Designing drugs against the fibroblast growth factor (FGF) pathway is complicated by the fact that there are several FGF family members with different biological activities. Blocking the hormonal FGFs causes toxicities; so, Harding et al. developed a soluble decoy receptor, FP-1039, that binds only the mitogenic FGFs. FP-1039 blocked FGF- and vascular endothelial growth factor (VEGF)-induced angiogenesis in vivo, and inhibited tumour growth in several xenograft mouse models with minimal toxicity. Xenografts of cancer cells with FGF pathway alterations were particularly sensitive to FP-1039.