natural killer (NK)-cell neoplasms lack effective treatments after failure of standard therapies. This phase 2 study evaluated the efficacy and safety of the programmed cell death protein 1 inhibitor tislelizumab in these patients. Seventy-seven patients were treated with 200 mg tislelizumab every 3 weeks. Twenty-two patients with extranodal NK-/T-cell lymphomas were enrolled in cohort 1; 44 patients with peripheral T-cell lymphoma (PTCL) were enrolled in cohort 2 (21 patients had PTCL not otherwise specified, 11 patients had angioimmunoblastic T-cell lymphoma, and 12 patients had anaplastic large-cell lymphoma). Cohort 3 comprised 11 patients with cutaneous T-cell lymphoma, of which 8 patients had mycosis fungoides (MF) and 3 had Sézary syndrome. Of the 77 patients, 76.6% had advanced-stage disease, 51.9% had refractory disease, and 49.4% received ≥3 prior systemic regimens. Promising efficacy was observed in cohort 3 (median follow-up [FU], 16.6 months; overall response rate [ORR], 45.5%; complete response [CR], 9.1%; median duration of response [DOR], 11.3 months; median progression-free survival, 16.8 months; median overall survival, not reached). Modest efficacy was observed in cohort 1 (median FU, 8.4 months; ORR, 31.8%; CR, 18.2%; median DOR, not reached) and cohort 2 (median FU, 9.3 months; ORR, 20.5%; CR, 9.1%; median DOR, 8.2 months). Most treatment-related adverse events were grade 1 or 2, and the safety profile was consistent with the known safety profile of tislelizumab. In conclusion, tislelizumab was well tolerated, achieving modest efficacy in R/R mature T- and NK-cell neoplasms, with some long-lasting remissions. This trial was registered at www.clinicaltrials.gov as #NCT03493451.

A phase 2 study of pembrolizumab after autologous stem cell transplantation in patients with T-cell non-Hodgkin lymphoma

Autologous stem cell transplantation (ASCT) is often used as consolidation for several subtypes of peripheral T-cell lymphoma (PTCL) in first remission. However, many patients relapse after ASCT and have a very poor prognosis. There are no approved treatment options for posttransplantation maintenance or consolidation in PTCL. PD-1 blockade has demonstrated some efficacy for patients with PTCL. We, therefore, conducted a phase 2 multicenter study of the anti-PD-1 monoclonal antibody pembrolizumab after ASCT in patients with PTCL in first remission. Pembrolizumab was administered at 200 mg IV every 3 weeks for up to 8 cycles within 21 days from post-ASCT discharge (and within 60 days of stem cell infusion). The primary end point was progression-free survival (PFS) at 18 months after ASCT. Twenty-one patients were treated in this study and 67% (n = 14) completed 8 cycles of treatment. Among all patients who were evaluable, 13 of 21 were alive and achieved PFS at 18 months after ASCT, meeting the study's primary end point. The estimated 18-month PFS was 83.6% (95% confidence interval [CI], 68-100), and overall survival 94.4% (95% CI, 84-100). The toxicity profile was consistent with the known toxicity profile of pembrolizumab, with no grade 5 toxicities. In conclusion, PD-1 blockade after ASCT with pembrolizumab is feasible with a favorable safety profile and promising activity, supporting further confirmatory studies. This trial was registered at www.clinicaltrials.gov as #NCT02362997.

First-line immunotherapy with anti-PD-1 antibody for extranodal NK/T-cell lymphoma: A retrospective study

Anti-PD-1 antibody has shown certain effects in patients with newly diagnosed extranodal NK/T-cell lymphoma (ENKTL). Here, we evaluated the clinical efficacy and safety of first-line anti-PD-1 antibody for the treatment of patients with ENKTL and explored biomarkers for treatment response. The clinical data of 107 patients with newly diagnosed ENKTL were retrospectively analysed. Patients received either first-line anti-PD-1 antibody induction treatment or anti-PD-1 antibody combined with asparaginase-based chemotherapy (immunochemotherapy). We found that immunochemotherapy was an independent prognostic factor for longer PFS (p < 0.001). The overall response rate and complete remission rate of immunochemotherapy group was higher than immunotherapy induction group (86.11% vs. 62.86% and 72.22% vs. 52.29%, respectively, p = 0.013). We also observed pretreatment CD4/CD8 ratio >0.83 was significant associated with better response and longer PFS in ENKTL patients received first-line anti-PD1-antibody. Plasma copy number of EBV decreased more significantly in patients with CD4/CD8 ratio >0.83 after treatment. PD-L1 expression was associated with better response and PFS, while elevated plasma IL-6, IL-10 and IFN-γ were associated with poor prognosis. Anti-PD-1 antibody treatment showed promising results in newly diagnosed ENKTL patients. The assessment of pretreatment CD4/CD8 ratio in ENKTL seems feasible for identifying responders to anti-PD-1 antibody treatment.

Novel target and treatment agents for natural killer/T-cell lymphoma

The rapidly increasing use of high-throughput screening had produced a plethora of expanding knowledge on the molecular basis of natural killer/T-cell lymphoma (NKTCL), which in turn has revolutionized the treatment. Specifically, the use of asparaginase-containing regimens has led to substantial improvement in survival outcomes in NKTCL patients. Novel treatment strategies that are currently under development include cell-surface-targeted antibodies, immune checkpoint inhibitors, Epstein-Barr virus targeted cytotoxic T lymphocyte, immunomodulatory agents, chimeric antigen receptor T cells, signaling pathway inhibitors and epigenetic targeted agents. In almost all cases, initial clinical studies of newly developed treatment are conducted in patients relapsed, and refractory NKTCL due to very limited treatment options. This review summarizes the results of these novel treatments for NKTCL and discusses their potential for likely use in NKTCL in a wider setting in the future.

