Paclitaxel-loaded Polymeric Micelles Research Articles

Evaluation of paclitaxel-loaded polymeric nanoparticles in 3D tumor model: impact of tumor stroma on penetration and efficacy

Since tumor stroma poses as a barrier to achieve efficacy of nanomedicines, it is essential to evaluate nano-chemotherapeutics in stroma-mimicking 3D models that reliably predict their behavior regarding these hurdles limiting efficacy. In this study, we evaluated the effect of paclitaxel-loaded polymeric micelles (PTX-PMCs) and polymeric nanoparticles (PTX-PNPs) in a tumor stroma–mimicking 3D in vitro model. PTX-PMCs (77 nm) based on a amphiphilic block copolymer of mPEG-b-p(HPMAm-Bz) and PTX-PNPs (159 nm) based on poly(lactic-co-glycolic acid) were prepared, which had an encapsulation efficiency (EE%) of 81 ± 15% and 45 ± 8%, respectively. 3D homospheroids of mouse 4T1 breast cancer cells and heterospheroids of NIH3T3 fibroblasts and 4T1 (5:1 ratio) were prepared and characterized with high content two-photon microscopy and immunostaining. Data showed an induction of epithelial-mesenchymal transition (α-SMA) in both homo- and heterospheroids, while ECM (collagen) deposition only in heterospheroids. Two-photon imaging revealed that both fluorescently labeled PMCs and PNPs penetrated into the core of homospheroids and only PMCs penetrated into heterospheroids. Furthermore, PTX-PMCs, PTX-PNPs, and free PTX induced cytotoxicity in tumor cells and fibroblasts grown as monolayer, but these effects were substantially reduced in 3D models, in particular in heterospheroids. Gene expression analysis showed that heterospheroids had a significant increase of drug resistance markers (Bcl2, Abgc2) compared to 2D or 3D monocultures. Altogether, this study shows that the efficacy of nanotherapeutics is challenged by stroma-induced poor penetration and development of resistant phenotype. Therefore, this tumor stroma–mimicking 3D model can provide an excellent platform to study penetration and effects of nanotherapeutics before in vivo studies.Graphical

P-210 - Development of 89Zr-radiolabeled paclitaxel-loaded polymeric micelles for potential applications in personalized treatment of triple-negative breast cancer

P-210 - Development of 89Zr-radiolabeled paclitaxel-loaded polymeric micelles for potential applications in personalized treatment of triple-negative breast cancer

Coarse-Grained Molecular Dynamics Simulations of Paclitaxel-Loaded Polymeric Micelles.

A continuous manufacturing technology based on coaxial turbulent jet in coflow was previously developed to produce paclitaxel-loaded polymeric micelles. Herein, coarse-grained molecular dynamics (CG-MD) simulations were implemented to better understand the effect of the material attributes (i.e., the drug-polymer ratio and the ethanol concentration) and process parameters (i.e., temperature) on the self-assembly process of polymeric micelles as well as to provide molecular details on micelle instability. An all-atom (AA) poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) polymer model was developed as the reference for parameterizing a coarse-grained (CG) model, and the AA polymer model was further validated with experimental glass transition temperature (Tg). The model transferability was verified by comparing structural properties between the AA and CG models. The CG model was further validated with experimental data, including micelle particle size measurements and drug encapsulation efficiency. Furthermore, the encapsulation of paclitaxel into the polymeric micelles was included in the simulations, taking into consideration the interactions between the paclitaxel and the polymers. The results from various points of view demonstrated a strong dependence of the shape of the micelles on the drug encapsulation, with micelles transitioning from spherical to ellipsoidal structures with an increasing paclitaxel amount. Simulation data were also used to identify the critical aggregation number (i.e., the number of polymer and drug molecules required for transition from one shape to another). Improved micellar structural stability was found with a larger micellar size and less solvent accessibility. Lastly, an evaluation was performed on the micellar dissociation free energy using a steered molecular dynamics simulation over a range of temperatures and ethanol concentrations. These simulations revealed that at higher ethanol and temperature conditions, micelles become destabilized, resulting in greater paclitaxel release. The increased drug release was determined to originate from the solvation of the hydrophobic core, which promoted micellar swelling and an associated reduction in hydrophobic interactions, leading to a loosely packed micellar structure.

