Fig. 4.

In vivo target inhibition by Polycefin and animal survival. (a) Survival of Polycefin-treated (0.5 mg/kg body weight) and control animals. After intracranial administration of four doses of Polycefin, the animal survival time was significantly increased (p < 0.0004) compared to saline treated or Polycefin(-mAb) treated rats. (b) Immunofluorescent analysis of xenotransplanted brain tumors with anti-human mAbs to laminin α4 or β1 chains. After Polycefin treatment, the number of tumor vessels positive for either laminin chain was markedly diminished. Therefore, Polycefin inhibited the expression of both its targets and their incorporation into basement membrane by human tumor cells. Asterisks denote tumor-adjacent (normal) brain area. This area has significantly decreased cellularity (revealed by blue nuclear staining with DAPI) compared to highly cellular tumor at the left. No vascular staining is observed in tumor-adjacent area with both mAbs, because the antibodies only recognized human laminin chains. Left lower panel, a hematoxylin-eosin (H&E) stained tumor showing a sharp boundary between highly cellular tumor and surrounding brain parenchyma with significantly fewer cells. Right lower panel, staining of a serial section with a pAb to laminin α4 chain recognizing human and rat protein that reveals all vessels. Note increased vascularity and cellularity of the tumor as opposed to hypocellular surrounding tissue (asterisk) that has only scattered vessels (arrows)