Allogeneic hematopoietic stem cell transplantation for NK/T-cell lymphoma: an international collaborative analysis

Natural killer/T-cell lymphomas (NKTCL) represent rare and aggressive lymphoid malignancies. Patients (pts) with relapsed/refractory disease after Asparaginase (ASPA)-based chemotherapy have a dismal prognosis. To better define the role of allogeneic hematopoietic stem cell transplantation (allo-HSCT), we conducted a retrospective analysis of data shared with the European Society for Blood and Marrow Transplantation (EBMT) and cooperating Asian centers. We identified 135 pts who received allo-HSCT between 2010 and 2020. Median age was 43.4 years at allo-HSCT, 68.1% were male. Ninety-seven pts (71.9 %) were European, 38 pts (28.1%) Asian. High Prognostic Index for NKTCL (PINK) scores were reported for 44.4%; 76.3% had >1 treatment, 20.7% previous auto-HSCT, and 74.1% ASPA-containing regimens prior to allo-HSCT. Most (79.3%) pts were transplanted in CR/PR. With a median follow-up of 4.8 years, 3-year progression-free(PFS) and overall survival were 48.6% (95%-CI:39.5-57%) and 55.6% (95%-CI:46.5-63.8%). Non-relapse mortality at 1 year was 14.8% (95%-CI:9.3-21.5%) and 1-year relapse incidence 29.6% (95%-CI:21.9-37.6%). In multivariate analyses, shorter time interval (0-12 months) between diagnosis and allo-HSCT [HR = 2.12 (95%-CI:1.03-4.34); P = 0.04] and transplantation not in CR/PR [HR = 2.20 (95%-CI:0.98-4.95); P = 0.056] reduced PFS. Programmed cell death protein 1(PD-1/PD-L1) treatment before HSCT neither increased GVHD nor impacted survival. We demonstrate that allo-HSCT can achieve long-term survival in approximately half of pts allografted for NKTCL.

Sugemalimab Monotherapy for Patients With Relapsed or Refractory Extranodal Natural Killer/T-Cell Lymphoma (GEMSTONE-201): Results From a Single-Arm, Multicenter, Phase II Study

PURPOSE

Relapsed or refractory extranodal natural killer/T-cell lymphoma (R/R ENKTL) is a rare and aggressive type of non-Hodgkin lymphoma with limited treatment options. This phase II study evaluated the efficacy and safety of sugemalimab, an anti-PD-L1 monoclonal antibody, in R/R ENKTL.

METHODS

Eligible patients received sugemalimab 1,200 mg intravenously once every 3 weeks for up to 24 months or until progression, death, or study withdrawal. The primary end point was objective response rate (ORR) assessed by an independent radiologic review committee. Key secondary end points included ORR assessed by the investigators, complete response rate, duration of response, and safety.

RESULTS

At the data cutoff (February 23, 2022), 80 patients were enrolled and followed for a median of 18.7 months. At baseline, 54 (67.5%) had stage IV disease and 39 (48.8%) had received ≥2 lines of prior systemic therapy. Independent radiologic review committee-assessed ORR was 44.9% (95% CI, 33.6 to 56.6); 28 (35.9%) patients achieved a complete response and seven (9.0%) achieved a partial response, with a 12-month duration of response rate of 82.5% (95% CI, 62.0 to 92.6). Investigator-assessed ORR was 45.6% (95% CI, 34.3 to 57.2), and 24 (30.4%) patients achieved a complete response. Most treatment-emergent adverse events were grade 1-2 in severity, and grade ≥ 3 events were reported in 32 (40.0%) patients.

CONCLUSION

Sugemalimab showed robust and durable antitumor activity in R/R ENKTL. Treatment was well tolerated with expected safety profile for this drug class.

T-cell dysfunction in natural killer/T-cell lymphoma

Natural killer/T-cell lymphoma (NKTCL) is an incurable aggressive T-cell lymphoma closely correlated with Epstein‒Barr virus (EBV) infection. Chronic and consistent viral infection induces T-cell exhaustion. Herein, we describe T-cell dysfunction in NKTCL patients for the first time. Peripheral blood mononuclear cells (PBMCs) from age-matched healthy donors (HDs) and NKTCL patients were collected, and lymphocyte distributions, multiple surface inhibitory receptors (IRs), effector cytokine production and cell proliferation were determined by flow cytometry. PBMCs from HDs were cocultured with NKTCL cell lines to verify the clinical findings. IR expression was further assessed in NKTCL tumor biopsies using multiplex immunohistochemistry (mIHC). NKTCL patients have higher frequencies than HDs of inhibitory T regulatory cells (Tregs) and myeloid-derived suppressor cells (MDSCs). T-cell distribution also varies between NKTCL patients and HDs. T cells from NKTCL patients demonstrated higher expression levels of multiple IRs than HDs. Meanwhile, T-cell proliferation and interferon-γ production was significantly reduced in NKTCL patients. More importantly, the number of EBV-specific cytotoxic cells was lower in NTKCL patients, and these cells demonstrated upregulation of multiple IRs and secreted fewer effector cytokines. Interestingly, NKTCL cells caused normal PBMCs to acquire T-cell exhaustion phenotypes and induced generation of Tregs and MDSCs. In line with ex vivo finding, mIHC results showed that CD8+ T cells from NKTCL tumor biopsies expressed much higher level of IRs compared with reactive lymphoid hyperplasia individuals. The immune microenvironment of NKTCL patients exhibited T-cell dysfunction and accumulation of inhibitory cell components, which may contribute to impaired antitumor immunity.

The emerging role of anti-PD-1 antibody-based regimens in the treatment of extranodal NK/T-cell lymphoma-associated hemophagocytic lymphohistiocytosis

PURPOSE

Anti-PD-1 antibody (anti-PD-1 mAb) showed favorable outcomes in some patients with relapsed/refractory (r/r) extranodal NK/T-cell lymphoma (ENKTL). However, the role of anti-PD-1 antibody in NK/T-cell lymphoma-associated hemophagocytic lymphohistiocytosis (NK/T-LAHS) remains unclear. Here, we evaluated the efficacy and toxicity of anti-PD-1 antibody-based treatment in NK/T-LAHS patients.

METHODS

The clinical data of 98 patients diagnosed with NK/T-LAHS at Sun Yat-sen University Cancer Center and the First Affiliated Hospital of Guangdong Pharmaceutical University from May 2014 to November 2021 were retrospectively analyzed. All patients received anti-HLH [HLH-2004 (etoposide, dexamethasone, cyclosporine A) or DEP-based (liposomal doxorubicin, etoposide, methylprednisolone)] regimen and sequential anti-ENKTL chemotherapy (ChT) combined with anti-PD-1 antibody or not.

