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1.  Peptide ligand and PEG-mediated long-circulating liposome targeted to FGFR overexpressing tumor in vivo 
Background and methods
Paclitaxel, a widely used antitumor agent, has limited clinical application due to its hydrophobicity and systemic toxicity. To achieve sustained and targeted delivery of paclitaxel to tumor sites, liposomes composed of egg phosphatidylcholine, cholesterol, and distearolyphosphatidyl ethanolamine-N-poly(ethylene glycol) (PEG2000) were prepared by a lipid film method. In addition, the liposomes also contained truncated fibroblast growth factor fragment-PEG-cholesterol as a ligand targeting the tumor marker fibroblast growth factor receptor. Physicochemical characteristics, such as particle size, zeta potential, entrapment efficiency, and release profiles were investigated. Pharmacokinetics and biodistribution were evaluated in C57BL/6 J mice bearing B16 melanoma after intravenous injection of paclitaxel formulated in Cremophor EL (free paclitaxel), conventional liposomes (CL-PTX), or in targeted PEGylated liposomes (TL-PTX).
Results
Compared with CL-PTX and free paclitaxel, TL-PTX prolonged the half-life of paclitaxel by 2.01-fold and 3.40-fold, respectively, in plasma and improved the AUC0→t values of paclitaxel by 1.56-fold and 2.31-fold, respectively, in blood. Biodistribution studies showed high accumulation of TL-PTX in tumor tissue and organs containing the mononuclear phagocyte system (liver and spleen), but a considerable decrease in other organs (heart, lung, and kidney) compared with CL-PTX and free paclitaxel.
Conclusion
The truncated fibroblast growth factor fragment-conjugated PEGylated liposome has promising potential as a long-circulating and tumor-targeting carrier system.
doi:10.2147/IJN.S32817
PMCID: PMC3423151  PMID: 22923988
paclitaxel; truncated fibroblast growth factor fragment; poly(ethylene glycol); liposomes; targeted drug delivery
2.  Preparation, Pharmacokinetics, Biodistribution, Antitumor Efficacy and Safety of Lx2-32c-Containing Liposome 
PLoS ONE  2014;9(12):e114688.
Lx2-32c is a novel taxane that has been demonstrated to have robust antitumor activity against different types of tumors including several paclitaxel-resistant neoplasms. Since the delivery vehicles for taxane, which include cremophor EL, are all associated with severe toxic effects, liposome-based Lx2-32c has been developed. In the present study, the pharmacokinetics, biodistribution, antitumor efficacy and safety characteristics of liposome-based Lx2-32c were explored and compared with those of cremophor-based Lx2-32c. The results showed that liposome-based Lx2-32c displayed similar antitumor effects to cremophor-based Lx2-32c, but with significantly lower bone marrow toxicity and cardiotoxicity, especially with regard to the low ratio of hypersensitivity reaction. In comparing these two delivery modalities, targeting was superior using the Lx2-32c liposome formulation; it achieved significantly higher uptake in tumor than in bone marrow and heart. Our data thus suggested that the Lx2-32c liposome was a novel alternative formulation with comparable antitumor efficacy and a superior safety profiles to cremophor-based Lx2-32c, which might be related to the improved pharmacokinetic and biodistribution characteristics. In conclusion, the Lx2-32c liposome could be a promising alternative formulation for further development.
doi:10.1371/journal.pone.0114688
PMCID: PMC4266495  PMID: 25506928
3.  Paclitaxel Prodrugs with Sustained Release and High Solubility in Poly(ethylene glycol)-b-poly(ε-caprolactone) Micelle Nanocarriers: Pharmacokinetic Disposition, Tolerability, and Cytotoxicity 
Pharmaceutical research  2007;25(1):194-206.
Purpose
Develop a Cremophor® and solvent free formulation of paclitaxel using amphiphilic block co-polymer micelles of poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL) and characterize their release, solubility, cytotoxicity, tolerability, and disposition.
Methods
Hydrophobic prodrugs of paclitaxel were synthesized via DCC/DMAP or anhydride chemistry to overcome the poor loading (<1% w/w) of paclitaxel in micelles of PEG-b-PCL. Micelles were prepared by a co-solvent extraction technique. A micellar formulation of paclitaxel prodrug (PAX7′C6) was dosed intravenously to rats (10 mg/kg) and compared to Taxol® (paclitaxel in CrEL:EtOH) and PAX7′C6 in CrEL:EtOH as controls at the same dose. Pharmacokinetic parameters and tissue distribution were assessed.
