(A) mAb 1339 (100 μg per mouse) was injected intraperitoneal (i.p.) in SCID mice and its pharmacokinetics was evaluated by quantification of MAbs concentration in serum. After a single injection of mAb 1339, peak serum levels were observed after 24 hours and the MAbs remained in circulation for more than 15 days. (B) After injection of INA-6 MM cells directly into the human bone implant, SCID-hu mice were monitored for productiron of shuIL-6R in murine sera as a marker for MM cell growth. After the first detection of shuIL-6R, mice were injected with isotype control (100 μg per mouse, 1×/week) (n=6), mAb 1339 (100 μg per mouse, 1×/week) (n=4), dexamethasone (1mg/kg, 3×/week) (n=4), or mAb 1339 plus dexamethasone (n=4). Baseline values before treatment were not significantly different among groups.