Abstract 5901: A targetable secreted protein drives pancreatic cancer metastatic colonization and HIF1a nuclear retention

Abstract Pancreatic ductal adenocarcinoma (PDAC) is an increasingly diagnosed cancer that kills 90% of afflicted patients. Thus, effective systemic therapy to PDAC remains a significant unmet medical need. NPTX1 is over-expressed in in vivoselected highly metastatic pancreatic cancer cells and promotes liver metastasis: Ex vivo mRNAseq of highly metastatic human and murine PDAC liver metastatic tumors identified neuronal pentraxin 1 (NPTX1) as a cancer secreted protein that becomes over-expressed during PDAC metastatic progression. CRISPRi-based silencing of NPTX1 reduced liver metastatic tumor burden by 15-fold in the highly metastatic clones. NPTX1 is over-expressed in PDAC liver metastases and predicts survival of PDAC patients: To assess NPTX1 protein expression in situ, two independent board-certified pathologists developed an immunohistochemical (IHC) scoring system and blindly scored NPTX1 expression in a large cohort of 125 primary and 47 liver metastatic PDAC tumors obtained through the rapid-autopsy program at MSKCC. Liver metastatic samples exhibited significantly higher IHC scores than primary PDAC samples (2-fold increase). NPTX1 upregulation promotes cell growth under hypoxia: NPTX1 depletion suppressed growth of PDAC cells under hypoxia but not normoxia. Extracellular supplementation of recombinant NPTX1 was sufficient to rescue cell growth of NPTX1 depleted cells supporting the critical role of secreted NPTX1 in promoting cell growth under hypoxia. AMIGO2 is a cell surface NPTX1 receptor and mediates HIF1a nuclear retention via specific HIF1a residues: We next sought to identify the cell surface receptor for NPTX1. We reasoned that a receptor for NPTX1 may become upregulated as a feedback response to depletion of its ligand. mRNA sequencing of ex vivo NPTX1-depleted tumors identified AMIGO2. AMIGO2 promoted nuclear retention of HIF1a and conversely, its depletion drove the degradation of HIF1a. HIF1a/hypoxia reporter assay revealed that AMIGO2 depletion led to 300-fold reduction of HIF1a activity. Overexpression of a phosphomimetic construct at HIF1a serine 641 and 643, not a full length HIF1a ORF rescued AMIGO2 mediated HIF1a reporter signal reduction. Therapeutic targeting of NPTX1-AMIGO2 axis in primary and metastatic PDAC: Through phage display and mouse immunization campaigns, we identified 6 human IgG1 and 1 murine IgG1 antibodies that exhibited high affinity binding to human NPTX1. We identified anti- NPTX1 murine IgG1 antibody 31B01 (31B01) as a lead antibody that substantially and significantly suppressed liver metastatic colonization by 80% outperforming gemcitabine. We also tested the impact of 31B01 on the pancreas orthotopic tumor growth. 31B01 suppressed orthotopic patient derived organoid (PDO) growth (70% reduction), caused a regression response and dramatically extended the overall survival of treated mice harboring PDAC PDO. Citation Format: Norihiro Yamaguchi, Gloria Wu, Ethan Ravetch, Mai Takahashi, Abdul G. Khan, Akimasa Hayashi, Wenbin Mei, Dennis Hsu, Elisa de Stanchina, Ivo C. Lorenz, Christine Iacobuzio-Donahue, Sohail F. Tavazoie. A targetable secreted protein drives pancreatic cancer metastatic colonization and HIF1a nuclear retention abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts) ; 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84 (6Suppl): Abstract nr 5901.