Hodgkin's Lymphomas: A Tumor Recognized by Its Microenvironment

Epigenetic abnormalities of classical Hodgkin lymphoma and its effect on immune escape

Classical Hodgkin lymphoma (cHL) is a particular kind of malignant tumour that originates from the B cells. The malignant phenotype of cHL is, at least in part, maintained by epigenetic aberrations, which primarily consist of abnormal histone methylation and acetylation. Progress has been made in clinical trials concerning the histone deacetylases inhibitors (HDACis) in cHL. Also, some demethylation regimens could serve the purpose of preventing and treating tumours. Programmed death-ligand receptor 1 (PD-L1, CD274) inhibitors or apoptosis receptor 1 (PD-1, CD279) inhibitors are used in treating patients with relapsed cHL in recent years. Academic researches indicated that PD-1/PD-L1 inhibitors, including nivolumab and pembrolizumab, demonstrate remarkable activity in relapsed cHL. In addition, in recent years, a close association between epigenetic aberrations and immune escape has been explored in cHL. DNA methyltransferase (DNMT) inhibitors, HDACis, and immune checkpoint blockade exhibit synergistic effects. Thus, this review aims to provide an overview on the epigenetic abnormalities of cHL and its effect on immune escape, in order to explore the optimal combination approach to treat the disease. SIGNIFICANCE OF THE STUDY: Cancer Statistics 2018 reported that more than 8000 new cases of Hodgkin lymphoma were diagnosed. In recent years, PD-1/PD-L1 inhibitors for cHL have been utilized, and the therapeutic strategies of HDACis combined with PD-1/PD-L1 inhibitors have been raised. It is critical for improving the efficacy and decreasing the toxicity in treating the patients with cHL.

CD163 is a predictive biomarker for prognosis of classical Hodgkin's lymphoma in Saudi patients

Hodgkin's lymphoma (HL) is a hematological malignancy characterized by a minority of neoplastic cells outnumbered by tumor-associated macrophages (TAMs). The overexpression of the CD163 antigen by TAMs is considered to be a significant predictive biomarker for risk stratification. This is likely caused by a genetic single-nucleotide polymorphism (SNP) at the gene promoter. The aim of the present retrospective case-control study was to establish a gene expression profile of a specific biomarker for classical HL (CHL) in order to predict the outcome and survival of CHL patients in Saudi Arabia. The protein expression of CD163 on TAMs was studied using immunohistochemistry (IHC). A prognosis index was calculated for the CD163 protein to assess the risk stratification of CHL. Genotyping of selected SNPs of this antigen was performed for 100 CHL cases and controls. The analysis revealed that the CD163 protein expression level was significantly correlated with disease relapse (DR) and overall survival (OS). In addition, the CD163 index threshold (15.0) was found to be significantly correlated with the relapse rate. Among the studied CD163 SNPs, rs75608120 exhibited a significant correlation with the DR rate of CHL patients, but not with OS. The findings of the present study confirmed that CD163 is a specific marker for TAMs, and its overexpression by TAMs is significantly associated with relapse and reduced survival post-therapy. In addition, a new methodology of indexing CD163 protein expression for HL risk stratification was proposed. Thus, the present study identified a specific predictive molecular and antigenic biomarker for CHL prognosis.

The prognostic value of the myeloid-mediated immunosuppression marker Arginase-1 in classic Hodgkin lymphoma

Purpose

Neutrophilia is hallmark of classic Hodgkin Lymphoma (cHL), but its precise characterization remains elusive. We aimed at investigating the immunosuppressive role of high-density neutrophils in HL.

Experimental design

First, N-HL function was evaluated in vitro, showing increased arginase (Arg-1) expression and activity compared to healthy subjects. Second, we measured serum level of Arg-1 (s-Arg-1) by ELISA in two independent, training (N = 40) and validation (N = 78) sets.

