Reed-Sternberg cells and the TNF family of receptors/ligands

CD30/CD30 Ligand and CD40/CD40 Ligand in Malignant Lymphoid Disorders

CD30 and CD40 are members of the tumor necrosis factor (TNF) receptor family. These two receptors have pleiotropic biologic functions including induction of apoptosis and enhancing cell survival. This review will discuss the pattern of expression of these receptors in malignant lymphoid disorders and their prospective ligands. Understanding issues related to these two ligands and their receptors in lymphoid malignancies may help to improve the classification of these diseases and could open the doors for new treatment strategies.

Treatment challenges in the management of relapsed or refractory non-Hodgkin's lymphoma - novel and emerging therapies

Over the last few decades, advances in immunochemotherapy have led to dramatic improvement in the prognosis of non-Hodgkin's lymphoma (NHL). Despite these advances, relapsed and refractory disease represents a major treatment challenge. For both aggressive and indolent subtypes of NHL, there is no standard of care for salvage regimens, with prognosis after relapse remaining relatively poor. Nevertheless, there are multiple emerging classes of targeted therapies for relapsed/refractory disease, including monoclonal antibodies, antibody- drug conjugates, radioimmunotherapy, small-molecule inhibitors of cell-growth pathways, and novel chemotherapy agents. This review will discuss treatment challenges of NHL, current available salvage regimens for relapsed/refractory NHL, and the safety and efficacy of novel emerging therapies.

Brentuximab Vedotin in CD30+ Lymphomas

Monoclonal antibodies (mAb) have become an effective treatment strategy for hematologic malignancies. CD30 is a rational target for therapy due to its limited expression on normal tissues and the strong and uniform expression on malignant cells in classical Hodgkin’s lymphoma (cHL) and anaplastic large-cell lymphoma (ALCL). Brentuximab vedotin, an anti-CD30 antibody-drug conjugate, utilizes the targeting properties of mAb to deliver a cytotoxic agent inside the malignant cell. Brentuximab vedotin has significant clinical activity in patients with relapsed or refractory cHL and relapsed or refractory ALCL, and has the potential to represent a significant advance in modern oncology.

Brentuximab vedotin in Hodgkin's lymphoma

INTRODUCTION

Monoclonal antibodies (mAbs) directed against antigens expressed by tumor cells have become an effective therapeutic option in hematologic malignancies. Antibody-drug conjugates (ADC) utilize the targeting properties of mAbs to deliver cytotoxic agents inside the malignant cell. Brentuximab vedotin is a CD30-specific ADC with significant clinical activity in Hodgkin's lymphoma (HL).

AREAS COVERED

CD30 is an ideal target for therapy due to its limited expression on normal tissues and the strong and uniform expression on malignant cells in classical Hodgkin's lymphoma (cHL). Early studies using unconjugated CD30 mAbs have demonstrated lack of objective responses in patients with recurrent cHL. Brentuximab vedotin is an ADC with significant clinical activity in patients with HL. Here, the authors review the biology of brentuximab vedotin, summarize available clinical data and discuss future treatment strategies.

EXPERT OPINION

Brentuximab vedotin is a well-tolerated and highly active drug in patients with relapsed cHL. This novel agent has the potential to be incorporated in the standard management of the disease with significant therapeutic impact.

New antibody drug treatments for lymphoma

INTRODUCTION

The advent of anti-CD20 monoclonal antibody (mAb) rituximab heralded a new era in the treatment of non-Hodgkin's lymphoma leading to significant improvements in outcome for patients. This unprecedented success has changed the mindset of the clinical community and catalyzed the interest in the pharmaceutical industry to develop the next-generation of antibodies and antibody conjugates in cancer.

AREAS COVERED

There are an ever increasing number of newer generation anti-CD20 and rituximab 'bio-similars' undergoing early phase clinical development. In addition emerging novel therapies including antibody drug conjugates (brentuximab vedotin, SGN-35) and mAb against T-cell lymphomas antigens (e.g., zanolimumab) offer hope of improved outcome for other lymphomas. Bispecific T-cell-engaging antibodies and combination immunotherapy, also provide the promise of further improvements. Radiolabelled antibodies or radioimmunotherapy (RIT) has also demonstrated high clinical activity and two drugs namely 131I-tositumomab (Bexxar) and 90Y-ibritumomab (Zevalin) are licensed.

EXPERT OPINION

Despite the large numbers of new anti-CD20 mAb currently undergoing clinical testing, improving on clinical efficacy of rituximab is a substantial challenge. Further improvements in outcome for patients will require rigorous testing in well designed clinical trials alongside the translation of new insights into mechanism of mAb action that lead to improvements in clinical efficacy.