RESULTS

The overall response rate (ORR) of the anti-PD-1 mAb plus ChT regimens was higher than that of the ChT regimens (73.3% vs. 45.5%, P = 0.041). The toxicity of the anti-PD-1 mAb plus ChT regimens was tolerable. Except for higher rate of neutropenia, no significant difference in adverse events (AEs) was observed between the two groups. When the optimal response to anti-ENKTL was achieved, the median EBV DNA levels in patients who received anti-PD-1 mAb plus ChT were significantly lower than patients who received ChT only (878 copies/mL vs. 18,600 copies/mL, P = 0.001). With a median follow-up of 26.6 months (range 0-65.9 months), the median overall survival (mOS) was 3.5 months (95% CI：2.3-4.7 months). Patients treated with anti-PD-1 mAb plus ChT experienced a longer mOS than those who received ChT only [5.2 months (95% CI: 2.5-7.8 months) vs. 1.5 months (95% CI: 0.5-2.6 months), P = 0.002]. Cox multivariate analysis found that anti-PD-1 mAb was an independent prognostic factor for all NK/T-LAHS patients.

CONCLUSION

In conclusion, anti-PD-1 mAb combined with ChT regimens seemed to be associated with prolonged survival in NK/T-LAHS patients and may represent a potentially promising treatment strategy for this population.

PET/CT in Non-Hodgkin Lymphoma: An Update

Non-Hodgkin lymphomas represents a heterogeneous group of lymphoproliferative disorders characterized by different clinical courses, varying from indolent to highly aggressive. ¹⁸F-FDG-PET/CT is the current state-of-the-art diagnostic imaging, for the staging, restaging and evaluation of response to treatment in lymphomas with avidity for ¹⁸F-FDG, despite it is not routinely recommended for surveillance. PET-based response criteria (using five-point Deauville Score) are nowadays uniformly applied in FDG-avid lymphomas. In this review, a comprehensive overview of the role of ¹⁸F-FDG-PET in Non-Hodgkin lymphomas is provided, at each relevant point of patient management, particularly focusing on recent advances on diffuse large B-cell lymphoma and follicular lymphoma, with brief updates also on other histotypes (such as marginal zone, mantle cell, primary mediastinal- B cell lymphoma and T cell lymphoma). PET-derived semiquantitative factors useful for patient stratification and prognostication and emerging radiomics research are also presented.

An update on viral-induced cutaneous lymphoproliferative disorders. CME Part I

Viral-induced cutaneous T-cell lymphomas are an uncommon group of lymphoproliferative disorders characterized by a viral infection of T and natural killer (NK) cells. This group of cutaneous T-cell lymphomas is more commonly encountered in Asians and Native Americans from Central and South America compared with Western populations. Viral-associated lymphoproliferative disorders include a spectrum of entities that range from nonneoplastic lesions, such as chronic active Epstein-Barr virus infection and infective dermatitis to malignant diseases, such as extranodal NK/T-cell lymphoma, hydroa vacciniforme-like T-cell lymphoma, and adult T-cell leukemia/lymphoma. This review article will focus on hydroa vacciniforme-like lymphoproliferative disorder, extranodal NK/T-cell lymphoma, adult T-cell leukemia/lymphoma, lymphomatoid granulomatosis, and Epstein-Barr virus-positive mucocutaneous ulcers. We will review the pathogenesis of these conditions and the challenges of making a timely diagnosis in early-stage disease and discuss the common clinicopathologic manifestations, mutational landscape, and approaches to treat these highly aggressive and frequently lethal types of lymphoma.

Education and Empowering Special Forces to Eradicate Secret Defectors: Immune System-Based Treatment Approaches for Mature T- and NK-Cell Malignancies

Mature T- and NK-cell leukemia/lymphoma (MTCL/L) constitute a heterogeneous group of, currently, 30 distinct neoplastic entities that are overall rare, and all present with a challenging molecular markup. Thus, so far, the use of first-line cancer treatment modalities, including chemotherapies, achieve only limited clinical responses associated with discouraging prognoses. Recently, cancer immunotherapy has evolved rapidly, allowing us to help patients with, e.g., solid tumors and also relapsed/refractory B-cell malignancies to achieve durable clinical responses. In this review, we systematically unveiled the distinct immunotherapeutic approaches available, emphasizing the special impediments faced when trying to employ immune system defense mechanisms to target 'one of their own-gone mad'. We summarized the preclinical and clinical efforts made to employ the various platforms of cancer immunotherapies including antibody-drug conjugates, monoclonal as well as bispecific antibodies, immune-checkpoint blockades, and CAR T cell therapies. We emphasized the challenges to, but also the goals of, what needs to be done to achieve similar successes as seen for B-cell entities.

Central nervous system involvement at initial diagnosis of extranodal NK/T-cell lymphoma: a retrospective study of a consecutive 12-year case series

Patients with central nervous system (CNS) involvement at initial diagnosis of extranodal NK/T-cell lymphoma (ENKTL) are exceedingly rare, and the clinicopathologic features of CNS involvement have not been well characterized. In this study, we reviewed 662 patients with ENKTL from August 2008 to September 2019. Their clinical and pathological features, treatments, and survival outcomes were analyzed. The median follow-up time was 72 months. Nine of 662 (1.4%) patients were diagnosed with CNS involvement. Among them, the median age was 37 years, and seven patients were male. All patients had positive EBV-DNA, and three patients were asymptomatic at the time of diagnosis with CNS involvement. Common extranodal involved sites included bone, paranasal sinuses, breast, kidney, adrenal gland, and bone marrow. All patients were positive for cytoplasmic CD3ε, cytotoxic granule proteins, and EBER and negative for CD20. All patients received intrathecal chemotherapy and at least one cycle of systemic chemotherapy. Seven patients had died and two were still alive by the last follow-up. The median overall survival (OS) in patients with CNS involvement at initial diagnosis of ENKTL was 9 months, and the 1-year OS was 44.4%. Five patients achieved a complete response after asparaginase-based chemotherapy; two were still alive, one died of systemic progression, one died of ENKTL-associated hemophagocytic syndrome, and one died of treatment-related infections. In conclusion, CNS involvement at initial diagnosis of ENKTL is extremely rare with poor prognosis. There is no standard treatment, and asparaginase-based chemotherapy combined with intrathecal chemotherapy might yield good efficacy.

