Functional activity of anti-LINGO-1 antibody opicinumab requires target engagement at a secondary binding site

MAbs. Jan-Dec 2020;12(1):1713648. doi: 10.1080/19420862.2020.1713648.

Abstract

LINGO-1 is a membrane protein of the central nervous system (CNS) that suppresses myelination of axons. Preclinical studies have revealed that blockade of LINGO-1 function leads to CNS repair in demyelinating animal models. The anti-LINGO-1 antibody Li81 (opicinumab), which blocks LINGO-1 function and shows robust remyelinating activity in animal models, is currently being investigated in a Phase 2 clinical trial as a potential treatment for individuals with relapsing forms of multiple sclerosis (AFFINITY: clinical trial.gov number NCT03222973). Li81 has the unusual feature that it contains two LINGO-1 binding sites: a classical site utilizing its complementarity-determining regions and a cryptic secondary site involving Li81 light chain framework residues that recruits a second LINGO-1 molecule only after engagement of the primary binding site. Concurrent binding at both sites leads to formation of a 2:2 complex of LINGO-1 with the Li81 antigen-binding fragment, and higher order complexes with intact Li81 antibody. To elucidate the role of the secondary binding site, we designed a series of Li81 variant constructs that eliminate it while retaining the classic site contacts. These Li81 mutants retained the high affinity binding to LINGO-1, but lost the antibody-induced oligodendrocyte progenitor cell (OPC) differentiation activity and myelination activity in OPC- dorsal root ganglion neuron cocultures seen with Li81. The mutations also attenuate antibody-induced internalization of LINGO-1 on cultured cortical neurons, OPCs, and cells over-expressing LINGO-1. Together these studies reveal that engagement at both LINGO-1 binding sites of Li81 is critical for robust functional activity of the antibody.

Keywords: LINGO-1; anti-LINGO-1 antibody; antibody engineering; cryptic site; internalization; mechanism of action; multiple sclerosis; oligodendrocyte; opicinumab; remyelination; therapeutic antibody.

MeSH terms

  • Antibodies, Monoclonal / immunology*
  • Binding Sites, Antibody / immunology*
  • Humans
  • Membrane Proteins / antagonists & inhibitors*
  • Membrane Proteins / immunology*
  • Nerve Tissue Proteins / antagonists & inhibitors*
  • Nerve Tissue Proteins / immunology*

Substances

  • Antibodies, Monoclonal
  • LINGO1 protein, human
  • Membrane Proteins
  • Nerve Tissue Proteins
  • opicinumab

Associated data

  • ClinicalTrials.gov/NCT03222973