Monitoring EPR Effect Dynamics during Nanotaxane Treatment with Theranostic Polymeric Micelles.

Cancer nanomedicines rely on the enhanced permeability and retention (EPR) effect for efficient target site accumulation. The EPR effect, however, is highly heterogeneous among different tumor types and cancer patients and its extent is expected to dynamically change during the course of nanochemotherapy. Here the authors set out to longitudinally study the dynamics of the EPR effect upon single‐ and double‐dose nanotherapy with fluorophore‐labeled and paclitaxel‐loaded polymeric micelles. Using computed tomography‐fluorescence molecular tomography imaging, it is shown that the extent of nanomedicine tumor accumulation is predictive for therapy outcome. It is also shown that the interindividual heterogeneity in EPR‐based tumor accumulation significantly increases during treatment, especially for more efficient double‐dose nanotaxane therapy. Furthermore, for double‐dose micelle therapy, tumor accumulation significantly increased over time, from 7% injected dose per gram (ID g–1) upon the first administration to 15% ID g–1 upon the fifth administration, contributing to more efficient inhibition of tumor growth. These findings shed light on the dynamics of the EPR effect during nanomedicine treatment and they exemplify the importance of using imaging in nanomedicine treatment prediction and clinical translation.

Evaluation of novel paclitaxel-loaded NO-donating polymeric micelles for an improved therapy for gastroenteric tumor

A NO-releasing polymer (mPEG-PLA-NO) is developed as a micellar nanoparticle delivery system for the carrier of antitumor drug paclitaxel.

A Novel Paclitaxel-Loaded Polymeric Micelle System with Favorable Biocompatibility and Superior Antitumor Activity.

Polymeric micelles are promising vehicles for paclitaxel delivery. Further improvement in the stability of the micelle formulation is desirable. Monomethoxy poly(ethylene glycol)-block-poly(D,L-lactide)-9-fluorenylmethoxycarbonyl-L-phenylalanine (mPEG-PDLLA-Phe(Fmoc)) was synthesized through a classical esterification reaction. Paclitaxel-loaded mPEG-PDLLA-Phe(Fmoc) micelles (PTX-PheMs) were prepared by the self-assembly method. Composition, structure and physicochemical properties were characterized. Pharmacokinetics were evaluated in rats. Therapeutic effect was evaluated in tumor-bearing mice. Safety profile was assessed by a hemolysis assay and an acute-toxicity study. The average size of PTX-PheMs was about 45 nm. The hemolysis and acute-toxicity tests confirmed its biocompatibility and safety. The pharmacokinetics and therapeutic effect experiments demonstrated its long circulation property and superior antitumor effect. mPEG-PDLLA-Phe(Fmoc) micelle is a biocompatible and effective drug delivery system for hydrophobic drugs such as PTX.

Abstract A118: Efflux of paclitaxel nanoformulation in cell culture model of human placental barrier

