A cross-linked polymeric micellar delivery system for cisplatin(IV) complex

Disruption of Iron Homeostasis to Induce Ferroptosis with Albumin-Encapsulated Pt(IV) Nanodrug for the Treatment of Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most common pathological type of lung cancer , accounting for approximately 85% of lung cancers. For more than 40 years, platinum (Pt)-based drugs are still one of the most widely used anticancer drugs even in the era of precision medicine and immunotherapy. However, the clinical limitations of Pt-based drugs, such as serious side effects and drug resistance, have not been well solved. This study constructs a new albumin-encapsulated Pt(IV) nanodrug (HSA@Pt(IV)) based on the Pt(IV) drug and nanodelivery system. The characterization of nanodrug and biological experiments demonstrate its excellent drug delivery and antitumor effects. The multi-omics analysis of the transcriptome and the ionome reveals that nanodrug can activate ferroptosis by affecting intracellular iron homeostasis in NSCLC. This study provides experimental evidence to suggest the potential of HSA@Pt(IV) as a nanodrug with clinical application.

MOF-based nanozyme grafted with cooperative Pt(IV) prodrug for synergistic anticancer therapy

Manipulating Fenton chemistry in tumor microenvironment (TME) for the generation of reactive oxygen species is an effective strategy for chemodynamic therapy. However, this is usually restricted by limited intracellular content of H₂O₂ and insufficient acidic environment at the tumor site. Herein, a ferric metal-organic framework (MOF) is covalently grafted with a prodrug of cisplatin (Pt(IV) prodrug) and loaded with a biocatalyst glucose oxidase (GOx) to afford a nanozyme MOF-Pt(IV)@GOx for cascade reactions. In this system, the attached Pt(IV) prodrug on MOF plays a significant role in the cooperative enhancement of GOx loading and chemotherapy. The high concentration of glutathione in TME reduces Fe(III) to Fe(II) for Fenton reaction, and converts Pt(IV) prodrug to cisplatin for DNA targeting and H₂O₂ production. Meanwhile, glucose oxidation catalyzed by GOx not only consumes glucose for starvation therapy, but also promotes the intracellular acidity and H₂O₂ supply in TME, which are in favor of Fenton reaction. Both in vitro and in vivo studies demonstrate that MOF-Pt(IV)@GOx enables remarkable anticancer efficacy due to the synergistic trimodal therapy consisting of ferroptosis, starvation therapy, and chemotherapy.

Polymeric Nanosystems Applied for Metal-Based Drugs and Photosensitizers Delivery: The State of the Art and Recent Advancements

Nanotechnology-based approaches for targeting the delivery and controlled release of metal-based therapeutic agents have revealed significant potential as tools for enhancing the therapeutic effect of metal-based agents and minimizing their systemic toxicities. In this context, a series of polymer-based nanosized systems designed to physically load or covalently conjugate metal-based therapeutic agents have been remarkably improving their bioavailability and anticancer efficacy. Initially, the polymeric nanocarriers were applied for platinum-based chemotherapeutic agents resulting in some nanoformulations currently in clinical tests and even in medical applications. At present, these nanoassemblies have been slowly expanding for nonplatinum-containing metal-based chemotherapeutic agents. Interestingly, for metal-based photosensitizers (PS) applied in photodynamic therapy (PDT), especially for cancer treatment, strategies employing polymeric nanocarriers have been investigated for almost 30 years. In this review, we address the polymeric nanocarrier-assisted metal-based therapeutics agent delivery systems with a specific focus on non-platinum systems; we explore some biological and physicochemical aspects of the polymer–metallodrug assembly. Finally, we summarize some recent advances in polymeric nanosystems coupled with metal-based compounds that present potential for successful clinical applications as chemotherapeutic or photosensitizing agents. We hope this review can provide a fertile ground for the innovative design of polymeric nanosystems for targeting the delivery and controlled release of metal-containing therapeutic agents.

