Faculty Bibliography

There is an unmet need to examine antitumor immune responses and predictive biomarkers in the peripheral blood to guide effective combination immunotherapies in classical Hodgkin lymphoma (cHL). We sought to evaluate T-cell specific immune responses as well as cytokine and chemokine profiles including levels of soluble CD30 (sCD30), sCD163, and thymus and activation-regulated chemokine (TARC) in relation to event-free survival in patients with cHL. The Children's Oncology Group (COG) clinical trial AHOD1331 was a randomized phase 3 trial for patients with newly diagnosed high-risk cHL, aged 2 to 21 years, which compared standard chemotherapy and doxorubicin, bleomycin, vincristine, etoposide, prednisone, and cyclophosphamide (ABVE-PC) with brentuximab vedotin (Bv) and AVE-PC with response adapted radiation. Our results demonstrate that chemotherapy with or without addition of anti-CD30 antibody-drug conjugate Bv is associated with a favorable cytokine environment for cellular and immunotherapies. Treatment of cHL on both arms increased tumor antigen-specific T-cell responses and resulted in decreased levels of sCD30, sCD163, and TARC. We demonstrate that treatment of cHL on COG AHOD1331 produced an environment that favors antitumor immune response, which may aid in application of further cellular and immunotherapies targeting cHL. This trial was registered at www.ClinicalTrials.gov as #NCT02166463.

Epstein-Barr virus (EBV) infects >95% of adults and contributes to several human cancers. EBV can remain latent where viral lytic genes are silenced, precluding the use of antiviral agents such as ganciclovir. Little is known about the host factors involved in EBV latency. Here we performed a human genome-wide CRISPR-Cas9 screen in Burkitt lymphoma B cells, which identified lysine-specific histone demethylase 1 (LSD1) and its corepressors REST corepressor 1 (CoREST) and zinc finger protein 217 (ZNF217) as critical for EBV latency. Gene knockout or LSD1 inhibition triggered EBV reactivation, and the latter sensitized cells to ganciclovir cytotoxicity, including in murine tumour xenografts. Mechanistically, ZNF217 recruits LSD1 and CoREST to form a complex that binds a specific DNA motif associated with regions implicated in EBV reactivation. It removes histone 3 lysine 4 (H3K4) methylation marks and restricts host DNA looping. Alternatively, the H3K4 lysine methyltransferase 2D supports EBV lytic reactivation. Our results highlight H3K4 methylation as a major EBV lytic switch regulator and therapeutic target.

UNLABELLED:The mutational profile of classic Hodgkin lymphoma (cHL) overlaps with that of related B cell lymphomas, including primary mediastinal B cell lymphoma (PMBL), and yet these are different histologically and clinically. To discover the molecular features that distinguish cHL, we deployed flow cytometric cell sorting and low-input RNA sequencing to generate full transcriptome data from viable, isolated Hodgkin and Red-Sternberg (HRS) cells from eighteen primary tumors, alongside matched intra-tumoral non-neoplastic B cells and four cell lines. Comparison of HRS cells to normal cellular subsets revealed evidence of abortive plasma cell differentiation, with an unfolded protein response signature, shared with plasma cell neoplasms, but not other B-cell lymphoma types. Comparison of cHL to PMBL revealed similarities but also key differences in B cell differentiation programs accompanied by upregulation of genes involved in microtubule cytoskeleton organization in cHL, which may be related to the unique multinucleated nature of HRS cells. In HRS cells, we also observed a downregulation of SLAM family receptors, which are crucial for NK cell activation, providing a potential mechanism for immune evasion from NK-mediated killing. STATEMENT OF SIGNIFICANCE/CONCLUSIONS:This study defines a unique transcriptional program in classic Hodgkin Lymphoma (cHL) marked by oncogenic signaling, chromatin integrity, DNA repair, and immune escape including loss of NK-activating receptors. HRS cells resemble plasma cells and have an unfolded protein response signature, which distinguishes them from diffuse large and primary mediastinal B cell lymphomas.

Cancer is a systemic disease with complications beyond the primary tumor site. Among them, thrombosis is the second leading cause of death in patients with certain cancers (e.g., pancreatic ductal adenocarcinoma [PDAC]) and advanced-stage disease. Here, we demonstrate that pro-thrombotic small extracellular vesicles (sEVs) are secreted by C-X-C motif chemokine 13 (CXCL13)-reprogrammed interstitial macrophages in the non-metastatic lung microenvironment of multiple cancers, a niche that we define as the pro-thrombotic niche (PTN). These sEVs package clustered integrin β₂ that dimerizes with integrin α_X and interacts with platelet-bound glycoprotein (GP)Ib to induce platelet aggregation. Blocking integrin β₂ decreases both sEV-induced thrombosis and lung metastasis. Importantly, sEV-β₂ levels are elevated in the plasma of PDAC patients prior to thrombotic events compared with patients with no history of thrombosis. We show that lung PTN establishment is a systemic consequence of cancer progression and identify sEV-β₂ as a prognostic biomarker of thrombosis risk as well as a target to prevent thrombosis and metastasis.