Novel therapies for Hodgkin Lymphoma

In recent years, improved understanding of the biology of Hodgkin Lymphoma (HL) has uncovered many potential targets for the treatment of this disease. Clarification of the B-ceLL origin of the Hodgkin Reed Sternberg (HRS) cell and of the complex interactions between the HRS cell and the HL microenvironment have provided new insights into the pathophysiology of HL and identified extracellular and intracellular molecules which are essential for HRS survival. New agents directed at these molecules are now in early phase clinical trials.

Novel treatment strategies for patients with relapsed classical Hodgkin lymphoma

Although classical Hodgkin lymphoma (HL) is considered one of the most curable human cancers, the treatment of patients with relapsed and refractory disease, especially those who relapse after autologous stem cell transplantation, remains challenging. Furthermore, because the median age of the patients is in the mid-30s, the impact of early mortality on the number of years lost from productive life is remarkable. Patients with HL whose disease relapses after stem cell transplantation are rarely cured with current treatment modalities. New drugs and novel treatment strategies that are based on our understanding of the disease biology and signaling pathways are needed to improve treatment outcome for these patients. This review will focus on emerging new treatment modalities that are currently under investigation for patients with relapsed classical HL.

Biologic features of Hodgkin lymphoma and the development of biologic prognostic factors in Hodgkin lymphoma: tumor and microenvironment

Classical Hodgkin lymphoma is now recognised as a B-cell lymphoma. Improved therapy has increased cure rates dramatically; however, relapse and death still occurs in a minority of patients. Much has been learned about the biology of Hodgkin and Reed Sternberg cells and their interactions with the microenvironment, which has informed studies exploring biologic markers that may improve upon clinical prognostic models. This manuscript reviews recent advances in our understanding of the pathobiology of cHL with an emphasis on biologic prognostic markers.

Phase 2 study of gemcitabine in combination with rituximab in patients with recurrent or refractory Hodgkin lymphoma

BACKGROUND

The management of recurrent or refractory Hodgkin lymphoma (HL) remains challenging. The objective of this phase 2 trial was to investigate the activity of gemcitabine in combination with rituximab in patients with recurring or refractory HL.

METHODS

Patients were considered eligible if they had recurring or refractory HL, had received >or=2 prior chemotherapy regimens, had an Eastern Cooperative Oncology Group (ECOG) performance status <or=2, and had adequate organ function. Rituximab was administered at a dose of 375 mg/m2 intravenously every week for 6 weeks. Gemcitabine was administered at a dose of 1250 mg/m2 intravenously on Days 1 and 8, with a week of rest on Day 15 of 21-day cycles in outpatient settings. Response was assessed after 2 cycles of gemcitabine, and those patients who demonstrated a response continued to receive a maximum of 4 additional courses of gemcitabine.

RESULTS

Thirty-three patients received the study drugs. The median age of patients was 32 years (range, 19-81 years), and 55% of the patients previously underwent autologous stem cell transplantation. Grade 3 or 4 (graded according to the National Cancer Center Institute Common Toxicity Criteria [version 2.0]) toxic effects included neutropenia (36%) and thrombocytopenia (15%). Objective responses occurred in 16 patients (48%). Responses were observed regardless of CD20 positivity in tumor cells. The median duration of failure-free survival was 2.7 months (range, 0.9-18.3 months). Seven patients (21%) eventually proceeded to either autologous (n = 2) or allogeneic (n = 5) stem cell transplantation.

CONCLUSIONS

Combination therapy with gemcitabine and rituximab is active in previously treated patients with recurrent or refractory HL. The favorable safety profile and the ease of its administration in outpatient settings warrant investigating it further in combination with other active drugs.

Hodgkin's lymphoma: molecular targets and novel treatment strategies

The WHO classification of Hodgkin's lymphoma (HL) distinguishes between two major subtypes, classical and nodular lymphocyte predominant HL. Approximately 95% of patients with HL will have the classical HL histology, which is characterized by the presence of rare malignant Hodgkin's and Reed-Sternberg cells among an overwhelming number of benign reactive cells. In recent years, new studies have shed more light on the biological and molecular features of Hodgkin's and Reed-Sternberg cells, providing hope that new targeted therapy may be developed to enhance the cure rate and to reduce treatment-related toxicity. In this review, the current understanding of the pathology and biology of HL will be discussed, as well as the current treatment approaches for patients with classical HL. Future treatment strategies will also be discussed based on our understanding of HL biology.

