Although these cases are too limited in number to draw any conclusion about the effect of targeting the VEGF/VEGFR pathway in pituitary tumors, the experience from other cancers showed that tumors may be inherently resistant or become resistant to VEGF/VEGFR inhibition, and moreover, that targeting the VEGF/VEGFR pathway may increase intra-tumor hypoxia in a dose- and time-dependent manner [8]. This evidence concerns the gene VEGFA and cancer.