The design of targeted
platinum(iv)
prodrugs is a very promising approach to enhance the low selectivity of
platinum(ii) drugs towards cancerous tissue in order to reduce the impact on healthy tissue and, consequently, the often severe side-effects. Herein, we report a set of mono-functionalized cis- and
oxaliplatin-based
platinum(iv) complexes bearing a
maleimide moiety, which allows selective binding to
serum albumin in the bloodstream. This leads not only to a prolonged plasma half-life by avoidance of fast renal clearance, but also to preferential accumulation of the drug in the
tumor tissue due to the EPR-effect. Additionally, analogous
succinimide-functionalized derivatives were prepared to verify the influence of the
maleimide moiety. First experiments showed that all the
maleimide compounds are stable and also possess good
albumin-binding properties in whole serum. Further analytical studies on in vivo samples proved the highly increased plasma half-life, as well as
tumor accumulation of the
maleimide-functionalized substances. In vivo antitumor experiments with CT-26-bearing mice showed that, in contrast to the
cisplatin derivatives, the
oxaliplatin-based complexes had exceptionally better activity than the free drug resulting in the cure of the majority of treated mice. Subsequent analysis suggested that a distinctly faster reduction as well as reduced
tumor accumulation of the
cisplatin derivative might explain the worse performance compared to the
oxaliplatin(iv) complexes. Taken together, a novel lead
platinum(iv) complex with outstanding antitumor activity is presented, which will now be further developed towards clinical phase I trials.