Outcomes of programmed death protein-1 inhibitors treatment of chronic active Epstein Barr virus infection: A single center retrospective analysis

Introduction

Chronic active Epstein-Barr virus (CAEBV) disease is a high-mortality disease, which is characterized by persistent infectious mononucleosis-like symptoms. There is no standard treatment for CAEBV and allogeneic hematopoietic stem cell transplantation (HSCT) was considered the only potentially therapeutic approach. PD-1 inhibitors have achieved high response in many Epstein-Barr virus-related diseases. In this single-center retrospective analysis, we report the outcomes of PD-1 inhibitors treatment of CAEBV.

Methods

All CAEBV patients without hemophagocytic lymphohistiocytosis (HLH), who were treated with PD-1 inhibitors in our center between 6/1/2017 and 12/31/2021, were retrospectively analyzed. The efficacy and safety of the PD-1 inhibitors were evaluated.

Results

Among the sixteen patients with a median age at onset of 33 years (range, 11-67 years), twelve patients responded to PD-1 inhibitors and the median progression-free survival (PFS) was 11.1 months (range, 4.9-54.8 months). Three achieved clinical complete response (clinical CR), as well as molecular CR. Five patients achieved and remained partial response (PR), and four converted from PR to no response (NR). For three CR patients, the median time and cycles from the first application of PD-1 inhibitor to clinical CR were 6 weeks (range, 4-10 weeks) and 3 cycles (range, 2-4 cycles), and molecular CR was achieved after a median of 16.7 weeks (range, 6.1-18.4 weeks) and 5 cycles (range, 3-6 cycles) of PD-1 inhibitor infusion. No immune-related adverse events have been observed except for one patient who suffered immune-related pancreatitis. There was no correlation of treatment outcome with blood count, liver function, LDH, cytokine or ferritin levels. NK cell function, PD-L1 expression in tumor tissue and gene mutation possibly correlated with treatment response.

Discussion

In patients with CAEBV, PD-1 inhibitors have tolerable toxicity and comparable outcomes while improving quality of life and financial toxicity. Larger prospective studies and longer follow-up time is needed to be conducted.

Rational Targets of Therapy in Extranodal NK/T-Cell Lymphoma

Extranodal NK/T-cell lymphoma (ENKTL) is an aggressive extranodal non-Hodgkin lymphoma (NHL) with poor outcomes, particularly in advanced-stage and relapsed/refractory disease. Emerging research on molecular drivers of ENKTL lymphomagenesis by next-generation and whole genome sequencing has revealed diverse genomic mutations in multiple signaling pathways, with the identification of multiple putative targets for novel therapeutic agents. In this review, we summarize the biological underpinnings of newly-understood therapeutic targets in ENKTL with a focus on translational implications, including epigenetic and histone regulatory aberrations, activation of cell proliferation signaling pathways, suppression of apoptosis and tumor suppressor genes, changes in the tumor microenvironment, and EBV-mediated oncogenesis. In addition, we highlight prognostic and predictive biomarkers which may enable a personalized medicine approach toward ENKTL therapy.

Chemo-free maintenance therapy in adult T-cell acute lymphoblastic leukemia: A case report and literature review

Maintenance therapy in adult T-cell acute lymphoblastic leukemia (T-ALL) is the longest phase but with limited option. The classic drugs used in the maintenance phase such as 6-mercaptopurine, methotrexate, corticosteroid and vincristine have potentially serious toxicities. Optimizing therapy in the modern age, chemo-free maintenance therapy regimens for patients with T-ALL may dramatically improve the maintenance therapeutic landscape. We report here the combination of Anti-programmed cell death protein 1 antibody and histone deacetylase inhibitor as chemo-free maintenance treatment in a T-ALL patient with literature review, thus providing a unique perspective in addition to valuable information which may inform novel therapeutic approaches.

A systematic review and meta-analysis of immune checkpoint therapy in relapsed or refractory non-Hodgkin lymphoma; a friend or foe?

Over the last decades, a revolution has occurred in oncology with the development of immune checkpoint inhibitors (ICIs). Following tremendous successes in solid tumors, interest has risen to explore these inhibitors in hematologic malignancies; while Hodgkin's lymphoma (HL) has shown overwhelming achievements, available data on different types of non-Hodgkin's lymphoma (NHL) vary considerably. To the best of our knowledge, no meta-analysis has assessed the efficacy and safety of ICI therapy in relapsed or refractory NHL patients. Meta-analysis of the included studies (n = 29) indicated PD-1 may probably be the more attractive ICI target rather than PD-L1 and CTLA-4 in NHL patients. Also, there is a plausible correlation between NHL subtypes and response to ICI therapy. While MF, ENKTL, RT, and PMBCL showed promising responses to ICI monotherapy, neither FL nor DLBCL had satisfactory responses; further necessitating novel strategies such as the application of ICIs in combination with other treatment strategies. Notably, among different combinations, BTK inhibitors showed an obvious improvement as compared to ICI monotherapy in both FL and DLBCL, however, the best results were obtained when ICI was combined with anti-CD20 monoclonal antibodies. Finally, while most NHL patients who received ICI treatment have experienced mild AEs, larger trials with long-term follow-up are required to confirm the safety, as well as the efficacy, of ICI therapy in NHL patients.

Emerging predictive biomarkers for novel therapeutics in peripheral T-cell and natural killer/T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) and natural killer/T-cell lymphoma (NKTCL) are rare subtypes of non-Hodgkin's lymphoma that are typically associated with poor treatment outcomes. Contemporary first-line treatment strategies generally involve the use of combination chemoimmunotherapy, radiation and/or stem cell transplant. Salvage options incorporate a number of novel agents including epigenetic therapies (e.g. HDAC inhibitors, DNMT inhibitors) as well as immune checkpoint inhibitors. However, validated biomarkers to select patients for individualized precision therapy are presently lacking, resulting in high treatment failure rates, unnecessary exposure to drug toxicities, and missed treatment opportunities. Recent advances in research on the tumor and microenvironmental factors of PTCL and NKTCL, including alterations in specific molecular features and immune signatures, have improved our understanding of these diseases, though several issues continue to impede progress in clinical translation. In this Review, we summarize the progress and development of the current predictive biomarker landscape, highlight potential knowledge gaps, and discuss the implications on novel therapeutics development in PTCL and NKTCL.

