R1MAbs induce hypophosphatemia.

(A) Serum phosphate and calcium levels in male C57BL/6 mice intraperioneally injected with R1MAb1 or isotype control (Control IgG) at 3 mg/kg. HFD-fed mice were on the diet for 15 weeks at the end of the study. Serum phosphate and calcium levels were determined at 7 days post injection. N = 8 mice/group. (B) Serum phosphate and calcium levels in female db/db mice intraperioneally injected with R1MAb1, OA-R1MAb1 or isotype control (Control IgG) at 3 mg/kg. Serum phosphate and calcium levels were determined at 7 days post injection. N = 5–7 mice/group. (C) Body weight, and serum phosphate and calcium levels in male C57BL/6 mice intraperioneally injected with R1MAb2 or isotype control (Control IgG) at 1 mg/kg. Control mice were subjected to pair feeding to adjust body weight. Body weight, serum phosphate and calcium levels were determined at 48 hour post injection. N = 8 mice/group. (A–C) * p<0.01, ** p<0.005 (versus control IgG). #<0.005 versus chow-fed group with the same antibody treatment.