R1530 inhibits multiple receptor tyrosine kinases involved in angiogenesis, such as VEGFR-1/2/3, PDGFR, Flt-3, and FGFR-1/2. In the presence of R1530, polyploid cancer cells underwent apoptosis or became senescent which translated into potent in vitro and in vivo efficacy. Normal proliferating cells were resistant to R1530-induced polyploidy. Mitotic checkpoint kinase BubR1 was found downregulated during R1530-induced exit from mitosis, a likely consequence of PLK4 inhibition [1]. R1530 strongly inhibited human tumor cell proliferation. Growth factor-driven proliferation of endothelial and fibroblast cells was also inhibited [2].

Showing significant tumor growth inhibition in a lung cancer xenograft model, R1530 was administered at doses ranging from once daily, weekly and twice weekly (3.125-50 mg/kg qd, 100 mg/kg qw, 100 mg/kg kg biw). Tumor regression occurred in all models treated with the maximum tolerated daily dose (50 mg/kg). Doses of 25 and 50 mg/kg qd resulted in biologically significant increases in survival in all models tested. After oral administration to nude mice, R1530 showed good tissue permeability. Exposure was dose-dependent, up to 100 mg/kg when administered orally[2].