Radiolabeled RGD Tracer Kinetics Annotates Differential αvβ3 Integrin Expression Linked to Cell Intrinsic and Vessel Expression

Purpose The purpose of this paper is to study the association between RGD binding kinetics and α v β 3 integrin receptor density in the complex tumor milieu. Procedures We assessed α v β 3 in vitro and by 68 Ga-DOTA-[c(RGDfK)] 2 positron emission tomography (PET) in tumors with varying α v β 3 . Results Intrinsic α v β 3 expression decreased in the order of M21 >>> MDA-MB-231 > M21L in cells. Tumor volume of distribution by PET, V T , was significantly higher in M21 compared to isogenic M21L tumors (0.40 ± 0.01 versus 0.25 ± 0.02; p