Clinical relevance of molecular characteristics in Burkitt lymphoma differs according to age

Pan-cancer analysis reveals age-associated genetic alterations in protein domains

Cancer incidence and mortality differ among individuals of different ages, but the functional consequences of genetic alterations remain largely unknown. We systematically characterized genetic alterations within protein domains stratified by affected individual's age and showed that the mutational effects on domains varied with age. We further identified potential age-associated driver genes with hotspots across 33 cancers. The candidate drivers involved numerous cancer-related genes that participate in various oncogenic pathways and play central roles in human protein-protein interaction (PPI) networks. We found widespread age biases in protein domains and identified the associations between hotspots and age. Age-stratified PPI networks perturbed by hotspots were constructed to illustrate the function of mutations enriched in domains. We found that hotspots in young adults were associated with premature senescence. In summary, we provided a catalog of age-associated hotspots and their perturbed networks, which may facilitate precision diagnostics and treatments for cancer.

Single-cell transcriptomics of pediatric Burkitt lymphoma reveals intra-tumor heterogeneity and markers of therapy resistance

Burkitt lymphoma (BL) is the most frequent B-cell lymphoma in pediatric patients. While most patients are cured, a fraction of them are resistant to therapy. To investigate BL heterogeneity and the features distinguishing therapy responders (R) from non-responders (NR), we analyzed by single-cell (sc)-transcriptomics diagnostic EBV-negative BL specimens. Analysis of the non-tumor component revealed a predominance of immune cells and a small representation of fibroblasts, enriched in NR. Tumors displayed patient-specific features, as well as shared subpopulations that expressed transcripts related to cell cycle, signaling pathways and cell-of-origin signatures. Several transcripts were differentially expressed in R versus NR. The top candidate, Tropomyosin 2 (TPM2), a member of the tropomyosin actin filament binding protein family, was confirmed to be significantly higher in NR both at the transcript and protein level. Stratification of patients based on TPM2 expression at diagnosis significantly correlated with prognosis, independently of TP53 mutations. These results indicate that BL displays transcriptional heterogeneity and identify candidate biomarkers of therapy resistance.

MYC-rearranged mature B-cell lymphomas in children and young adults are molecularly Burkitt Lymphoma

Aggressive B-cell non-Hodgkin lymphomas (NHL) in children, adolescents, and young adults (CAYA) include Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), and a subset of high-grade tumors with features intermediate between these entities whose genetic and molecular profiles have not been completely elucidated. In this study, we have characterized 37 aggressive B-NHL in CAYA, 33 with high-grade morphology, and 4 DLBCL with MYC rearrangement (MYC-R), using targeted next-generation sequencing and the aggressive lymphoma gene expression germinal center B-cell-like (GCB), activated B-cell-like (ABC), and dark zone signatures (DZsig). Twenty-two tumors had MYC-R without BCL2 breaks, and two MYC-non-R cases had BCL6 translocations. MYC-R cases, including DLBCL, carried BL-related mutations and copy number alterations. Conversely, MYC-non-R lymphomas had alterations in the B-cell receptor signaling/NF-κB pathway (71%). DZsig was expressed in 12/13 of MYC-R tumors but only in 2/10 of MYC-non-R GCB tumors (P < 0.001). The 3-year event-free survival (EFS) of the whole cohort was 79.6%. TP53 and KMT2C mutations conferred inferior outcome (3-year EFS P < 0.05). Overall, MYC-R lymphomas in CAYA have a molecular profile similar to BL regardless of their high-grade or DLBCL morphology, whereas MYC-non-R has more heterogeneous genetic alterations closer to that of DLBCL.

TP53 DNA binding domain mutational status and rituximabbased treatment are independent prognostic factors for pediatric Burkitt lymphoma patients stratification

Not available.