Results
Paclitaxel prodrugs had solubilities >5 mg/ml in PEG-b-PCL micelles. Resulting PEG-b-PCL micelles contained 17-22% w/w prodrug and were less than 50 nm in diameter. PEG-b-PCL micelles released paclitaxel prodrugs over several days, t1/2>3 d. Only the 7′derivative of paclitaxel with the shortest acylchain 7′hexonoate (PAX7′C6) maintained cytotoxic activity similar to unmodified paclitaxel. PAX7′C6 micelles demonstrated an increase in area under the curve, half-life, and mean residence time while total clearance and volume of distribution decreased.
Conclusions
Paclitaxel prodrugs in PEG-b-PCL micelle nanocarriers augment the disposition and increase tolerability making further studies on tumor efficacy warranted.
doi:10.1007/s11095-007-9451-9
PMCID: PMC4872624  PMID: 17912488
nanocarrier; paclitaxel; pharmacokinetics; polymer micelle; prodrug
4.  Formulation and pharmacokinetic evaluation of a paclitaxel nanosuspension for intravenous delivery 
Paclitaxel is a diterpenoid isolated from Taxus brevifolia. It is effective for various cancers, especially ovarian and breast cancer. Due to its aqueous insolubility, it is administered dissolved in ethanol and Cremophor® EL (BASF, Ludwigshafen, Germany), which can cause serious allergic reactions. In order to eliminate Cremophor EL, paclitaxel was formulated as a nanosuspension by high-pressure homogenization. The nanosuspension was lyophilized to obtain the dry paclitaxel nanoparticles (average size, 214.4 ± 15.03 nm), which enhanced both the physical and chemical stability of paclitaxel nanoparticles. Paclitaxel dissolution was also enhanced by the nanosuspension. Differential scanning calorimetry showed that the crystallinity of paclitaxel was preserved during the high-pressure homogenization process. The pharmacokinetics and tissue distribution of paclitaxel were compared after intravenous administration of paclitaxel nanosuspension and paclitaxel injection. In rat plasma, paclitaxel nanosuspension exhibited a significantly (P < 0.01) reduced area under the concentration curve (AUC)0–∞ (20.343 ± 9.119 μg · h · mL−1 vs 5.196 ± 1.426 μg · h · mL−1), greater clearance (2.050 ± 0.616 L · kg−1 · h−1 vs 0.556 ± 0.190 L · kg−1 · h−1), and shorter elimination half-life (5.646 ± 2.941 vs 3.774 ± 1.352 hours) compared with the paclitaxel solution. In contrast, the paclitaxel nanosuspension resulted in a significantly greater AUC0–∞ in liver, lung, and spleen (all P < 0.01), but not in heart or kidney.
doi:10.2147/IJN.S21097
PMCID: PMC3141875  PMID: 21796250
high-pressure homogenization; tissue distribution; surfactant
5.  A Liposomal Formulation Able to Incorporate a High Content of Paclitaxel and Exert Promising Anticancer Effect 
Journal of Drug Delivery  2010;2011:629234.
A liposome formulation for paclitaxel was developed in this study. The liposomes, composed of naturally unsaturated and hydrogenated phosphatidylcholines, with significant phase transition temperature difference, were prepared and characterized. The liposomes exhibited a high content of paclitaxel, which was incorporated within the segregated microdomains coexisting on phospholipid bilayer of liposomes. As much as 15% paclitaxel to phospholipid molar ratio were attained without precipitates observed during preparation. In addition, the liposomes remained stable in liquid form at 4°C for at least 6 months. The special composition of liposomal membrane which could reduce paclitaxel aggregation could account for such a capacity and stability. The cytotoxicity of prepared paclitaxel liposomes on the colon cancer C-26 cell culture was comparable to Taxol. Acute toxicity test revealed that LD50 for intravenous bolus injection in mice exceeded by 40 mg/kg. In antitumor efficacy study, the prepared liposomal paclitaxel demonstrated the increase in the efficacy against human cancer in animal model. Taken together, the novel formulated liposomes can incorporate high content of paclitaxel, remaining stable for long-term storage. These animal data also demonstrate that the liposomal paclitaxel is promising for further clinical use.
