Fig. 3.

In vivo efficacy and pharmacokinetics. (A) In vivo efficacy studies were performed with two 5 mg/kg i.v. doses of anti–Her2-IgG(HC-A121X)-nAF, anti–Her2-IgG alone, or DPBS against MDA-MB-435/Her2⁺ tumors in C.B-1.7/SCID mice. Anti–Her2-IgG(HC-A121X)-nAF (■) shows reduction of MDA-MB-435/Her2⁺ F-luc tumors 14 d after treatment (n = 8 mice/group; significant, P < 0.01). Tumors were implanted in the fourth mammary fat pad and sizes were monitored by longitudinal noninvasive bioluminescence imaging (IVIS 200; Caliper Life Science). (B) Dose effects were observed with a single injection of 5 mg/kg, 1 mg/kg, and 0.2 mg/kg (n = 8 mice/group). The 5-mg/kg group (■) had undetectable tumor after 14 d (significant, P < 0.01), the 1-mg/kg group (□) decreased the tumor, and 0.2 mg/kg (○) showed no difference from DPBS control. (C) MDA-MB-435/Her2⁻ cells were treated in a similar manner with a single dose of 5 mg/kg anti–Her2-IgG-nAF. No regression of tumor was observed, and the growth curve was similar to that of DPBS control. (D) Pharmacokinetics study of serum concentration versus time of anti–Her2-IgG-nAF and anti–Her2-IgG in male Sprague–Dawley rats (n = 5 rats/group). Compound was injected at 1 mg/kg intravenously at time 0 and blood was collected at regular intervals for 14 d. Serum concentration was determined by capturing antibody with ErbB2 receptor protein and detecting with biotinylated anti–κ-antibody using 96-well ElectroChemiLuminescent technology (Meso Scale Discovery). The IgG-nAF (■) was not different from unconjugated mutant IgG alone (○). Datapoints represent mean and error bars represent SEM.