GPNMB: exploring a novel target for therapy in Hodgkin lymphoma

Glycoprotein non-metastatic melanoma protein B (GPNMB) is a transmembrane protein highly expressed in multiple tumours, including classical Hodgkin lymphoma (cHL); a tumour in which the malignant Hodgkin and Reed-Sternberg (HRS) cells rely on the tumour microenvironment (TME) to survive and evade detection by the host immune system. In this study, I explore the contribution of GPNMB to immune evasion of cHL as a novel therapeutic target. I have shown that GPNMB is highly expressed in tumour-associated macrophages (TAM) in cHL tissues but expression is highly variable. In vitro differentiation of macrophages (from CD14$^+$ monocytes) was shown to be associated with an increase in GPNMB expression, including the generation of a soluble form of GPNMB (sGPNMB). sGPNMB partially inhibited T-cell activation and T-cell recognition of Epstein-Barr virus (EBV)-specific epitopes in cHL cell lines. Preliminary experiments indicated that the inhibition of T cell activation by GPNMB could be overcome with GPNMB neutralising antibodies. This work provides evidence in support of the hypothesis that GPNMB can mediate an immune checkpoint that inhibits anti-tumour cytotoxic T-lymphocytes (CTL). It provides a basis for further investigations designed to explore the therapeutic potential of targeting GPNMB in cHL

The Oncogenic Lipid Sphingosine-1-Phosphate Impedes the Phagocytosis of Tumor Cells by M1 Macrophages in Diffuse Large B Cell Lymphoma

Background: A total of 30–40% of diffuse large B cell lymphoma (DLBCL) patients will either not respond to the standard therapy or their disease will recur. The first-line treatment for DLBCL is rituximab and combination chemotherapy. This treatment involves the chemotherapy-induced recruitment of tumor-associated macrophages that recognize and kill rituximab-opsonized DLBCL cells. However, we lack insights into the factors responsible for the recruitment and functionality of macrophages in DLBCL tumors. Methods: We have studied the effects of the immunomodulatory lipid sphingosine-1-phosphate (S1P) on macrophage activity in DLBCL, both in vitro and in animal models. Results: We show that tumor-derived S1P mediates the chemoattraction of both monocytes and macrophages in vitro and in animal models, an effect that is dependent upon the S1P receptor S1PR1. However, S1P inhibited M1 macrophage-mediated phagocytosis of DLBCL tumor cells opsonized with the CD20 monoclonal antibodies rituximab and ofatumumab, an effect that could be reversed by an S1PR1 inhibitor. Conclusions: Our data show that S1P signaling can modulate macrophage recruitment and tumor cell killing by anti-CD20 monoclonal antibodies in DLBCL. The administration of S1PR1 inhibitors could enhance the phagocytosis of tumor cells and improve outcomes for patients

Defects in NK cell immunity of pediatric cancer patients revealed by deep immune profiling

Systemic immunity plays an important role in cancer immune surveillance and response to therapy, but little is known about the immune status of children with solid cancers. We performed a high-dimensional single-cell analysis of systemic immunity in 50 treatment-naïve pediatric cancer patients, comparing them to age-matched healthy children. Children with cancer had a lower frequency of peripheral NK cells, which was not due to tumour sequestration, had lower surface levels of activating receptors and increased levels of the inhibitory NKG2A receptor. Furthermore, the NK cells of pediatric cancer patients were less mature and less cytotoxic when tested in vitro. Culture of these NK cells with interleukin-2 restored their cytotoxicity. Collectively, our data show that NK cells in pediatric cancer patients are impaired through multiple mechanisms and identifies rational strategies to restore their functionality

The Oncogenic lipid sphingosine-1-phosphate impedes the phagocytosis of tumor cells by M1 macrophages in diffuse large B cell lymphoma

Abstract: Background: A total of 30–40% of diffuse large B cell lymphoma (DLBCL) patients will either not respond to the standard therapy or their disease will recur. The first-line treatment for DLBCL is rituximab and combination chemotherapy. This treatment involves the chemotherapy-induced recruitment of tumor-associated macrophages that recognize and kill rituximab-opsonized DLBCL cells. However, we lack insights into the factors responsible for the recruitment and functionality of macrophages in DLBCL tumors. Methods: We have studied the effects of the immunomodulatory lipid sphingosine-1-phosphate (S1P) on macrophage activity in DLBCL, both in vitro and in animal models. Results: We show that tumor-derived S1P mediates the chemoattraction of both monocytes and macrophages in vitro and in animal models, an effect that is dependent upon the S1P receptor S1PR1. However, S1P inhibited M1 macrophage-mediated phagocytosis of DLBCL tumor cells opsonized with the CD20 monoclonal antibodies rituximab and ofatumumab, an effect that could be reversed by an S1PR1 inhibitor. Conclusions: Our data show that S1P signaling can modulate macrophage recruitment and tumor cell killing by anti-CD20 monoclonal antibodies in DLBCL The administration of S1PR1 inhibitors could enhance the phagocytosis of tumor cells and improve outcomes for patients.</p

Defects in NK cell immunity of pediatric cancer patients revealed by deep immune profiling

Systemic immunity plays an important role in cancer immune surveillance and response to therapy, but little is known about the immune status of children with solid cancers. We performed a high-dimensional single-cell analysis of systemic immunity in 50 treatment-naive pediatric cancer patients, comparing them to age-matched healthy children. Children with cancer had a lower frequency of peripheral NK cells, which was not due to tumor sequestration, had lower surface levels of activating receptors and increased levels of the inhibitory NKG2A receptor. Furthermore, the natural killer (NK) cells of pediatric cancer patients were less mature and less cytotoxic when tested in vitro. Culture of these NK cells with interleukin-2 restored their cytotoxicity. Collectively, our data show that NK cells in pediatric cancer patients are impaired through multiple mechanisms and identify rational strategies to restore their functionality.</p