Case report: Relapsed/refractory extranodal natural killer/T-cell lymphoma nasal type with extensive central nervous system involvement

Background: Extranodal natural killer/T-cell lymphoma (ENKL) is a rare subtype of mature T and natural killer cell lymphomas associated with Epstein-Barr virus. Case: A 20-year-old presented with severe neurological symptoms and was diagnosed with stage IV ENKL, nasal type, with CNS involvement. Overall, the patient received nine treatment lines, including chemotherapy, craniospinal irradiation, allogeneic stem cell transplant (alloSCT), donor lymphocyte infusions, and novel agents (Nivolumab, Daratumumab, Thalidomide, Lenalidomide, virus-specific T cells) combined with intrathecal chemotherapy. The treatment effect was evaluated in both blood and CSF (cerebrospinal fluid). First-line SMILE chemotherapy resulted in systemic and CNS remission. Later Cytarabine-based chemotherapy and Daratumumab combination helped to reinduce remission before alloSCT. Conclusion: We show that efficacy monitoring should include both blood and CSF analysis. High-dose Cytarabine-based chemotherapy in combination with Daratumumab and intrathecal chemotherapy may be considered as salvage CNS-directed therapies. We add to existing limited data that Daratumumab penetrates the blood-brain barrier.

Resistance mechanisms of immune checkpoint inhibition in lymphoma: Focusing on the tumor microenvironment

Immune checkpoint inhibitors (ICIs) have revolutionized the therapeutic strategies of multiple types of malignancies including lymphoma. However, efficiency of ICIs varies dramatically among different lymphoma subtypes, and durable response can only be achieved in a minority of patients, thus requiring unveiling the underlying mechanisms of ICI resistance to optimize the individualized regimens and improve the treatment outcomes. Recently, accumulating evidence has identified potential prognostic factors for ICI therapy, including tumor mutation burden and tumor microenvironment (TME). Given the distinction between solid tumors and hematological malignancies in terms of TME, we here review the clinical updates of ICIs for lymphoma, and focus on the underlying mechanisms for resistance induced by TME, which play important roles in lymphoma and remarkably influence its sensitivity to ICIs. Particularly, we highlight the value of multiple cell populations (e.g., tumor infiltrating lymphocytes, M2 tumor-associated macrophages, and myeloid-derived suppressor cells) and metabolites (e.g., indoleamine 2, 3-dioxygenase and adenosine) in the TME as prognostic biomarkers for ICI response, and also underline additional potential targets in immunotherapy, such as EZH2, LAG-3, TIM-3, adenosine, and PI3Kδ/γ.

Extranodal natural killer/T-cell lymphoma invading a patient's heart: A rare case report and literature review

Extranodal NK/T-cell lymphoma (ENKTL) is a rare but aggressive subtype of non-Hodgkin lymphoma, which is derived from NK cells or T cells. There are very few cases of ENKTL invading the heart. Only 12 cases of ENKTL invading the heart have been reported in the English literature. Due to the rarity of this lymphoma, an effective therapeutic strategy has not been defined. Here, we present a case of a 51-year-old Chinese male with extranodal NK/T-cell lymphoma invading the heart and review the literature. The patient received a chemotherapy regimen of PD1 monoclonal antibody (Sintilimab) in combination with first-line P-Gemox. The patient survived for 2 months after diagnosis.

Identification of immune-related genes and development of a prognostic model in mantle cell lymphoma

Background

The immune landscape, prognostic model, and molecular variations of mantle cell lymphoma (MCL) remain unclear. Hence, an integrated bioinformatics analysis of MCL datasets is required for the development of immunotherapy and the optimization of targeted therapies.

Methods

Data were obtained from the Gene Expression Omnibus (GEO) database (GSE32018, GSE45717 and GSE93291). The differentially expressed immune-related genes were selected, and the hub genes were screened by three machine learning algorithms, followed by enrichment and correlation analyses. Next, MCL molecular clusters based on the hub genes were identified by K-Means clustering, the probably approximately correct (PAC) algorithm, and principal component analysis (PCA). The landscape of immune cell infiltration and immune checkpoint molecules in distinct clusters was explored by single-sample gene-set enrichment analysis (ssGSEA) as well as the CIBERSORT and xCell algorithms. The prognostic genes and prognostic risk score model for MCL clusters were identified by least absolute shrinkage and selection operator (LASSO)-Cox analysis and cross-validation for lambda. Correlation analysis was performed to explore the correlation between the screened prognostic genes and immune cells or immune checkpoint molecules.

Results

Four immune-related hub genes (CD247, CD3E, CD4, and GATA3) were screened in MCL, mainly enriched in the T-cell receptor signaling pathway. Based on the hub genes, two MCL molecular clusters were recognized. The cluster 2 group had a significantly worse overall survival (OS), with down-regulated hub genes, and a variety of activated immune effector cells declined. The majority of immune checkpoint molecules had also decreased. An efficient prognostic model was established, including six prognostic genes (LGALS2, LAMP3, ICOS, FCAMR, IGFBP4, and C1QA) differentially expressed between two MCL clusters. Patients with a higher risk score in the prognostic model had a poor prognosis. Furthermore, most types of immune cells and a range of immune checkpoint molecules were positively correlated with the prognostic genes.

Conclusions

Our study identified distinct molecular clusters based on the immune-related hub genes, and showed that the prognostic model affected the prognosis of MCL patients. These hub genes, modulated immune cells, and immune checkpoint molecules might be involved in oncogenesis and could be potential prognostic biomarkers in MCL.

Genomic profiling for clinical decision making in lymphoid neoplasms

With the introduction of large-scale molecular profiling methods and high-throughput sequencing technologies, the genomic features of most lymphoid neoplasms have been characterized at an unprecedented scale. Although the principles for the classification and diagnosis of these disorders, founded on a multidimensional definition of disease entities, have been consolidated over the past 25 years, novel genomic data have markedly enhanced our understanding of lymphomagenesis and enriched the description of disease entities at the molecular level. Yet, the current diagnosis of lymphoid tumors is largely based on morphological assessment and immunophenotyping, with only few entities being defined by genomic criteria. This paper, which accompanies the International Consensus Classification of mature lymphoid neoplasms, will address how established assays and newly developed technologies for molecular testing already complement clinical diagnoses and provide a novel lens on disease classification. More specifically, their contributions to diagnosis refinement, risk stratification, and therapy prediction will be considered for the main categories of lymphoid neoplasms. The potential of whole-genome sequencing, circulating tumor DNA analyses, single-cell analyses, and epigenetic profiling will be discussed because these will likely become important future tools for implementing precision medicine approaches in clinical decision making for patients with lymphoid malignancies.

