PD153035 (SU 5271) inhibits EGF-stimulated receptor autophosphorylation in A431 human epidermoid carcinoma cells, with an IC 50 of 14 nM. PD153035 (SU 5271) has little effect on PDGFR, FGFR, CSF-1 receptor, the insulin receptor, or on src tyrosine kinases at concentrations as high as 50 μM. PD153035 (SU 5271) rapidly suppresses autophosphorylation of the EGF receptor at low nanomolar concentrations in fibroblasts or in human epidermoid carcinoma cells and selectively blocks EGF-mediated cellular processes including mitogenesis, early gene expression, and oncogenic transformation. PD153035 (SU 5271) causes a dose-dependent growth inhibition of EGF receptor-positive cell lines, beginning at less than micromolar concentrations, and the IC 50 is less than 1 pM in most cases.
PD153035 (SU 5271) levels in the plasma and tumor rise to 50 and 22 μM within 15 minutes following a single i.p. dose of 80 mg/kg. While the plasma levels of PD153035 (SU 5271) falls below 1 μM by 3 hours, in the tumors it remains at micromolar concentrations for at least 12 hours. The tyrosine phosphorylation of the EGF receptor is rapidly suppressed by 80-90% in the tumors.