title: Inhibition of CD73 AMP hydrolysis by a therapeutic antibody with a dual, non-competitive mechanism of action.
abstract: CD73 (ecto-5'-nucleotidase) has recently been established as a promising immuno-oncology target. Given its role in activating purinergic signaling pathways to elicit immune suppression, antagonizing CD73 (i.e., releasing the brake) offers a complimentary pathway to inducing anti-tumor immune responses. Here, we describe the mechanistic activity of a new clinical therapeutic, MEDI9447, a human monoclonal antibody that non-competitively inhibits CD73 activity. Epitope mapping, structural, and mechanistic studies revealed that MEDI9447 antagonizes CD73 through dual mechanisms of inter-CD73 dimer crosslinking and/or steric blocking that prevent CD73 from adopting a catalytically active conformation. To our knowledge, this is the first report of an antibody that inhibits an enzyme's function through 2 distinct modes of action. These results provide a finely mapped epitope that can be targeted for selective, potent, and non-competitive inhibition of CD73, as well as establish a strategy for inhibiting enzymes that function in both membrane-bound and soluble states.
authors: a Department of Antibody Discovery and Protein Engineering , MedImmune LLC , Gaithersburg , MD , USA.
authors: James C
authors: JC
authors: Geoghegan
authors: a Department of Antibody Discovery and Protein Engineering , MedImmune LLC , Gaithersburg , MD , USA.
authors: Gundo
authors: G
authors: Diedrich
authors: b Department of Analytical Biotechnology , MedImmune LLC , Gaithersburg , MD , USA.
authors: Xiaojun
authors: X
authors: Lu
authors: a Department of Antibody Discovery and Protein Engineering , MedImmune LLC , Gaithersburg , MD , USA.
authors: Kim
authors: K
authors: Rosenthal
authors: c Department of Oncology Research , MedImmune LLC , Gaithersburg , MD , USA.
authors: Kris F
authors: KF
authors: Sachsenmeier
authors: a Department of Antibody Discovery and Protein Engineering , MedImmune LLC , Gaithersburg , MD , USA.
authors: Herren
authors: H
authors: Wu
authors: a Department of Antibody Discovery and Protein Engineering , MedImmune LLC , Gaithersburg , MD , USA.
authors: William F
authors: WF
authors: Dall'Acqua
authors: a Department of Antibody Discovery and Protein Engineering , MedImmune LLC , Gaithersburg , MD , USA.
authors: Melissa M
authors: MM
authors: Damschroder
mesh_terms: D015720:5'-Nucleotidase / Q000037:antagonists & inhibitors / Q000737:chemistry; D000249:Adenosine Monophosphate / Q000737:chemistry; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D000970:Antineoplastic Agents / Q000737:chemistry*; D004791:Enzyme Inhibitors / Q000737:chemistry*; D058851:GPI-Linked Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry; D006801:Humans; D006868:Hydrolysis
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D058851:GPI-Linked Proteins; D000249:Adenosine Monophosphate; D015720:5'-Nucleotidase; C548241:NT5E protein, human
keywords: CD73; epitope mapping; hydrogen deuterium exchange; immuno-oncology; monoclonal antibody