(2015) Affinity maturation of a novel antagonistic human monoclonal antibody with a long V H CDR3 targeting the Class A GPCR formyl-peptide receptor 1, mAbs, 7:1, 152-166, DOI: 10.4161/19420862.2014.985158 To link to this article: https://doi.org/10. 4161/19420862.2014 Therapeutic monoclonal antibodies targeting G-protein-coupled receptors (GPCRs) are desirable for intervention in a wide range of disease processes. The discovery of such antibodies is challenging due to a lack of stability of many GPCRs as purified proteins. We describe here the generation of Fpro0165, a human anti-formyl peptide receptor 1 (FPR1) antibody generated by variable domain engineering of an antibody derived by immunization of transgenic mice expressing human variable region genes. Antibody isolation and subsequent engineering of affinity, potency and species cross-reactivity using phage display were achieved using FPR1 expressed on HEK cells for immunization and selection, along with calcium release cellular assays for antibody screening. Fpro0165 shows full neutralization of formyl peptide-mediated activation of primary human neutrophils. A crystal structure of the Fpro0165 Fab shows a long, protruding V H CDR3 of 24 amino acids and in silico docking with a homology model of FPR1 suggests that this long V H CDR3 is critical to the predicted binding mode of the antibody. Antibody mutation studies identify the apex of the long V H CDR3 as key to mediating the species cross-reactivity profile of the antibody. This study illustrates an approach for antibody discovery and affinity engineering to typically intractable membrane proteins such as GPCRs.

Type 2 diabetes (T2D) is a complex and progressive disease requiring polypharmacy to manage hyperglycaemia and cardiovascular risk factors. However, most patients do not achieve combined treatment goals. To address this therapeutic gap, we have developed MEDI4166, a novel glucagon-like peptide-1 (GLP-1) receptor agonist peptide fused to a proprotein convertase subtilisin/kexin type 9 (PCSK9) neutralising antibody that allows for glycaemic control and low-density lipoprotein cholesterol (LDL-C) lowering in a single molecule. The fusion has been engineered to deliver sustained peptide activity in vivo in combination with reduced potency, to manage GLP-1 driven adverse effects at high dose, and a favourable manufacturability profile. MEDI4166 showed robust and sustained LDL-C lowering in cynomolgus monkeys and exhibited the anticipated GLP-1 effects in T2D mouse models. We believe MEDI4166 is a novel molecule combining long acting agonist peptide and neutralising antibody activities to deliver a unique pharmacology profile for the management of T2D.

Antibodies play an important role in therapy and investigative biomedical research. The TNF-family member Receptor Activator of NF-κB (RANK) is known for its role in bone homeostasis and is increasingly recognized as a central player in immune regulation and epithelial cell activation. However, the study of RANK biology has been hampered by missing or insufficient characterization of high affinity tools that recognize RANK. Here, we present a careful description and comparison of two antibodies, RANK-02 obtained by phage display (Newa, 2014 [1]) and R12-31 generated by immunization (Kamijo, 2006 [2]). We found that both antibodies recognized mouse RANK with high affinity, while RANK-02 and R12-31 recognized human RANK with high and lower affinities, respectively. Using a cell apoptosis assay based on stimulation of a RANK:Fas fusion protein, and a cellular NF-κB signaling assay, we showed that R12-31 was agonist for both species. R12-31 interfered little or not at all with the binding of RANKL to RANK, in contrast to RANK-02 that efficiently prevented this interaction. Depending on the assay and species, RANK-02 was either a weak agonist or a partial antagonist of RANK. Both antibodies recognized human Langerhans cells, previously shown to express RANK, while dermal dendritic cells were poorly labeled. In vivo R12-31 agonist activity was demonstrated by its ability to induce the formation of intestinal villous microfold cells in mice. This characterization of two monoclonal antibodies should now allow better evaluation of their application as therapeutic reagents and investigative tools.

Glucocorticoid-induced tumor necrosis factor receptor-related protein (GITR) is a co-stimulatory receptor, and programmed cell death protein 1 (PD-1) is an important co-inhibitory receptor involved in controlling T-cell activation and function. Preclinical studies using murine cross-reactive molecules demonstrate that the combination of an αPD-1 monoclonal antibody (mAb) with a GITR-ligand (GITRL) fusion protein can elicit synergistic antitumor activity and long-term survival benefit in syngeneic mouse tumor models. Here we describe the activity of two bispecific fusion proteins, each comprising two GITR ligand trimers fused to the Fc region of an αPD1 mAb, in an IgG1 (MEDI5771) or IgG4P (MEDI3387) format. We show that these bispecific molecules are able to concurrently engage both targets and are effective in cell-based PD-1 and GITR reporter assays, and in a range of human primary T-cell assays. Furthermore, the PD-1/GITRL FP bispecific constructs elicit T-cell responses in vitro that are at least equivalent to a combination of a) the parental molecules and b) MEDI1873 (a GITR agonist currently undergoing clinical evaluation) and an αPD-1 mAb. Moreover, using surrogate molecules we demonstrate that IV administration leads to dose-dependent pharmacodynamic responses on CD4+ and CD8+ T cells for both isotypes of the bispecific molecule. These data demonstrate that the antitumor activity for these novel molecules is equivalent to the combination of GITRL-FP and PD-1 mAb in the B16 model. In summary, the simultaneous dual targeting of PD-1 and GITR pathways mediated by these two novel bispecific molecules induces robust T-cell activity that is at least equivalent to a combination of molecules targeting these pathways, thereby demonstrating strong potential as a novel anticancer therapy. Citation Format: Simon J. Dovedi, Jonathan Seaman, Ines Osma-Garcia, Katharina Deschler, Edmund Poon, Ronald Herbst, Robert Wilkinson. Novel PD-1/GITRL bispecific fusion protein delivering concurrent T cell co-stimulation and checkpoint pathway inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3820.