A Theranostic Nanocomplex Combining with Magnetic Hyperthermia for Enhanced Accumulation and Efficacy of pH-Triggering Polymeric Cisplatin(IV) Prodrugs

Although polymeric platinum(IV) (Pt(IV)) prodrugs can reduce the side effects of cisplatin, the efficacy of the prodrug is still limited by its non-targeted distribution, poor penetration in deep tumor tissue, and low cytotoxicity in tumor cells. To improve the clinical potential of polymeric prodrug micelle, we synthesized amphiphilic polymeric Pt(IV) with high Pt content (22.5%), then developed a theranostic nanocomplex by integrating polymeric Pt(IV) with superparamagnetic Mn_0.6Zn_0.4Fe₂O₄ via simple self-assembly. Due to the high content of Mn_0.6Zn_0.4Fe₂O₄ (41.7% w/w), the theranostic nanocomplex showed high saturation magnetization (103.1 emu g⁻¹) and excellent magnetocaloric effect (404 W g⁻¹), both of them indicating its advantages in efficient magnetic targeting (MT), magnetic hyperthermia (MH), and magnetic resonance imaging (MRI). In vitro, in combination with MH, the theranostic nanocomplex showed as high cytotoxicity as cisplatin because of a significant increase in platinum of cellular uptake. In vivo, the accumulation of theranostic nanocomplex in tumors was increased by MT and confirmed by MRI. Furthermore, MH improved penetration of theranostic nanocomplex in tumors as expanding blackened area in tumors was observed by MRI. Based on these properties, the theranostic nanocomplex, under the assistance of MT and MH, showed the highest tumor growth inhibition rate (88.38%) after different treatments, while the body weight of mice increased slightly, indicating low side effects compared to those of cisplatin. The study provided an advanced theranostic nanocomplex with low toxicity and high efficacy, indicating a great clinical potential of polymeric Pt(IV).

Metallodrugs in cancer nanomedicine

Metal complexes are extensively used for cancer therapy. The multiple variables available for tuning (metal, ligand, and metal-ligand interaction) offer unique opportunities for drug design, and have led to a vast portfolio of metallodrugs that can display a higher diversity of functions and mechanisms of action with respect to pure organic structures. Clinically approved metallodrugs, such as cisplatin, carboplatin and oxaliplatin, are used to treat many types of cancer and play prominent roles in combination regimens, including with immunotherapy. However, metallodrugs generally suffer from poor pharmacokinetics, low levels of target site accumulation, metal-mediated off-target reactivity and development of drug resistance, which can all limit their efficacy and clinical translation. Nanomedicine has arisen as a powerful tool to help overcome these shortcomings. Several nanoformulations have already significantly improved the efficacy and reduced the toxicity of (chemo-)therapeutic drugs, including some promising metallodrug-containing nanomedicines currently in clinical trials. In this critical review, we analyse the opportunities and clinical challenges of metallodrugs, and we assess the advantages and limitations of metallodrug delivery, both from a nanocarrier and from a metal-nano interaction perspective. We describe the latest and most relevant nanomedicine formulations developed for metal complexes, and we discuss how the rational combination of coordination chemistry with nanomedicine technology can assist in promoting the clinical translation of metallodrugs.

Targeted drug delivery in cervical cancer: Current perspectives

Cervical cancer is preventable yet one of the most prevalent cancers among women around the globe. Though regular screening has resulted in the decline in incidence, the disease claims a high number of lives every year, especially in the developing countries. Owing to rather aggressive and non-specific nature of the conventional chemotherapeutics, there is a growing need for newer treatment modalities. The advent of nanotechnology has assisted in this through the use of nanocarriers for targeted drug delivery. A number of nanocarriers are continuously being developed and studied for their application in drug delivery. The present review summarises the different drug delivery approaches and nanocarriers that can be useful, their advantages and limitation.

Micelles Based on Lysine, Histidine, or Arginine: Designing Structures for Enhanced Drug Delivery

Natural amino acids and their derivatives are excellent building blocks of polymers for various biomedical applications owing to the non-toxicity, biocompatibility, and ease of multifunctionalization. In the present review, we summarized the common approaches to designing and constructing functional polymeric micelles based on basic amino acids including lysine, histidine, and arginine and highlighted their applications as drug carriers for cancer therapy. Different polypeptide architectures including linear polypeptides and dendrimers were developed for efficient drug loading and delivery. Besides, polylysine- and polyhistidine-based micelles could enable pH-responsive drug release, and polyarginine can realize enhanced membrane penetration and gas therapy by generating metabolites of nitric oxide (NO). It is worth mentioning that according to the structural or functional characteristics of basic amino acids and their derivatives, key points for designing functional micelles with excellent drug delivery efficiency are importantly elaborated in order to pave the way for exploring micelles based on basic amino acids.

