The Development of PDGF Receptor Inhibitors for the Treatment of Glioma: A Review

The platelet-derived growth factor (PDGF-A, PDGF-B, PDGF-C, PDGF-D) family is composed of homo- and hetero-dimers that are potent mitogens for a wide variety of cell types. They exert their biological effects by binding to two receptor tyrosine kinases (α- and β-PDGFR). PDGF-AA, -AB, -BB and -CC dimers bind to the α-PDGFR with high affinity, whereas PDGF-BB and -DD dimers bind to β-PDGFR. Aberrant PDGF signaling leads to increased interstitial fluid pressure, stromal cell recruitment and neo-angiogenesis in glioblastoma multiforme (GBM) due to deregulated autocrine/paracrine signaling. Therefore, targeting the PDGFR tyrosine kinase domain with small molecule tyrosine kinase inhibitors (TKIs) alone or in combination with chemotherapy may provide therapeutic benefit in GBM. Here we review PDGFR antagonists in clinical development including novel multi-targeted TKIs.