Effect of VEGF blockade on CLL-cell migration on and through endothelium. (A) Percentage of CLL cells motile on HUVECs and the reduction in the number of motile cells induced by a blocking anti-VEGF mAb and by an inhibitor of VEGF receptor kinase activity (SU5416). In the presence of VEGF blockade, the residual motile CLL cells closely resembled their untreated counterparts with regard to their velocity and extent of movement. (B) Effects of these inhibitors on CCL21-dependent CLL-cell TEM, expressed as a migration index (see “Patients, materials, and methods”). When the patients were considered together as a group, the inhibition of motility/TEM with or without blocking anti-VEGF mAb or SU5416 was always significant (P always < .003). Although there was case-to-case variation in both the percentage of motile cells and migration indices, when a given case was tested on more than one occasion similar results were obtained.