DSP107 combines inhibition of CD47/SIRPα axis with activation of 4-1BB to trigger anticancer immunity.

BACKGROUND: Treatment of Diffuse Large B Cell Lymphoma (DLBCL) patients with rituximab and the CHOP treatment regimen is associated with frequent intrinsic and acquired resistance. However, treatment with a CD47 monoclonal antibody in combination with rituximab yielded high objective response rates in patients with relapsed/refractory DLBCL in a phase I trial. Here, we report on a new bispecific and fully human fusion protein comprising the extracellular domains of SIRPα and 4-1BBL, termed DSP107, for the treatment of DLBCL. DSP107 blocks the CD47:SIRPα 'don't eat me' signaling axis on phagocytes and promotes innate anticancer immunity. At the same time, CD47-specific binding of DSP107 enables activation of the costimulatory receptor 4-1BB on activated T cells, thereby, augmenting anticancer T cell immunity. METHODS: Using macrophages, polymorphonuclear neutrophils (PMNs), and T cells of healthy donors and DLBCL patients, DSP107-mediated reactivation of immune cells against B cell lymphoma cell lines and primary patient-derived blasts was studied with phagocytosis assays, T cell activation and cytotoxicity assays. DSP107 anticancer activity was further evaluated in a DLBCL xenograft mouse model and safety was evaluated in cynomolgus monkey. RESULTS: Treatment with DSP107 alone or in combination with rituximab significantly increased macrophage- and PMN-mediated phagocytosis and trogocytosis, respectively, of DLBCL cell lines and primary patient-derived blasts. Further, prolonged treatment of in vitro macrophage/cancer cell co-cultures with DSP107 and rituximab decreased cancer cell number by up to 85%. DSP107 treatment activated 4-1BB-mediated costimulatory signaling by HT1080.4-1BB reporter cells, which was strictly dependent on the SIRPα-mediated binding of DSP107 to CD47. In mixed cultures with CD47-expressing cancer cells, DSP107 augmented T cell cytotoxicity in vitro in an effector-to-target ratio-dependent manner. In mice with established SUDHL6 xenografts, the treatment with human PBMCs and DSP107 strongly reduced tumor size compared to treatment with PBMCs alone and increased the number of tumor-infiltrated T cells. Finally, DSP107 had an excellent safety profile in cynomolgus monkeys. CONCLUSIONS: DSP107 effectively (re)activated innate and adaptive anticancer immune responses and may be of therapeutic use alone and in combination with rituximab for the treatment of DLBCL patients.

Phenotypic knock out of heparan sulfates in myotubes impairs excitation-induced calcium spiking.

Little is known about the physiological functions of heparan sulfates (HSs), which are present in the basal lamina surrounding skeletal muscle fibers. Here, we present a new system in which HS is phenotypically knocked out by endogenous expression of epitope-specific anti-HS antibodies. Single-chain antibodies, containing an immunoglobulin leader peptide, were produced by using various expression systems. Antibodies were detected in the Golgi apparatus, the site of HS biosynthesis. Likewise, the HS-degrading enzyme heparanase was expressed. Endogenous expression of antibodies or heparanase in myoblasts resulted in HS-defective myotubes. Excitability and calcium kinetics of HS-defective myotubes were severely compromised, as determined by analysis of electrically induced calcium spikes via video-speed UV confocal laser scanning microscopy. Phenotypically knocking out of individual HS epitopes resulted in specific effects on excitability and calcium kinetics. These data indicate important roles for HSs in skeletal muscle calcium kinetics.

Decreased expression of heparanase in glioblastoma multiforme.

OBJECT: The authors investigated the presence of endoglycosidase heparanase in human glioblastoma multiforme (GBM) and metastatic brain tumors as well as in healthy brain tissue to explore the relationship between the biological characteristics of GBM and the role of heparanase. METHODS: Heparanase messenger (m)RNA was almost undetectable in GBMs in vivo, whereas it was frequently seen in metastatic brain tumors according to results of reverse transcription-polymerase chain reaction (RT-PCR). Immunohistochemical analysis of paraffin-embedded tissue sections showed that neoplastic cells in metastatic brain tumors, especially in cells that invaded blood vessels, exhibit intense heparanase immunoreactivity. Heparanase was present in two highly invasive glioma cell lines, U87MG and U251MG, in vitro. These cell lines did not have metastatic capability, which was tested in an experimental pulmonary metastases model in mice. The activity of heparanase in these cell lines was almost the same as that in the highly metastatic melanoma cell line B16-F1. After nude mice were inoculated with U87MG cells, however, heparanase was no longer detected in subcutaneous or intracerebral experimental glioma in vivo based on results of immunohistochemical analysis. According to results of real-time quantitative PCR, there was a 10-fold increase in heparanase mRNA in U87MG glioma cells in vitro compared with that in experimental U87MG glioma tissue in vivo in nude mice. CONCLUSIONS: These results indicate that the expression of heparanase was downregulated in GBM in vivo, which rarely metastasizes to distant organs outside the central nervous system. Heparanase is not implicated in the invasiveness of GBM to surrounding healthy brain tissue in vivo.

[Clinical significance of heparanase and basic fibroblast growth factor expression in human non-small cell lung cancer].