Results

s-Arg-1 was higher in patients with advanced stage (p = 0.045), B-symptoms (p = 0.0048) and a positive FDG-PET scan after two cycles of chemotherapy (PET-2, p = 0.012). Baseline levels of s-Arg-1 > 200 ng/mL resulted in 92% sensitivity and 56% specificity to predict a positive PET-2.

Patients showing s-Arg-1 levels > 200 ng/mL had a shorter progression free survival (PFS). In multivariate analysis, PET-2 and s-Arg-1 at diagnosis were the only statistically significant prognostic variables related to PFS (respectively p = 0.0004 and p = 0.012).

Moving from PET-2 status and s-Arg-1 level we constructed a prognostic score to predict long-term treatment outcome: low s-Arg-1 and negative PET-2 scan (score 0, N = 63), with a 3-Y PFS of 89.5%; either positive PET-2 or high s-Arg-1 (score 1, N = 46) with 3-Y PFS of 67.6%, and both positive markers (score 2, N = 9) with a 3-Y PFS of 37% (p = 0.0004).

Conclusions

We conclude that N-HL are immunosuppressive through increased Arg-1 expression, a novel potential biomarker for HL prognosis.

Immunotherapy for the treatment of Hodgkin lymphoma

INTRODUCTION

Most patients with Hodgkin lymphoma (HL) enjoy durable remissions following front-line treatment but 30% of patients are refractory or relapse after first line therapy. Salvage chemotherapy followed by autologous stem cell transplantation (ASCT) can cure an additional 50-55% of relapsing patients but new treatments are needed for patients with HL who are refractory or relapse after ASCT. Immunotherapy has emerged as a promising treatment for the management of these patients. The availability of the anti-CD30 antibody brentuximab vedotin and new targeted drugs such as immune checkpoint inhibitors, show promising clinical activity in patients with HL and are important milestones for the management of patients with HL particularly for those who have progressed after standard initial therapy and ASCT. Areas covered: Overview of the results from the most relevant clinical trials including monoclonal antibody-based therapy in HL. Phase 2 and phase 3 trials including brentuximab vedotin and immune checkpoints inhibitors in patients with Hodgkin lymphoma have been reviewed. In addition, the potential impact of these new therapies in the management of patients with newly diagnosed HL has also been addressed. Expert commentary: Anti-CD30 antibody brentuximab vedotin and immune checkpoint inhibitors have shown promising results in patients with relapsed and refractory HL. Administration of these therapies earlier in the course of the disease might reduce the proportion of relapsed or refractory patients and, subsequently, minimize the number of patients undergoing high-dose therapy and autologous stem cell transplantation. We have little doubt that this will have substantial effects on the outcome for future generations of HL patients.

Where Do Programmed Death-1 Inhibitors Fit in the Management of Malignant Lymphoma?

Tumor-specific cytotoxic T cells have the capacity to target and eradicate malignant B cells in patients with Hodgkin and non-Hodgkin lymphoma; however, multiple mechanisms, including regulatory T cells, immunosuppressive ligands, and immune exhaustion, suppress an effective antitumor immune response. One mechanism that is used by malignant cells to inhibit the immune response is overexpression of programmed death ligand 1 or 2 (PD-L1 or PD-L2) on the cancer cell surface. These ligands interact with the programmed death-1 (PD-1) receptor expressed on intratumoral T cells and provide an inhibitory signal, thereby suppressing the antitumor immune response. Monoclonal antibodies that block PD-1 signaling prevent T-cell inhibition and promote a T-cell-mediated antilymphoma response. Blocking antibodies that are directed against PD-1 or PD-L1 are currently being tested in patients with lymphoma and have shown remarkable efficacy, particularly in patients with relapsed Hodgkin lymphoma. On the basis of the promising activity of this approach, PD-1 inhibitors are being used as single-agent therapy in patients with relapsed Hodgkin lymphoma, and these inhibitors are also being tested in combination with standard chemotherapy or targeted agents in ongoing clinical trials.