Polypeptides-Drug Conjugates for Anticancer Therapy

Polypeptides are an important class of biodegradable polymers that have been widely used in drug delivery field. Owing to the controllable synthesis and robust side chain-functionalization ability, polypeptides have long been ideal candidates for conjugation with anticancer drugs. The chemical conjugation of anticancer drugs with polypeptides, termed polypeptides-drug conjugates, has demonstrated several advantages in improving pharmacokinetics, enhancing drug targeting, and controlling drug release, thereby leading to enhanced therapeutic outcomes with reduced side toxicities. This review focuses on the recent advances in the design and preparation of polypeptides-drug conjugates for enhanced anticancer therapy. Strategies for conjugation of different types of drugs, including small-molecule chemotherapeutic drugs, proteins, vascular disrupting agents, and gas molecules, onto polypeptides backbone are summarized. Finally, the challenges and future perspectives on the development of innovative polypeptides-drug conjugates for clinical cancer treatment are also presented.

Supramolecular Assembled Programmable Nanomedicine As In Situ Cancer Vaccine for Cancer Immunotherapy

Using nanotechnology for improving the immunotherapy efficiency represents a major research interest in recent years. However, there are paradoxes and obstacles in using a single nanoparticle to fulfill all the requirements in the complicated immune activation processes. Herein, a supramolecular assembled programmable immune activation nanomedicine (PIAN) for sequentially finishing multiple steps after intravenous injection and eliciting robust antitumor immunity in situ is reported. The programmable nanomedicine is constructed by supramolecular assembly via host-guest interactions between poly-[(N-2-hydroxyethyl)-aspartamide]-Pt(IV)/β-cyclodextrin (PPCD), CpG/polyamidoamine-thioketal-adamantane (CpG/PAMAM-TK-Ad), and methoxy poly(ethylene glycol)-thioketal-adamantane (mPEG-TK-Ad). After intravenous injection and accumulation at the tumor site, the high level of reactive oxygen species in the tumor microenvironment promotes PIAN dissociation and the release of PPCD (mediating tumor cell killing and antigen release) and CpG/PAMAM (mediating antigen capturing and transferring to the tumor-draining lymph nodes). This results in antigen-presenting cell activation, antigen presentation, and robust antitumor immune responses. In combination with anti-PD-L1 antibody, the PIAN cures 40% of mice in a colorectal cancer model. This PIAN provides a new framework for designing programmable nanomedicine as in situ cancer vaccine for cancer immunotherapy.

Combination Therapy of Lung Cancer Using Layer-by-Layer Cisplatin Prodrug and Curcumin Co-Encapsulated Nanomedicine

Purpose

Lung cancer remains the leading cancer-associated deaths worldwide. Cisplatin (CDDP) was used in combination with curcumin (CUR) for the treatment of non-small cell lung cancer. The aim of this study was to prepare and characterize CDDP prodrug and CUR co-encapsulated layer-by-layer nanoparticles (CDDP-PLGA/CUR LBL NPs) to induce cooperative response, maximize the therapeutic effect, overcome drug resistance, and reduce adverse side effects.

Methods

CDDP prodrug (CDDP-PLGA) was synthesized. CDDP-PLGA/CUR LBL NPs were constructed and their physicochemical properties were investigated by particle-size analysis, zeta potential measurement, drug loading, drug entrapment efficiency, and in vitro drug release behavior. In vitro cytotoxicity against human lung adenocarcinoma cell line (A549 cells) was investigated, and in vivo anti-tumor efficiency of CDDP-PLGA/CUR LBL NPs was evaluated on mice bearing A549 cell xenografts.

