Methodology for characterization of platinum-based drug's targeted delivery nanosystems

Conventional anticancer therapies exploiting platinum-based drugs rely principally on the intravascular injection of the therapeutic agent. The anticancer drug is distributed throughout the body by the systemic blood circulation undergoing cellular uptake, rapid clearance and excretion. Consequently, only a small portion of the platinum-based drug reaches the tumor site, which is associated with severe side effects. For this reason, targeted delivery systems are of great need since they offer enhanced and selective delivery of a drug to cancerous cells making the therapy safe and more effective. Up to date, a variety of the Pt-based drug targeted delivery systems (Pt-based DTDSs) utilizing nanomaterials have been developed and tested using a range of analytical techniques that provided essential information on their synthesis, stability, biodistribution and cytotoxicity. Here we summarize those experimental techniques indicating their applicability at different stages of the research, as well as pointing out their strengths, advantages, drawbacks and limitations. Also, the existing strategies and approaches are critically reviewed with the objective to reveal and give rise to the development of the analytical methodology suitable for reliable Pt-based DTDSs characterization which would eventually result in novel therapies and better patients' outcomes.

Stimuli-Responsive Therapeutic Metallodrugs

The success of platinum-based anticancer agents has motivated the exploration of novel metal-based drugs for several decades, whereas problems such as drug-resistance and systemic toxicity hampered their clinical applications and efficacy. Stimuli-responsiveness of some metal complexes offers a good opportunity for designing site-specific prodrugs to maximize the therapeutic efficacy and minimize the side effect of metallodrugs. This review presents a comprehensive and up-to-date overview on the therapeutic stimuli-responsive metallodrugs that have appeared in the past two decades, where stimuli such as redox, pH, enzyme, light, temperature, and so forth were involved. The compounds are classified into three major categories based on the nature of stimuli, that is, endo-stimuli-responsive metallodrugs, exo-stimuli-responsive metallodrugs, and dual-stimuli-responsive metallodrugs. Representative examples of each type are discussed in terms of structure, response mechanism, and potential medical applications. In the end, future opportunities and challenges in this field are tentatively proposed. With diverse metal complexes being introduced, the foci of this review are pointed to platinum and ruthenium complexes.

DACHPt-Loaded Unimolecular Micelles Based on Hydrophilic Dendritic Block Copolymers for Enhanced Therapy of Lung Cancer

Combining sufficient stability during circulation and desirable drug release is still a great challenge for the clinical applications of nanocarriers. To satisfy this demand, we developed a novel unimolecular micelle (UM) to deliver the antitumor agent 1,2-diaminocyclohexane-platinum(II) (DACHPt) for enhanced therapy of lung cancer. This DACHPt-loaded UM (UM/DACHPt) was formed through chelate complexation between DACHPt and a hydrophilic and biodegradable dendritic block copolymer poly(amidoamine)-polyglutamic acid-b-polyethylene glycol (PAM-PGlu-b-PEG), which was composed of generation 3 PAMAM (PAMAM-G3), polyglutamic acid, and long-circulating polymer PEG. This UM/DACHPt displayed robust stability and would effectively inhibit the undesired release under physiological condition, thus exhibiting much longer in vivo half-life than diblock copolymer micelles. With significant in vitro cell cytotoxicity to A549 lung cancer cells, this UM/DACHPt demonstrated efficient antitumor efficacy on an A549 xenograft tumor model with negligible tissue cytotocxity. Therefore, this UM/DACHPt provides a promising new strategy for lung cancer therapy.

VP, Dasgupta S, Bose K JC, Mukherjee S, Linert W, Moi SC. Benzimidazole based Pt(ii) complexes with better normal cell viability than cisplatin: synthesis, substitution behavior, cytotoxicity, DNA binding and DFT study

Water soluble Pt(ii) complexes with higher viability towards normal cells and comparable cytotoxicity to cancer cells as compared to cisplatin.

Polymeric biomaterials for the delivery of platinum-based anticancer drugs

Since cisplatin, cis-diamminedichloroplatinum(ii), received FDA approval for use in cancer treatment in 1978, platinum-based drugs have been one of the most widely used drugs for the treatment of tumors in testicles, ovaries, head and neck. However, there are concerns associated with the use of platinum-based anticancer drugs, owing to severe side effects and drug resistance. In order to overcome these limitations, various drug-delivery systems have been developed based on diverse organic and inorganic materials. In particular, the versatility of polymeric materials facilitates the tuning of drug-delivery systems to meet their primary goals. This review focuses on the progress made over the last five years in the application of polymeric nanoparticles for the delivery of platinum-based anticancer drugs. The present article not only describes the fundamental principles underlying the implementation of polymeric nanomaterials in platinum-based drug delivery, but also summarizes concepts and strategies employed in the development of drug-delivery systems.

Challenges for metals in medicine: how nanotechnology may help to shape the future

Encapsulation of the platinum(IV) prodrug mitaplatin in block copolymer nanoparticles increases drug circulation time in the blood and reduces accumulation in the kidneys, as reported by Lippard and colleagues in this issue of ACS Nano. Importantly, controlled drug release from the nanoparticles produces long-term anticancer efficacy, with the prospect of reduced side effects. We highlight the potential that such a strategy holds for the future development of metallodrugs. Metal coordination complexes offer the prospect of novel mechanisms of activity on account of their unique architectures, as well as potential activation mechanisms, including ligand substitution and metal- and ligand-centered redox properties. Nanoparticles offer exciting prospects for improving delivery, cell uptake, and targeting of metallodrugs, especially anticancer drugs, to make them more effective and safer.