Tumor growth inhibition and reduction of blood vessel density in tumors following the administration of mAb AA98. Mean tumor volumes at specific time points after injection of human hepatocarcinoma SSMC 7721 (A), leiomyosarcoma SK-LMS-1 (B), or pancreatic cancer SW1990 (C-D) cells subcutaneously into the back of BALB/c nude mice are shown. Mean tumor volumes of mice carrying human hepatocarcinoma (n = 10; P < .05), leiomyosarcoma (n = 10; P < .05), or pancreatic cancer (n = 10; P < .05) treated with mAb AA98 (A-C) or with [¹³¹I]-labeled mAb AA98 (D) (n = 10; P < .05) were significantly smaller when compared with mean tumor volumes from tumor-bearing mice treated with isotope-matched mIgG (B-C), [¹³¹I]-mIgG (D), and/or PBS (A-D) as controls (n = 10; P < .05). (E-F) Sections from a mAb AA98 or control IgG-treated hepatocellular carcinoma stained with anti-CD31 mAbs are shown. (G) The numbers of blood vessels in pancreatic tumors treated with mIgG or mAb AA98 and [¹³¹I]-mIgG or [¹³¹I]-mAb AA98 were counted from 3 sections within × 200 fields. Data are the average values of 3 high-power fields at × 200 per section. (H) Hematoxylin and eosin—stained section from a mAb AA98—treated leiomyosarcoma. Black arrows indicate blood vessels with narrowed lumen surrounded by an increased eosinophilic layer of extracellular material.