Discovery of first-in-class PROTACs targeting maternal embryonic leucine zipper kinase (MELK) for the treatment of Burkitt lymphoma

Maternal embryonic leucine zipper kinase (MELK) is a novel target for the treatment of various kinds of B-cell malignancies. However, the toxicity of inhibitors of MELK has led to clinical failures in cancer treatments. Moreover, inactivation of MELK catalytic domain is insufficient for achieving cancer cell apoptosis. To further confirm the role of MELK in Burkitt lymphoma treatment, we describe herein a structure-guided design of PROTACs targeting MELK. Through design, computer-assisted optimization and SAR studies, we developed the first-in-class MELK-targeting PROTAC MGP-39, which promoted a rapid and potent degradation of MELK in RAMOS cells. Additionally, the newly designed MELK degrader induced significant cell cycle arrest and apoptosis in cancer cells. Notably, compared to MELK inhibitors, MGP-39 has better anti-cancer activity and lower toxicity, indicating the practical role of PROTACs in avoiding the side effects of traditional inhibitors. More importantly, our results show that the use of a PROTAC can be adopted as a general and effective strategy for targeted cancer therapy.

SOX11 expression is restricted to EBV-negative Burkitt lymphoma and is associated with molecular genetic features

ABSTRACT

SRY-related HMG-box gene 11 (SOX11) is a transcription factor overexpressed in mantle cell lymphoma (MCL), a subset of Burkitt lymphomas (BL) and precursor lymphoid cell neoplasms but is absent in normal B cells and other B-cell lymphomas. SOX11 has an oncogenic role in MCL but its contribution to BL pathogenesis remains uncertain. Here, we observed that the presence of Epstein-Barr virus (EBV) and SOX11 expression were mutually exclusive in BL. SOX11 expression in EBV-negative (EVB-) BL was associated with an IG∷MYC translocation generated by aberrant class switch recombination, whereas in EBV-negative (EBV-)/SOX11-negative (SOX11-) tumors the IG∷MYC translocation was mediated by mistaken somatic hypermutations. Interestingly, EBV- SOX11-expressing BL showed higher frequency of SMARCA4 and ID3 mutations than EBV-/SOX11- cases. By RNA sequencing, we identified a SOX11-associated gene expression profile, with functional annotations showing partial overlap with the SOX11 transcriptional program of MCL. Contrary to MCL, no differences on cell migration or B-cell receptor signaling were found between SOX11- and SOX11-positive (SOX11+) BL cells. However, SOX11+ BL showed higher adhesion to vascular cell adhesion molecule 1 (VCAM-1) than SOX11- BL cell lines. Here, we demonstrate that EBV- BL comprises 2 subsets of cases based on SOX11 expression. The mutual exclusion of SOX11 and EBV, and the association of SOX11 with a specific genetic landscape suggest a role of SOX11 in the early pathogenesis of BL.

Childhood and Adolescent Relapsed/Refractory Aggressive B-Cell Lymphomas With t(8;14) and BCL2 Expression, Burkitt Lymphoma Versus Diffuse Large B-Cell Lymphoma: A Diagnostic Challenge

We present 2 diagnostically challenging cases of pediatric/adolescent relapsed/refractory aggressive mature B-cell non-Hodgkin lymphoma (B-NHL) within the spectrum of Burkitt lymphoma and diffuse large B-cell lymphoma and illustrate the different therapeutic regimens that are employed for pediatric and adult cancer centers. Both cases displayed varying-sized lymphoma cells with occasional single prominent nucleoli and heterogeneous BCL2 expression. Cytogenetics revealed complex karyotypes with t(8:14)(q24.2;q32) and IGH::MYC rearrangement by FISH. Next generation sequencing revealed deleterious TP53 and MYC mutations. We concluded that both could be diagnosed as "DLBCL-NOS with MYC rearrangement" using the current pathologic classifications, 2022 International Consensus Classification (ICC) and World Health Organization Classifications of Haematolymphoid Tumors (WHO-HAEM5). This report illustrates diagnostic challenges and treatment dilemmas that may be encountered, particularly for adolescent and young adults (AYA).

Genetic alterations in mature B- and T-cell lymphomas - a practical guide to WHO-HAEM5

The identification of recurrent genomic alterations in tumour cells has a significant role in the classification of mature B- and T-cell lymphomas. Following the development of new technologies, such as next generation sequencing and the improvement of classical technologies such as conventional and molecular cytogenetics, a huge catalogue of genomic alterations in lymphoid neoplasms has been established. These alterations are relevant to refine the taxonomy of the classification of lymphomas, to scrutinize the differential diagnosis within different lymphoma entities and to help assessing the prognosis and clinical management of the patients. Consequently, here we describe the key genetic alterations relevant in mature B- and T-cell lymphomas.

