Prodrug Micelles Research Articles

Irinotecan delivery by unimolecular micelles composed of reduction-responsive star-like polymeric prodrug with high drug loading for enhanced cancer therapy.

Nanomedicine based polymeric prodrug have showed high impact in the inhibition of tumor growth due to its high therapeutic efficiency and improved biocompatibility. Herein, we synthesized a novel star-like amphiphilic copolymer [β-CD-P(Ir-co-OEGMA), denoted as CPIO] through atom transfer radical polymerization (ATRP) to deliver the hydrophilic anticancer drug irinotecan (Ir). The polymer could form monodisperse unimolecular micelles and had excellent stability in aqueous solution. Moreover, the reduction-responsive feature of the micelles facilitated controlled release of drug, thus achieving targeted therapy and reduced toxicity to healthy cells. The in vitro cytotoxicity assays indicated that CPIO had a notable anticancer effect against HeLa and MCF-7 tumor cells. The confocal laser scanning microscopy and flow cytometry experiments revealed that CPIO micelles could be internalized into tumor cells efficiently. Furthermore, the obtained prodrug micelles produced better efficacy compared to free Ir. Moreover, the CPIO micelles showed excellent biocompatibility in vivo after intravenous injection on a mouse model. This study demonstrated that CPIO carrier could provide a rational design of a stimuli-responsive polymeric prodrug for delivery of irinotecan.

Prodrug-Based Cascade Self-Assembly Strategy for Precisely Controlled Combination Drug Therapy.

The development of codelivery systems for combination therapy that can load different drugs in a single carrier and precisely deliver payloads (ratio and administration time) via programmable administration has proven to be challenging. By taking advantage of the increased dimension or space from particle self-assembly approach, we have developed a prodrug-based cascade self-assembly strategy to construct a supramolecular hydrogel that can load different drugs in stages yet temporally/spatially release drugs by cascade disassembly of supramolecular hydrogel under different microenvironments. The cascade self-assembly mechanism has been investigated in detail by morphology evolution of prodrug micelles. Using tumor cell uptake, cytotoxicity assay, and a tumor-bearing animal model, the effectiveness of the prodrug micelle-based cascade self-assembly system was studied, such as loading, controlling the drug ratio, and the administration time for possible therapeutic applications. These studies fully demonstrate the proof of concept and open up an attractive new way to construct multidrug-loaded carriers for combination therapy.

Reduction-active polymeric prodrug micelles based on α-cyclodextrin polyrotaxanes for triggered drug release and enhanced cancer therapy

As one of the medical polymers approved by US Food and Drug Administration (FDA), poly(ethylene glycol) has low toxicity, high stability, good biocompatibility, unique physical and chemical properties. Cyclodextrin is an ideal candidate as a drug carrier due to its special structures and characteristics. These two materials were successfully assembled through chemosynthesis in combination with the hydrophilic poly(ethylene glycol) methyl ether methacrylate (OEGMA) chain and hydrophobic polymeric camptothecin (CPT) chain by atom transfer radical polymerization (ATRP). The introduction of disulfide bond of monomer was aimed to realize reduction agent-triggered release of active CPT. The obtained amphipathic prodrug [(Denoted as PC-PCPT-b-POEGMA (PCCO)] could form nano-sized polymeric micelles, which could release more than 85% of the loaded CPT via triggered cleavage of the disulfide linker. The cellular co-localization study revealed the potential pathway of drug internalization. Moreover, the PCCO micelles showed good biocompatibility in vivo after intravenous injection on a mouse model. This new CPT-loaded prodrug system could be prepared with low cost, and showed efficient and controlled drug release and favorable biocompatibility, demonstrating a promising potential as a stimuli-responsive polymeric prodrug for future clinical applications.