Treatment of refractory/relapsed extranodal NK/T cell lymphoma with decitabine plus anti-PD-1: A case report

BACKGROUND

Extranodal natural killer/T cell lymphoma, nasal type (ENKL) is a highly aggressive malignancy characterized by its association with Epstein-Barr virus (EBV) and extranodal involvement, which shows a poor clinical outcome. Although L-asparaginase-based chemotherapy has improved the response rates of relapsed/refractory (R/R) ENKL, relapse occurs in up to 50% of patients with disseminated disease.

CASE SUMMARY

Immune evasion has emerged as a critical pathway for survival in ENKL and may be effectuated via STAT3-driven upregulation of programmed cell death ligand 1 (PD-L1) or other molecular pathways. Anti-PD-1 is effective for R/R ENKL with EBV-driven upregulation of PD-L1 expression. Anti-PD-1 combined with decitabine showed positive preliminary results in a patient with R/R ENKL and resistance to anti-PD-1.

CONCLUSION

The treatment experience, in this case, demonstrated the potential ability of decitabine combined with PD-1 inhibitor to treat R/R ENKL, thus providing a new treatment strategy for this tumor.

Primary small intestinal extranodal NK/T cell lymphoma, nasal type with kidney involvement: a rare case report and literature review

Background

Extranodal NK/T cell lymphoma, nasal type (EN-NK/T-NT) is a rare and aggressive type of non-Hodgkin’s lymphoma. EN-NK/T-NT seldom occurs in the gastrointestinal tract, and renal involvement is relatively rare.

Case presentation

Here we report a case of primary small intestinal EN-NK/T-NT with kidney involvement. We present the case of a 71-year-old female who was admitted to our hospital for coronary heart disease with a fever of unknown origin. Laboratory examination showed renal impairment and PET/CT showed a locally thickened wall of the small intestine, abnormally increased FDG metabolism in the right lower abdomen, and multiple slightly high-density masses with abnormal increased FDG metabolism in the right kidney. The gross specimen showed a grayish-white lump located in the ileum approximately 15 cm away from the ileocecum, and two grayish-white lumps located in the upper and lower poles of the right kidney, respectively. The pathological diagnosis was EN-NK/T-NT. The patient died approximately 10 months after the operation.

Conclusion

EN-NK/T-NT is a rare type of non-Hodgkin’s lymphoma and may develop insidiously, with fever as the only clinical manifestation. The disease was found to be difficult to diagnose in the early stage, resulting in a highly aggressive clinical course and short survival time.

Extranodal natural killer/T-cell lymphoma: An overview on pathology and clinical management

Natural killer (NK)/T-cell lymphomas arise mainly from NK-cells and occasionally T-cells, and are universally infected with Epstein Barr virus (EBV). They are uncommon lymphomas more prevalent in Asian and Central/South American populations. NK/T-cell lymphomas are clinically aggressive and predominantly extranodal. The most commonly involved sites are the nasal cavity, followed by non-nasal sites including the skin, gastrointestinal tract and testis. The diagnosis of extranodal NK/T-cell lymphoma is established with histological and immunohistochemical examination, together with the demonstration of EBV in the tumour cells. Staging by positron emission tomography computed tomography is essential to inform the optimal management. Plasma EBV DNA quantification should be performed as it serves as a marker for prognostication and treatment response. Survival outcomes of patients with early-stage disease are good following treatment with nonanthracycline based chemotherapy, together with sequential/concurrent radiotherapy. For advanced-stage disease, asparaginase-containing regimens are mostly used and allogeneic haematopoietic stem cell transplantation should be considered for those at high risk of relapse. Salvage chemotherapy is largely ineffective for relapsed/refractory disease, which has a grave prognosis. Novel therapeutic approaches including immune check-point blockade, EBV-specific cytotoxic T-cells, and monoclonal antibodies are being investigated to improve outcomes for those with high risk and relapsed/refractory disease.

Effect of CD4+ T cell count on treatment-emergent adverse events among patients with and without HIV receiving immunotherapy for advanced cancer

BACKGROUND

The Food and Drug Administration recommends that people living with HIV (PWH) with a CD4+ T cell count (CD4) ≥350 cells/µL may be eligible for any cancer clinical trial, but there is reluctance to enter patients with lower CD4 counts into cancer studies, including immune checkpoint inhibitor (ICI) studies. Patients with relapsed or refractory cancers may have low CD4 due to prior cancer therapies, irrespective of HIV status. It is unclear how baseline CD4 prior to ICI impacts the proportion of treatment-emergent adverse events (TEAE) and whether it differs by HIV status in ICI treated patients.

METHODS

We conducted a pilot retrospective cohort study of participants eligible for ICI for advanced cancers from three phase 1/2 trials in the USA and Spain. We determined whether baseline CD4 counts differed by HIV status and whether the effect of CD4 counts on incidence of TEAE was modified by HIV status using a multivariable logistic regression model.

RESULTS

Of 122 participants, 66 (54%) were PWH who received either pembrolizumab or durvalumab and 56 (46%) were HIV-negative who received bintrafusp alfa. Median CD4 at baseline was 320 cells/µL (IQR 210-495) among PWH and 356 cells/µL (IQR 260-470) among HIV-negative participants (p=0.5). Grade 3 or worse TEAE were recorded among 7/66 (11%) PWH compared with 7/56 (13%) among HIV-negative participants. When adjusted for prior therapies, age, sex, and race, the effect of baseline CD4 on incidence of TEAE was not modified by HIV status for any TEAE (interaction term p=0.7), or any grade ≥3 TEAE (interaction term p=0.1).

CONCLUSIONS

There was no significant difference in baseline CD4 or the proportions of any TEAE and grade ≥3 TEAE by HIV status. CD4 count thresholds for cancer clinical trials should be carefully reviewed to avoid unnecessarily excluding patients with HIV and cancer.

EBV-associated NK and T-cell lymphoid neoplasms

PURPOSE OF REVIEW

Epstein-Barr virus (EBV)-associated neoplasms derived from natural killer (NK) or T cells comprise a group of clinically and biologically heterogenous disorders affecting children and adults, which are overall rare but more prevalent in Asia and South America. This review focuses on neoplasms presenting in the adulthood, addressing recent genomic discoveries as well as therapeutic developments in these highly aggressive disorders.

