Suppression of an IL-13 autocrine growth loop in a human Hodgkin/Reed-Sternberg tumor cell line by a novel IL-13 antagonist

JAK/STAT blockade reverses the malignant phenotype of Hodgkin and Reed-Sternberg cells

Constitutive activation of the JAK/STAT pathway is a common phenomenon in classic Hodgkin lymphoma (cHL). The clinical potential of anti-JAK/STAT therapy is being explored in early-stage clinical trials. Notwithstanding, very little information is available about the complex biological consequences of this blockade. Here, we investigated the effects of JAK/STAT pharmacological inhibition on cHL cell models using ruxolitinib, a JAK 1/2 inhibitor that induces apoptosis by concentration- and time-dependent mechanisms. An unbiased whole-transcriptome approach identified expression of the anti-GCSF receptor (CSF3R) as a potential surrogate biomarker of JAK/STAT overactivation. In addition, longitudinal gene expression analyses provided further mechanistic information about pertinent biological pathways involved, including 37 gene pathways distributed in 3 main clusters: cluster 1 was characterized by upregulation of the G2/M checkpoint and major histocompatibility complex-related clusters; 2 additional clusters (2 and 3) showed a progressive downregulation of the tumor-promoting inflammation signatures: JAK/STAT and interleukin 1 (IL-1)/IL-4/IL-13/IL-17. Together, our results confirm the therapeutic potential of JAK/STAT inhibitors in cHL, identify CSF3R as a new biomarker, and provide supporting genetic data and mechanistic understanding.

Fibroblasts in Nodular Sclerosing Classical Hodgkin Lymphoma Are Defined by a Specific Phenotype and Protect Tumor Cells from Brentuximab-Vedotin Induced Injury

Classical Hodgkin lymphoma (cHL) is one of the most common malignant lymphomas in Western Europe. The nodular sclerosing subtype of cHL (NS cHL) is characterized by a proliferation of fibroblasts in the tumor microenvironment, leading to fibrotic bands surrounding the lymphoma infiltrate. Several studies have described a crosstalk between the tumour cells of cHL, the Hodgkin- and Reed-Sternberg (HRS) cells, and cancer-associated fibroblasts. However, to date a deep molecular characterization of these fibroblasts is lacking. Thus, the aim of the present study is a comprehensive characterization of these fibroblasts. Gene expression profiling and methylation profiles of fibroblasts isolated from primary lymph node suspensions revealed persistent differences between fibroblasts obtained from NS cHL and lymphadenitis. NS cHL derived fibroblasts exhibit a myofibroblastic phenotype characterized by myocardin (MYOCD) expression. Moreover, TIMP3, an inhibitor of matrix metalloproteinases, was strongly upregulated in NS cHL fibroblasts, likely contributing to the accumulation of collagen in sclerotic bands of NS cHL. As previously shown for other types of cancer-associated fibroblasts, treatment by luteolin could reverse this fibroblast phenotype and decrease TIMP3 secretion. NS cHL fibroblasts showed enhanced proliferation when they were exposed to soluble factors released from HRS cells. For HRS cells, soluble factors from fibroblasts were not sufficient to protect them from Brentuximab-Vedotin induced cell death. However, HRS cells adherent to fibroblasts were protected from Brentuximab-Vedotin induced injury. In summary, we confirm the importance of fibroblasts for HRS cell survival and identify TIMP3 which probably contributes as a major factor to the typical fibrosis observed in NS cHL.

CD137 signaling in Hodgkin and Reed-Sternberg cell lines induces IL-13 secretion, immune deviation and enhanced growth

CD137 and its ligand, CD137L, are expressed on activated T cells and antigen-presenting cells (APC), respectively, and are powerful inducers of cellular, type 1 immune responses. CD137 is ectopically expressed by Hodgkin and Reed-Sternberg (HRS) cells, the malignant cells in Hodgkin lymphoma (HL). Here we report that CD137 transmits signals into HRS cells, which induce the secretion of IL-13. IL-13 in conditioned supernatants of HRS cell lines inhibits the secretion of IFNγ by peripheral blood mononuclear cells (PBMC). Since IFNγ is essential for the development of a type 1 immune response, CD137-induced IL-13 secretion facilitates escape from immune surveillance. Further, CD137-induced IL-13 enhances the growth of HRS cell lines. CD137, IL-13 double-positive cells could be detected in the majority (58%) of HL patient samples, providing clinical evidence for a role of IL-13 induction by CD137 during HL pathogenesis. This study validates CD137 as a candidate target for immunotherapy of HL.

