title: The RAV12 monoclonal antibody recognizes the N-linked glycotope RAAG12: expression in human normal and tumor tissues.
abstract: BACKGROUND
  RAAG12 is a primate-restricted N-linked carbohydrate antigen present on multiple membrane-associated proteins. RAAG12 is recognized by the RAV12 monoclonal antibody. RAV12 binds to RAAG12-expressing gastrointestinal adenocarcinomas, modifies growth factor-mediated signaling, induces oncotic cell death in vitro, and has antitumor activity toward gastrointestinal tumor xenografts.
  
  
  OBJECTIVE
  To determine the expression pattern of RAAG12 in normal and tumor tissue to identify indications for clinical study and potential safety issues.
  
  
  METHODS
  Immunohistochemistry of 36 normal human tissues and a broad range of tumor tissues to profile RAAG12 expression.
  
  
  RESULTS
  More than 90% of colon, gastric, and pancreatic adenocarcinomas expressed RAAG12, and expression was uniform in most samples. Expression of RAAG12 at lower frequency and/or uniformity was observed in other cancers, including esophageal, ovarian, liver, breast, and prostate carcinomas and adenocarcinomas. Similar RAAG12 expression was observed between primary and metastatic colon adenocarcinomas. No staining was seen on cardiovascular, endocrine, neuromuscular, hematopoietic, or nervous system tissue from non-tumor-bearing individuals. RAAG12 was expressed on mucosal and glandular/ductal epithelium. The gastrointestinal tract mucosa and pancreatic/biliary ducts displayed the most uniform reactivity. RAAG12 exhibited differential subcellular localization in these normal, compared with tumor, tissues. Normal polarized epithelia primarily displayed apical membrane and cytoplasmic staining, whereas tumors exhibited whole membrane staining that increased with decreasing differentiation.
  
  
  CONCLUSIONS
  High expression of RAAG12 on tumors of gastrointestinal origin suggests these cancers are appropriate targets for RAV12 therapy. Differential subcellular location of RAAG12 on normal epithelia may limit accessibility of RAV12 to the subset of normal tissues that exhibit antigen expression.
authors.affiliation: Department of Pathology, MacroGenics West, Inc, South San Francisco, California 94080, USA.
authors.forename: Suzanne K
authors.initials: SK
authors.lastname: Coberly
authors.forename: Francine Z
authors.initials: FZ
authors.lastname: Chen
authors.forename: Mark P
authors.initials: MP
authors.lastname: Armanini
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.forename: Peter F
authors.initials: PF
authors.lastname: Young
authors.forename: Jennie P
authors.initials: JP
authors.lastname: Mather
authors.forename: Deryk T
authors.initials: DT
authors.lastname: Loo
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D015295:Antigens, Tumor-Associated, Carbohydrate / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009369:Neoplasms / Q000276:immunology*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000911:Antibodies, Monoclonal; D015295:Antigens, Tumor-Associated, Carbohydrate; C543696:RAAG12