RECENT FINDINGS

Distinct molecular subtypes of extranodal NK/T-cell lymphomas (ENKTCLs) have been described, with differences in cell of origin, EBV pattern, genomic alterations, clinical characteristics, response to asparaginase-based therapies and to more recent approaches targeting molecular aberrations of the lymphoma. For the last two decades, progress in the clinical management of ENKTCL was based on L-asapraginase containing combinations and the incoroperation of radiotherapy. A subset of cases with PDL1-2 structural alterations may be more responsive to treatment with immune checkpoint inhibitors. Primary nodal EBV+ lymphomas derived from T or NK cells have distinctive features separating them from both peripheral T-cell lymphoma not otherwise specified and ENKTCL. Treatment algorithms correspond to those for advanced ENKTCL.

SUMMARY

With better understanding of lymphomagenesis, genomic landscape and immunologic aspects of the diseases, future treatment options will include targeted therapies including immune checkpoint inhibitors and novel antibodies.

The clinical characteristics and prognostic factors of 410 patients with natural killer/T-cell lymphoma

PURPOSE

To investigate the clinical characteristics and prognostic factors of natural killer/T-cell lymphoma (NKTCL).

METHODS

We retrospectively reviewed 410 NKTCL patients admitted to our lymphoma center from 2000 to 2019. Overall survival (OS) and progression-free survival (PFS) were estimated with the Kaplan-Meier method, and the differences between the study groups were compared by the log-rank test.

RESULTS

The median age of the 410 patients was 44 (range 8-84), and the 5-year OS and PFS were 61.2% and 38.4%, respectively. For patients with stage I/II, the 5-year PFS rate was 57.5%, and the 5-year OS rate was 77.2%. For patients with stage III/IV, the 5-year PFS rate was 17.4%, and the 5-year OS rate was 43.7%. Compared to the patients who received radiotherapy alone or chemotherapy alone as their initial treatment, the patients who received combined chemoradiotherapy had longer PFS (P = 0.013). Independent prognostic factors for OS were stage III/IV (P = 0.001), elevated IPI/aaIPI score (P = 0.019), elevated PINK score (P < 0.001) and elevated plasma EBV-DNA (P = 0.003). An elevated PINK score (P < 0.001) was an independent prognostic factor for PFS.

CONCLUSION

Stage III/IV, elevated IPI/aaIPI score, elevated PINK score and elevated plasma EBV-DNA were independent prognostic factors for OS. Elevated PINK score was an independent prognostic factor for PFS. In stage III/IV patients, the patients who received combined chemoradiotherapy had significantly longer PFS.

A genomic-augmented multivariate prognostic model for the survival of Natural-killer/T-cell lymphoma patients from an international cohort

With lowering costs of sequencing and genetic profiling techniques, genetic drivers can now be detected readily in tumors but current prognostic models for Natural-killer/T cell lymphoma (NKTCL) have yet to fully leverage on them for prognosticating patients. Here, we used next-generation sequencing to sequence 260 NKTCL tumors, and trained a genomic prognostic model (GPM) with the genomic mutations and survival data from this retrospective cohort of patients using LASSO Cox regression. The GPM is defined by the mutational status of 13 prognostic genes and is weakly correlated with the risk-features in International Prognostic Index (IPI), Prognostic Index for Natural-Killer cell lymphoma (PINK) and PINK-Epstein-Barr virus (PINK-E). Cox-proportional hazard multivariate regression also showed that the new GPM is independent and significant for both progression-free survival (PFS, HR: 3.73, 95% CI 2.07-6.73; P<0.001) and overall survival (OS, HR: 5.23, 95% CI 2.57-10.65; P=0.001) with known risk-features of these indices. When we assign an additional risk-score to samples, which are mutant for the GPM, the Harrell's C-indices of GPM-augmented IPI, PINK and PINK-E improved significantly (P<0.001, χ² test) for both PFS and OS. Thus, we report on how genomic mutational information could steer towards better prognostication of NKTCL patients. This article is protected by copyright. All rights reserved.

Rhino-Orbital-Cerebral Mycosis and Extranodal Natural Killer or/and T-Cell Lymphoma, Nasal Type

Background

Extranodal natural killer/T-cell lymphoma, nasal type is a syndrome of middle face destruction with an association to Epstein-Barr virus. Fungi have been recovered from the diseased tissue now and then but were often seen as a lymphoma-associated secondary infection. However, there are ENKTL-NT cases with the recoveries of fungi and complete recovery with antifungal therapy, which are quite similar to rhino-orbital-cerebral mycosis (ROCM) that often confuses the physicians.

Methods

We searched Medline for English-language manuscripts limited to “human” and “case reports,” “letters,” “reviews,” and “clinical conferences” from 1966 to 2022. We used MeSH terms “lymphoma, extranodal nk-t-cell” [MeSH Terms] or “lethal midline granuloma” [MeSH Terms], in combination with MeSH terms “microbiology” [subheading] or “microbiology” [all fields] or “fungi” [all fields] or “fungi” [MeSH Terms] for ENKTL-NT with infections. We used MeSH terms “Mycoses” in combination with “Nose” [Mesh] OR “Orbital Diseases” [Mesh] for rhino-orbital-cerebral fungal infections.

Results

We appraised 149 included articles and extracted references related to ENKTL-NT and/or ROCM. Themes and subcategories were subsequently derived. Our findings revealed that ROCM and ENKTL-NT are characterized by progressive and destructive ulcers in the midline face or rhino-orbital structures. ROCM is mainly caused by fungi in the order of Mucorales, and ENKTL-NT is usually associated with Epstein-Barr virus and sometimes fungi. Radiologically, both are characterized by non-specific features of sinusitis, soft tissue infection, and necrosis. Pathologically, ROCM and ENKTL-NT share the same characteristics of inflammation, necrosis, and granuloma. ROCM is characterized by the detection of fungi in tissue, while ENKTL-NT is typically positive for NK/T-cell markers and cytotoxic granule-associated proteins, proliferation, and vascular damage of angioinvasion, which could be incited by Mucor irregularis and Rhizopus arrhizus in patients and mice.