doi:10.1155/2011/629234
PMCID: PMC3065869  PMID: 21490755
6.  Paclitaxel chemotherapy: from empiricism to a mechanism-based formulation strategy 
Paclitaxel is an anticancer agent effective for the treatment of breast, ovarian, lung, and head and neck cancer. Because of water insolubility, paclitaxel is formulated with the micelle-forming vehicle Cremophor EL to enhance drug solubility. However, the addition of Cremophor EL results in hypersensitivity reactions, neurotoxicity, and altered pharmacokinetics of paclitaxel. To circumvent these unfavorable effects resulting from the addition of Cremophor EL, efforts have been made to develop new delivery systems for paclitaxel administration. For example, ABI-007 is a Cremophor-free, albumin-stabilized, nanoparticle paclitaxel formulation that was found to have significantly less toxicity than Cremophor-containing paclitaxel in mice. Pharmacokinetic studies indicate that in contrast to Cremophor-containing paclitaxel, ABI-007 displays linear pharmacokinetics over the clinically relevant dose range of 135–300 mg/m2. In a phase III study conducted in patients with metastatic breast cancer, patients treated with ABI-007 achieved a significantly higher objective response rate and time to progression than those treated with Cremophor-containing paclitaxel. Together these findings suggest that nanoparticle albumin-bound paclitaxel may enable clinicians to administer paclitaxel at higher doses with less toxicity than is seen with Cremophor-containing paclitaxel. The role of this novel paclitaxel formulation in combination therapy with other antineoplastic agents needs to be determined.
PMCID: PMC1661618  PMID: 18360550
paclitaxel; nanoparticle; albumin-bound paclitaxel; pharmacokinetics
7.  Pharmacokinetics and pharmacodynamics of combination chemotherapy with paclitaxel and epirubicin in breast cancer patients 
Aims
To investigate the pharmacokinetics and pharmacodynamics of epirubicin and paclitaxel in combination, as well as the effects of paclitaxel and its vehicle Cremophor EL on epirubicin metabolism.
Methods
Twenty-seven female patients with metastatic breast cancer received epirubicin 90 mg m−2 i.v. followed 15 min or 30 h later by a 3 h i.v. infusion of paclitaxel 175, 200 and 225 mg m−2. Plasma concentrations of paclitaxel, epirubicin and epirubicinol were measured and the relationship between neutropenia and drug pharmacokinetics was evaluated using a sigmoid maximum effect (Emax) model. Finally, the influence of paclitaxel and Cremophor EL on epirubicin metabolism by whole blood was examined.
Results
An increase in epirubicinol plasma concentrations occurred after the start of the paclitaxel infusion, resulting in a significant increase in the area under the plasma concentration-time curve (AUC) of epirubicinol (+0.5 µmol l−1 h [95% CI for the difference: 0.29, 0.71],+0.66 µmol l−1 h [95% CI for the difference: 0.47, 0.85] and +0.82 µmol l−1 h [95% CI for the difference: 0.53, 1.11] at paclitaxel doses of 175, 200 and 225 mg m−2, respectively), compared with epirubicin followed by paclitaxel 30 h later (0.61±0.1 µmol l−1 h). A significant increase in epirubicin AUC (+0.74 µmol l−1 h [95% CI for the difference: 0.14, 1.34] and +1.09 µmol l−1 h [95% CI for the difference: 0.44, 1.74]) and decrease in drug clearance (CLTB) (−25.35 l h−1 m−2[95% CI for the difference: −50.18, −0.52] and −35.9 l h−1 m−2[95% CI for the difference −63,4,−8,36]) occurred in combination with paclitaxel 200 and 225 mg m−2 with respect to the AUC (3.16±0.6 µmol l−1 h) and CLTB (74.4±28.4 l h−1 m−2) of epirubicin followed by paclitaxel 30 h later. An Emax relationship was observed between neutropaenia and the time over which paclitaxel plasma concentrations were equal to or greater than 0.1 µmol l−1 (tC0.1). The tC0.1 value predicted to yield a 50% decrease in neutrophil count was 7.7 h. Finally, Cremophor EL markedly inhibited the metabolism of epirubicin to epirubicinol in whole blood.