Brentuximab: a major advance in treatment of CD30-positive malignancies

Antibody-directed therapies allow greater selectivity in targeting of tumor associated antigens and spare normal cells. Brentuximab vedotin is an anti-CD30 antibody–drug conjugate. It has demonstrated impressive activity in the treatment of refractory and or relapsed Hodgkin's lymphoma, anaplastic large cell lymphoma and other CD30+ lymphoid malignancies. Several ongoing trials are testing the potential use of brentuximab vedotin for treatment of various CD30+ and CD30- malignancies in the setting of high-risk untreated disease. It is being tested in combination with chemotherapy, and testing in combination with immune therapy is also planned. CD30 plays a pivotal role in immune regulation and is also an attractive new target for intervention in the setting of select auto-immune diseases, as well as graft versus host disease.

Targeting and killing of glioblastoma with activated T cells armed with bispecific antibodies

Background

Since most glioblastomas express both wild-type EGFR and EGFRvIII as well as HER2/neu, they are excellent targets for activated T cells (ATC) armed with bispecific antibodies (BiAbs) that target EGFR and HER2.

Methods

ATC were generated from PBMC activated for 14 days with anti-CD3 monoclonal antibody in the presence of interleukin-2 and armed with chemically heteroconjugated anti-CD3×anti-HER2/neu (HER2Bi) and/or anti-CD3×anti-EGFR (EGFRBi). HER2Bi- and/or EGFRBi-armed ATC were examined for in vitro cytotoxicity using MTT and ⁵¹Cr-release assays against malignant glioma lines (U87MG, U118MG, and U251MG) and primary glioblastoma lines.

Results

EGFRBi-armed ATC killed up to 85% of U87, U118, and U251 targets at effector:target ratios (E:T) ranging from 1:1 to 25:1. Engagement of tumor by EGFRBi-armed ATC induced Th1 and Th2 cytokine secretion by armed ATC. HER2Bi-armed ATC exhibited comparable cytotoxicity against U118 and U251, but did not kill HER2-negative U87 cells. HER2Bi- or EGFRBi-armed ATC exhibited 50—80% cytotoxicity against four primary glioblastoma lines as well as a temozolomide (TMZ)-resistant variant of U251. Both CD133– and CD133+ subpopulations were killed by armed ATC. Targeting both HER2Bi and EGFRBi simultaneously showed enhanced efficacy than arming with a single BiAb. Armed ATC maintained effectiveness after irradiation and in the presence of TMZ at a therapeutic concentration and were capable of killing multiple targets.

Conclusion

High-grade gliomas are suitable for specific targeting by armed ATC. These data, together with additional animal studies, may provide the preclinical support for the use of armed ATC as a valuable addition to current treatment regimens.

Mechanisms of aberrant GATA3 expression in classical Hodgkin lymphoma and its consequences for the cytokine profile of Hodgkin and Reed/Sternberg cells

The transcription factor network in Hodgkin lymphoma (HL) represents a unique composition of proteins found in no other hematopoietic cell. Among these factors, an aberrant expression of the T-cell transcription factor GATA3 is observed in B cell–derived Hodgkin and Reed/Sternberg (HRS) tumor cells. Herein, we elucidate the regulation and function of this factor in HL. We demonstrate binding of NFκB and Notch-1, 2 factors with deregulated activity in HL to GATA3 promoter elements. Interference with NFκB and Notch-1 activity led to decreased GATA3 expression, indicating a dependency of deregulated GATA3 expression on these transcription factors. Down-regulation of GATA3 in HL cell lines demonstrated its role in the regulation of IL-5, IL-13, STAT4, and other genes. A correlation between GATA3 and IL-13 expression was confirmed for HRS cells in HL tissues. Thus, GATA3 shapes the cytokine expression and signaling that is typical of HL. Conclusively, aberrant GATA3 expression in HRS cells is stimulated by the deregulated constitutive activity of NFκB and Notch-1, indicating a complex network of deregulated transcription factors in these cells. GATA3 activity significantly contributes to the typical cytokine secretion of and signaling in HRS cells, which presumably plays an essential role in HL pathogenesis.