The diosgenin prodrug nanoparticles with pH-responsive as a drug delivery system uniquely prevents thrombosis without increased bleeding risk

Thrombosis is the leading cause of death in patients with cardiovascular disease in the world. Current antithrombotic agent aspirin has serious side effects such as higher bleeding risk and serious gastrointestinal ulcers. Diosgenin reported in clinical research could prevent thrombosis without side effects. However, poor bioavailability and low knowledge on its molecular targets limit its clinical application. A novel prodrug with antithrombotic effect was prepared based on conjugating diosgenin derivatives to PEG with Schiff-base bond. The prodrug with long blood circulation time and satisfying safety could self-assemble into micelles in water. The prodrug micelles with pH-responsibility could targetedly release diosgenin in position of thrombus in vivo. The results indicate that the prodrug micelles without bleeding risk and histological damages prevent thrombosis by inhibiting platelet activation and apoptosis. Our studies demonstrate that the prodrug micelles could obviously enhance the efficacy in the prevention of arterial thrombus and venous thrombus than aspirin.

A reactive oxygen species-responsive prodrug micelle with efficient cellular uptake and excellent bioavailability.

Stimuli-responsive polymeric drug delivery systems are of great interest in anticancer research. Here, a reactive oxygen species (ROS)-responsive prodrug was prepared by thioketal linkage of poly(ethylene glycol) (PEG) and the anticancer drug doxorubicin (DOX). The ROS-responsive property of the prodrug was confirmed by dynamic light scattering and 1H NMR. The prodrug was then used as a drug carrier to further load DOX, to form a DOX-loaded prodrug micelle, which showed dual ROS and pH-responsive release behaviors. The prodrug micelle exhibited rapid intracellular uptake. Interestingly, the in vitro anticancer activity of the ROS-responsive prodrug micelle was better than that of the DOX-loaded prodrug micelle because of its faster cellular uptake and better bioavailability. However, both the ROS-responsive prodrug and drug-loaded prodrug micelles showed better anticancer efficacy than a non-responsive DOX-loaded poly(ethylene glycol)-block-polycaprolactone (PEG2k-PCL5k) micelle. Consistent results were obtained in in vivo animal experiments as the antitumor efficacy of the prodrug micelle was superior to that of the DOX-loaded prodrug micelle. Both micelles showed negligible systemic toxicity in vivo.

Bortezomib-catechol conjugated prodrug micelles: combining bone targeting and aryl boronate-based pH-responsive drug release for cancer bone-metastasis therapy.

The treatment of metastatic tumors is highly desirable in clinics, which has also increased the interest in the design of nanoscale drug delivery systems. Bone metastasis is one of the most common pathways in the metastasis of breast cancer, and it is also an important cause for tumor recurrence and death. The aryl boronate group, as an acid-labile linker, has been introduced into nano-assemblies in recent years. Especially, as a proteasome inhibitor anticancer drug with a boric acid group, bortezomib can facilitate the formation of pH-sensitive aryl boric acid ester linkage with the catecholic group. In this study, bortezomib-loaded micelles with bone targeting properties were constructed for the treatment of breast cancer bone metastasis. The mixed micelles employed alendronate (ALN) as the bone-targeting ligand and encapsulated bortezomib-catechol conjugates as the cargo. In vitro and in vivo studies showed that compared with free drugs or control micelles, these prodrug micelles (ALN-NP) exhibited many favorable properties such as reduced systemic toxicity and improved therapeutic effects. Therefore, ALN-NP is promising as a nanovehicle for bone-targeting delivery of chemotherapeutic drugs. Furthermore, this study offers a novel strategy combining bone targeting and aryl boronate-based pH-responsive drug release for anti-metastasis therapy.

Improving the carrier stability and drug loading of unimolecular micelle-based nanotherapeutics for acid-activated drug delivery and enhanced antitumor therapy.