Challenging our understanding of B-cell lymphomagenesis and risk: Paediatric high-grade B-cell lymphoma, not otherwise specified with a DDX3X::MLLT10 fusion and an IGH deletion

We report a unique case of high-grade B-cell lymphoma, not otherwise specified in a 5-year-old child. Whole-genome sequencing revealed a DDX3X::MLLT10 fusion, usually seen in T-cell acute lymphoblastic leukaemia (ALL). This suggests the novel idea that MLLT10 fusions are capable of driving B-cell malignancies. An IGH deletion usually only seen in adults was also found. These unique genetic findings provide novel insights into B-cell lymphomagenesis. The child remains in remission 7 year post chemotherapy, which demonstrates that novel complex molecular findings do not always denote high-risk disease.

Integration of RNA Sequencing, Whole Exome Sequencing, and Flow Cytometry Into Routine Diagnostic Workup of Pediatric Lymphomas

The study was conducted to assess the feasibility of integrating state-of-the-art sequencing techniques and flow cytometry into diagnostic workup of pediatric lymphoma. RNA sequencing (RNAseq), whole exome sequencing, and flow cytometry were implemented into routine diagnostic workup of pediatric biopsies with lymphoma in the differential diagnosis. Within 1 year, biopsies from 110 children (122 specimens) were analyzed because of suspected malignant lymphoma. The experience with a standardized workflow combining histology and immunohistochemistry, flow cytometry, and next-generation sequencing technologies is reported. Flow cytometry was performed with fresh tissue in 83% (102/122) of specimens and allowed rapid diagnosis of T-cell and B-cell non-Hodgkin lymphomas. RNAseq was performed in all non-Hodgkin lymphoma biopsies and 42% (19/45) of Hodgkin lymphoma samples. RNAseq detected all but one of the translocations found by fluorescence in situ hybridization and PCR. RNAseq and whole exome sequencing identified additional genetic abnormalities not detected by conventional approaches. Finally, 3 cases are highlighted to exemplify how synergy between different diagnostic techniques and specialists can be achieved. This study demonstrates the feasibility and discusses the added value of integrating modern sequencing techniques and flow cytometry into a workflow for routine diagnostic workup of lymphoma. The inclusion of RNA and DNA sequencing not only supports diagnostics but also will lay the ground for the development of novel research-based treatment strategies for pediatric lymphoma patients.

Cytogenomics of B-cell non-Hodgkin lymphomas: The "old" meets the "new"

For the routine diagnosis of haematological neoplasms an integrative approach is used considering the morphology, and the immunophenotypic, and molecular features of the tumor sample, along with clinical information. The identification and characterization of recurrent chromosomal aberrations mainly detected by conventional and molecular cytogenetics in the tumor cells has a major impact on the classification of lymphoid neoplasms. Some of the B-cell non-Hodgkin lymphomas are characterized by particular chromosomal aberrations, highlighting the relevance of conventional and molecular cytogenetic studies in their diagnosis and prognosis. In the current genomics era, next generation sequencing provides relevant information as the mutational profiles of haematological malignancies, improving their classification and also the clinical management of the patients. In addition, other new technologies have emerged recently, such as the optical genome mapping, which can overcome some of the limitations of conventional and molecular cytogenetics and may become more widely used in the cytogenetic laboratories in the upcoming years. Moreover, epigenetic alterations may complement genetic changes for a deeper understanding of the pathogenesis underlying B-cell neoplasms and a more precise risk-based patient stratification. Overall, here we describe the current state of the genomic data integrating chromosomal rearrangements, copy number alterations, and somatic variants, as well as a succinct overview of epigenomic changes, which altogether constitute a comprehensive diagnostic approach in B-cell non-Hodgkin lymphomas.