Deregulated NF-kappaB activity in haematological malignancies

The NF-kappaB family of transcription factors plays key roles in the control of cell proliferation and apoptosis. Constitutive NF-kappaB activation is a common feature for most haematological malignancies and is therefore believed to be a crucial event for enhanced proliferation and survival of these malignant cells. In this review, we will describe the molecular mechanisms underlying NF-kappaB deregulation in haematological malignancies and will highlight what is still unclear in this field, 20 years after the discovery of this transcription factor.

Immunobiology and pathophysiology of Hodgkin lymphomas

Classical Hodgkin lymphoma (HL) is characterized by the presence of Reed-Sternberg (RS) cells, which are transformed post-germinal center B cells destined for apoptosis since they have not undergone successful immunoglobulin gene rearrangement. Several mechanisms, including latent infection by Epstein-Barr virus (EBV), allow these cells to survive. It is remarkable that many of the signaling pathways that promote survival are shared between the EBV-induced proteins, such as EBNA1, LMP1, and LMP2, and other molecules that are upregulated in RS cells. A key role is played by the presence of constitutive nuclear factor (NF)-kappaB, which is induced by LMP1, as well as by CD30, CD40, tumor necrosis factor (TNF)-alpha, and Notch1 interactions, and results in the upregulation of at least 45 genes including chemokines, cytokines, receptors, apoptotic regulators, intracellular signaling molecules, and transcription factors. The other characteristic of classical HL is the presence of an extensive inflammatory infiltrate. Key features of this infiltrate are that it comprises Th2 and T regulatory cells and generally lacks Th1 cells, CD8 cytotoxic T cells, and natural killer (NK) cells. The RS cells appear to induce this infiltrate by the secretion of Th2 type chemokines such as TARC and MDC. The RS cells also produce cytokines that inhibit Th1 responses, as interleukin (IL)-10 and transforming growth factor (TGF)-beta express CD95 ligand, which induces apoptosis of activated Th1 and CD8 T cells. Other important mechanisms that allow the RS cells to escape an effective anti-EBV immune response include the downregulation of HLA class I in EBV-negative cases or the presence of a polymorphism in HLA class I in EBV-positive cases that allow escape from CD8-mediated cytotoxicity. On the other hand, expression of HLA-G allows the escape from NK cells that would normally recognize the HLA class I-negative RS cells. Overall, the cellular infiltrate in HL appears to play a decisive role in allowing the RS cells to survive by providing an environment that suppresses cytotoxic immune responses and providing cellular interactions and cytokines that support the growth and survival of RS cells. Future therapeutic strategies could focus directly on the NF-kappaB activation, on various receptors to ligand interactions, on the chemokine and cytokine network, or on the induction of effective anti-EBV latent protein immune responses.

MEK/ERK pathway is aberrantly active in Hodgkin disease: a signaling pathway shared by CD30, CD40, and RANK that regulates cell proliferation and survival

The mitogen-activated protein kinase (MAPK) (also called extracellular signal-regulated kinase [ERK]) pathway has been implicated in malignant transformation and in the regulation of cellular growth and proliferation of several tumor types, but its expression and function in Hodgkin disease (HD) are unknown. We report here that the active phosphorylated form of MAPK/ERK is aberrantly expressed in cultured and primary HD cells. Inhibition of the upstream MAPK kinase (also called MEK) by the small molecule UO126 inhibited the phosphorylation of ERK and demonstrated a dose- and time-dependent antiproliferative activity in HD cell lines. UO126 modulated the levels of several intracellular proteins including B-cell lymphoma protein 2 (Bcl-2), myeloid cell leukemia-1 (Mcl-1) and caspase 8 homolog FLICE-inhibitory protein (cFLIP), and induced G2M cell-cycle arrest or apoptosis. Furthermore, UO126 potentiated the activity of apoliprotein 2/tumor necrosis factor-related apoptosis-inducing ligand (APO2L/TRAIL) and chemotherapy-induced cell death. Activation of CD30, CD40, and receptor activator of nuclear kappabeta (RANK) receptors in HD cells by their respective ligands increased ERK phosphorylation above the basal level and promoted HD cell survival. UO126 inhibited basal and ligand-induced ERK phosphorylation, and inhibited ligand-induced cell survival of HD cell lines. These findings provide a proof-of-principle that inhibition of the MEK/ERK pathway may have therapeutic value in HD.

