FIG. 3.

Comparison of CD20-targeting conventional RIT and PRIT in human lymphoma xenografts. Gamma camera images of Ramos xenograft-bearing athymic mice injected with either directly ¹¹¹In-labeled anti-CD20 antibody (1F5; at left) or pretargeted 1F5–streptavidin conjugate followed 24 hours later by a clearing agent and then by ¹¹¹In-1,4,7,10-tetraazacyclododecane-N,N′,N′′,N′′′-tetraacetic-biotin (at right). Arrows indicate radioactivity in tumors (T) and blood pool (B) at 24 hours after injection of ¹¹¹In-reagents. Bladder activity is also seen in the conventional RIT mouse. Reproduced with permission from Subbiah et al.⁸⁴ RIT, radioimmunotherapy; PRIT, pretargeted RIT.