[Lymphomas in children and adolescents]

BACKGROUND

Lymphomas in children and adolescents differ from adulthood in relative frequency and variety of entities. In addition, young patients are cared for according to the specific standards of pediatric lymphoma study groups.

OBJECTIVE

To present lymphomas of diagnostic and clinical relevance in the pediatric and adolescent group.

MATERIAL AND METHODS

Selective literature research ( http://www.ncbi.nlm.nih.gov ) was combined with clinico-pathological experience of the authors.

RESULTS

Children and adolescents are much more likely to suffer from aggressive and precursor cell lymphoma than is the case in adulthood. Unlike adult patients, Burkitt lymphomas and diffuse large B‑cell lymphomas are not treated fundamentally differently. Entities that have been described relatively recently and are particularly common in young patients are high-grade B‑cell lymphoma with 11q aberrations and large-cell B‑cell lymphoma with IRF4 translocations.

CONCLUSION

Lymphoma diagnosis in children and adolescents is characterized by the particular spectrum of diseases that occur at this age. Special knowledge about the clinical relevance of the diagnoses in childhood is helpful in order to enable rapid clinical decision making.

Aggressive non-Hodgkin lymphoma in the pediatric and young adult population; diagnostic and molecular pearls of wisdom

Mature non-Hodgkin lymphomas (NHLs) of the pediatric and young adults(PYA), including Burkitt lymphoma (BL), diffuse large B cell lymphoma (DLBCL), high-grade B cell lymphoma (HGBCL), primary mediastinal large B cell lymphoma (PMBL) and anaplastic large cell lymphoma (ALCL), generally have excellent prognosis compared to the adult population. BL, DLBCL and HGBCL are usually of germinal center (GCB) origin in the PYA population. PMBL neither belongs to the GCB nor the activated B cell subtype and is associated with a poorer outcome than BL or DLBCL of comparable stage. Anaplastic large cell lymphoma is the most frequent peripheral T cell lymphoma occurring in the PYA and accounts for 10-15% of childhood NHL. Most pediatric ALCL, unlike in the adult, demonstrate expression of anaplastic lymphoma kinase (ALK). In recent years, the understanding of the biology and molecular features of these aggressive lymphomas has increased tremendously. This has led to reclassification of newer PYA entities including Burkitt-like lymphoma with 11q aberration. In this review, we will discuss the current progress discovered in frequently encountered aggressive NHLs in the PYA, highlighting the clinical, pathologic and molecular features that aid in the diagnosis of these aggressive lymphomas. We will be updating the new concepts and terminologies used in the new classification systems.

Identification of alternative splicing associated with clinical features: from pan-cancers to genitourinary tumors

Background

Alternative splicing events (ASEs) are vital causes of tumor heterogeneity in genitourinary tumors and many other cancers. However, the clinicopathological relevance of ASEs in cancers has not yet been comprehensively characterized.

Methods

By analyzing splicing data from the TCGA SpliceSeq database and phenotype data for all TCGA samples from the UCSC Xena database, we identified differential clinical feature-related ASEs in 33 tumors. CIBERSORT immune cell infiltration data from the TIMER2.0 database were used for differential clinical feature-related immune cell infiltration analysis. Gene function enrichment analysis was used to analyze the gene function of ASEs related to different clinical features in tumors. To reveal the regulatory mechanisms of ASEs, we integrated race-related ASEs and splicing quantitative trait loci (sQTLs) data in kidney renal clear cell carcinoma (KIRC) to comprehensively assess the impact of SNPs on ASEs. In addition, we predicted regulatory RNA binding proteins in bladder urothelial carcinoma (BLCA) based on the enrichment of motifs around alternative exons for ASEs.

Results

Alternative splicing differences were systematically analyzed between different groups of 58 clinical features in 33 cancers, and 30 clinical features in 24 cancer types were identified to be associated with more than 50 ASEs individually. The types of immune cell infiltration were found to be significantly different between subgroups of primary diagnosis and disease type. After integrating ASEs with sQTLs data, we found that 63 (58.9%) of the race-related ASEs were significantly SNP-correlated ASEs in KIRC. Gene function enrichment analyses showed that metastasis-related ASEs in KIRC mainly enriched Rho GTPase signaling pathways. Among those ASEs associated with metastasis, alternative splicing of GIT2 and TUBB3 might play key roles in tumor metastasis in KIRC patients. Finally, we identified several RNA binding proteins such as PCBP2, SNRNP70, and HuR, which might contribute to splicing differences between different groups of neoplasm grade in BLCA.

