Design of GFB-111, a platelet-derived growth factor binding molecule with antiangiogenic and anticancer activity against human tumors in mice

We have designed a molecule, GFB-111, that binds to platelet-derived growth factor (PDGF), prevents it from binding to its receptor tyrosine kinase, and blocks PDGF-induced receptor autophosphorylation, activation of Erk1 and Erk2 kinases, and DNA synthesis. GFB-111 is highly potent (IC₅₀ = 250 nM) and selective for PDGF over EGF, IGF-1, aFGF, bFGF, and HRGβ (IC₅₀ values > 100 μM), but inhibits VEGF-induced Flk-1 tyrosine phosphorylation and Erk1/Erk2 activation with an IC₅₀ of 10 μM. GFB-111 treatment of nude mice bearing human tumors resulted in significant inhibition of tumor growth and angiogenesis. The results demonstrate the feasibility of designing novel growth factor-binding molecules with potent anticancer and antiangiogenic activity.