Extended Data Fig. 3. REGN5381 activated human NPR1-mediated cGMP production.

A, Schematic diagram of cGMP accumulation assay measuring hNPR1 activation-induced cGMP production. B, C, The activity of REGN5381 and ligand at hNPR1 was measured with HEK293/hNPR1 cells using different conditions due to the limit of quantitation for ligand at high concentrations. B, REGN5381 activated hNPR1 in the absence or presence of ligand (ANP or BNP) as measured by cGMP accumulation assays with HEK293/hNPR1 cells. Activation at higher ligand concentrations was seen, but cGMP level was not calculated due to the limit of quantitation. C, The full activity of ligand was evaluated with optimized conditions, where REGN5381 exhibited partial agonism compared to the ligand. Open symbols indicate assay conditions when no test article was added, and closed symbols indicate assay conditions when the test article was added in a range of concentrations. Key: blue solid circles, ANP; light brown solid square, BNP; brown solid triangle, REGN5381; dark grey solid diamond, REGN5381 + 40 pM ANP; grey solid circle, REGN5381 + 150 pM BNP; blue solid triangle, IgG4P; dark grey open diamond, 40 pM ANP; grey open circle, 150 pM BNP; blue open circle, dilution buffer control. ANP, atrial natriuretic peptide; BNP, brain natriuretic peptide; cGMP, cyclic guanosine monophosphate; FRET, fluorescence resonance energy transfer; GTP, guanosine triphosphate; hNPR1, human NPR1; IgG4^P, non-binding immunoglobulin G control; NPR1, natriuretic peptide receptor 1.