Conclusion

We demonstrated the significant clinical relevance of ASEs in multiple cancer types. Furthermore, we identified and validated alternative splicing of TUBB3 and RNA binding proteins such as PCBP2 as critical regulators in the progression of urogenital cancers.

The variant landscape and function of DDX3X in cancer and neurodevelopmental disorders

RNA molecules rely on proteins across their life cycle. DDX3X encodes an X-linked DEAD-box RNA helicase with a Y-linked paralog, DDX3Y. DDX3X is central to the RNA life cycle and is implicated in many conditions, including cancer and the neurodevelopmental disorder DDX3X syndrome. DDX3X-linked conditions often exhibit sex differences, possibly due to differences between expression or function of the X- and Y-linked paralogs DDX3X and DDX3Y. DDX3X-related diseases have different mutational landscapes, indicating different roles of DDX3X. Understanding the role of DDX3X in normal and disease states will inform the understanding of DDX3X in disease. We review the function of DDX3X and DDX3Y, discuss how mutation type and sex bias contribute to human diseases involving DDX3X, and review possible DDX3X-targeting treatments.

Targeting ARID1A-Deficient Cancers: An Immune-Metabolic Perspective

Epigenetic remodeling and metabolic reprogramming, two well-known cancer hallmarks, are highly intertwined. In addition to their abilities to confer cancer cell growth advantage, these alterations play a critical role in dynamically shaping the tumor microenvironment and antitumor immunity. Recent studies point toward the interplay between epigenetic regulation and metabolic rewiring as a potentially targetable Achilles' heel in cancer. In this review, we explore the key metabolic mechanisms that underpin the immunomodulatory role of AT-rich interaction domain 1A (ARID1A), the most frequently mutated epigenetic regulator across human cancers. We will summarize the recent advances in targeting ARID1A-deficient cancers by harnessing immune-metabolic vulnerability elicited by ARID1A deficiency to stimulate antitumor immune response, and ultimately, to improve patient outcome.

Biopathology of childhood, adolescent and young adult non-Hodgkin lymphoma

Mature non-Hodgkin lymphomas (NHL) in the childhood, adolescent and young adult (CAYA) population are rare and exhibit unique clinical, immunophenotypic and genetic characteristics. Application of large-scale unbiased genomic and proteomic technologies such as gene expression profiling and next generation sequencing (NGS) have led to enhanced understanding of the genetic basis for many lymphomas in adults. However, studies to investigate the pathogenetic events in CAYA population are relatively sparse. Enhanced understanding of the pathobiologic mechanisms involved in non-Hodgkin lymphomas in this unique population will allow for improved recognition of these rare lymphomas. Elucidation of the pathobiologic differences between CAYA and adult lymphomas will also lead to the design of more rational and much needed, less toxic therapies for this population. In this review, we summarize recent insights gained from the proceedings of the recent 7th International CAYA NHL Symposium held in New York City, New York October 20-23, 2022.

Improving outcomes of childhood and young adult non-Hodgkin lymphoma: 25 years of research and collaboration within the framework of the European Intergroup for Childhood Non-Hodgkin Lymphoma

The European Intergroup for Childhood Non-Hodgkin Lymphoma (EICNHL) was established 25 years ago with the goal to facilitate clinical trials and research collaborations in the field both within Europe and worldwide. Since its inception, much progress has been made whereby major improvements in outcomes have been achieved. In this Review, we describe the different diagnostic entities of non-Hodgkin lymphoma in children and young adults describing key features of each entity and outlining clinical achievements made in the context of the EICNHL framework. Furthermore, we provide an overview of advances in biopathology with an emphasis on the role of biological studies and how they have shaped available treatments. Finally, for each entity, we describe future goals, upcoming clinical trials, and highlight areas of research that require our focus going forward.