Novel agents in the treatment of Hodgkin lymphoma: Biological basis and clinical results

Hodgkin Lymphoma (HL) is a lymphoproliferative disorder of B cells that commonly has a favorable prognosis when treated with either combination chemotherapy and radiation therapy, or chemotherapy alone. However, the prognosis for patients who relapse, or have evidence for refractory disease, is poor and new treatments are needed for patients with progressive disease. HL has a unique tumor microenvironment consisting of a predominance of inflammatory cells and a minority of malignant Hodgkin and Reed-Sternberg (HRS) cells. This unique biology provides an opportunity for novel therapy approaches that either specifically target the malignant HRS cell or target the inflammatory tumor microenvironment. New therapies including antibody drug conjugates targeting CD30, small molecule inhibitors that inhibit critical cell signaling pathways, monoclonal antibodies that block immune checkpoints, or agents that modulate the immune microenvironment have all recently been tested in HL with significant clinical activity. Multiple clinical trials are currently ongoing testing these agents in the relapsed and refractory setting but also in earlier phases of therapy often in combination with more standard treatment.

Targeting immune checkpoints in lymphoma

PURPOSE OF REVIEW

The purpose of this article is to discuss the tumor microenvironment in lymphoma, and to review potential immune targets that are now becoming relevant because of clinical responses seen with the use of immune checkpoint inhibitors.

RECENT FINDINGS

Recent data have shown that cells within the immune microenvironment in lymphoma express programmed death ligand-1 (PD-L1) and many of the intratumoral T cells with an exhausted immune phenotype express programmed cell death-1 (PD-1). This provides a novel opportunity to inhibit the immune checkpoints and initial clinical trials utilizing antibodies that block the interaction between PD-1 and PD-L1 have demonstrated significant clinical responses in various lymphomas, including Hodgkin lymphoma.

SUMMARY

The use of immune checkpoint inhibitors, including nivolumab and pembrolizumab, in relapsed and refractory patients with lymphoma is proving highly successful. Patients with Hodgkin lymphoma, in particular, have a very high response rate to PD-1 blockade and responses in these patients appear durable.

Salvage treatment for relapsed/refractory Hodgkin lymphoma: role of allografting, brentuximab vedotin and newer agents

INTRODUCTION

Second-line, salvage chemotherapy followed by high-dose chemotherapy and autologous stem cell transplantation (AUTO-SCT) is the standard of care for patients with relapsed/refractory (R/R) Hodgkin lymphoma (HL). Approximately 50% of patients relapse after AUTO-SCT and their prognosis is generally poor. Brentuximab Vedotin (BV) has demonstrated efficacy in this setting and allogeneic (ALLO)-SCT represents an option with curative potential in this subgroup of patients.

AREAS COVERED

A systematic review has been conducted to explore the actual knowledge on ALLO-SCT, BV and newer agents in R/R HL.

EXPERT OPINION

The introduction of BV in clinical practice has significantly improved the management of post-AUTO-SCT relapses and the drug can induce durable remissions in a subset of R/R HL. Allografting select patients has been used to improve clinical outcomes and recent case series have begun to explore BV as a potential 'bridge' to allo-SCT, even though the optimal timing of ALLO-SCT after BV response remains undetermined. However, reduced tumor burden at the time of ALLO-SCT is a key factor to decrease relapse risk. Based on the unique composition of the tumor, more recently new agents such as PD-1 inhibitors have been developed. The potential role of PD-1 inhibitors with ALLO-SCT remains to be explored.

Novel agents in the therapy of Hodgkin lymphoma

Hodgkin lymphoma (HL) is a B-cell malignancy that typically has a favorable prognosis when treated with chemotherapy, often in combination with radiation therapy. The prognosis for patients whose disease relapses or is refractory, however, is far less favorable and novel therapies are needed for these patients. The unique cellular composition of HL provides a number of opportunities to target either the malignant Reed-Sternberg cell or the inflammatory tumor microenvironment. Antibody-drug conjugates targeting CD30, small molecule inhibitors of cell signaling, and antibodies that inhibit immune checkpoints, have all demonstrated activity in HL. Current and future trials are exploring the use of these agents in combination with each other and with standard chemotherapy.