Results

CDDP-PLGA/CUR LBL NPs have a size of 179.6 ± 6.7 nm, a zeta potential value of −29.9 ± 3.2 mV, high drug entrapment efficiency of 85.6 ± 3.9% (CDDP) and 82.1 ± 2.8% (CUR). The drug release of LBL NPs exhibited a sustained behavior, which made it an ideal vehicle for drug delivery. Furthermore, CDDP-PLGA/CUR LBL NPs could significantly enhance in vitro cytotoxicity and in vivo antitumor effect against A549 cells and lung cancer animal model compared to the single drug-loaded LBL NPs and free drug groups.

Conclusion

CDDP-PLGA/CUR LBL NPs were reported for the first time in the combination therapy of lung cancer. The results demonstrated that the CDDP-PLGA/CUR LBL NPs might be a novel promising system for the synergetic treatment of lung carcinoma.

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.

Gastric cancer combination therapy: synthesis of a hyaluronic acid and cisplatin containing lipid prodrug coloaded with sorafenib in a nanoparticulate system to exhibit enhanced anticancer efficacy and reduced toxicity

Purpose

Gastric cancer is one of the most common human epithelial malignancies, and using nanoparticles (NPs) in the diagnosis and treatment of cancer has been extensively studied. The aim of this study was to develop hyaluronic acid (HA) containing lipid NPs coloaded with cisplatin (CDDP) and sorafenib (SRF) for the treatment of gastric cancer.

Materials and methods

HA and CDDP containing lipid prodrug was synthesized using polyethylene glycol (PEG) as a linker (HA-PEG-CDDP). HA-PEG-CDDP and SRF were entrapped into the lipid NPs by nanoprecipitation method (H-CS-NPs). The physicochemical and biochemical properties such as size, zeta potential, and drug release pattern were studied. In vitro viability was also evaluated with MKN28 and SGC7901 human gastric cancer cells. In vivo testing including biodistribution and accumulation in tumor tissue was applied in gastric tumor-bearing mice to confirm the inhibition of gastric cancer.

Results

H-CS-NP has a particle size of 173.2±5.9 nm, with a zeta potential of −21.5±3.2 mV. At day 21 of in vivo treatment, H-CS-NPs inhibited the tumor volume from 1,532.5±41.3 mm³ to 259.6±16.3 mm³ with no obvious body weight loss. In contrast, mice treated with free drugs had body weight loss from 20 to 15 g at the end of study.

Conclusion

The results indicate that H-CS-NPs enhanced the antitumor effect of drugs and reduced the systemic toxicity effects. It could be used as a promising nanomedicine for gastric cancer combination therapy.

Lung cancer targeted therapy: Folate and transferrin dual targeted, glutathione responsive nanocarriers for the delivery of cisplatin

To achieve lung cancer targeted therapy, folic acid (FA) and transferrin (Tf) modified cisplatin (CDDP) loaded nanoparticles were applied for the in vitro and in vivo evaluation. The aim of this research was to develop FA modified SS bonds based prodrug of CDDP (namely FA-ss-CDDP) and Tf modified cystamine-oleic acid (Tf-ss-OA). Further, FA-ss-CDDP and Tf-ss-OA were used to prepare NPs, which could target the lung tumor cells through receptor-mediated pathways to increase the efficiency of CDDP. FA and Tf modified CDDP loaded NPs (FA/Tf-CDDP-NPs) were constructed. The physiochemical properties, in vitro drug release profiles, in vitro cytotoxicity, and in vivo biodistribution were investigated. The antitumor effect of self-assembed NPs was evaluated both in vitro and in vivo. FA/Tf-CDDP-NPs exhibited remarkably enhanced accumulation in tumor tissue and better tumor inhibition effect in vitro and in vivo. FA/Tf-CDDP-NPs displayed almost complete suppression of tumor growth with no obviously body weight change of the treated mice. The newly constructed NPs could successfully load drugs and showed better efficiency than free drug formula; and FA/TF could function as excellent targeting ligands to improve the cell targeting ability of the NPs. The resulting FA/Tf-CDDP-NPs offered a promising tumor therapy strategy for the treatment of lung cancer.