Nanomedicines based on unimolecular micelles (UMs) have shown unique advantages such as high micellar stability, programmed cargo delivery and enhanced therapeutic efficiency. Herein, we report an acid-activated amphiphilic prodrug based on a dextran (DEX) polymeric framework (DEX-PDOX-b-POEGMA, labelled DMO@DOX), which conjugates a diblock copolymer of a hydrophobic doxorubicin (DOX) prodrug block and a hydrophilic poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) block by atom transfer radical polymerization. The DMO@DOX prodrug can form nano-sized UMs in aqueous media attributed to its amphiphilic structure and achieve a very high drug loading rate of 80.4 wt%. In the presence of an acidic medium resembling a tumor microenvironment, the hydrazone bond embedded in the prodrug is broken, which releases the loaded drug of DOX. The DMO@DOX prodrug shows a notable and preferential inhibition effect on the growth of tumor cells in vitro compared to healthy cells, leading to advantageous biocompatibility and effective antitumor activity. For verification, the DMO@DOX prodrug was applied in the treatment of a mouse model bearing xenograft tumors and showed a remarkable therapeutic performance. This study demonstrates an effective design of UM-based nanoagents to improve the micellar stability of polymeric prodrug micelles with enhanced performance in cancer therapy.

Synthesis and Characterization of Nitric Oxide-Releasing Platinum(IV) Prodrug and Polymeric Micelle Triggered by Light.

Herein, we report the proof of concept of photoresponsive chemotherapeutics comprising nitric oxide-releasing platinum prodrugs and polymeric micelles. Photoactivatable nitric oxide-releasing donors were integrated into the axial positions of a platinum(IV) prodrug, and the photolabile hydrophobic groups were grafted in the block copolymers. The hydrophobic interaction between nitric oxide donors and the photolabile groups allowed for the loading of platinum drugs and nitric oxide-releasing donors in the photolabile polymeric micelles. After cellular uptake of micelles, light irradiation induced the release of nitric oxide, which sensitized the cancer cells. Simultaneously, photolabile hydrophobic groups were cleaved from micelles, and the nitric oxide-releasing donor was altered to be more hydrophilic, resulting in the rapid release of platinum(IV) prodrugs. The strategy of using platinum(IV) prodrugs and nitric oxide led to enhanced anticancer effects.

Pendant HDAC inhibitor SAHA derivatised polymer as a novel prodrug micellar carrier for anticancer drugs

Suberoylanilide hydroxamic acid (SAHA), a histone deacetylase inhibitor (HDACi) approved by FDA for the treatment of cutaneous T cell lymphoma, is a promising anticancer drug for various cancers with a unique mode of action. However, it demonstrates limited clinical benefits in solid tumours as a single drug. In order to achieve enhanced and synergistic co-delivery of SAHA and doxorubicin (DOX), a cleavable SAHA-based prodrug polymer (POEG-b-PSAHA), consisting of hydrophilic poly(oligo(ethylene glycol) methacrylate) (POEG) blocks and hydrophobic SAHA segments, has been developed. POEG-b-PSAHA prodrug polymer was able to form spherical micelles with a diameter around 60 nm and well retained the pharmacological activity of SAHA in either inhibiting the proliferation of tumour cells or inducing histone acetylation. DOX formulated in POEG-b-PSAHA-based micelles showed a sustained release profile. DOX-loaded POEG-b-PSAHA exhibited more potent cytotoxicity towards tumour cells than free DOX and DOX loaded in a pharmacologically ‘inert’ nanocarrier, POEG-b-POM. Consistently, DOX/POEG-b-PSAHA formulation resulted in an improved therapeutic effect in vivo compared to free DOX, Doxil or DOX formulated in POEG-b-POM micelles. These results suggest that SAHA-based prodrug micelles may serve as a dual functional carrier for combination strategies in epigenetic-oriented anticancer therapy.

Acetal-Linked Paclitaxel Polymeric Prodrug Based on Functionalized mPEG-PCL Diblock Polymer for pH-Triggered Drug Delivery.