Genetic subgroups inform on pathobiology in adult and pediatric Burkitt lymphoma

Burkitt lymphoma (BL) accounts for most pediatric non-Hodgkin lymphomas, being less common but significantly more lethal when diagnosed in adults. Much of the knowledge of the genetics of BL thus far has originated from the study of pediatric BL (pBL), leaving its relationship to adult BL (aBL) and other adult lymphomas not fully explored. We sought to more thoroughly identify the somatic changes that underlie lymphomagenesis in aBL and any molecular features that associate with clinical disparities within and between pBL and aBL. Through comprehensive whole-genome sequencing of 230 BL and 295 diffuse large B-cell lymphoma (DLBCL) tumors, we identified additional significantly mutated genes, including more genetic features that associate with tumor Epstein-Barr virus status, and unraveled new distinct subgroupings within BL and DLBCL with 3 predominantly comprising BLs: DGG-BL (DDX3X, GNA13, and GNAI2), IC-BL (ID3 and CCND3), and Q53-BL (quiet TP53). Each BL subgroup is characterized by combinations of common driver and noncoding mutations caused by aberrant somatic hypermutation. The largest subgroups of BL cases, IC-BL and DGG-BL, are further characterized by distinct biological and gene expression differences. IC-BL and DGG-BL and their prototypical genetic features (ID3 and TP53) had significant associations with patient outcomes that were different among aBL and pBL cohorts. These findings highlight shared pathogenesis between aBL and pBL, and establish genetic subtypes within BL that serve to delineate tumors with distinct molecular features, providing a new framework for epidemiologic, diagnostic, and therapeutic strategies.

The RNA helicase DDX3 and its role in c-MYC driven germinal center-derived B-cell lymphoma

DDX3X is an RNA helicase with many functions in RNA metabolism such as mRNA translation, alternative pre-mRNA splicing and mRNA stability, but also plays a role as a regulator of transcription as well as in the Wnt/beta-catenin- and Nf-κB signaling pathways. The gene encoding DDX3X is located on the X-chromosome, but escapes X-inactivation. Hence females have two active copies and males only one. However, the Y chromosome contains the gene for the male DDX3 homologue, called DDX3Y, which has a very high sequence similarity and functional redundancy with DDX3X, but shows a more restricted protein expression pattern than DDX3X. High throughput sequencing of germinal center (GC)-derived B-cell malignancies such as Burkitt Lymphoma (BL) and Diffuse large B-cell lymphoma (DLBCL) samples showed a high frequency of loss-of-function (LOF) mutations in the DDX3X gene revealing several features that distinguish this gene from others. First, DDX3X mutations occur with high frequency particularly in those GC-derived B-cell lymphomas that also show translocations of the c-MYC proto-oncogene, which occurs in almost all BL and a subset of DLBCL. Second, DDX3X LOF mutations occur almost exclusively in males and is very rarely found in females. Third, mutations in the male homologue DDX3Y have never been found in any type of malignancy. Studies with human primary GC B cells from male donors showed that a loss of DDX3X function helps the initial process of B-cell lymphomagenesis by buffering the proteotoxic stress induced by c-MYC activation. However, full lymphomagenesis requires DDX3 activity since an upregulation of DDX3Y expression is invariably found in GC derived B-cell lymphoma with DDX3X LOF mutation. Other studies with male transgenic mice that lack Ddx3x, but constitutively express activated c-Myc transgenes in B cells and are therefore prone to develop B-cell malignancies, also showed upregulation of the DDX3Y protein expression during the process of lymphomagenesis. Since DDX3Y is not expressed in normal human cells, these data suggest that DDX3Y may represent a new cancer cell specific target to develop adjuvant therapies for male patients with BL and DLBCL and LOF mutations in the DDX3X gene.