Conclusions
Paclitaxel/Cremophor EL affects the disposition of epirubicinol and epirubicin. Furthermore, the slope factor of the Emax relationship between neutropenia and tC0.1 of paclitaxel suggests that the drugs might also interact at the pharmacodynamic level.
doi:10.1046/j.1365-2125.2002.01579.x
PMCID: PMC1874362  PMID: 11994057
drug interaction; epirubicin; metabolism; paclitaxel; pharmacodynamics; pharmacokinetics
8.  Development of paclitaxel-loaded liposomal nanocarrier stabilized by triglyceride incorporation 
Studies have highlighted the challenge of developing injectable liposomes as a paclitaxel (PTX) carrier, a challenge attributable to the limitations in liposomal stability caused by PTX loading. Poor stability of PTX-loaded liposomes is caused by PTX-triggered aggregation or fusion of liposomal membranes and is exacerbated in the presence of PEGylated lipid. In the present study, the effect of triglyceride incorporation on the stability of PTX-loaded/PEGylated liposomes was explored. Incorporation of a medium chain triglyceride Captex 300 into saturated phosphatidylcholine (PC)-based liposomes (1,2-dimyristoyl-sn-glycero-3-phosphocholine [DMPC]:cholesterol [CHOL]:N-(Carbonyl-methoxypolyethyleneglycol 2000)-1, 2-distearoyl-sn-glycero-3-phospho-ethanolamine [PE-PEG]), produced a fine, homogeneous, and membrane-filterable PTX-loaded liposomes fulfilling the requirement of an injectable lipid formulation. Triglyceride incorporation also greatly inhibited the time-dependent leakage of PTX from saturated PC-based liposomes, which appears to be mediated by the inhibition of liposome fusion. In contrast, triglyceride incorporation induced the destabilization and PTX leakage of unsaturated PC-based liposomes, indicating the opposite effect of triglyceride depending on the fluidity status of PC constituting the liposomal membrane. PTX release profile and the in vitro and in vivo anticancer efficacy of triglyceride-incorporated DMPC:CHOL:PE-PEG liposomes were similar to Taxol® while the toxicity of liposomal PTX was significantly lower than that of Taxol. Taken together, triglyceride incorporation provided an injectable PTX formulation by functioning as a formulation stabilizer of PEGylated/saturated PC-based liposomes.
doi:10.2147/IJN.S113723
PMCID: PMC5019274  PMID: 27660440
paclitaxel; triglyceride; PEGylation; liposome; stability; formulation
9.  Biodistribution and pharmacokinetics of a telodendrimer micellar paclitaxel nanoformulation in a mouse xenograft model of ovarian cancer 
Background
A multifunctional telodendrimer-based micelle system was characterized for delivery of imaging and chemotherapy agents to mouse tumor xenografts. Previous optical imaging studies demonstrated qualitatively that these classes of nanoparticles, called nanomicelles, preferentially accumulate at tumor sites in mice. The research reported herein describes the detailed quantitative imaging and biodistribution profiling of nanomicelles loaded with a cargo of paclitaxel.
Methods
The telodendrimer was covalently labeled with 125I and the nanomicelles were loaded with 14C-paclitaxel, which allowed measurement of pharmacokinetics and biodistribution in the mice using microSPECT/CT imaging and liquid scintillation counting, respectively.
Results
The radio imaging data showed preferential accumulation of nanomicelles at the tumor site along with a slower clearance rate than paclitaxel formulated in Cremophor EL (Taxol®). Liquid scintillation counting confirmed that 14C-labeled paclitaxel sequestered in nanomicelles had increased uptake by tumor tissue and slower pharmacokinetics than Taxol.
Conclusion
Overall, the results indicate that nanomicelle-formulated paclitaxel is a potentially superior formulation compared with Taxol in terms of water solubility, pharmacokinetics, and tumor accumulation, and may be clinically useful for both tumor imaging and improved chemotherapy applications.
doi:10.2147/IJN.S29306
PMCID: PMC3352867  PMID: 22605931
telodendrimer; nanomicelle; paclitaxel; microSPECT/CT; imaging guided drug delivery
10.  SPARC independent drug delivery and antitumour effects of nab-paclitaxel in genetically engineered mice 
Gut  2013;63(6):974-983.
Design
Pharmacokinetic and pharmacodynamic parameters of cremophor-paclitaxel, nab-paclitaxel (human-albumin-bound paclitaxel, Abraxane) and a novel mouse-albumin-bound paclitaxel (m-nab-paclitaxel) were evaluated in genetically engineered mouse models (GEMMs) by liquid chromatography-tandem mass spectrometry (LC-MS/MS), histological and biochemical analysis. Preclinical evaluation of m-nab-paclitaxel included assessment by three-dimensional high-resolution ultrasound and molecular analysis in a novel secreted protein acidic and rich in cysteine (SPARC)-deficient GEMM of pancreatic ductal adenocarcinoma (PDA).