The differences in micro-environment between cancer cells and the normal ones offer the possibility to develop stimuli-responsive drug-delivery systems for overcoming the drawbacks in the clinical use of anticancer drugs, such as paclitaxel, doxorubicin, and etc. Hence, we developed a novel endosomal pH-sensitive paclitaxel (PTX) prodrug micelles based on functionalized poly(ethylene glycol)-poly(ε-caprolactone) (mPEG-PCL) diblock polymer with an acid-cleavable acetal (Ace) linkage (mPEG-PCL-Ace-PTX). The mPEG-PCL-Ace-PTX5 with a high drug content of 23.5 wt % was self-assembled in phosphate buffer (pH 7.4, 10 mM) into nanosized micelles with an average diameter of 68.5 nm. The in vitro release studies demonstrated that mPEG-PCL-Ace-PTX5 micelles was highly pH-sensitive, in which 16.8%, 32.8%, and 48.2% of parent free PTX was released from mPEG-PCL-Ace-PTX5 micelles in 48 h at pH 7.4, 6.0, and 5.0, respectively. Thiazolyl Blue Tetrazolium Bromide (MTT) assays suggested that the pH-sensitive PTX prodrug micelles displayed higher therapeutic efficacy against MCF-7 cells compared with free PTX. Therefore, the PTX prodrug micelles with acetal bond may offer a promising strategy for cancer therapy.

Self-Assembled Hyaluronic Acid Nanoparticles for pH-Sensitive Release of Doxorubicin: Synthesis and In Vitro Characterization.

The nanoparticulate drug delivery systems (NDDS) demonstrate a relatively ideal therapeutic efficacy during cancer therapy Regarding the high tumor-target capacity and efficient drug release at the tumor site. Thus, in the present study, a novel macromolecular prodrug conjugates was designed and developed, which can target CD44-overexpressed tumor cells in addition to releasing doxorubicin (Dox) that is passively triggered by the acidic microenvironment of tumor cells. Briefly, the best reaction route from three different alternatives was selected and then the synthetic reaction conditions to get grafted hyaluronic acid products were optimized. Through constructing a schiff base covalent bond conjugation between grafted hyaluronic acid and Dox, the macromolecular prodrug micelles were endowed with acid-sensitive character. This character resulted in a delayed release at pH 7.4 and expedited release at pH 5.0. This was proved by the release experiments in vitro. In the aspect of nanostructure, the polymer prodrug can self-assembly into the core-shell structure nanoparticles in aqueous solution with the hyaluronic acid as the hydrophilic shell and doxorubicin as the hydrophobic core. By optimizing the process of preparation, nanoparticles showed the mean size of around 200 nm and a narrow particle size distribution which were verified by dynamic light scattering (DLS) and transmission electron microscopy (TEM). CCK-8 assays and fluorescence microscope experiments showed that the polymer prodrug nanoparticles possessed an enhanced targeting ability and antitumor activity toward HeLa cells.

Camptothecin prodrug nanomicelle based on a boronate ester-linked diblock copolymer as the carrier of doxorubicin with enhanced cellular uptake

A novel pH-sensitive polymeric prodrug of camptothecin (CPT) by polymerizing γ-camptothecin-glutamate N-carboxyanhydride (Glu (CPT)-NCA) on boronate ester-linked poly (ethyleneglycol) (PEG) directly via the amine-initiated ring open polymerization (ROP) has been developed. The resulting amphiphilic prodrug (mPEG-BC-PGluCPT) could self-assemble into nanoparticles and encapsulate doxorubicin (Dox) simultaneously in aqueous solution for dual-drug delivery. The formation of polymeric prodrug micelles (mPEG-BC@PGluCPT) was confirmed by the measurements of critical aggregation concentration (CAC), particle size, and morphology observations. The mPEG-BC@PGluCPT micelles were colloidally stable in solutions for two weeks. Polymeric prodrug micelles mPEG-BC@PGluCPT and Dox-loaded micelles mPEG-BC@PGluCPT⋅Dox showed sustained drug release profiles over 48 h. As expected, drug release was accelerated by the decreasement of pH value from 7.4 to 6.0, which demonstrated pH-dependent manner of drug release. Additionally, it was found that cellular uptake of mPEG-BC@PGluCPT⋅Dox micelles on HepG2 cells was higher than that on HL-7702 cells, especially in culture medium at pH 6.0. The enhanced cellular uptake of mPEG-BC@PGluCPT⋅Dox micelles under acidic condition on HepG2 cells resulted in the higher cytotoxicity of mPEG-BC@PGluCPT⋅Dox micelles at acidic pH than that at pH 7.4.

