In vivo anti-myeloma activity of hsp90 inhibition. (A) Representative results of whole-body fluorescence imaging of SCID/NOD mice injected intravenously with 5 × 10⁶ RPMI-8226/S-GFP⁺ human MM cells and receiving either 17-AAG treatment or vehicle. Imaging results obtained 4 weeks after intravenous injection of GFP⁺ MM cells indicate extensive diffuse GFP⁺ bone lesions (arrows) in the spine, skull, lower extremities, and pelvis, as well as subcutaneous GFP⁺ lesions in the control cohort, in marked contrast to the absence of MM lesions in 17-AAG-treated mice. (B) Kaplan-Meier survival curve of 17-AAG-treated vs. control SCID/NOD mice injected intravenously with RPMI-8226/S-GFP⁺ cells. 17-AAG treatment significantly prolonged median overall survival of mice (> 250 days, with 14/20 of 17-AAG-treated mice surviving at the last interim analysis, vs 29 days median overall survival for control mice, with 0/20 mice surviving) (P < .001, log-rank test).