Circulating myeloid-derived suppressor cells correlate with clinical outcome in Hodgkin Lymphoma patients treated up-front with a risk-adapted strategy

In the attempt to find a peripheral blood biological marker that could mirror the dysregulated microenvironment of Hodgkin Lymphoma (HL), we analysed the amount of myeloid-derived suppressor cells (MDSC), including the three main sub-types (monocytic, granulocytic and CD34 + fraction). The absolute MDSC count was investigated in 60 consecutive newly diagnosed HL patients and correlated with clinical variables at diagnosis and outcome. Patients received standard-of-care chemotherapy with the exception of interim fluorodeoxyglucose positron emission tomography (PET-2)-positive patients, who were switched early to a salvage regimen. All MDSC subsets were increased in HL patients compared to normal subjects (P < 0·0001) and were higher in non-responders. However, a strong prognostic significance was limited to immature (CD34(+) ) MDSC. A cut-off level of 0·0045 × 10(9) /l for CD34(+) MDSC resulted in 89% (95% confidence interval [CI] 52-99%) sensitivity and 92% (95% CI 81-98%) specificity. The positive predictive value to predict progression-free survival was 0·90 for PET-2 and 0·98 for CD34(+) MDSC count; the negative predictive value was 0·57 for PET-2 and 0·73 for CD34(+) MDSC. PFS was significantly shorter in patients with more than 0·0045 × 10(9) CD34(+) MDSC cells/l at diagnosis and/or PET-2 positivity (P < 0·0001). In conclusion, all circulating MDSC subsets are increased in HL; CD34(+) MDSC predict short PFS, similarly to PET-2 but with the advantage of being available at diagnosis.

Immunological deregulation in classic hodgkin lymphoma

Classic Hodgkin Lymphoma (cHL) has a unique histology since only a few neoplastic cells are surrounded by inflammatory accessory cells that in the last years have emerged as crucial players in sustaining the course of disease. In addition, recent studies suggest that the abnormal activity of these inflammatory cells (such as deregulation in regulatory T cells signaling, expansion of myeloid derived suppressor cells, HLA-G signaling and natural killer cells dysfunction) may have prognostic significance. This review is focused on summarizing recent advanced in immunological defects in cHL with translational implications.

Mechanisms of tumor escape from immune system: role of mesenchymal stromal cells

Tumor microenvironment represents the site where the tumor tries to survive and escape from immune system-mediated recognition. Indeed, to proliferate tumor cells can divert the immune response inducing the generation of myeloid derived suppressor cells and regulatory T cells which can limit the efficiency of effector antitumor lymphocytes in eliminating neoplastic cells. Many components of the tumor microenvironment can serve as a double sword for the tumor and the host. Several types of fibroblast-like cells, which herein we define mesenchymal stromal cells (MSC), secrete extracellular matrix components and surrounding the tumor mass can limit the expansion of the tumor. On the other hand, MSC can interfere with the immune recognition of tumor cells producing immunoregulatory cytokines as transforming growth factor (TGF)ß, releasing soluble ligands of the activating receptors expressed on cytolytic effector cells as decoy molecules, affecting the correct interaction among lymphocytes and tumor cells. MSC can also serve as target for the same anti-tumor effector lymphocytes or simply impede the interaction between these lymphocytes and neoplastic cells. Thus, several evidences point out the role of MSC, both in epithelial solid tumors and hematological malignancies, in regulating tumor cell growth and immune response. Herein, we review these evidences and suggest that MSC can be a suitable target for a more efficient anti-tumor therapy.