OBJECTIVE: To assess protein and mRNA expression levels of heparanase and basic fibroblast growth factor (bFGF) genes in human non-small cell lung cancer (NSCLC) and their roles in tumor invasion, metastasis and prognosis. METHODS: A total of 115 paraffin-embedded and 45 fresh-frozen tissue specimens of NSCLC were studied by immunohistochemistry, Western Blot and in situ hybridization to evaluate the protein and mRNA expression status of heparanase and bFGF genes. The data was analyzed by SPSS statistical software. RESULTS: Both human heparanase and bFGF were highly expressed in NSCLC cells, in contrast to none or a low expression in normal lung tissue. Expression of heparanase also showed a significantly higher than that in the normal tissue by Western blot (P = 0.041). Immunohistochemistry showed that heparanase expression was both cytoplasmic and membranous. The agreement between heparanase and bFGF was significant. A significant correlation was found between the expression of either protein and TNM stage, vascular invasion, lymphatic metastasis and microvascular density (MVD). Co-expression of the two proteins demonstrated an even higher correlation with the tumor stage and MVD. In addition, expression of bFGF correlated with tumor cell differentiation. Data of a multivariate analysis indicated that tumor cell differentiation, vascular invasion, lymphatic metastasis and expression of bFGF were identified as significant prognostic parameters. CONCLUSIONS: Both heparanase and bFGF may play important roles in tumor angiogenesis, metastasis, and prognosis of NSCLC.

Heparanase expression in human leukemias is restricted to acute myeloid leukemias.

OBJECTIVE: Matrix metalloproteinases and an endo-beta-D-glucuronidase (heparanase) are enzymes that degrade the protein and carbohydrate constituents of basement membranes, thereby facilitating transendothelial migration of blood-borne cells. Heparanase activity was found to correlate with the metastatic potential of solid tumors. We evaluated heparanase expression, at the levels of gene and protein expression and activity in a variety of leukemias, and compared it with normal hematopoietic cells. MATERIALS AND METHODS: Heparanase expression was evaluated in leukocytes isolated from peripheral blood of 71 patients with myeloid and lymphoid leukemias, or non-Hodgkin's lymphoma. Analysis was performed at two levels: heparanase RNA was determined by reverse transcriptase polymerase chain reaction, and heparanase protein was evaluated by immunocytochemistry and flow cytometry. RESULTS: In eight peripheral blood samples from normal donors, heparanase RNA was detected, and protein was found within the cytoplasm of granulocytes. In mononuclear cells derived from various leukemias, heparanase RNA was expressed in 14 of 15 acute myeloid leukemia (AML) samples. In contrast, cells derived from all 33 chronic lymphoblastic leukemia, all 7 non-Hodgkin's lymphoma, 7 of 8 chronic myeloid leukemia, and 6 of 8 acute lymphoblastic leukemia patients showed no detectable expression of the heparanase RNA. Heparanase protein was detected primarily within the cytoplasm of AML cells, indicating that the enzyme is produced and stored within the cytoplasm of myeloid cells, with limited expression on the cell surface. CONCLUSION: We propose that heparanase expression is associated with the myeloid lineage and may serve as an independent marker to support the identification of AMLs.

[Expression of heparanase in human non-small cell lung cancer].

BACKGROUND: To study the relationship between human heparanase expression and biological factors regarding invasion, metastasis and prognosis of human non-small cell lung cancer (NSCLC). METHODS: The expression of heparanase was assessed in 122 paraffin-embedded specimens and 38 freshly-taken tissues by immunohistochemical staining and Western blot. The relationship between heparanase expression and the clinicopathological factors was analyzed by Chi square test, multivariate analysis and Kaplan-Meier method. RESULTS: In the immunoreactive cells, staining was mainly located in cytoplasma and membrane. Human heparanase was highly expressed in lung cancer tissues (78.7%, 96/122) while negative in epithelia of normal lung tissues. The level of heparanase was remarkably higher in NSCLC than that in normal tissues ( P = 0.043 ). Expression of heparanase significantly correlated with TNM stage ( P =0.025), lymphatic metastasis ( P =0.002) and vascular invasion ( P =0.000 3). The patients with positive heparanase expression had a significantly shorter survival than those with negative heparanase expression ( P =0.000 6). In multivariate analysis, only p-TNM stage, lymphatic metastasis and vascular invasion could be considered as prognostic factors. CONCLUSIONS: Heparanase might play an important role in the development, invasion and metastasis of NSCLC. It is indicated that patients with positive heparanase expression would have a greater chance of metastasis and a poorer prognosis. However, heparanase expression is not an independent prognostic factor.

Activation, processing and trafficking of extracellular heparanase by primary human fibroblasts.

Heparanase is a heparan-sulfate-degrading endoglycosidase that has important roles in various biological processes, including angiogenesis, wound healing and metastatsis. Human heparanase is synthesized as a 65 kDa latent precursor, which is proteolytically processed into a highly active 50 kDa form. Extracellular heparanase is found in various tissues and is utilized by both normal cells and metastatic cancer cells to degrade heparan sulfate moieties in basement membranes and extracellular matrices. This study characterizes the processing and trafficking events associated with cellular activation of extracellular heparanase. We show that primary human fibroblasts are capable of binding and converting the 65 kDa heparanase precursor into its highly active 50 kDa form, concomitantly with its cytoplasmic accumulation. Heparanase uptake depends on the actin cytoskeleton integrity, resulting in a prolonged storage of the enzyme, mainly in endosomal structures. Heparanase endocytosis and its proteolytic activation are independent processes, indicating that heparanase cleavage is a cell surface event. Heparin completely inhibits heparanase endocytosis but only partially inhibits its association with the cells, suggesting that cell surface heparan sulfate moieties play a specific role in its endocytosis. Cellular binding and uptake of extracellular heparanase control its activation, clearance rate and storage within the cells.