Abstract Background: Breast cancer affects 1 of every 3000 pregnancies, and is treated with chemotherapeutics including paclitaxel. Chemotherapy administration in pregnancy is associated with fetal morbidity. Purpose: Here, we investigated the transplacental transfer of both paclitaxel and new paclitaxel nanoformulations that are entering clinical studies or are commercially available for use in breast cancer. In addition, we examined the transfer of fluorescent albumin-based and polymeric micellar nanoformulations with similar properties to those paclitaxel nanoformulations. Methods: Transport studies were performed using BeWo b30 cells (human placental trophoblast cells) seeded in TranswellTM plates coated with human placental collagen. Cells were treated with 20 μg/mL of paclitaxel from marketed formulations. Since paclitaxel undergoes efflux by P-glycoprotein (P-gp) substrate, 100 μM of verapamil was used as a competitive P-gp inhibitor to prevent efflux of free paclitaxel released from the nanoformulations. In order to determine the role of nanomaterials in transport and uptake of paclitaxel, we synthesized fluorescent albumin nanoparticles and fluorescent polymeric micelles with similar properties to the paclitaxel nanoformulations for use in transport studies. Samples were analyzed by high-performance liquid chromatography or fluorometer. Uptake measurements were corrected for protein content. Particle size and polydispersity index were determined using dynamic light scattering. Results: There were no formulation-dependent differences in paclitaxel permeability between the formulations of paclitaxel, nanoparticle albumin-bound paclitaxel (nab-paclitaxel), and paclitaxel-loaded polymeric micelles. In the presence of verapamil, nab-paclitaxel showed a twofold increase in permeability, in contrast to the other formulations. The size of fluorescent albumin nanoparticles (130.3nm) was matched with nab-Paclitaxel (156.2 nm), and the fluorescent micelles (27.6 nm) with paclitaxel-loaded polymeric micelles (27.7nm). The apparent permeability of the fluorescent albumin nanoparticles across the BeWo cells was 1.98 x 10-6 ± 0.81 x 10-6 cm/s, whereas the apparent permeability of the fluorescent micelles was 59.5 x 10-6 ± 10.5 x 10-6 cm/s. Conclusion: These data suggest that paclitaxel-encapsulated micelles may evade efflux by P-gp and cross the trophoblast to a significant extent, while paclitaxel albumin nanoparticles behave like free paclitaxel. Therefore, choice of formulation may have a significant impact on fetal exposure to paclitaxel. We anticipate that these findings will have an impact on future pharmaceutical design and rational development of safe treatment strategies for pregnancy-associated breast cancer and other diseases. Citation Format: Shariq Ali, Sanaalarab Alenazy, Mansi Shah, Luke Bourner, Erik Rytting. Efflux of paclitaxel nanoformulation in cell culture model of human placental barrier [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2017 Oct 26-30; Philadelphia, PA. Philadelphia (PA): AACR; Mol Cancer Ther 2018;17(1 Suppl):Abstract nr A118.

Extraction protocol and liquid chromatography/tandem mass spectrometry method for determining micelle-entrapped paclitaxel at the cellular and subcellular levels: Application to a cellular uptake and distribution study.

Paclitaxel-loaded polymeric micelles (PTX-PM) are commonly used as tumor-targeted nanocarriers and display outstanding antitumor features in clinic, but its accumulation and distribution in vitro are lack of investigation. It is probably due to the complex micellar system and its low concentration at the cellular or subcellular levels. In this study, we developed an improved extraction method, which was a combination of mechanical disruption and liquid-liquid extraction (LLE), to extract the total PTX from micelles in the cell lysate and subcellular compartments. An ultra-performance liquid chromatography tandem mass spectroscopy (UPLC-MS/MS) method was optimized to detect the low concentration of PTX at cellular and subcellular levels simultaneously, using docetaxel as internal standard (IS). The method was proved to release PTX totally from micelles (≥95.93%) with a consistent and reproducible extraction recovery (≥75.04%). Good linearity was obtained at concentrations ranging from 0.2 to 20ng/mL. The relative error (RE%) for accuracy varied from 0.68 to 7.56%, and the intra- and inter-precision (relative standard deviation, RSD%) was less than 8.64% and 13.14%, respectively. This method was fully validated and successfully applied to the cellular uptake and distribution study of PTX-loaded PLGA-PEG micelles in human breast cancer cells (MCF-7).

GRP78 enabled micelle-based glioma targeted drug delivery

GRP78, a specific cancer cell-surface marker, is implicated in cancer cells proliferation, apoptosis resistance, metastasis and drug resistance. l-VAP (SNTRVAP) is a tumor homing peptide exhibiting high binding affinity in vitro to GRP78 protein overexpressed on glioma, glioma stem cells, vasculogenic mimicry and neovasculature. Even though short peptides are often non-immunogenic and demonstrate high affinity to tumor cells, their targeting efficacy is always undermined by rapid blood clearance and enzymatic degradation. In the present study, two d peptides RI-VAP (retro inverso isomer of l-VAP) and d-VAP (retro isomer of l-VAP) were developed by structure-guided peptide design and retro-inverso isomerization technique for glioma targeting. RI-VAP and d-VAP were predicted to bind their receptor GRP78 protein with similar binding affinity, which was experimentally confirmed. The results of in vivo imaging demonstrated that RI-VAP and d-VAP had remarkably advantage over l-VAP for tumor accumulation. In addition, RI-VAP and d-VAP modified paclitaxel-loaded polymeric micelle had better anti-tumor efficacy in comparison to taxol, paclitaxel-loaded plain micelles and l-VAP modified micelles. Overall, the VAP modified micelles suggested in the present study could effectively achieve glioma-targeted drug delivery, validating the potential of the stable VAP peptides in improving the therapeutic efficacy of paclitaxel for glioma.