Electrospray biodegradable microcapsules loaded with curcumin for drug delivery systems with high bioactivity

Biodegradable microcapsules as novel drug delivery systems were successfully fabricated by one-step processing using an electrospray technique.

Drug Release by Direct Jump from Poly(ethylene-glycol-b-ε-caprolactone) Nano-Vector to Cell Membrane

Drug delivery by nanovectors involves numerous processes, one of the most important being its release from the carrier. This point still remains unclear. The current work focuses on this point using poly(ethyleneglycol-b-ε-caprolactone) micelles containing either pheophorbide-a (Pheo-a) as a fluorescent probe and a phototoxic agent or fluorescent copolymers. This study showed that the cellular uptake and the phototoxicity of loaded Pheo-a are ten times higher than those of the free drug and revealed a very low cellular penetration of the fluorescence-labeled micelles. Neither loaded nor free Pheo-a displayed the same cellular localization as the labeled micelles. These results imply that the drug entered the cells without its carrier and probably without a disruption, as suggested by their stability in cell culture medium. These data allowed us to propose that Pheo-a directly migrates from the micelle to the cell without disruption of the vector. This mechanism will be discussed.

Nanoparticle formulations of cisplatin for cancer therapy

The genotoxic agent cisplatin, used alone or in combination with radiation and/or other chemotherapeutic agents, is an important first-line chemotherapy for a broad range of cancers. The clinical utility of cisplatin is limited both by intrinsic and acquired resistance and dose-limiting normal tissue toxicity. That cisplatin shows little selectivity for tumor versus normal tissue may be a critical factor limiting its value. To overcome the low therapeutic ratio of the free drug, macromolecular, liposomal, and nanoparticle drug delivery systems have been explored toward leveraging the enhanced permeability and retention effect and promoting delivery of cisplatin to tumors. Here, we survey recent advances in nanoparticle formulations of cisplatin, focusing on agents that show promise in preclinical or clinical settings. WIREs Nanomed Nanobiotechnol 2016, 8:776-791. doi: 10.1002/wnan.1390 For further resources related to this article, please visit the WIREs website.

Targeted hepatocellular carcinoma therapy: transferrin modified, self-assembled polymeric nanomedicine for co-delivery of cisplatin and doxorubicin

BACKGROUND

Targeted hepatocellular carcinoma (HCC) therapy was carried out to improve the efficacy of liver cancers. The aim of this study was to develop transferrin (Tf) modified, self-assembled polymeric nanoparticles for co-delivery doxorubicin (DOX) and cisplatin (DDP), to achieve combination tumor therapy.

METHODS

Tf modified polyethylene glycol (PEG) containing DOX prodrug (Tf-PEG-DOX) was synthesized. DDP containing poly(lactic-co-glycolic) acid (PLGA) materials (PLGA-DDP) were prepared. Tf modified DOX and DDP loaded PLGA nanoparticles (Tf-DOX/DDP NPs) were prepared by using nanoprecipitation method. The particles sizes, zeta potentials, drug loading effects were characterized. The cytotoxicity of the NPs was evaluated in human hepatoma carcinoma cell lines (HepG2 cells), and in vivo anti-tumor was observed in mice bearing human HepG2 cells model.

RESULTS

Tf-DOX/DDP NPs displayed higher cytotoxicity and enhanced antitumor activity both in vitro and in vivo over their non-modified and single drug loaded counterparts.

CONCLUSION

Tf-DOX/DDP NPs can achieve outstanding anti-tumor activity due to the combination effect of two drugs and the active targeting ability of Tf ligands. The self-assembled polymeric nanomedicine could act as an efficient therapy method for HCC treatment.