Epstein-Barr virus (EBV) contributes to ~1.5% of human cancers, including lymphomas, gastric and nasopharyngeal carcinomas. In most of these, nearly 80 viral lytic genes are silenced by incompletely understood epigenetic mechanisms, precluding use of antiviral agents such as ganciclovir to treat the 200,000 EBV-associated cancers/year. To identify host factors critical for EBV latency, we performed a human genome-wide CRISPR-Cas9 screen in Burkitt B-cells. Top hits included the lysine-specific histone demethylase LSD1 and its co-repressors ZNF217 and CoREST. LSD1 removes histone 3 lysine 4 (H3K4) and histone 3 lysine 9 (H3K9) methylation marks to downmodulate chromatin activation. LSD1, ZNF217 or CoREST knockout triggered EBV reactivation, as did a LSD1 small molecule antagonist, whose effects were additive with histone deacetylase inhibition. LSD1 blockade reactivated EBV in Burkitt lymphoma, gastric carcinoma and nasopharyngeal carcinoma models, sensitized cells to ganciclovir cytotoxicity and induced EBV reactivation in murine xenografts. ZNF217 and LSD1 co-occupied the EBV immediate early gene BZLF1 promoter, which drives B-cell lytic cycle, as well as to the oriLyt enhancer regions recently implicated in EBV reactivation. LSD1 depletion increased levels of activating histone 3 lysine 4 (H3K4) methylation but not repressive histone lysine 9 methylation marks at BZLF1 and oriLyt and induced their interaction by long-range DNA looping. An orthogonal CRISPR screen highlighted a key H3K4 methyltransferase KMT2D role in driving EBV reactivation. Our results highlight H3K4 methylation as a major EBV lytic switch regulator and suggest novel therapeutic approaches.

Classic Hodgkin lymphoma (cHL) exhibits a bimodal age distribution with incidence peaks in adolescents and young adults (AYAs) aged 15-39 years and in older adults over 50 years. The unique biology of cHL, characterized by a tumor microenvironment (TME) composed predominantly of non-malignant immune and stromal cells, plays a pivotal role in supporting Hodgkin and Reed-Sternberg (HRS) cells, the malignant cells of cHL. Understanding the role of the TME in cHL and its age-related differences is crucial for deciphering differential disease etiologies and developing biomarker-driven targeted therapies. Recent technical advances in single-cell sequencing and multiplexed spatial imaging have revealed age-related differences in TME composition and function, including key cellular interactions, leading to the development of age-specific prognostic indicators. In addition, advances in our ability to isolate nucleic acids from HRS cells have accelerated our understanding of the molecular alterations in cHL, many of which drive interactions within the TME. Molecular differences in cHL between pediatric/AYA and older adult patients have also emerged. This review summarizes the unique biology of cHL and its TME in children, adolescents, and young adults, highlighting recent breakthroughs in our understanding of cHL biology, differences across the age spectrum, and advances in biomarker development.

Necroptosis is a lytic form of regulated cell death reported to contribute to inflammatory diseases of the gut, skin and lung, as well as ischemic-reperfusion injuries of the kidney, heart and brain. However, precise identification of the cells and tissues that undergo necroptotic cell death in vivo has proven challenging in the absence of robust protocols for immunohistochemical detection. Here, we provide automated immunohistochemistry protocols to detect core necroptosis regulators - Caspase-8, RIPK1, RIPK3 and MLKL - in formalin-fixed mouse and human tissues. We observed surprising heterogeneity in protein expression within tissues, whereby short-lived immune barrier cells were replete with necroptotic effectors, whereas long-lived cells lacked RIPK3 or MLKL expression. Local changes in the expression of necroptotic effectors occurred in response to insults such as inflammation, dysbiosis or immune challenge, consistent with necroptosis being dysregulated in disease contexts. These methods will facilitate the precise localisation and evaluation of necroptotic signaling in vivo.

Epstein-Barr virus (EBV) persistently infects 95% of adults worldwide and is associated with multiple human lymphomas that express characteristic EBV latency programs used by the virus to navigate the B-cell compartment. Upon primary infection, the EBV latency III program, comprised of six Epstein-Barr Nuclear Antigens (EBNA) and two Latent Membrane Protein (LMP) antigens, drives infected B-cells into germinal center (GC). By incompletely understood mechanisms, GC microenvironmental cues trigger the EBV genome to switch to the latency II program, comprised of EBNA1, LMP1 and LMP2A and observed in GC-derived Hodgkin lymphoma. To gain insights into pathways and epigenetic mechanisms that control EBV latency reprogramming as EBV-infected B-cells encounter microenvironmental cues, we characterized GC cytokine effects on EBV latency protein expression and on the EBV epigenome. We confirmed and extended prior studies highlighting GC cytokine effects in support of the latency II transition. The T-follicular helper cytokine interleukin 21 (IL-21), which is a major regulator of GC responses, and to a lesser extent IL-4 and IL-10, hyper-induced LMP1 expression, while repressing EBNA expression. However, follicular dendritic cell cytokines including IL-15 and IL-27 downmodulate EBNA but not LMP1 expression. CRISPR editing highlighted that STAT3 and STAT5 were necessary for cytokine mediated EBNA silencing via epigenetic effects at the EBV genomic C promoter. By contrast, STAT3 was instead necessary for LMP1 promoter epigenetic remodeling, including gain of activating histone chromatin marks and loss of repressive polycomb repressive complex silencing marks. Thus, EBV has evolved to coopt STAT signaling to oppositely regulate the epigenetic status of key viral genomic promoters in response to GC cytokine cues.

Primary lymphoma of the bone (PLB) is a rare entity, with a majority of pediatric cases presenting in the metaphysis of long bones. There have been only seven reported cases to date of pediatric lymphoma of the bone arising from the epiphysis, of which only two have been described in the proximal tibia. We report a pediatric case of PLB in the tibial epiphysis which presented initially with knee pain. Imaging was performed with X-ray, MRI, CT, and PET-CT with bone biopsies revealing diffuse large B-cell lymphoma. This patient also showed a second, synchronous lesion in the left iliac bone, which was also biopsy proven to diffuse large B-cell lymphoma. Lymphoma in the epiphysis for children is rare and often confused with infectious etiologies or other types of tumors. Misdiagnosis may result in inappropriate treatment and possible progression of the disease, thus making early identification important to initiate therapy.