Anti-cancer ProTides: tuning the activity of BVDU phosphoramidates related to thymectacin

Based on our wide ranging knowledge of phosphoramidate ProTides as anti-viral agents we have tuned the lead anti-cancer agent thymectacin in the ester and amino acid regions and revealed a substantial enhancement in in vitro potency versus colon and prostate cancer cell lines. Twelve analogues have been reported, with yields of 29-78%. The compounds are fully characterised and data clearly reveal the presence of two phosphate diastereoisomers, as expected, in roughly equi-molar proportions. The compounds were evaluated in tissue culture versus three different tumour cell lines, using thymectacin as the control. It is notable that minor structural modification of the parent phenyl methoxyalaninyl structure of thymectacin leads to significant enhancements in potency. In particular, replacement of the methyl ester moiety in the lead by a benzyl ester gave a 175-fold boost in potency versus colon cancer HT115. This derivative emerges as a low micromolar inhibitor of HT115 cells and a new lead for further optimisation.