The Next Generation of Platinum Drugs: Targeted Pt(II) Agents, Nanoparticle Delivery, and Pt(IV) Prodrugs

The platinum drugs, cisplatin, carboplatin, and oxaliplatin, prevail in the treatment of cancer, but new platinum agents have been very slow to enter the clinic. Recently, however, there has been a surge of activity, based on a great deal of mechanistic information, aimed at developing nonclassical platinum complexes that operate via mechanisms of action distinct from those of the approved drugs. The use of nanodelivery devices has also grown, and many different strategies have been explored to incorporate platinum warheads into nanomedicine constructs. In this Review, we discuss these efforts to create the next generation of platinum anticancer drugs. The introduction provides the reader with a brief overview of the use, development, and mechanism of action of the approved platinum drugs to provide the context in which more recent research has flourished. We then describe approaches that explore nonclassical platinum(II) complexes with trans geometry or with a monofunctional coordination mode, polynuclear platinum(II) compounds, platinum(IV) prodrugs, dual-threat agents, and photoactivatable platinum(IV) complexes. Nanoparticles designed to deliver platinum(IV) complexes will also be discussed, including carbon nanotubes, carbon nanoparticles, gold nanoparticles, quantum dots, upconversion nanoparticles, and polymeric micelles. Additional nanoformulations, including supramolecular self-assembled structures, proteins, peptides, metal-organic frameworks, and coordination polymers, will then be described. Finally, the significant clinical progress made by nanoparticle formulations of platinum(II) agents will be reviewed. We anticipate that such a synthesis of disparate research efforts will not only help to generate new drug development ideas and strategies, but also will reflect our optimism that the next generation of approved platinum cancer drugs is about to arrive.

Poly[platinum(iv)-alt-PEI]/Akt1 shRNA complexes for enhanced anticancer therapy

Co-delivery of Akt1 shRNA and platinum(iv) prodrug using DP/Akt1 shRNA complexes for synergetic cancer inhibition.

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.

Platinum (IV) coiled coil nanotubes selectively kill human glioblastoma cells

Malignant glioma are often fatal and pose a significant therapeutic challenge. Here we have employed α-helical right handed coiled coils (RHCC) which self-assemble into tetrameric nanotubes that stably associate with platinum (Pt) (IV) compound. This Pt(IV)-RHCC complex showed superior in vitro and in vivo toxicity in human malignant glioma cells at up to 5 fold lower platinum concentrations when compared to free Pt(IV). Pt(IV)-RHCC nanotubes activated multiple cell death pathways in GB cells without affecting astrocytes in vitro or causing damage to normal mouse brain. This Pt(IV)-RHCC nanotubes may serve as a promising new therapeutic tool for low dose Pt(IV) prodrug application for highly efficient and selective treatment of human brain tumors.

FROM THE CLINICAL EDITOR

The prognosis of malignant glioma remains poor despite medical advances. Platinum, one of the chemotherapeutic agents used, has significant systemic side effects. In this article, the authors employed α-helical right handed coiled coil (RHCC) protein nanotubes as a carrier for cisplatin. It was shown that the new compound achieved higher tumor kill rate but lower toxicity to normal cells and thus may hold promise to be a highly efficient treatment for the future.

The effect of crosslinking agent on sustained release of bFGF–collagen microspheres

Initial burst release and loss of bioactivity of drugs are the shortcomings of drug delivery systems (DDSs) used for in vivo treatment.

Thermogelling polymer-platinum(IV) conjugates for long-term delivery of cisplatin

In this study, we suggest a novel strategy of constituting an in situ-formed hydrogel composed of polymer-platinum(IV) conjugate to realize a long-term delivery of cisplatin. A unique conjugate was designed and synthesized by covalent linking of Pt(IV) complex to the hydrophobic end of two methoxyl poly(ethylene glycol)-b-poly(d,l-lactide) (mPEG-PLA) copolymer chains, resulting in the formation of Bi(mPEG-PLA)-Pt(IV). The conjugate could self-assemble into micelles in water, and its concentrated solution exhibited a thermoreversible sol-gel transition and formed a semisolid thermogel at body temperature. The incorporation of the cisplatin analogue Pt(IV) prodrug into the conjugate had a significant influence on its thermogelling properties and the conjugate thermogelation was attributed to the micellar aggregation. In vitro release experiments of Pt(IV)-conjugated thermogel showed that the platinum release lasted as long as two months. Furthermore, we demonstrated that the Pt(IV) prodrug was released mainly in the form of micelles and micellar aggregates from the gel depot. Compared with free cisplatin, the formation of conjugate micelles led to the enhanced in vitro cytotoxicity against cancer cells due to the effective accumulation into cells via endocytosis.