Results
nab-Paclitaxel exerted its antitumoural effects in a dose-dependent manner and was associated with less toxicity compared with cremophor-paclitaxel. SPARC nullizygosity in a GEMM of PDA, KrasG12D;p53flox/−;p48Cre (KPfC), resulted in desmoplastic ductal pancreas tumours with impaired collagen maturation. Paclitaxel concentrations were significantly decreased in SPARC null plasma samples and tissues when administered as low-dose m-nab-paclitaxel. At the maximally tolerated dose, SPARC deficiency did not affect the intratumoural paclitaxel concentration, stromal deposition and the immediate therapeutic response.
Conclusions
nab-Paclitaxel accumulates and acts in a dose-dependent manner. The interaction of plasma SPARC and albumin-bound drugs is observed at low doses of nab-paclitaxel but is saturated at therapeutic doses in murine tumours. Thus, this study provides important information for future preclinical and clinical trials in PDA using nab-paclitaxel in combination with novel experimental and targeted agents.
doi:10.1136/gutjnl-2013-305559
PMCID: PMC4033275  PMID: 24067278
Pancreatic Cancer
11.  VIP-targeted Cytotoxic Nanomedicine for Breast Cancer 
Cancer chemotherapy is hampered by serious toxicity to healthy tissues. Conceivably, encapsulation of cytotoxic drugs in actively-targeted, biocompatible nanocarriers could overcome this problem. Accordingly, we used sterically stabilized mixed micelles (SSMM) composed of biocompatible and biodegradable phospholipids to solubilize paclitaxel (P), a hydrophobic model cytotoxic drug, and deliver it to breast cancer in rats. To achieve active targeting, the surface of SSMM was grafted with a ligand, human vasoactive intestinal peptide (VIP) that selectively interacts with its cognate receptors overexpressed on breast cancer cells. We found that even in vitro cytotoxicity of P-SSMM-VIP was 2-fold higher that that of free paclitaxel (p<0.05). Given the unique attributes of P-SSMM and P-SSMM-VIP, most notable small hydrodynamic diameter (~15nm) and stealth properties, biodistribution of paclitaxel was significantly altered. Accumulation of paclitaxel in breast tumor was highest for P-SSMM-VIP, followed by P-SSMM and Cremophor based paclitaxel (PTX). Importantly, bone marrow accumulation of paclitaxel encapsulated in both SSMM-VIP and SSMM was significantly less than that of PTX. Administration of clinically-relevant dose of paclitaxel (5mg/kg) as P-SSMM-VIP and P-SSMM eradicated carcinogen-induced orthotopic breast cancer in rats, whereas PTX decreased tumor size by only 45%. In addition, a 5-fold lower dose (1mg/kg) of paclitaxel in actively targeted P-SSMM-VIP was associated with ~80% reduction in tumor size while the response to PTX and P-SSMM was significantly less. Hypotension was not observed when VIP was grafted onto SSMM. Based on our findings, we propose further development of effective and safe VIP-grafted phospholipid micelle nanomedicines of anti-cancer drugs for targeted treatment of solid tumors in humans.
doi:10.1007/s13346-012-0107-x
PMCID: PMC3546828  PMID: 23336096
phospholipid mixed micelles; targeted drug delivery; human vasoactive intestinal peptide; breast cancer; paclitaxel; MNU-induced breast cancer
12.  The co-solvent Cremophor EL limits absorption of orally administered paclitaxel in cancer patients 
British Journal of Cancer  2001;85(10):1472-1477.