A pilot study of rituximab in patients with recurrent, classic Hodgkin disease

BACKGROUND

To explore the potential role of infiltrating benign B cells in classic Hodgkin disease (HD) lesions in supporting the survival of malignant Hodgkin and Reed-Sternberg (H/RS) cells, the authors initiated a pilot study of rituximab. Rituximab is used to primarily deplete normal B cells from HD lesions.

METHODS

Patients with recurrent, classic HD who had received a minimum of two prior treatment regimens, regardless of whether H/RS cells expressed CD20, were treated with 6 weekly doses of 375 mg/m2 rituximab to selectively deplete infiltrating benign B cells. Objective tumor response was determined 3 weeks after completion of the last dose of rituximab and every 3 months thereafter. Serum samples were collected from patients before they started rituximab therapy and 3 weeks after the final course of rituximab. Serum cytokine levels of interleukin 6 (IL-6), IL-10, IL-12, IL-13, and interferon gamma were determined using commercially available enzyme-linked immunosorbent assay kits.

RESULTS

Twenty-two patients with nodular sclerosis histology were evaluable for treatment response. Five patients (22%) achieved partial or complete remission that lasted for a median of 7.8 months (range, 3.3-14.9 months). Remissions were observed in patients only at lymph node and splenic sites, but not at extranodal sites, and were irrespective of CD20 expression by H/RS cells. Furthermore, systemic (B) symptoms resolved in six of seven patients after therapy. In two patients, partial remissions were associated with a decline in serum IL-6 levels.

CONCLUSIONS

The current data suggest that rituximab therapy in patients with recurrent, classic HD can alter serum IL-6 cytokine levels, can improve B symptoms, and may result in clinical remissions.

Role of homeostatic chemokine and sphingosine-1-phosphate receptors in the organization of lymphoid tissue

Chemokines regulate both homeostatic leukocyte recirculation and trafficking to sites of infection and inflammation. Apart from the well-established physiological functions, chemokines receive growing interest for their role in pathophysiological processes such as autoimmune diseases, cancer, and allograft rejection. The chemokine receptor CCR7, which is responsible for directing T cells, B cells, and dendritic cells (DCs) into secondary lymphoid organs and their precise positioning therein, has already been implicated in lymphoid organ infiltration by neoplastic cells and the localization of metastasis formation. We have shown that the differential expression of CCR7 by neoplastic cells in two entities of Hodgkin's disease (HD), classic HD (cHD) and the nodular lymphocyte predominant HD (NLPHD), may account for the differences observed in tumor cell dissemination within the affected lymph nodes. Because of the prominent role of the chemokine receptors CCR7 and CXCR5 in lymphocyte homing to secondary lymphoid organs, we hypothesized that they may also be involved in the action of FTY720, a synthetic immunosuppressant inducing lymphopenia. By using CXCR5 and CCR7 knockout mice, we have tested for a possible function of these receptors in the FTY720-induced migration of lymphocytes into Peyer's patches (PPs) and peripheral lymph nodes (PLNs). Lymphopenia is noticeably delayed in mice lacking CCR7, whereas CXCR5 knockout mice show a significant reduction of lymphocyte accumulation in secondary lymphoid organs that are infrequently present in these mice. However, FTY720-induced lymphocyte sequestration appears to be essentially independent of CCR7 and CXCR5.

Functional expression of receptor activator of nuclear factor kappaB in Hodgkin disease cell lines

The malignant Hodgkin and Reed-Sternberg (H/RS) cells of Hodgkin disease (HD) express several members of the tumor necrosis factor (TNF) receptor family, including CD30 and CD40, and secrete several cytokines and chemokines. However, little is known about what regulates cytokine and chemokine secretion in H/RS cells. Although H/RS cells are predominantly of B-cell origin, they frequently share phenotypic and functional features with dendritic cells (DCs). Previous studies reported that receptor activator of nuclear factor kappaB (NF-kappaB) (RANK), a member of the TNF receptor family, is expressed on DCs, and that RANK ligand (RANKL) enhances DC survival and induces them to secrete cytokines. This study reports that, similar to DCs, cultured H/RS cells expressed RANK. However, unlike DCs, H/RS cells also expressed RANKL. Soluble RANKL activated NF-kappaB and induced messenger RNA expression of interferon-gamma, interleukin-8 (IL-8), IL-13, IL-9, IL-15, and RANTES, in addition to the receptors for IL-9, IL-13, IL-15, and CCR4. RANKL increased IL-8 and IL-13 levels in the supernatants of H/RS cell lines, an effect that was blocked by soluble RANK. Furthermore, soluble RANK decreased the basal level of IL-8 in one cell line, suggesting that IL-8 was induced by an autocrine RANKL/RANK loop. RANKL had no effect on H/RS cell survival in culture, and it did not modulate the expression of bcl-2, bcl-xL, bax, or inhibitors of apoptosis proteins. These data provide evidence of further functional similarities between DCs and H/RS cells. The coexpression of RANK and RANKL in H/RS cells suggests that they may regulate cytokine and chemokine secretion in H/RS cells by an autocrine mechanism.