Systematic evaluation of multifunctional paclitaxel-loaded polymeric mixed micelles as a potential anticancer remedy to overcome multidrug resistance.

In this work, a novel FA-TPGS2K copolymer has been synthesized and used it to construct mixed micelles with HDP copolymer to overcome MDR effect. Furthermore, a series in vitro and in vivo evaluations have been made, which supported enough evidences for the efficient delivery of antitumor drug to MDR cells.

Enhanced antiproliferative and apoptosis effect of paclitaxel-loaded polymeric micelles against non-small cell lung cancers.

Amphiphilic copolymer monomethoxy poly(ethylene glycol)-poly(caprolactone)-D-α-tocopheryl polyethylene glycol 1000 succinate (MPEG-PCL-TPGS) was prepared. In the present study, MPEG-PCL-TPGS was used as a novel nanovehicle for the delivery of paclitaxel (PTX) in the treatment of resistant lung cancers. The PTX-loaded MPEG-PCL-TPGS (PTX/MPT) micelles exhibited sustained release profile (168 h) with accelerated drug release at acidic pH conditions. The blank polymeric micelles showed excellent biocompatibility with cell viability of >85 %, making it suitable for all in vivo applications. PTX/MPT micelles displayed superior cytotoxicity in A-549 lung cancer cells than that of free PTX. The selective delivery of PTX to cancer cells resulted in enhanced cancer cell death. The PTX/MPT micelles showed higher cellular uptake via endocytosis pathways. The PTX-bound micelles preferentially arrested the cells at G2/M phase and showed a marked increase in sub G1 cell population (∼ 20 %). The pharmacokinetic study revealed a long blood circulation for PTX/MPT micelles. Finally, micellar formulation showed a remarkable tumor suppression effect in resistant A549/Taxol cells bearing xenograft nude mice along with no toxicity profile. The results indicate that the PTX-loaded biocompatible polymeric nanosystem could act as a potential delivery system for the treatment of lung carcinomas.

P204 A paclitaxel–cisplatin loaded thermosensitive hydrogel for in situ treatment of lung cancer

Background An in situ, gelling, dual drug co-delivery system (PEG-PCL-PEG/DDP + MPEG-PCL/PTX [PDMP]) was prepared through the combination of a cisplatin-containing thermosensitive hydrogel (PEG-PCL-PEG/DDP, PECE/DDP) and paclitaxel-loaded polymeric micelles (MPEG-PCL/PTX micelles). Methods PDMP was a free-flowing solution at ambient temperature and formed a non-flowing gel at body temperature, serving as a drug depot for the in situ treatment of lung cancer. The MPEG-PCL/PTX spherical micelles had a diameter of 20.1 nm and a narrow particle size distribution. Paclitaxel loading and encapsulation efficiency of micelles were 3.96 ± 0.03% and 99.18 ± 0.65%, respectively. Findings Compared with blank micelles, paclitaxel-loaded micelles showed significant tumour inhibition in A549 cells. A xenografted lung cancer model was used to evaluate the antitumour efficiency of PDMP in vivo. PDMP was effective in inhibiting tumour growth and prolonging survival time of tumour-bearing BALB/c nude mice. Immunohistochemical images also showed that tumours in the PDMP group had fewer microvessels and lower proliferation activity compared with the control group. Interpretation Prepared PDMP could have potential for in situ local treatment of lung cancer through in vitro minimal invasive injection.

