Targeting Cancer Cells and Tumor Microenvironment in Preclinical and Clinical Models of Hodgkin Lymphoma Using the Dual PI3Kδ/γ Inhibitor RP6530.

PURPOSE: Tumor-associated macrophages (TAMs) and the hyperactivation of the PI3K/AKT pathway are involved in the pathogenesis of Hodgkin lymphoma and affect disease outcome. Because the δ and γ isoforms of PI3K are overexpressed in Hodgkin/Reed-Sternberg (HRS) cells and the tumor microenvironment (TME), we propose that the PI3Kδ/γ inhibitor RP6530 might affect both HRS cells and TME, ultimately leading to an enhanced antitumor response. EXPERIMENTAL DESIGN: Hodgkin lymphoma cell lines (L-540, KM-H2, and L-428) and primary human macrophages were used to investigate the activity of RP6530 in vitro and in vivo in Hodgkin lymphoma cell line xenografts. RESULTS: In vitro, RP6530 besides killing and inhibiting the proliferation of Hodgkin lymphoma cells, downregulated lactic acid metabolism, switching the activation of macrophages from an immunosuppressive M2-like phenotype to a more inflammatory M1-like state. By RNA sequencing, we define tumor glycolysis as a specific PI3Kδ/γ-dependent pathway implicated in the metabolic reprogramming of cancer cells. We identify the metabolic regulator pyruvate kinase M2 as the main mediator of tumor-induced immunosuppressive phenotype of macrophages. Furthermore, we show in human tumor xenografts that RP6530 repolarizes TAMs into proinflammatory macrophages and inhibits tumor vasculature, leading to tumor regression. Interestingly, patients with Hodgkin lymphoma experiencing objective responses (complete response and partial response) in a phase I trial using RP6530 showed a significant inhibition of circulating myeloid-derived suppressor cells and an average mean reduction in serum thymus and activation-regulated chemokine levels of 40% (range, 4%-76%). CONCLUSIONS: Our results support PI3Kδ/γ inhibition as a novel therapeutic strategy that targets both malignant cells and the TME to treat patients with Hodgkin lymphoma.

Expression of PIM kinases in Reed-Sternberg cells fosters immune privilege and tumor cell survival in Hodgkin lymphoma.

Reed-Sternberg (RS) cells of classical Hodgkin lymphoma (cHL) express multiple immunoregulatory proteins that shape the cHL microenvironment and allow tumor cells to evade immune surveillance. Expression of certain immunoregulatory proteins is modulated by prosurvival transcription factors, such as NFκB and STATs. Because these factors also induce expression of the oncogenic PIM1/2/3 serine/threonine kinases, and as PIMs modulate transcriptional activity of NFκB and STATs, we hypothesized that these kinases support RS cell survival and foster their immune privilege. Here, we investigated PIM1/2/3 expression in cHL and assessed their role in developing RS cell immune privilege and survival. PIM1/2/3 were ubiquitously expressed in primary and cultured RS cells, and their expression was driven by JAK-STAT and NFκB activity. Genetic or chemical PIM inhibition with a newly developed pan-PIM inhibitor, SEL24-B489, induced RS cell apoptosis. PIM inhibition decreased cap-dependent protein translation, blocked JAK-STAT signaling, and markedly attenuated NFκB-dependent gene expression. In a cHL xenograft model, SEL24-B489 delayed tumor growth by 95.8% (P = .0002). Furthermore, SEL24-B489 decreased the expression of multiple molecules engaged in developing the immunosuppressive microenvironment, including galectin-1 and PD-L1/2. In coculture experiments, T cells incubated with SEL24-B489-treated RS cells exhibited higher expression of activation markers than T cells coincubated with control RS cells. Taken together, our data indicate that PIM kinases in cHL exhibit pleiotropic effects, orchestrating tumor immune escape and supporting RS cell survival. Inhibition of PIM kinases decreases RS cell viability and disrupts signaling circuits that link these cells with their niches. Thus, PIM kinases are promising therapeutic targets in cHL.

Reed-Sternberg cells form by abscission failure in the presence of functional Aurora B kinase.

