Update of the preclinical situation of anticancer platinum complexes: Novel design strategies and innovative analytical approaches

Research in the field of bioinorganic chemistry has been stimulated by the worldwide success of the anticancer drug cisplatin. 40 years after the first report about its biological activity, carboplatin and oxaliplatin are in routine clinical use today, whereas nedaplatin, lobaplatin, and heptaplatin (SK12053R) are only approved in Japan, China, and South Korea, respectively. Up to now, about 35 platinum complexes entered clinical trials in order to circumvent the side-effects and the problem of tumor resistance to cisplatin. Additionally, improvement of tumor selectivity as well as the need for a broader spectrum of indications are the motivations for tremendous efforts in the development of novel anticancer platinum-based drugs. New synthetic strategies and innovative analytical approaches provide a basis for a deeper understanding of the pharmacological profile of cisplatin and analogues (biodistribution, clearance, detoxification, side-effects, tumor specificity, cellular uptake, acquired or intrinsic resistance, platinum-DNA adduct removal by the cellular machinery) and give rise to a rational design of promising anticancer platinum coordination compounds. This article reviews the recent development of preclinical platinum complexes with interesting in vitro and in vivo tumor inhibiting properties. It focuses also on innovative synthetic strategies leading to novel classes of platinum complexes. A small part of the review is dedicated to new analytical approaches which have been supplied to or emerged in this field of research.