Titanocene dichloride and two of its derivatives (Titanocene Y and C) were tested on human umbilical vein endothelial cells (HUVEC) sprouting in a spheroid-based cellular angiogenesis assay in order to determine IC50 values of inhibition. Titanocene dichloride and Titanocene Y inhibited HUVEC sprouting in this angiogenesis assay with IC50 values of 19 microM and 4.9 microM, while Titanocene C surprisingly showed no inhibition. This classifies Titanocene dichloride as a purely anti-angiogenic anticancer drug and Titanocene C as a purely cytotoxic anticancer drug. On the other hand, Titanocene Y combines both favourable anticancer activities and seems to be the drug candidate of choice for further optimisation.