Large multinucleated Reed-Sternberg cells (RS) and large mononucleated Hodgkin cells (H) are traditionally considered to be the neoplastic population in classical Hodgkin lymphoma, (cHL) and postulated to promote the disease. However, the contribution of these larger cells to the progression of cHL remains debatable. We used established cHL cell lines and cHL cellular fractions composed of small mononucleated cells only or enriched in large RS/H cells to investigate RS/H cell origin and to characterize the cells which they derive from. We confirm that the small mononucleated cells give rise to RS/H cells, and we show that the latter proliferate significantly more slowly than the small cells. By using live-cell imaging, we demonstrate that binucleated RS cells are generated by failure of abscission when a few small cells attempt to divide. Finally, our results reveal that the small mononucleated cells are chromosomally unstable, but this is unlikely to be related to a malfunctioning chromosomal passenger protein complex. We propose that the small mononucleated cells, rather than the RS/H cells, are the main drivers of cHL.

Radiation therapy overcomes adverse prognostic role of cyclooxygenase-2 expression on Reed-Sternberg cells in early Hodgkin lymphoma.

PURPOSE: To analyze the role of radiation therapy (RT) on the adverse prognostic influence of cyclooxygenase-2 (COX-2) expression on Reed-Sternberg (RS) cells, in the setting of early Hodgkin lymphoma (HL) treated with ABVD (adriamycin, vinblastine, bleomycin, dacarbazine). METHODS AND MATERIALS: In the present study we retrospectively investigated the prognostic value of COX-2 expression in a large (n=143), uniformly treated early HL population from the Spanish Network of HL using tissue microarrays. Univariate and multivariate analyses were done, including the most recognized clinical variables and the potential role of administration of adjuvant RT. RESULTS: Median age was 31 years; the expression of COX-2 defined a subgroup with significantly worse prognosis. Considering COX-2(+) patients, those who received RT had significantly better 5-year progression-free survival (PFS) (80% vs 54% if no RT; P=.008). In contrast, COX-2(-) patients only had a modest, nonsignificant benefit from RT in terms of 5-year PFS (90% vs 79%; P=.13). When we compared the outcome of patients receiving RT considering the expression of COX-2 on RS cells, we found a nonsignificant 10% difference in terms of PFS between COX-2(+) and COX-2(-) patients (P=.09), whereas the difference between the 2 groups was important (25%) in patients not receiving RT (P=.04). CONCLUSIONS: Cyclooxygenase-2 RS cell expression is an adverse independent prognostic factor in early HL. Radiation therapy overcomes the worse prognosis associated with COX-2 expression on RS cells, acting in a chemotherapy-independent way. Cyclooxygenase-2 RS cell expression may be useful for determining patient candidates with early HL to receive consolidation with RT.

Matrix metalloproteinase-9 expression by Hodgkin-Reed-Sternberg cells is associated with reduced overall survival in young adult patients with classical Hodgkin lymphoma.

Previous studies have investigated the prognostic relevance of MMP9 in classical Hodgkin lymphoma (cHL), with negative results. However, we have found that MMP9 immunoistochemical expression by Hodgkin-Reed-Sternberg cells is associated with reduced overall survival in a subset of young adult Brazilian patients diagnosed with cHL. Additionally, we have observed that MMP9 expression by neoplastic cells in cHL is associated with EBV positivity. These results may support a rational basis for additional studies on the role of this metalloproteinase as a target for therapy in classical Hodgkin lymphoma.

Induction of endoplasmic reticulum stress by sorafenib and activation of NF-κB by lestaurtinib as a novel resistance mechanism in Hodgkin lymphoma cell lines.

Hodgkin-Reed/Sternberg (HRS) cells of classical Hodgkin lymphoma show aberrant expression and activation of several receptor tyrosine kinases (RTK) in the majority of cases. Therefore, we tested whether tyrosine kinase inhibitors (TKI) already in clinical use or late stages of clinical trials have antiproliferative effects on HRS cell lines and evaluated the targets, affected signaling pathways, and mechanisms of cell death and resistance. Sorafenib and lestaurtinib had antiproliferative effects on HRS cell lines at concentrations achievable in patients. Sorafenib inhibited platelet-derived growth factor receptor (PDGFR) α, TRKA and RON, caused decreases in total and phosphorylated amounts of several signaling molecules, and provoked caspase-3-independent cell death, most likely due to endoplasmic reticulum stress as indicated by upregulation of GADD34 and GADD153 and phosphorylation of PERK. Lestaurtinib inhibited TRKA, PDGFRα, RON, and JAK2 and had only a cytostatic effect. Besides deactivation, lestaurtinib also caused activation of signaling pathways. It caused increases in CD30L and TRAIL expression, and CD30L/CD30 signaling likely led to the observed concomitant activation of extracellular signal-regulated kinase 1/2 and the alternative NF-κB pathway. These data disclose the possible use of sorafenib for the treatment of Hodgkin lymphoma and highlight NF-κB activation as a potential novel mechanism of resistance toward TKIs.

