Abstract 5291: Netrin-1 expression and targeting in multiple myeloma

Abstract

Abstract Netrin-1 was first described as an axonal chemoattractant in peripheral nervous system leading to axon outgrowth. Later on, after well characterizing its receptors, deleted in colorectal cancer (DCC) and uncoordinated-5 (UNC5), and their role in apoptosis, they were classified as dependence receptors. Dependence receptors belong to a family of receptors distinguished from other classical receptors by their capability of inducing cell death in the absence of their respective ligands. Their importance in tumorigenesis suggest that this family of receptors along with their ligands could constitute a novel target in cancer therapy. Recent studies showed upregulation of netrin-1 and its receptors in lung cancer tumors after treatment with conventional chemotherapies. The aim of our study was to analyze the expression of netrin 1 and its receptors UNC5B and DCC in multiple myeloma and to determine the impact of a monoclonal antibody targeting netrin-1 on myeloma cell lines in vitro and in vivo. This antibody, NP137, produced by NetrisPharma, is now in early phase clinical trials. In the first place, we performed a screening of various human myeloma cell lines, including AMO-1, LP-1, MM1S, RPMI8226, U266 and OPM-2, for netrin-1 and its different receptors using RT-qPCR and western blotting. We also analyzed the expression of netrin 1 and its receptors in fresh bone marrow aspirates by flow cytometry and in bone marrow biopsies using immunohistochemistry obtained from patients with multiple myeloma. Our results showed that myeloma cell lines expressed netrin-1 and its receptors DCC and UNC5B as determined both by RTqPCR and by western blotting. This expression was also analyzed in patient samples with 16 bone marrow biopsies using immunohistochemistry and in 10 fresh bone marrow aspirates by flow cytometry. Netrin-1 was identified by IHC in 6/16 samples while DCC and UNC5B were identified in all and in 13 samples, respectively. In fresh samples, both netrin-1 and its receptors were found to be more highly expressed than in normal lymphocytes. The exposure of myeloma cell lines to anti-netrin-1 humanized antibody in vitro did not induce a significant decrease in cell viability in vitro, whereas treatment of SCID mice with established RPMI8226 myeloma tumors lead to a significant reduction of tumor size in comparison to controls, suggesting a possible targeting of netrin 1 in this disease. Combination of NP137 with conventional anti-myeloma agents will be presented. In conclusion, these results suggest that netrin 1 signaling could constitute a novel original target in multiple myeloma. Citation Format: David Fahed, Kamel Chettab, Patrick Mehlen, Doriane Mathe, Anne Tourette, Morgane Denis, Alexandra Traverse-Glehen, Lionel Karlin, Charles Dumontet. Netrin-1 expression and targeting in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5291.