title: Role of crosslinking for agonistic CD40 monoclonal antibodies as immune therapy of cancer.
abstract: Agonists of the TNF superfamily of receptors hold promise as novel therapy for cancer. Recent data on agonistic anti-murine TNF receptors (TNFR) such as CD40 suggest that the specific engagement of Fc-receptor (FcR) is required for optimal antitumor effects, prompting calls to engineer anti-human CD40 and other TNFR mAb accordingly. CP-870,893 is a fully human anti-CD40 mAb, selected in part because it is an IgG2 which is presumed to have poor reactivity with FcR; however, CP-870,893 has been evaluated in multiple clinical trials with beneficial activity in patients with melanoma, pancreatic and other cancers. Here, we confirmed that the activity of anti-murine CD40 mAb was dependent on FcγRIIB engagement, was decreased significantly in FcγRIIB (-/-) mice, and upon Fc-crosslinking anti-mouse CD40 mAb enhanced the activation of antigen presenting cells. In contrast, the CP-870,893-mediated activation of human B cells was not enhanced with anti-IgG-crosslinking nor abrogated when used as an F(ab)'2 reagent. Crosslinking of CP-870,893 using the CD32-expressing K562 cells yielded an Fc-dependent modest increase in the expression of some activation markers relative to that of the soluble CP-870,893 mAb. Classic Fc-dependent functions such as antibody-dependent cellular cytotoxicity (ADCC) and complement-mediated cytotoxicity (CMC) were minimal for CP-870,893 as compared to the IgG1 anti-CD20 mAb rituximab, which mediated both ADCC and CMC in parallel assays. Anti-mouse CD40 mAb competed for the CD40 ligand binding site, but CP-870,893 did not. Thus, Fc-crosslinking is not an essential requirement for agonistic anti-human CD40 mAb, whose potency is more dependent on the CD40 epitope recognized and the strength of the signal achieved.
authors.affiliation: Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
authors.forename: Lee P
authors.initials: LP
authors.lastname: Richman
authors.affiliation: Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Vonderheide
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism / Q000494:pharmacology*; D000918:Antibody Specificity / Q000276:immunology; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D019013:CD40 Antigens / Q000819:agonists*; D004195:Disease Models, Animal; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000378:metabolism; D007167:Immunotherapy; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D009369:Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding; D017452:Receptors, IgG / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000970:Antineoplastic Agents; D019013:CD40 Antigens; C080571:Fc gamma receptor IIB; D007141:Immunoglobulin Fc Fragments; D017452:Receptors, IgG
keywords: CD40; Fc Receptor; tumor immunity