Novel recombinant adenoviral vector that targets the interleukin-13 receptor alpha2 chain permits effective gene transfer to malignant glioma

Transduction of malignant glioma with adenovirus serotype 5 (Ad5) vectors is limited by the low levels of coxsackievirus and adenovirus receptor (CAR) on tumor cells. However, malignant brain tumors have been found to overexpress a glioma-associated receptor, interleukin-13 receptor alpha2 chain (IL-13Ralpha2), a marker of both glial transformation and tumor grade. To selectively target Ad5 to IL-13Ralpha2, we constructed a replication-deficient adenoviral vector that possesses an IL-13 ligand presented by a T4 phage fibritin shaft, and designated the new virus LU-13. Western blot and sequence analyses confirmed proper trimerization and ligand presentation by the T4 fibritin shaft. Confocal microscopy analysis of primary glioma suspensions incubated with viral recombinants showed that LU-13 colocalized with IL-13Ralpha2. Luciferase transduction assays conducted in both primary and passaged glioma cell cultures exhibited at least 10-fold enhanced gene transduction. Moreover, the virus preferentially bound to glioma cells, as documented by increased adenoviral E4 DNA copy number. In vitro competition assays performed with anti-human IL-13 monoclonal antibody confirmed significant attenuation of LU-13 transduction. These results were further confirmed in vivo, where LU-13 showed a 300-fold increase in transgene expression. In summary, we describe here the development of a novel and targeted adenoviral vector that binds IL-13Ralpha2. Our findings confirm the ability of LU-13 to bind IL-13Ralpha2 and increase transgene expression, making it an attractive gene therapy vector for the treatment of malignant glioma in a clinical setting.

Genomic Alterations in Hodgkin's Lymphoma

Cytogenetic analysis of Hodgkin's lymphoma (HL) is hampered by the scarcity of neoplastic cells within a sea of reactive cells. There is accumulating evidence that HL represents 2 disease entities, classic HL (cHL) with its morphologic variants and nodular lymphocyte predominant HL (NLPHL). This subdivision, initially worked out in morphologic and immunohistochemical studies, has been further substantiated by molecular cytogenetic investigations. Two recurrent chromosomal aberrations, namely gains of 2p13-p16 and 9p24, have been found by comparative genomic hybridization analysis in microdissected cells from cHL patients as well as in cHL cell lines, but not in NLPHL cells. The available cHL cell lines are remarkably heterogeneous in their karyotypes, suggesting profound genomic instability leading to numeric chromosomal aberration and multiple chromosomal breaks and translocations. In this article, we review genomic aberrations that may contribute to the development and maintenance of the morphologic and clinical presentation of these beta-cell lymphoma entities. Furthermore, we delineate current data on the genomic changes observed in the neoplastic cells of HL that are created by epigenetic mechanisms, which are alternative mechanisms that regulate the expression of relevant genes.

Hodgkin lymphoma therapy with interleukin-4 receptor-directed cytotoxin in an infiltrating animal model

