Studies on the role of basic fibroblast growth factor in vivo: Inability of neutralizing antibodies to block tumor growth

Affinity‐purified polyclonal rabbit antibodies prepared against recombinant basic fibroblast growth factor (bFGF) neutralized the ability of bFGF to stimulate plasminogen activator (PA) production and endothelial cell migration in vitro. After iodination and intraperitoneal injection of the antibodies in mice, approximately 76% of the maximum circulating level of ¹²⁵l‐anti‐bFGF antibodies (AF) was found as intact IgG after 24 hr. Furthermore, the circulating ¹²⁵I‐AF retained the ability to bind bFGF. Studies were performed to determine whether the growth of three different murine tumors (CT26, EHS, or B16/BL6) could be inhibited with affinity‐purified neutralizing antibodies against bFGF. Tumors were injected subcutaneously in syngeneic mice, and neutralizing antibodies against bFGF were injected daily into the peritoneum. All studies, which varied in tumor burden, antibody dose, and study length, indicated that neutralizing antibod es against bFGF had no effect on tumor size, tumor growth, or tumor histology.