Matrix metalloproteinase-9 is consistently expressed in Hodgkin/Reed-Sternberg cells and has no impact on survival in patients with Epstein-Barr virus (EBV)-related and non-related Hodgkin lymphoma in Brazil.

Clinical and histological features of classical Hodgkin lymphoma (cHL) are primarily due to the effects of cytokines and enzymes produced by Hodgkin/Reed-Sternberg (HRS) cells and their surrounding inflammatory cells. In EBV-related cancers, the expression of viral latent membrane protein 1 correlates with an increased MMP9 expression. In this study, we evaluated the prognostic relevance of MMP9 expression and EBV status in HRS cells in patients with cHL in Brazil. We selected 97 patients with cHL for EBV and MMP9 detection. EBV was detected in 52.5%, and MMP9 expression positivity was found in 87.6%. Of all cases, there was no correlation between MMP9 expression and EBV status. Response to treatment and relapse rate was independent of MMP9 expression and EBV status. MMP9 positivity did not influence overall survival and event-free survival. The consistent and increased intensity of MMP9 expression in HRS cells make this enzyme a potential target for therapy.

Expression patterns of nicotinamide phosphoribosyltransferase and nicotinic acid phosphoribosyltransferase in human malignant lymphomas.

The purpose of the study was to determine in human malignant lymphomas the expression patterns of nicotinamide phosphoribosyltransferase (NAMPT) and nicotinic acid phosphoribosyltransferase (NAPRT), the primary, rate-limiting enzymes in the synthesis of NAD+. NAMPT is a potential biomarker for sensitivity to NAMPT inhibitors and NAPRT is a biomarker for the use of nicotinic acid as a chemoprotectant in treatment with NAMPT inhibitors. The NAMPT inhibitor, APO866, is currently in clinical phase II trials in lymphomas. The expression of NAMPT and NAPRT was investigated in 53 samples of malignant lymphomas (diffuse large B-cell lymphoma, follicular B-cell lymphoma, Hodgkin's lymphoma and peripheral T-cell lymphoma). The expression of NAMPT was generally high in the more aggressive malignant lymphomas, with >80% strong expression, whereas the expression in the more indolent follicular lymphoma (FL) was significantly lower (>75% moderate or low expression, p = 0.0002). NAMPT was very highly expressed in Hodgkin Reed-Sternberg cells in Hodgkin's lymphoma. NAPRT expression was more varied (p > 0.0001) with 30-50% low expression except for Hodgkin's lymphoma where 85% displayed low expression (p = 0.0024). In conclusion, FL are a promising target for NAMPT inhibitors whereas substantial subsets of malignant lymphomas especially in Hodgkin lymphoma may be suitable for a combination treatment with nicotinic acid and NAMPT inhibitors.

Expression and prognostic significance of Cox-2 and p-53 in Hodgkin lymphomas: a retrospective study.

BACKGROUND: Cyclooxygenase (cox) is the rate-limiting enzyme, which catalyzes the conversion of arachidonic acid into prostaglandins and contributes to the inflammatory process. Cyclooxygenase-2 (cox-2), which is one of the two isoforms, plays a role in tumor progression and carcinogenesis. p53 contributes to apoptosis, DNA renewal and cell cycle. Studies concerning the relationship of cox-2 and p53 expressions and carcinogenesis are available, but the association between cox-2 and p53 in Hodgkin lymphoma (HL) is not exactly known.In our study, we examined the association of cox-2 and p53 expression, with age, stage, histopathological subtype, and survival in HL. We also examined correlation between cox-2 and p53 expression. METHODS: Cox-2 and p53 expressions in Hodgkin-Reed Sternberg cells (HRS) were examined in 54 patients with HL depending on cox-2 expression, stained cases were classified as positive, and unstained cases as negative. Nuclear staining of HRS cells with p53 was evaluated as positive. The classifications of positivity were as follows: negative if<10%; (1+) if 10-25%; (2+) if 25-50%; (3+) if 50-75%, (4+) if >75%. RESULTS: Cox-2 and p53 expressions were found in 49 (80%) and 29 (46%) patients, respectively. There were differences between histological subtypes according to cox-2 expression (p = 0.012). Mixed cellular (MC) and nodular sclerosing (NS) subtypes were seen most of the patients and cox-2 expression was evaluated mostly in the mixed cellular subtype.There were no statistically significant relationships between p53 and the histopathological subtypes; or between p53, cox-2 and the factors including stage, age and survival; or between p53 and cox-2 expression (p > 0.05). CONCLUSION: Considering the significant relationship between the cox-2 expression and the subtypes of HL, cox-2 expression is higher in MC and NS subtypes. However the difference between these two subtypes was not significant. This submission must be advocated by studies with large series.