Hodgkin lymphoma represents unique clinicopathologic features because Hodgkin and Reed-Sternberg (H-RS) cells produce a variety of cytokines, express a variety of cytokine receptors, and are surrounded by numerous nonmalignant immunoreactive cells. We found that receptors for interleukin-4 (IL-4R) are highly expressed in H-RS cells. To target interleukin-4 receptor (IL-4R), we used a recombinant protein fusing circularly permuted human IL-4 and Pseudomonas exotoxin termed IL4(38-37)-PE38KDEL, or IL-4 cytotoxin. The cytotoxic effect of IL-4 cytotoxin on H-RS cell lines was determined to be moderate to high in vitro. We developed an infiltrating model of Hodgkin disease (HD) by injecting an adherent population of HD-MyZ cells subcutaneously into the flanks of beige/nude/X-linked immunodeficient mice. The animal model exhibited spontaneous metastasis of H-RS cells to lymph nodes and dissemination to vital organs, including the lungs. Intraperitoneal or intratumoral treatment of these mice with IL-4 cytotoxin resulted in regression of the primary tumor mass and a decrease in the incidence of lymph node metastasis. Mice injected with HD-MyZ cells demonstrated 203% prolonged survival (mean survival, 63 days) compared with control (mean survival, 31 days) when they received systemic IL-4 cytotoxin treatment. Because numerous H-RS cell lines express receptors for IL-4, IL-4 cytotoxin may be a unique agent for the treatment of Hodgkin lymphoma.

Potent receptor-mediated cytotoxicity of granulocyte colony-stimulating factor-Pseudomonas exotoxin, a fusion protein against myeloid leukemia cells

A chimeric toxin in which the cell-surface binding domain of Pseudomonas exotoxin A was replaced with mature human granulocyte colony-stimulating factor (G-CSF) was produced in Escherichia coli, purified and tested for its biological activity on the human G-CSF-responsive myeloid leukemia cell line, UT7/GR. This fusion protein, termed G-CSF-PE40, showed potent cytotoxicity in the cell line in a dose-dependent manner. G-CSF-PE40 displaced binding of biotinylated G-CSF to its receptor, and the cytotoxicity of G-CSF-PE40 was neutralized by an excess of wild-type G-CSF, indicating the receptor-mediated effects of this chimeric toxin. When G-CSF-PE40 was injected into normal mice, they showed transient neutropenia but no significant changes in the numbers of red blood cells or platelets. Furthermore, G-CSF-PE40 prolonged the survival of mice transplanted with syngeneic myeloid leukemia cells. These observations suggest that G-CSF-PE40 may be useful in targeted therapy of myeloid leukemia cells expressing G-CSF receptors.

Soluble Interleukin-13Rα2 Decoy Receptor Inhibits Hodgkin’s Lymphoma Growth in Vitro and in Vivo

Recent studies have demonstrated that the malignant Reed-Sternberg cells of Hodgkin's lymphoma (HL) secrete and are responsive to interleukin (IL)-13. We hypothesized that overexpression of a soluble IL-13 decoy receptor (sIL-13Ralpha2) via adenoviral-mediated gene transfer would inhibit IL-13-induced Reed-Sternberg cell proliferation. Western blot and ELISA analysis verified expression of sIL-13Ralpha2 in cell lysates and supernatants of AdsIL-13Ralpha2-transduced COS-7 cells. Treatment of two IL-13-responsive HL-derived cell lines, HDLM-2 and L-1236, with AdsIL-13Ralpha2-conditioned medium, resulted in the inhibition of cell proliferation, and down-regulated the phosphorylation of signal transducer and activator of transcription 6 (STAT6), an important mediator of IL-13 signaling. i.v. delivery of AdsIL-13Ralpha2 in NOD/SCID mice with s.c. implanted HDLM-2 cells delayed tumor onset and growth while enhancing survival compared with control mice. Intratumoral administration of AdsIL-13Ralpha2 led to the regression or stabilization of established tumors and was associated with diminished STAT6 phosphorylation. Our data demonstrate that AdsIL-13Ralpha2 can suppress HL growth in vitro and in vivo.

Specifically targeted killing of interleukin-13 (IL-13) receptor-expressing breast cancer by IL-13 fusion cytotoxin in animal model of human disease

