Fig. 2
From: Treating cat allergy with monoclonal IgG antibodies that bind allergen and prevent IgE engagement
REGN1908 and REGN1909 simultaneously bind to distinct Fel d 1 epitopes and prevent Fel d 1 binding to Fel d 1-specific IgE. a Non-competitive binding of REGN1908 and REGN1909 was assessed by first injecting nFel d 1 over a CM5 sensor surface immobilized with REGN1908 (left) or REGN1909 (right), followed by the injection of REGN1908 (light blue) or REGN1909 (dark blue). b Using hydrogen/deuterium exchange (HDX), REGN1909 protected a single peptide region in rFel d 1 (dark blue) corresponding to amino acids 32–41 of Chain 2. REGN1908 (light blue) protected two peptide regions corresponding to Chain 1 amino acids 43–47 and 57–71. Light gray lowercase sequence denotes regions not detected by HDX. Violet dots denote residues making contact with REGN1909 Fab as shown in c. c The crystal structure of rFel d 1 bound to the REGN1909 Fab is shown with chain 1 surface colored in white and chain 2 colored in gray. The HDX-protected residues are colored light blue and dark blue as in (b). Atoms making contact (distance <3.5 Å) with the REGN1909 Fab are colored violet. d Representative ELISA using IgE from 1 of 4 donors testing antibody blocking of 0.7 nM rFel d 1.mmh from binding to Fel d 1-specific IgE is shown with mean and SD plotted. e REGN1908, REGN1909, or REGN1908–1909 blocking of 200 pM nFel d 1-induced basophil activation from cat-allergic donors, measured by flow cytometry and shown as percent maximum inhibition of pErk response relative to isotype control antibody. C and C* represent independent blood donations from the same donor 2 months apart. Individual donor and antibody dose–response data are shown in Supplementary Fig. 2. f REGN1908–1909 blocking of 20 pM nFel d 1-induced basophil upregulation of CD203chi (left) or CD63hi (right) was measured by flow cytometry. Average value of duplicate wells and SD are shown. One representative donor out of 8 tested and 1 of 4 are shown for CD203c and CD63 activation, respectively. For combination studies REGN1908–1909 are combined in a 1:1 molar ratio and total antibody is plotted. Flow cytometry gating strategies are shown in Supplementary Fig. 5