Expression of histone deacetylases in lymphoma: implication for the development of selective inhibitors.

Unselective histone deacetylase (HDAC) inhibitors are a promising novel therapy for lymphoid malignancies. However, these treatments remain empiric as the pattern of HDAC enzymes in different types of cancer, including lymphoid malignancies, remains unknown. We examined the expression of class I and class II HDACs in a panel of cell lines and tissue sections from primary lymphoid tumours. Class I enzymes were highly expressed in all cell lines and primary tumours studied, including the non-malignant reactive cells in the Hodgkin lymphoma (HL) microenvironment. The most frequently altered HDAC expression was HDAC6, as it was either weakly expressed or undetected in 9/14 (64%) of lymphoid cell lines and in 83/89 (93%) of primary lymphoma tissue specimens, including 50/52 (96%) cases of diffuse large B-cell lymphoma, and 18/22 (82%) cases of classical HL. Cell lines that had low expression level of HDAC6 demonstrated aberrant expression of hyper-acetylated tubulin, and were found to be more sensitive to the growth inhibitory effects of the class I HDAC inhibitor MGCD0103. Collectively, our data demonstrate that HDAC6 is rarely expressed in primary lymphoma cases, suggesting that it may not be an important therapeutic target in these lymphoid malignancies.

On the biosynthesis and biological role of eoxins and 15-lipoxygenase-1 in airway inflammation and Hodgkin lymphoma.

This mini-review is focused on the enzyme 15-lipoxygenase-1 (15-LO-1) and eoxins in airway inflammatory diseases and Hodgkin lymphoma. Several studies have demonstrated increased expression and activity of 15-LO-1 in the respiratory tissue from asthma patients , indicating a pathophysiological role of this enzyme in airway inflammation. Eoxins were recently identified as pro-inflammatory metabolites of arachidonic acid, formed through the 15-LO-1 pathway, in human eosinophils, mast cells, airway epithelial cells and Hodgkin lymphoma. Mice deficient of 12/15-LO, the ortholog to human 15-LO-1, had an attenuated allergic airway inflammation compared to wild type controls, also indicating a pathophysiological role of this enzyme in respiratory inflammation. The putative therapeutic implications of 15-LO-1 inhibitors in the treatment of asthma, chronic obstructive pulmonary disorder and Hodgkin lymphoma are discussed.

Role of immunoexpression of nitric oxide synthases by Hodgkin and Reed-Sternberg cells on apoptosis deregulation and on clinical outcome of classical Hodgkin lymphoma.

Hodgkin and Reed-Sternberg (H-RS) cells of classical Hodgkin lymphoma (cHL) present an impaired expression of immunoglobulin genes, but escape apoptotic death. We investigated whether nitric oxide synthases (NOS) are expressed by H-RS cells, studied their association with EBV status and the expression of apoptotic proteins, and investigated their relationship to the clinical outcome of 171 patients. NOS1 and NOS2 were expressed in a large number of cases, whereas NOS3 expression was not detected. Positive associations were found between NOS1 and p53, bax and NOS2, bcl-2 and NOS2, bax and p53, and between bax and fasL. Inverse correlations were established between EBV and NOS2 and between EBV and bcl-2. A shorter overall survival (OS) was associated with strong expression of NOS2. In conclusion, NOS are expressed by H-RS cells of cHL.

Hodgkin Reed-Sternberg cells express 15-lipoxygenase-1 and are putative producers of eoxins in vivo: novel insight into the inflammatory features of classical Hodgkin lymphoma.