Interleukin-13 receptor (IL-13R) α2 chain binds IL-13 with high affinity and can internalize after binding to ligand. We have exploited this property of IL-13Rα2 chain by receptor-targeted breast cancer therapy. Previous studies have demonstrated that in vivo intratumoral (i.t.) gene transfer of this chain followed by IL-13 cytotoxin [comprised of IL-13 and Pseudomonas exotoxin (IL13-PE38QQR)] therapy causes regression of established human tumors in xenografted models. Breast carcinoma cells do not express IL-13Rα2 chain and are resistant to the antitumor effect of IL-13 cytotoxin. To determine whether IL-13Rα2 chain can render sensitivity of breast cancer to IL-13 cytotoxin, we injected IL-13Rα2 plasmid in s.c. established tumors by i.t. route, followed by systemic or i.t. IL-13 cytotoxin administration. This combination approach showed profound antitumor activity against human breast tumors in xenografted immunodeficient mice. Interestingly, there was dominant infiltration of inflammatory cells in regressing tumors, which were identified to be macrophages producing nitric oxide (NO) and natural killer cells. The partial role of inducible nitric oxide synthase (iNOS)-positive macrophages was confirmed by in vivo macrophage depletion experiments. Serum chemistry, hematology, and organ histology from treated mice did not show any remarkable toxicity resulting from the combination therapy. Taken together, local gene transfer of IL-13Rα2 followed by receptor-targeted IL-13 cytotoxin therapy may be applied safely and effectively to the treatment of localized breast cancer.

Epstein-Barr Virus (EBV) LMP2A induces alterations in gene transcription similar to those observed in Reed-Sternberg cells of Hodgkin lymphoma

Epstein-Barr virus (EBV) is associated with the development of a variety of malignancies, including Hodgkin lymphoma. One of the few viral transcripts expressed in EBV-positive Hodgkin/Reed-Sternberg (HRS) cells of Hodgkin lymphoma is latent membrane protein 2A (LMP2A). This viral protein blocks B-cell receptor (BCR)-signaling in vitro. Furthermore, expression of LMP2A in developing B cells in vivo induces a global down-regulation of genes necessary for proper B-cell development. In this study we have analyzed gene transcription in primary B cells from LMP2A transgenic mice, LMP2A-expressing human B-cell lines, and LMP2A-positive and -negative EBV-infected lymphoblastoid cell lines (LCLs). We demonstrate that LMP2A increases the expression of genes associated with cell cycle induction and inhibition of apoptosis, alters the expression of genes involved in DNA and RNA metabolism, and decreases the expression of B-cell-specific factors and genes associated with immunity. Furthermore, many alterations in gene expression induced by LMP2A are similar to those recently described in HRS cells of Hodgkin lymphoma and activated, proliferating germinal center centroblasts/centrocytes. These correlations suggest that LMP2A expression in EBV-infected B cells may lead to the induction and maintenance of an activated, proliferative state that could ultimately result in the development of Hodgkin lymphoma.

IL-13 effector functions

IL-13 was first recognized for its effects on B cells and monocytes, where it upregulated class II expression, promoted IgE class switching and inhibited inflammatory cytokine production. It was also thought to be functionally redundant with IL-4. However, studies conducted with knockout mice, neutralizing antibodies, and novel antagonists demonstrate that IL-13 possesses several unique effector functions that distinguish it from IL-4. Resistance to most gastrointestinal nematodes is mediated by type-2 cytokine responses, in which IL-13 plays a dominant role. By regulating cell-mediated immunity, IL-13 modulates resistance to intracellular organisms including Leishmania major, Leishmania mexicana, and Listeria monocytogenes. In the lung, IL-13 is the central mediator of allergic asthma, where it regulates eosinophilic inflammation, mucus secretion, and airway hyperresponsiveness. Manipulation of IL-13 effector function may also prove useful in the treatment of some cancers like B-cell chronic lymphocytic leukemia and Hodgkin's disease, where IL-13 modulates apoptosis or tumor cell growth. IL-13 can also inhibit tumor immunosurveillance. As such, inhibitors of IL-13 might be effective as cancer immunotherapeutics by boosting type-1-associated anti-tumor defenses. Finally, IL-13 was revealed as a potent mediator of tissue fibrosis in both schistosomiasis and asthma, which indicates that it is a key regulator of the extracellular matrix. The mechanisms that regulate IL-13 production and/or function have also been investigated, and IL-4, IL-12, IL-18, IFN-gamma, IL-10, TGF-beta, TNF-alpha, and the IL-4/IL-13 receptor complex play important roles. This review highlights the effector functions of IL-13 and describes multiple pathways for modulating its activity in vivo.