Non-viral TRAC-knocked-in CD19KICAR-T and gp350KICAR-T cells tested against Burkitt lymphomas with type 1 or 2 EBV infection: In vivo cellular dynamics and potency

Introduction

The ubiquitous Epstein-Barr virus (EBV) is an oncogenic herpes virus associated with several human malignancies. EBV is an immune-evasive pathogen that promotes CD8⁺ T cell exhaustion and dysregulates CD4⁺ T cell functions. Burkitt lymphoma (BL) is frequently associated with EBV infections. Since BL relapses after conventional therapies are difficult to treat, we evaluated prospective off-the-shelf edited CAR-T cell therapies targeting CD19 or the EBV gp350 cell surface antigen.

Methods

We used CRISPR/Cas9 gene editing methods to knock in (KI) the CD19CAR.CD28z or gp350CAR.CD28z into the T cell receptor (TCR) alpha chain (TRAC) locus.

Results

Applying upscaled methods with the ExPERT ATx^® MaxCyte system, KI efficacy was ~20% of the total ~2 × 10⁸ TCR-knocked-out (KO) generated cells. ^KOTCR^KICAR-T cells were co-cultured in vitro with the gp350⁺CD19⁺ BL cell lines Daudi (infected with type 1 EBV) or with Jiyoye (harboring a lytic type 2 EBV). Both types of CAR-T cells showed cytotoxic effects against the BL lines in vitro. CD8^{+ KI}CAR-T cells showed higher persistency than CD4^{+ KI}CAR-T cells after in vitro co-culture with BL and upregulation of the activation/exhaustion markers PD-1, LAG-3, and TIM-3. Two preclinical in vivo xenograft models were set up with Nod.Rag.Gamma mice injected intravenously (i.v.) with 2 × 10⁵ Daudi/fLuc-GFP or with Jiyoye/fLuc-GFP cells. Compared with the non-treated controls, mice challenged with BL and treated with CD19^KICAR-T cells showed delayed lymphoma dissemination with lower EBV DNA load. Notably, for the Jiyoye/fLuc-GFP model, almost exclusively CD4⁺ CD19^KICAR-T cells were detectable at the endpoint analyses in the bone marrow, with increased frequencies of regulatory T cells (T_regs) and TIM-3⁺CD4⁺ T cells. Administration of gp350^KICAR-T cells to mice after Jiyoye/GFP-fLuc challenge did not inhibit BL growth in vivo but reduced the EBV DNA load in the bone marrow and promoted gp350 antigen escape. CD8⁺PD-1⁺LAG-3⁺ gp350^KICAR-T cells were predominant in the bone marrow.

Discussion

The two types of ^KOTCR^KICAR-T cells showed different therapeutic effects and in vivo dynamics. These findings reflect the complexities of the immune escape mechanisms of EBV, which may interfere with the CAR-T cell property and potency and should be taken into account for future clinical translation.

Burkitt lymphoma

Burkitt lymphoma (BL) is an aggressive form of B cell lymphoma that can affect children and adults. The study of BL led to the identification of the first recurrent chromosomal aberration in lymphoma, t(8;14)(q24;q32), and subsequent discovery of the central role of MYC and Epstein-Barr virus (EBV) in tumorigenesis. Most patients with BL are cured with chemotherapy but those with relapsed or refractory disease usually die of lymphoma. Historically, endemic BL, non-endemic sporadic BL and the immunodeficiency-associated BL have been recognized, but differentiation of these epidemiological variants is confounded by the frequency of EBV positivity. Subtyping into EBV⁺ and EBV^- BL might better describe the biological heterogeneity of the disease. Phenotypically resembling germinal centre B cells, all types of BL are characterized by dysregulation of MYC due to enhancer activation via juxtaposition with one of the three immunoglobulin loci. Additional molecular changes commonly affect B cell receptor and sphingosine-1-phosphate signalling, proliferation, survival and SWI-SNF chromatin remodelling. BL is diagnosed on the basis of morphology and high expression of MYC. BL can be effectively treated in children and adolescents with short durations of high dose-intensity multiagent chemotherapy regimens. Adults are more susceptible to toxic effects but are effectively treated with chemotherapy, including modified versions of paediatric regimens. The outcomes in patients with BL are good in high-income countries with low mortality and few late effects, but in low-income and middle-income countries, BL is diagnosed late and is usually treated with less-effective regimens affecting the overall good outcomes in patients with this lymphoma.