Study on antitumor activity of paclitaxel-loaded polymeric micelles

Objective To develop paclitaxel-loaded polymeric micelles from poly (e-caprolactone)-poly (ethylene glycol)-poly(e-caprolactone) (PCL-PEG-PCL),and to evaluate in vitro cytotoxicity as well as in vivo antitumor activity against EMT-6 tumor breast cell.Methods Paclitaxel-loaded polymeric micelles were prepared by thin-film hydration and ultrasonic method.The physical status of paclitaxel inside the polymeric micelles was investigated by differential scanning calorimetry (DSC).In vitro cytotoxicity of paclitaxel-loaded polymeric micelles against EMT-6 cell line was assessed by MTT assay.In vivo anticancer activity was evaluated against EMT-6 tumorbearing mice,with commercially available Taxol injection as control.Results Paclitaxel-loaded polymeric micelles exhibited homogeneous spherical shapes with apparent core-shell morphology.The average diameter of paclitaxelloaded polymeric micelles was 93 nm.DSC study indicated that paclitaxel was in solid amorphous state after being encapsulated in the polymeric micelles.In vitro cytotoxicity demonstrated that the cytotoxic effect of paclitaxelloaded polymeric micelles was lower than that of Taxol injection at the same paclitaxel content.Paclitaxel-loaded polymeric micelles showed greater tumor growth-inhibition effect in vivo on EMT-6 breast tumor in comparison with that of Taxol injection,with tumor growth inhibition of 85.79％ and 63.37％,respectively (P＜0.05).Conculsions The prepared paclitaxel-loaded polymeric micelles showed high anti-tumoral efficacy and low toxicity,and might have the potential to be developed as an effective anticancer drug-delivery system for cancer chemotherapy. Key words: Polymeric micelles; PCL-PEG-PCL; Paclitaxel; Anti-tumoral effect

Paclitaxel-Loaded Polymeric Micelle (230 mg/m2) and Cisplatin (60 mg/m2) vs. Paclitaxel (175 mg/m2) and Cisplatin (60 mg/m2) in Advanced Non–Small-Cell Lung Cancer: A Multicenter Randomized Phase IIB Trial

IntroductionThe development of paclitaxel-loaded polymeric micelle (PPM) has circumvented many of the infusion-related difficulties associated with standard solvent-based paclitaxel. PPM plus cisplatin combination chemotherapy showed significant antitumor activity in phase I and II studies. This prospective randomized controlled phase IIB study assessed the noninferiority of the efficacy and tolerability of high-dose PPM plus cisplatin to a standard dose of paclitaxel plus cisplatin. Patients and MethodsPatients with stage IIIB/IV or recurrent non–small-cell lung cancer (NSCLC) who were chemonaive were eligible for participation. The patients were randomly assigned to receive PPM 230 mg/m2 plus cisplatin 60 mg/m2 or paclitaxel 175 mg/m2 plus cisplatin 60 mg/m2 once every 3-week cycle. The primary endpoint was to compare the response rate (RR) between the groups with coprimary analyses to assess noninferiority. Secondary endpoints included progression-free survival, overall survival, and safety. ResultsA total of 276 patients were randomized to PPM plus cisplatin (n = 140) or paclitaxel plus cisplatin (n = 136). RR was 43.6% in the PPM plus cisplatin group and 41.9% in the paclitaxel plus cisplatin group. Noninferiority of PPM plus cisplatin compared with paclitaxel plus cisplatin was confirmed for RR. There were no differences in progression-free survival and overall survival between the groups. Although there was a higher rate of grade 3 neutropenia in the PPM plus cisplatin group, the overall rate of adverse events was comparable between the 2 groups. ConclusionPPM in combination with cisplatin was well tolerated, and its response rate was noninferior to that of paclitaxel plus cisplatin in patients with advanced NSCLC and who were chemonaive.