Immunotoxin therapy of hematologic malignancies

Patients with chemotherapy relapsed or refractory hematologic malignancies may be effectively treated with allogeneic or autologous stem cell transplants. However, many patients cannot be transplanted due to age, comorbidities, or lack of suitable donors. Further, a fraction of patients relapse post-transplant. Novel therapeutic agents that can kill multidrug-resistant malignant stem cells and are not myelosuppressive are needed. One class of such agents is immunotoxins. Immunotoxins consist of cell-selective ligands covalently linked to peptide toxins. The ligand delivers the molecule to specific cell surface receptors on malignant cells. The toxin triggers cell death either by reaching the cytosol and catalytically inactivating vital cell processes or by modifying the tumor cell surface membrane. We have synthesized immunotoxins for therapy of chemoresistant hematologic diseases. In this review, we will detail the synthesis of a number of these drugs and describe their preclinical and clinical activity. Several of these agents have shown dramatic antitumor effects in patients with hematologic neoplasms, and one immunotoxin has been approved for use by the US Food and Drug Administration (FDA). Over the next several decades, a growing number of these agents should reach the clinic.

TCR-independent CD30 signaling selectively induces IL-13 production via a TNF receptor-associated factor/p38 mitogen-activated protein kinase-dependent mechanism

Initiation of T lymphocyte responses to most Ags requires concurrent stimulation through the TCR and costimulatory receptors such as CD28. Following initial activation, secondary receptors are up-regulated that can costimulate T cells in concert with TCR engagement. One such receptor is the TNFR family member CD30. In this study, we report that unlike CD28, ligation of CD30 on normal effector T cells induces IL-13 production in the absence of concurrent TCR engagement. TCR-independent CD30-mediated IL-13 release correlated with activation of c-Jun N-terminal kinase, p38 mitogen-activated protein kinase (MAPK), and NF-kappaB, and was completely inhibited by the expression of a TNFR-associated factor 2 (TRAF2) dominant-negative transgene (TRAF2.DN-Tg), but not by that of an I-kappaBalpha dominant-negative transgene. In parallel, expression of the TRAF2.DN-Tg selectively prevented the induction of c-Jun N-terminal kinase and p38 MAPK, but not that of NF-kappaB. Furthermore, IL-13 production was reduced in a dose-dependent manner by the p38 MAPK inhibitor SB203580. Together, these results suggest that TCR-independent CD30-mediated production of IL-13 is triggered by association of CD30 with TRAF family members and subsequent activation of p38 MAPK. Inasmuch as IL-13 can promote airway inflammation and cancer progression, production of IL-13 in a TCR-independent manner has important pathological implications in vivo.

The role of cytokines in classical Hodgkin lymphoma

The clinical and pathologic features of classical Hodgkin lymphoma (cHL) reflect an abnormal immune response that is thought to be due to the elaboration of a variety of cytokines by the malignant Reed-Sternberg (RS) cells or surrounding tissues. The majority of cHL cases are characterized by expression of tumor necrosis factor receptor (TNFR) family members and their ligands, as well as an unbalanced production of Th2 cytokines and chemokines. Activation of TNFR members results in constitutive activation of nuclear factor-kappa B (NF-kappa B), a transcription factor important for the in vitro and in vivo growth of RS cell lines. The expression of Th2 cytokines and chemokines leads to the reactive infiltrate of eosinophils, Th2 cells, and fibroblasts characteristic of cHL, and can also contribute to a local suppression of Th1 cell-mediated cellular immune response. Another particularly important growth and survival factor for RS cell lines is the Th2 cytokine interleukin 13, which is also commonly expressed by primary RS cells. In approximately 40% of cHL cases, the presence of Epstein-Barr virus influences the Th1/Th2 balance toward the production of Th1 cytokines and chemokines, but this shift is apparently insufficient for the stimulation of an effective antitumor cell-mediated immune response. This review summarizes the current literature on cytokine expression by and activity on RS cell lines and primary cHL tissues, examines cytokine signaling pathways in RS cells, and discusses the role that cytokines play in the specific clinical and pathologic features of cHL.