How to exploit stress-related immunity against Hodgkin's lymphoma: Targeting ERp5 and ADAM sheddases

Stress-related immunity can be activated in the course of lymphoproliferative disorders, including Hodgkin’s lymphoma, upon the interaction between killer cell lectin-like receptor subfamily K, member 1 (KLRK1, best known as NKG2D) on effector lymphocytes and NKG2D ligands (NKG2DL), such as MHC class I polypeptide-related sequence A (MICA), MICB and various UL16-binding proteins (ULBPs), on lymphoma cells. However, NKG2DLs can also bind NKG2D upon shedding, thus affecting the recognition of lymphoma cells by the immune system. The proteolytic cleavage of MICA depends on protein disulfide isomerase family A, member 6 (PDIA6, a thiol isomerase best known as ERp5) as well as on the disintegrins and metalloproteinases ADAM metallopeptidase domain 10 (ADAM10) and ADAM17, which also cleave ULPBs. These enzymes can be targeted in novel therapeutic schemes to avoid the escape of malignant cells from stress-evoked immune responses.

Intranodular clusters of activated cells with T follicular helper phenotype in nodular lymphocyte predominant Hodgkin lymphoma: a pilot study of 32 cases from Finland

In nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), little is known about the presence of intranodular clusters of cytologically activated lymphoid cells producing a moth-eaten pattern histologically. This pilot study of 32 NLPHL cases from Finland ascertained (1) the frequency of the intranodular clusters of activated lymphoid cells, (2) the immunophenotype of the activated cells, (3) the size and immunophenotype of the rosetting cells, and (4) the clinical significance of the activated cells. Histologically, intranodular clusters of activated cells produced a moth-eaten pattern in 100% (32 cases; subtle in 62.5%, overt in 37.5%). In immunostains, activated cells in subtle clusters (20 cases) were very difficult to identify. Twelve cases had overt clusters of activated cells, which were positive with CD3, CD4, PD1, CXCL13 (T follicular helper [T(FH)] phenotype), but rarely with Ki-67 and BCL2. Most activated rosetting cells had the same immunophenotype as the nonrosetting cells, except for CXCL13. Clinical presentation for all 32 Finnish patients was distinctive: 97% men, 97% with peripheral lymphadenopathy and 35.5% with stage III/IV disease. Only 22% relapsed; 97% were in remission. There was no significant clinical difference between cases with overt and subtle clusters. Intranodular activated TFH cells in NLPHL appeared to be nonproliferating and not long-living, and they were not associated with any adverse clinical outcome. Although most activated cells were TFH cells, it seemed that they were unable to increase the number of malignant cells. The pathogenetic role of the intranodular activated TFH and the small T cells in NLPHL needs further investigation.

Brentuximab Vedotin (SGN-35)

Brentuximab vedotin (SGN-35) is an antibody-drug conjugate (ADC) directed against the CD30 antigen expressed on Hodgkin lymphoma and anaplastic large cell lymphoma. SGN-35 consists of the cAC10 chimerized IgG1 monoclonal antibody SGN30, modified by the addition of a valine-citrulline dipeptide linker to permit attachment of the potent inhibitor of microtubule polymerization monomethylauristatin E (MMAE). In phase II trials, SGN-35 produced response rates of 75% in patients with Hodgkin lymphoma (n = 102) and 87% in patients with anaplastic large cell lymphoma (n = 30). Responses to SGN-35 might be related not only to the cytotoxic effect due to release of MMAE within the malignant cell but also to other effects. First, SGN-35 may signal malignant cells through CD30 ligation to deliver an apoptotic or proliferative response. The former would amplify the cytotoxicity of MMAE. A proliferative signal delivered in the context of MMAE intoxication could enhance cell death. Second, the efficacy of SGN-35, particularly in Hodgkin lymphoma, might be attributed to its effect on the tumor microenvironment. Diffusion of free MMAE from the targeted tumor cells could result in a bystander effect that kills the normal supporting cells in close proximity to the malignant cells. The elimination of T regulatory cells that inhibit cytotoxic effector cells and elimination of cells that provide growth factor support for Hodgkin/Reed-Sternberg cells could further enhance the cytotoxic activity of SGN-35. Here we review the biology of SGN-35 and the clinical effects of SGN-35 administration.