Antitumor activity of folate-targeted, paclitaxel-loaded polymeric micelles on a human esophageal EC9706 cancer cell line

BackgroundEsophageal cancer is recognized as one of the most refractory pernicious diseases. In addition, it is an aggressive malignancy with a propensity for local progression and distant dissemination. Because of the poor long-term prognosis for patients with esophageal cancer, increasing attention has focused on the integration of targeted agents into current therapeutics. Nevertheless, there have been few studies reported concerning the therapeutic efficacy of paclitaxel-conjugated polymeric micelles in human esophageal cancer in vivo. Therefore, the aim of this research was to investigate the tumor inhibition effect of composite micelles containing folic acid and paclitaxel on the human esophageal EC9706 cancer cell line.Methods and resultsIntravenous administration of folate-targeted, paclitaxel-loaded micelles was demonstrated to be more efficient in inhibiting subcutaneous xenograft tumors and extending the survival rate of tumor-bearing nude mice than free paclitaxel and plain paclitaxel micelles at an equivalent paclitaxel dose of 20 mg/kg, which was further backed up by flow cytometry, TUNEL, and expression of apoptosis-related proteins, including Bax, Bcl2, and caspase 3 in this study.ConclusionThe folate-mediated paclitaxel-loaded polymeric micelle is a promising agent for the treatment of human esophageal cancer.

Paclitaxel-loaded polymeric micelles based on poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone) triblock copolymers: in vitro and in vivo evaluation

The purpose of this study was to develop polymeric nanoscale drug-delivery system (nano-DDS) for paclitaxel (PTX) from poly(ɛ-caprolactone)-poly(ethylene glycol)-poly(ɛ-caprolactone) (PCL-PEG-PCL, PCEC) copolymers, intended to be intravenously administered, able to improve the therapeutic efficacy of the drug and devoid of the adverse effects of Cremophor EL. Both of the PTX-loaded polymeric micelles and polymersomes were successfully prepared from PCEC copolymers. The obtained PTX-loaded micelles exhibited core-shell morphology with satisfactory size (93 nm), and were favorable for intravenous injection. In vitro cytotoxicity demonstrated that the cytotoxic effect of PTX-loaded micelles was lower than that of Taxol (Bristol-Myers Squibb, Princeton, New Jersey). Pharmacokinetic results indicated that the PTX-loaded micelles had longer systemic circulation time and slower plasma elimination rate than those of Taxol. Furthermore, PTX-loaded micelles showed greater tumor growth-inhibition effect in vivo on EMT6 breast tumor, in comparison with Taxol. Therefore, the prepared polymeric micelles might be potential nano-DDS for PTX delivery in cancer chemotherapy. From the Clinical EditorIn this paper, a paclitaxel- loaded polymeric micelle system is demonstrated to provide optimized intravenous delivery method of this anti-cancer agent. While the study is early preclinical, this approach may have the potential to eventually be studied in clinical trials as well.

Phase II study of a polyethoxylated castor oil–free, polymeric micelle formulation of paclitaxel for patients with advanced urothelial cancer previously treated with gemcitabine and platinum.

272 Background: Paclitaxel-loaded polymeric micelle (Genexol-PM; G-PM) is a novel polyethoxylated castor oil (Cremophor EL [CrEL])-free formulation of paclitaxel. This multicenter phase II study was designed to evaluate the efficacy and safety of the G-PM monotherapy for the treatment of gemcitabine- and cisplatin-refractory advanced urothelial cancer. Methods: Patients with advanced urothelial cancer received G-PM 240 mg/m2 intravenously over 3 hours every 3 weeks without premedication as salvage chemotherapy after failure to gemcitabine and cisplatin combination chemotherapy. Intrapatient dose escalation of G-PM to 300 mg/m2 was carried out from the second cycle if the prespecified toxicities were not observed after the first cycle. Results: Thirty-seven patients were enrolled in this study. Platinum-free interval was less than 6 months in 72% of patients and 64% of patients were categorized into intermediate or poor prognostic group. Overall response rate was 19% including one complete response. When response occurs it is long lasting with a median response duration of 7.8 months (range 1.5∼19.3+). The median progression-free survival was 2.7 months (95% CI, 09-4.6) with a median overall survival of 5.7 months (95% CI, 3.1-8.3). The most common major grade 3-4 non-hematologic toxicity was peripheral neuropathy (sensory type 5.6% and motor type 8.3%) followed by infection (5.6%). Grade 3 or worse hematologic toxicities were observed in only one patient. Conclusions: G-PM showed modest activity with favorable toxicity profiles when used as salvage therapy after gemcitabine-cisplatin failure in advanced urothelial cancer. No significant financial relationships to disclose.