Reduction-Triggered Release of CPT from Acid-Degradable Polymeric Prodrug Micelles Bearing Boronate Ester Bonds with Enhanced Cellular Uptake.

The aim of this research is to develop a novel type of camptothecin (CPT) prodrug micelles bearing boronate ester bonds as a smart nanosystem with enhanced cellular uptake and controlled drug release based on diblock copolymer abbreviated as PEG-BC-PGlu-ss-CPT. Particularly, boronate ester bond was introduced to achieve acid-triggered de-PEGylation and succeeding boronic acid-mediated enhanced cellular uptake. Besides, CPT was conjugated to the prodrug monomer through a disulfide bond to realize reduction-responsive drug release. The resultant copolymer PEG-BC-PGlu-ss-CPT could self-assemble into spherical nanomicelles in water. The degradation half-life time of PEG-BC-PGlu-ss-CPT copolymer decreased sharply from 96.27 h to only 5.7 h with pH value decreasing from 7.4 to 5.0, indicating the acid-degradable potential, which corresponded to size change monitoring. The cumulative CPT release from prodrug micelles increased significantly from 8.5 ± 1.73 to 82.9 ± 2.29% with an increase of dithiothreitol (DTT) concentration from 20 μM to 10 mM at pH 7.4, illustrating the reduction-responsive drug release property of prodrug micelles. The half maximal inhibitory concentration (IC50) value of prodrug micelles against HepG2 cells decreased from 1.06 to 0.68 μg/mL with the decrement of pH value from 7.4 to 6.0, proving that the utilization of boronate ester bonds was beneficial for enhancing antiproliferative activity. Interestingly, prodrug micelles exhibited enhanced cellular uptake ability against HepG2 cells compared to that of HL7702 cells, further confirming boronic acid-mediated enhanced endocytosis. In brief, this novel type of intelligent prodrug micelles possessed great potential as a smart nanosystem for antitumor drug delivery.

Acid-activatable doxorubicin prodrug micelles with folate-targeted and ultra-high drug loading features for efficient antitumor drug delivery

Stimuli-responsive nanomedicine shows high therapeutic effects and low side effects to tumor cells and tissues, representing a preferable therapeutics for cancer therapy. Herein, we design an acid-stimuli-responsive doxorubicin polymeric prodrug (OM@DOX), and this amphiphilic prodrug has a unique chemical structure with prominent advantages, including high drug loading rate (as high as 61.5 wt%), pH-triggered drug release and targeted access to cells. This smart polymeric prodrug has a preferable size of ~40 nm and strong micellar stability in aqueous solution, which is benefited to the long blood circulation and efficient extravasation from tumor vessel. Moreover, the prodrug micelles showed a higher cytotoxicity against tumor cells (HeLa cells) than normal cells (L929 cells), likely suggesting the potential tumor-specific targeting ability. To render this prodrug micelles with targeting function, folic acid (FA) molecules conjugated prodrug (FA-OM@DOX) further showed selectively higher cytotoxicity to KB tumor cells (FA-receptor-positive) than A549 tumor cells (FA-receptor-negative). Considering the rapidly cell-penetrating ability and aforementioned features, we believe that the present prodrug strategy has the potential as a promising nanomedicine and providing inspired insights to design multifunctional drug delivery nanoplatforms.