Expression of the c-met proto-oncogene and its ligand, hepatocyte growth factor, in Hodgkin disease

The receptor for hepatocyte growth factor (HGF) is a transmembrane tyrosine kinase that is encoded by the proto-oncogene c-met. Recently, c-MET was detected in Reed-Sternberg (RS) cells from Epstein-Barr virus-positive (EBV(+)) Hodgkin disease (HD). The c-MET, EBER-1, and LMP-1 expression in 45 lymph node biopsies and 12 bone marrow biopsies obtained from patients with HD was analyzed. In addition, HGF levels in serum samples from 80 healthy individuals and 135 HD patients in different phases of disease. In all 45 lymph node and 12 bone marrow samples examined, RS cells expressed c-MET but not HGF(+). These results were independent of the EBV infection. Interestingly, several HGF(+) dendritic-reticulum cells were found scattered around c-MET(+) RS cells. The mean +/- SEM serum HGF levels in HD patients at diagnosis and at the time of relapse were 1403 +/- 91 (95% confidence interval [CI], 1221-1585) and 1497 +/- 242 pg/mL (95% CI, 977-2017), respectively. HGF values were significantly higher than those of healthy individuals (665 +/- 28 pg/mL; 95% CI, 600-721; and P <.001 for both groups of patients) and of HD patients in remission (616 +/- 49 pg/mL; 95% CI, 517-714; and P <.001 for both groups of patients). A significant correlation was found between serum HGF levels and B symptoms at diagnosis (P =.014). In conclusion, this study indicates that HGF and c-MET constitute an additional signaling pathway between RS cells and the reactive cellular background, thereby affecting adhesion, proliferation, and survival of RS cells. Furthermore, the serum concentration of HGF in HD patients may be a useful tool in monitoring the status of disease.

Hodgkin/Reed-Sternberg Cells Induce Fibroblasts to Secrete Eotaxin, a Potent Chemoattractant for T Cells and Eosinophils

Hodgkin’s disease is histopathologically characterized by the relative scarcity of neoplastic Hodgkin and Reed-Sternberg cells and for yet unknown reasons by an abundant reactive background of T lymphocytes and often eosinophils. Eotaxin is a CC-chemokine attracting eosinophils and T helper 2 (Th2) cells in allergic inflammation. We now report that eotaxin is strongly expressed in fibroblasts of Hodgkin’s disease tissues, whereas Hodgkin/Reed-Sternberg cells do not express this chemokine. In tissue culture, Hodgkin’s disease tumor cells induce eotaxin expression in cocultured dermal fibroblasts in a concentration leading to a specific chemotactic response of a Th2 cell clone. Production of tumor necrosis factor- (TNF-) by Hodgkin/Reed-Sternberg cells appears to be responsible for this induction, because blocking of TNF- by neutralizing antibodies prevented fibroblast eotaxin expression. Our data suggest that eotaxin is involved in the pathobiology of Hodgkin’s disease by contributing to eosinophil and T-lymphocyte recruitment.

Hodgkin/Reed-Sternberg Cells Induce Fibroblasts to Secrete Eotaxin, a Potent Chemoattractant for T Cells and Eosinophils

Hodgkin’s disease is histopathologically characterized by the relative scarcity of neoplastic Hodgkin and Reed-Sternberg cells and for yet unknown reasons by an abundant reactive background of T lymphocytes and often eosinophils. Eotaxin is a CC-chemokine attracting eosinophils and T helper 2 (Th2) cells in allergic inflammation. We now report that eotaxin is strongly expressed in fibroblasts of Hodgkin’s disease tissues, whereas Hodgkin/Reed-Sternberg cells do not express this chemokine. In tissue culture, Hodgkin’s disease tumor cells induce eotaxin expression in cocultured dermal fibroblasts in a concentration leading to a specific chemotactic response of a Th2 cell clone. Production of tumor necrosis factor- (TNF-) by Hodgkin/Reed-Sternberg cells appears to be responsible for this induction, because blocking of TNF- by neutralizing antibodies prevented fibroblast eotaxin expression. Our data suggest that eotaxin is involved in the pathobiology of Hodgkin’s disease by contributing to eosinophil and T-lymphocyte recruitment.