Paclitaxel-Loaded Polymeric Micelles Modified with MCF-7 Cell-Specific Phage Protein: Enhanced Binding to Target Cancer Cells and Increased Cytotoxicity

Polymeric micelles are used as pharmaceutical carriers to increase solubility and bioavailability of poorly water-soluble drugs. Different ligands are used to prepare targeted polymeric micelles. Earlier, we developed the method for use of specific landscape phage fusion coat proteins as targeted delivery ligands and demonstrated the efficiency of this approach with doxorubicin-loaded PEGylated liposomes. Here, we describe a MCF-7 cell-specific micellar formulation self-assembled from the mixture of the micelle-forming amphiphilic polyethylene glycol-phosphatidylethanolamine (PEG-PE) conjugate, MCF-7-specific landscape phage fusion coat protein, and the hydrophobic drug paclitaxel. These micelles demonstrated a very low cmc value and specific binding to target cells. Using an in vitro coculture model, FACS analysis, and fluorescence microscopy we showed that MCF-7 targeted phage-micelles preferentially bound to target cells compared to nontarget cells. As a result, targeted paclitaxel-loaded phage-micelles demonstrated a significantly higher cytotoxicity toward target MCF-7 cells than free drug or nontargeted micelle formulations, but failed to show such a differential toxicity toward nontarget C166 cells. Overall, cancer cell-specific phage proteins identified from phage display peptide libraries can serve as targeting ligands ("substitute antibody") for polymeric micelle-based pharmaceutical preparations.

Morphology and in vitro release kinetics of drug-loaded micelles based on well-defined PMPC–b–PBMA copolymer

Well-defined amphiphilic diblock copolymers with different poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) content were successfully synthesized via RAFT polymerization technology. The structure of the copolymers was confirmed using GPC, 1H NMR and FTIR. The polymers have very low critical micelles concentration (6.32 × 10 −7 mol/L to 1.01 × 10 −6 mol/L), which indicates their high thermodynamic stability needed for intravenous injection. Blank and paclitaxel-loaded polymeric micelles were prepared from the PMPC–b–PBMA copolymers using self-emulsion/evaporation method. TEM analysis revealed a regular spherical shape, small diameter (less than 30 nm) and narrow size distribution of the micelles. The paclitaxel-loaded polymeric micelles had high loading content (above 13%). In vitro release kinetics of paclitaxel from the micelles was also investigated. Less than 30% of the paclitaxel was released within 320 h and the increase of the length of PMPC leads to slower release rate.

Sensitive HPLC method for quantitation of paclitaxel (Genexol ®) in biological samples with application to preclinical pharmacokinetics and biodistribution

A sensitive, specific and reproducible HPLC method has been developed and validated for the quantitative determination of paclitaxel in plasma, tissues and tumor of mice. Tissue specimens including liver, kidneys, spleen, lungs, heart and tumor were separately homogenized in bovine serum albumin (BSA, 40 g/l) in water. Plasma or tissue homogenates (0.1 ml) containing paclitaxel and internal standard (dimethyl-4,4′-dimethoxy-5,6,5′,6′-dimethylene dioxy biphenyl-2′,2′ dicarboxylate (DDB), I.S.) were extracted by ethyl acetate (10 ml). A 4.6 mm × 250 mm ODS column was used to separate the components in biological samples with UV detection at 227 nm and gradient system was applied to a quantitation of paclitaxel consisting of acetonitrile-deionized water. The I.S. and paclitaxel were eluted at 13.7 and 18.0 min, respectively, and no interfering peaks were observed. Linear relationships ( r 2 > 0.999) were obtained between the peak height ratios and the corresponding biological sample concentrations over the range of 0.1–20 μg/ml. The average intra- and inter-day variations (% R.S.D.s and % deviations) of the assay for biological samples were less than 10%. The LOD and LOQ were 5 and 10 ng/ml, respectively, for paclitaxel using a microsample volume (100 μl) of plasma sample. This HPLC method has been successfully applied for the determination of paclitaxel in pharmacokinetic and biodistribution study in after administration of 50 mg equivalent paclitaxel/kg dose of paclitaxel-loaded polymeric micelle and 20 mg equivalent paclitaxel/kg dose of Taxol ® to female SPF C57BL/6 mice.