Classical Hodgkin lymphoma has unique clinical and pathological features and tumour tissue is characterized by a minority of malignant Hodgkin Reed-Sternberg cells surrounded by inflammatory cells. In the present study, we report that the Hodgkin lymphoma-derived cell line L1236 has high expression of 15-lipoxygenase-1 and that these cells readily convert arachidonic acid to eoxin C(4), eoxin D(4) and eoxin E(4). These mediators were only recently discovered in human eosinophils and mast cells and found to be potent proinflammatory mediators. Western blot and immunocytochemistry analyses of L1236 cells demonstrated that 15-lipoxygenase-1 was present mainly in the cytosol and that the enzyme translocated to the membrane upon calcium challenge. By immunohistochemistry of Hodgkin lymphoma tumour tissue, 15-lipoxygenase-1 was found to be expressed in primary Hodgkin Reed-Sternberg cells in 17 of 20 (85%) investigated biopsies. The enzyme 15-lipoxygenase-1, however, was not expressed in any of 10 biopsies representing nine different subtypes of non-Hodgkin lymphoma. In essence, the expression of 15-lipoxygenase-1 and the putative formation of eoxins by Hodgkin Reed-Sternberg cells in vivo are likely to contribute to the inflammatory features of Hodgkin lymphoma. These findings may have important diagnostic and therapeutic implications in Hodgkin lymphoma. Furthermore, the discovery of the high 15-lipoxygenase-1 activity in L1236 cells demonstrates that this cell line comprises a useful model system to study the chemical and biological roles of 15-lipoxygenase-1.

A clinicopathological study of nm23-H1 expression in classical Hodgkin's lymphoma.

BACKGROUND: We carried out immunohistochemistry to examine the expression of nm23-H1 in Hodgkin and Reed-Sternberg cells in patients with classical Hodgkin's lymphoma (CHL). PATIENTS AND METHODS: We evaluated 128 patients with CHL [87 patients with nodular sclerosis (NS) and 41 patients with mixed cellularity (MC)] for CD15, CD20, Ki-67, EBER, TIA-1, and nm23-H1 by immunohistochemistry. RESULTS: CD15 was expressed in 79%, CD20 in 11%, Ki-67 in 93%, EBER in 34%, TIA-1 in 11%, and nm23-H1 in 60% of the CHL patients. NS patients showed a significantly higher rate of nm23-H1 expression than MC patients (P < 0.001). The serum nm23-H1 level was significantly higher in patients with positive nm23 expression. Univariate analysis showed that stage IV, poor performance status, low hemoglobin level, low serum albumin level, age of 45 years or older, TIA-1-positive status, and nm23-H1-positive status were associated with significantly shorter progression-free survival. Multivariate analysis with these factors showed TIA-1 and cytoplasmic nm23-H1 expression to be significant and independent prognostic factors. CONCLUSIONS: Our results indicate that nm23-H1 expression is a prognostic factor for CHL and that it is as important as serum nm23-H1, both of which are useful for planning the treatment strategy.

Overexpressed NF-kappaB-inducing kinase contributes to the tumorigenesis of adult T-cell leukemia and Hodgkin Reed-Sternberg cells.

The nuclear factor-kappaB (NF-kappaB) transcription factors play important roles in cancer development by preventing apoptosis and facilitating the tumor cell growth. However, the precise mechanisms by which NF-kappaB is constitutively activated in specific cancer cells remain largely unknown. In our current study, we now report that NF-kappaB-inducing kinase (NIK) is overexpressed at the pretranslational level in adult T-cell leukemia (ATL) and Hodgkin Reed-Sternberg cells (H-RS) that do not express viral regulatory proteins. The overexpression of NIK causes cell transformation in rat fibroblasts, which is abolished by a super-repressor form of IkappaBalpha. Notably, depletion of NIK in ATL cells by RNA interference reduces the DNA-binding activity of NF-kappaB and NF-kappaB-dependent transcriptional activity, and efficiently suppresses tumor growth in NOD/SCID/gammac(null) mice. These results indicate that the deregulated expression of NIK plays a critical role in constitutive NF-kappaB activation in ATL and H-RS cells, and suggest also that NIK is an attractive molecular target for cancer therapy.

Expression of mast cell tryptases in Hodgkin and Reed-Sternberg (HRS) cells.