Dual-Targeted Cascade-Responsive Prodrug Micelle System for Tumor Therapy in Vivo

This study reports a cascade-responsive disassemble micellar drug delivery system with dual-targeting potential (cell and mitochondria targeting), which optimizes the distribution of antitumor drugs on systemic, local, and subcellular levels to enhance antitumor efficacy. A new cationic porphyrin derivative 5-(3-hydroxy-p-(4-trimethylammonium)butoxyphenyl)-10,15,20-triphenylporphyrin chlorine (MTPP) is synthesized as a mitochondria-targeting photosensitizer. After accumulating at a tumor site, the micellar nanosystem is endocytosed by tumor cells facilitated by the folate receptor-mediated pathway. Then, the hydrophobic PDEA block would be protonated in intracellular acidic endo-/lysosomes and promote the escape of prodrug micelles from endo-/lysosome to cytoplasm, resulting in the first-stage destabilization of micelles. Subsequently, the CPT is released in response to high concentration of GSH in cytoplasm, which would greatly increase the hydrophilicity of the BOH block and initiate the complete disass...

Dual pH-responsive 5-aminolevulinic acid supramolecular prodrug micelles for enhanced photodynamic ablation of cancer cells

Dual pH-responsive 5-aminolevulinic acid supramolecular prodrug micelles for enhanced photodynamic ablation of cancer cells

CRGD-installed docetaxel-loaded mertansine prodrug micelles: redox-triggered ratiometric dual drug release and targeted synergistic treatment of B16F10 melanoma

Combinatorial chemotherapy, which has emerged as a promising treatment modality for intractable cancers, is challenged by a lack of tumor-targeting, robust and ratiometric dual drug release systems. Here, docetaxel-loaded cRGD peptide-decorated redox-activable micellar mertansine prodrug (DTX-cRGD-MMP) was developed for targeted and synergistic treatment of B16F10 melanoma-bearing C57BL/6 mice. DTX-cRGD-MMP exhibited a small size of ca. 49 nm, high DTX and DM1 loading, low drug leakage under physiological conditions, with rapid release of both DTX and DM1 under a cytoplasmic reductive environment. Notably, MTT and flow cytometry assays showed that DTX-cRGD-MMP brought about a synergistic antitumor effect to B16F10 cancer cells, with a combination index of 0.37 and an IC50 over 3- and 13-fold lower than cRGD-MMP (w/o DTX) and DTX-cRGD-Ms (w/o DM1) controls, respectively. In vivo studies revealed that DTX-cRGD-MMP had a long circulation time and a markedly improved accumulation in the B16F10 tumor compared with the non-targeting DTX-MMP control (9.15 versus 3.13% ID/g at 12 h post-injection). Interestingly, mice treated with DTX-cRGD-MMP showed almost complete growth inhibition of B16F10 melanoma, with tumor inhibition efficacy following an order of DTX-cRGD-MMP > DTX-MMP (w/o cRGD) > cRGD-MMP (w/o DTX) > DTX-cRGD-Ms (w/o DM1) > free DTX. Consequently, DTX-cRGD-MMP significantly improved the survival rates of B16F10 melanoma-bearing mice. Importantly, DTX-cRGD-MMP caused little adverse effects as revealed by mice body weights and histological analyses. The combination of two mitotic inhibitors, DTX and DM1, appears to be an interesting approach for effective cancer therapy.

