2. Academic Validation
  3. CD40/anti-CD40 antibody complexes which illustrate agonist and antagonist structural switches

CD40/anti-CD40 antibody complexes which illustrate agonist and antagonist structural switches

  • BMC Mol Cell Biol. 2019 Aug 5;20(1):29. doi: 10.1186/s12860-019-0213-4.
Maria A Argiriadi 1,  Lorenzo Benatuil 2,  Ievgeniia Dubrovska 3,  David A Egan 3,  Lei Gao 2,  Amy Greischar 3,  Jennifer Hardman 2,  John Harlan 3,  Ramesh B Iyer 3,  Russell A Judge 3,  Marc Lake 3,  Denise C Perron 2,  Ramkrishna Sadhukhan 2,  Bernhard Sielaff 2,  Silvino Sousa 2,  Rui Wang 2,  Bradford L McRae 2
Affiliations

Affiliations

  • 1 AbbVie Bioresearch Center, 381 Plantation Street, Worcester, MA, 01605, USA. [email protected].
  • 2 AbbVie Bioresearch Center, 100 Research Drive, Worcester, MA, 01605, USA.
  • 3 AbbVie Inc., 1 North Waukegan Road, North Chicago, IL, 60064, USA.
PMID: 31382872 DOI: 10.1186/s12860-019-0213-4
Abstract

Background: CD40 is a 48 kDa type I transmembrane protein that is constitutively expressed on hematopoietic cells such as dendritic cells, macrophages, and B cells. Engagement of CD40 by CD40L expressed on T cells results in the production of proinflammatory cytokines, induces T helper cell function, and promotes macrophage activation. The involvement of CD40 in chronic immune activation has resulted in CD40 being proposed as a therapeutic target for a range of chronic inflammatory diseases. CD40 antagonists are currently being explored for the treatment of autoimmune diseases and several anti-CD40 agonist mAbs have entered clinical development for oncological indications.

Results: To better understand the mode of action of anti-CD40 mAbs, we have determined the x-ray crystal structures of the ABBV-323 (anti-CD40 antagonist, ravagalimab) Fab alone, ABBV-323 Fab complexed to human CD40 and FAB516 (anti-CD40 agonist) complexed to human CD40. These three crystals structures 1) identify the conformational CD40 epitope for ABBV-323 recognition 2) illustrate conformational changes which occur in the CDRs of ABBV-323 Fab upon CD40 binding and 3) develop a structural hypothesis for an agonist/antagonist switch in the LCDR1 of this proprietary class of CD40 Antibodies.

Conclusions: The structure of ABBV-323 Fab demonstrates a unique method for antagonism by stabilizing the proposed functional antiparallel dimer for CD40 receptor via novel contacts to LCDR1, namely residue position R32 which is further supported by a closely related agonist antibody FAB516 which shows only monomeric recognition and no contacts with LCDR1 due to a mutation to L32 on LCDR1. These data provide a structural basis for the full antagonist activity of ABBV-323.

Keywords

Agonist; Antagonist; Antibody; CD40; Crystal structure.

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