Tryptase is the most abundant protease in human mast cells, and is often used as a marker for the enumeration of mast cells in tissue. Here we report that tumour cells from Hodgkin lymphoma, the so called Hodgkin and Reed-Sternberg cells, can express tryptase. Hodgkin lymphoma cell lines expressed mRNA for both alpha- and beta-tryptase and also produced the protein, although at much lower concentrations than mast cells. However, the frequency of tryptase positive HRS-cells in situ was very low. This report demonstrates that tumour cells of lymphoid origin can express tryptase in vitro and in situ.

JunB induced by constitutive CD30-extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase signaling activates the CD30 promoter in anaplastic large cell lymphoma and reed-sternberg cells of Hodgkin lymphoma.

High expression of CD30 and JunB is characteristic of tumor cells in anaplastic large cell lymphoma (ALCL) and Hodgkin lymphoma (HL). Possible interactions of CD30 and JunB were examined in this study. We found that the CD30 promoter in tumor cells of both nucleophosmin (NPM)-anaplastic lymphoma kinase (ALK)-positive and NPM-ALK-negative ALCL and HL is regulated by a constitutively active CD30-extracellular signal-regulated kinase (ERK) 1/2 mitogen-activated protein kinase (MAPK). Phosphorylation of ERK1/2 MAPK was confirmed in nuclei of tumor cells in both ALCL and HL. CD30-ERK1/2 MAPK signals induce JunB expression, which maintains high activity of the CD30 promoter. JunB induction seems to be largely independent of nuclear factor kappaB in ALCL and HL. These results show a common mechanism of CD30 overexpression in ALCL and HL, although the outcome of CD30 signaling differs between NPM-ALK-positive ALCL and NPM-ALK-negative ALCL, cutaneous ALCL, and HL as we recently reported.

Matrix-metalloproteinases in Hodgkin lymphoma.

BACKGROUND: Classical Hodgkin lymphomas are characterized by relatively few tumour cells and prominent proliferation of plasma cells, histiocytes, lymphocytes and eosinophils. In addition there is a varying degree of sclerosis, which is especially prominent in nodular sclerosis. These morphological peculiarities led to the idea that the interaction between tumour cells and bystander cells as well as the extracellular matrix may be important in Hodgkin lymphomas. MATERIALS AND METHODS: Thirty-four classical Hodgkin lymphomas (CHL) were analysed regarding the expression of EMMPRIN, MMP-2, -7, -9, -10 and-11 using immunohistochemistry. RESULTS: The tumour cells were positive for EMMPRIN in 100% of the cases. In 82% of CHL the Hodgkin and Reed-Sternberg cells (HRS) were negative for MMP-2. In contrast the surrounding non-neoplastic cells were MMP-2-positive in 71% of the cases. The HRS cells stained positive for MMP-7 in 68% of CHL, whereas only a few surrounding cells were positive for this marker. In all but one case (97%) the HRS cells were negative for MMP-9. However, the surrounding cells stained positive in 32%, thus resembling the staining pattern for MMP-2. Only scattered cells of both populations, HRS cells as well as bystander cells, stained for MMP-10 and -11, and no specific staining pattern was observed. CONCLUSION: Our data indicate a complex interaction between tumour cells and bystander cells with regard to metalloproteinases. The expression of EMMPRIN in the tumour cells may induce the expression of MMP-2 in the surrounding non-neoplastic cells. MMP-2 can be activated by MMP-7, which is expressed in the tumour cells. It is tempting to speculate that an interruption of this cycle could be of therapeutic benefit.

Diverse role of MMP-2 and MMP-9 in the clinicopathological behavior of Hodgkin's lymphoma.

This is the first study to describe the role of MMP-2 and MMP-9 in Hodgkin's disease. Strong MMP-2 expression correlated with a favorable prognosis, while MMP-9 expression showed a tendency toward an adverse outcome. MMP-9 expression correlated with B symptoms and decreased new vessel formation. MMP-2 expression was associated with the nodular sclerosis subtype, and its expression was most pronounced in the vicinity of sclerosis. Neither of the gelatinases nor the extent of neovascularization correlated with tumor stage, the occurrence of bulky disease, or extranodal infiltrates. Together, these findings imply that the adverse role of MMP-9 may be associated with the controlling of immunological processes but not the invasion probabilities or neovascularization of the tumor. The favorable prognostic value of MMP-2 is surprising in view of the role of MMPs in solid tumors. This, however, may be linked to the basic biological differences of hematological malignancies vs. other tumors.