Conclusion

ENKTL-NT and ROCM share many similarities in clinical presentations, radiology, and histopathology, and might have the same etiology. This may explain why the two diseases are tangled together in the reported cases, and suggests the role that the fungi may play in the development of these ENKTL-NT/ROCM diseases. The reason why ENKTL-NT and ROCM are sometimes confused is that the main pathogens of ROCM, Mucor irregularis and Rhizopus arrhizus, are the fungal causative agents of ENKTL-NT.

How we treat NK/T-cell lymphomas

Natural killer (NK)/T-cell lymphomas are aggressive malignancies with a predilection for Asian and South American populations. Epstein-Barr virus (EBV) infection in lymphoma cells is universal. Predominantly extranodal, NK/T-cell lymphomas are divided clinically into nasal (involving the nose and upper aerodigestive tract), non-nasal (involving the skin, gastrointestinal tract, testes, and other organs), and aggressive leukaemia/lymphoma (involving the marrow and multiple organs) subtypes. Initial assessment should include imaging with positron emission tomography computed tomography (PET/CT), quantification of plasma EBV DNA as a surrogate marker of lymphoma load, and bone marrow examination with in situ hybridization for EBV-encoded small RNA. Prognostication can be based on presentation parameters (age, stage, lymph node involvement, clinical subtypes, and EBV DNA), which represent patient factors and lymphoma load; and dynamic parameters during treatment (serial plasma EBV DNA and interim/end-of-treatment PET/CT), which reflect response to therapy. Therapeutic goals are to achieve undetectable plasma EBV DNA and normal PET/CT (Deauville score ≤ 3). NK/T-cell lymphomas express the multidrug resistance phenotype, rendering anthracycline-containing regimens ineffective. Stage I/II nasal cases are treated with non-anthracycline asparaginase-based regimens plus sequential/concurrent radiotherapy. Stage III/IV nasal, and non-nasal and aggressive leukaemia/lymphoma cases are treated with asparaginase-containing regimens and consolidated by allogeneic haematopoietic stem cell transplantation (HSCT) in suitable patients. Autologous HSCT does not improve outcome. In relapsed/refractory cases, novel approaches comprise immune checkpoint blockade of PD1/PD-L1, EBV-specific cytotoxic T-cells, monoclonal antibodies, and histone deacetylase inhibitors. Future strategies may include inhibition of signalling pathways and driver mutations, and immunotherapy targeting the lymphoma and its microenvironment.

Nivolumab in patients with relapsed or refractory peripheral T-cell lymphoma: modest activity and cases of hyperprogression

Peripheral T-cell lymphomas (PTCL), a heterogeneous group of mature aggressive non-Hodgkin's lymphomas, carry a worse prognosis for most subtypes when compared with their B-cell counterparts. Despite recent approval of newer therapies, the outlook for patients with relapsed/refractory (RR) PTCL remains poor and new treatment strategies are clearly needed. Targeting the profoundly immunosuppressive tumor microenvironment in PTCL is one such approach. To determine whether immune checkpoint blockade targeting program death receptor 1 would be effective in PTCL, we conducted an investigator-initiated phase 2 prospective study of single-agent nivolumab for RR PTCL. We report here results of the pre-specified interim analysis.

METHODS

The primary objective was to assess the overall response rate (ORR). Secondary objectives were to assess safety and tolerability of nivolumab in PTCL and to assess progression-free survival (PFS), duration of response (DOR) and overall survival (OS). Hyperprogressive disease (HPD) was defined as time-to-treatment failure of less than or equal to one month from initiation of therapy.

RESULTS

Twelve patients who received at least one cycle of nivolumab were included in this interim analysis. Half (6/12) of the patients had angioimmunoblastic T-cell lymphoma (AITL), 3/12 had PTCL, not otherwise specified. Most (11/12) were advanced stage, had extranodal disease (97.1%) and had received a prior autologous stem cell transplant (50%). The ORR was 33% (95% CI: 12.3 to 63.7%) with two complete response and two partial response. The median PFS was however short at 2.7 months (95% CI: 1.5 to NE); and the median OS was 6.7 months (95% CI: 3.4 to NE). The median DOR was also short at 3.6 months (95% CI: 1.9 to NE). HPD occurred in four patients, three of whom had AITL. Observed grade 3 and higher adverse events (AEs) were non-hematologic in 5/12 (42%), while hematologic AEs were seen in 3/12 (25%).

CONCLUSIONS

Nivolumab had modest clinical activity in R/R PTCL. Due to a high number of hyperprogression and short DOR, a decision was made to halt the study. These findings likely reflect the distinct biology of PTCL and should be considered when designing future studies using checkpoint inhibitors in these diseases.

TRIAL REGISTRATION NUMBER

NCT03075553.

Cellular Origins and Pathogenesis of Gastrointestinal NK- and T-Cell Lymphoproliferative Disorders

The intestinal immune system, which must ensure appropriate immune responses to both pathogens and commensal microflora, comprises innate lymphoid cells and various T-cell subsets, including intra-epithelial lymphocytes (IELs). An example of innate lymphoid cells is natural killer cells, which may be classified into tissue-resident, CD56bright NK-cells that serve a regulatory function and more mature, circulating CD56dim NK-cells with effector cytolytic properties. CD56bright NK-cells in the gastrointestinal tract give rise to indolent NK-cell enteropathy and lymphomatoid gastropathy, as well as the aggressive extranodal NK/T cell lymphoma, the latter following activation by EBV infection and neoplastic transformation. Conventional CD4+ TCRαβ+ and CD8αβ+ TCRαβ+ T-cells are located in the lamina propria and the intraepithelial compartment of intestinal mucosa as type 'a' IELs. They are the putative cells of origin for CD4+ and CD8+ indolent T-cell lymphoproliferative disorders of the gastrointestinal tract and intestinal T-cell lymphoma, NOS. In addition to such conventional T-cells, there are non-conventional T-cells in the intra-epithelial compartment that express CD8αα and innate lymphoid cells that lack TCRs. The central feature of type 'b' IELs is the expression of CD8αα homodimers, seen in monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL), which primarily arises from both CD8αα+ TCRαβ+ and CD8αα+ TCRγδ+ IELs. EATL is the other epitheliotropic T-cell lymphoma in the GI tract, a subset of which arises from the expansion and reprograming of intracytoplasmic CD3+ innate lymphoid cells, driven by IL15 and mutations of the JAK-STAT pathway.