Amphipathic dextran-doxorubicin prodrug micelles for solid tumor therapy

A group of micelles self-assembled from deoxycholic acid-doxorubicin-conjugated dextran (denoted as Dex-DCA-DOX) prodrugs were designed and prepared for pH-triggered drug release and cancer chemotherapy. These prodrugs could be successfully produced by chemically coupling hydrophobic deoxycholic acid (DCA) to dextran hydrazine (denoted as Dex-NHNH2) and hydrazone linker formation between doxorubicin (DOX) and Dex-NHNH2. These Dex-DCA-DOX prodrugs self-assembled to form micelles under physiological conditions with varied particle sizes depending on molecular weight of dextran, degree of substitution (DS) of DCA and DOX. After optimization, Dex10k-DCA9-DOX5.5 conjugate comprising dextran of 10kDa, DCA of DS 9 and DOX loading content of 5.5wt%, formed the micelles with the smallest size (110nm). These prodrug micelles could slowly liberate DOX under physiological conditions but efficiently released the drug at an acidified endosomal pH by the hydrolysis of acid-labile hydrazone linker. In vitro cytotoxicity experiment indicated that Dex10k-DCA9-DOX5.5 micelles exerted marked antitumor activity against MCF-7 and SKOV-3 cancer cells. Besides, intravenous administration of the micelles afforded growth inhibition of SKOV-3 tumor bearing in nude mice at a dosage of 2.5mg per kg with anti-cancer efficacy comparable to free DOX-chemotherapy but low systemic toxicity. This study highlights the feasibility of bio-safe and efficient dextran-based prodrug micelles designed for cancer chemotherapy.

Redox-triggered mitoxantrone prodrug micelles for overcoming multidrug-resistant breast cancer

Multidrug resistance (MDR) severely hinders the efficient chemotherapeutic treatments of cancer. d-α-Tocopherol polyethylene 1000 succinate (TPGS) based drug delivery system holds the potential of re-sensitizing resistant cancer cells. In this study, a TPGS prodrug containing both TPGS and mitoxantrone (MTO) via a disulphide bond was synthesised and assembled into micelle (TSMm) with a monodispersed diameter of 46.50 ± 1.12 nm. The disulphide bonds within the micelles could be cleaved in response to a high concentration of intracellular glutathione (GSH) after entering the tumour cells, leading a rapid release of MTO. In vitro cytotoxicity study showed TSMm significantly inhibited the growth of resistant breast tumour cells MDA-MB-231/MDR comparing to either free MTO or disulphide-free prodrug micelle (TCMm). In addition, TSMm could sustain favourable intracellular retention and cause the depletion of ATP activity, leading to the preferential transportation of MTO into the nucleus and the reversal of MDR. In vivo imaging also verified that TSMm was specifically targeted to the tumour regions at 24 h post injection. Finally, TSMm has significantly stronger antitumor activity in xenograft nude mice with negligible side effects. Hence, TSMm can serve as promising prodrug candidates to strengthen the reversal of MDR in tumours with less side effects.

Doxorubicin delivered by a redox-responsive dasatinib-containing polymeric prodrug carrier for combination therapy

Two novel prodrug polymers POEG-b-PSSDas (redox-sensitive) and POEG-b-PCCDas (redox-insensitive), which consist of poly(oligo(ethylene glycol) methacrylate) (POEG) hydrophilic blocks and dasatinib (DAS, an oncogenic tyrosine kinases inhibitor) conjugated hydrophobic blocks, were designed as dual-functional carriers for codelivery with doxorubicin (DOX). Both carriers retained antitumor activity of DAS and could form mixed micelles with DOX. Compared to POEG-b-PCCDas micelles, incorporation of disulfide linkage into POEG-b-PSSDas micelles facilitated efficient cleavage of DAS from prodrug micelles in tumor cells/tissues, leading to a higher level of anti-tumor activity in vitro and in vivo. In addition, DOX-loaded POEG-b-PSSDas micelles exhibited triggered DOX release under a redox environment (10mM glutathione, GSH), and demonstrated enhanced cytotoxicity against 4T1.2 and PC3 cell lines compared to DOX and DOX-loaded POEG-b-PCCDas micelles. More importantly, DOX-loaded POEG-b-PSSDas micelles were more effective in inhibiting the tumor growth and prolonging the survival rate in an aggressive murine breast cancer model (4T1.2) compared to DOX-loaded POEG-b-PCCDas micelles and a micellar formulation co-loaded with DOX and DAS. This redox-responsive prodrug micellar system provides an attractive strategy for effective combination of tumor targeted therapy and traditional chemotherapy, which warrants further investigation.