The present study reports findings related to two cases of PAIS with PDGF and VEGF expression following treatment with pazopanib. A case with a moderate to strong expression of PDGFR-α and -β presented a long-term stable disease when treated with pazopanib (progression-free survival, 5.8 months)...The level of PDGFR expression in the tumor tissue may therefore be predictive of pazopanib efficacy.