The purpose of this study was to investigate the effect of the co-solvents Cremophor EL and polysorbate 80 on the absorption of orally administered paclitaxel. 6 patients received in a randomized setting, one week apart oral paclitaxel 60 mg m−2 dissolved in polysorbate 80 or Cremophor EL. For 3 patients the amount of Cremophor EL was 5 ml m−2, for the other three 15 ml m−2. Prior to paclitaxel administration patients received 15 mg kg−1 oral cyclosporin A to enhance the oral absorption of the drug. Paclitaxel formulated in polysorbate 80 resulted in a significant increase in the maximal concentration (C max) and area under the concentration–time curve (AUC) of paclitaxel in comparison with the Cremophor EL formulations (P = 0.046 for both parameters). When formulated in Cremophor EL 15 ml m−2, paclitaxel C max and AUC values were 0.10 ± 0.06 μM and 1.29 ± 0.99 μM h−1, respectively, whereas these values were 0.31 ± 0.06 μM and 2.61 ± 1.54 μM h−1, respectively, when formulated in polysorbate 80. Faecal data revealed a decrease in excretion of unchanged paclitaxel for the polysorbate 80 formulation compared to the Cremophor EL formulations. The amount of paclitaxel excreted in faeces was significantly correlated with the amount of Cremophor EL excreted in faeces (P = 0.019). When formulated in Cremophor EL 15 ml m−2, paclitaxel excretion in faeces was 38.8 ± 13.0% of the administered dose, whereas this value was 18.3 ±15.5% for the polysorbate 80 formulation. The results show that the co-solvent Cremophor EL is an important factor limiting the absorption of orally administered paclitaxel from the intestinal lumen. They highlight the need for designing a better drug formulation in order to increase the usefulness of the oral route of paclitaxel © 2001 Cancer Research Campaign   http://www.bjcancer.com
doi:10.1054/bjoc.2001.2118
PMCID: PMC2363961  PMID: 11720431
paclitaxel; oral administration; Cremophor EL
13.  Paclitaxel Nano-Delivery Systems: A Comprehensive Review 
Paclitaxel is one of the most effective chemotherapeutic drugs ever developed and is active against a broad range of cancers, such as lung, ovarian, and breast cancers. Due to its low water solubility, paclitaxel is formulated in a mixture of Cremophor EL and dehydrated ethanol (50:50, v/v) a combination known as Taxol. However, Taxol has some severe side effects related to Cremophor EL and ethanol. Therefore, there is an urgent need for the development of alternative Taxol formulations. The encapsulation of paclitaxel in biodegradable and non-toxic nano-delivery systems can protect the drug from degradation during circulation and in-turn protect the body from toxic side effects of the drug thereby lowering its toxicity, increasing its circulation half-life, exhibiting improved pharmacokinetic profiles, and demonstrating better patient compliance. Also, nanoparticle-based delivery systems can take advantage of the enhanced permeability and retention (EPR) effect for passive tumor targeting, therefore, they are promising carriers to improve the therapeutic index and decrease the side effects of paclitaxel. To date, paclitaxel albumin-bound nanoparticles (Abraxane®) have been approved by the FDA for the treatment of metastatic breast cancer and non-small cell lung cancer (NSCLC). In addition, there are a number of novel paclitaxel nanoparticle formulations in clinical trials. In this comprehensive review, several types of developed paclitaxel nano-delivery systems will be covered and discussed, such as polymeric nanoparticles, lipid-based formulations, polymer conjugates, inorganic nanoparticles, carbon nanotubes, nanocrystals, and cyclodextrin nanoparticles.
doi:10.4172/2157-7439.1000164
PMCID: PMC3806207  PMID: 24163786
Nanoparticles; Poly(lactic-co-glycolic acid); Nanocapsules; Drug-polymer conjugates; Multi-drug resistance; Solid lipid nanoparticles
14.  Albumin-bound nanoparticle (nab) paclitaxel exhibits enhanced paclitaxel tissue distribution and tumor penetration 
Purpose
nab-paclitaxel demonstrates improved clinical efficacy compared with conventional Cremophor EL (CrEL)-paclitaxel in multiple tumor types. This study explored the distinctions in drug distribution between nab-paclitaxel and CrEL-paclitaxel and the underlying mechanisms.
Methods
Uptake and transcytosis of paclitaxel were analyzed by vascular permeability assay across human endothelial cell monolayers. The tissue penetration of paclitaxel within tumors was evaluated by local injections into tumor xenografts and quantitative image analysis. The distribution profile of paclitaxel in solid-tumor patients was assessed using pharmacokinetic modeling and simulation.
Results
Live imaging demonstrated that albumin and paclitaxel were present in punctae in endothelial cells and could be observed in very close proximity, suggesting cotransport. Uptake and transport of albumin, nab-paclitaxel and paclitaxel were inhibited by clinically relevant CrEL concentrations. Further, nab-paclitaxel causes greater mitotic arrest in wider area within xenografted tumors than CrEL- or dimethyl sulfoxide-paclitaxel following local microinjection, demonstrating enhanced paclitaxel penetration and uptake by albumin within tumors. Modeling of paclitaxel distribution in patients with solid tumors indicated that nab-paclitaxel is more dependent upon transporter-mediated pathways for drug distribution into tissues than CrEL-paclitaxel. The percent dose delivered to tissue via transporter-mediated pathways is predicted to be constant with nab-paclitaxel but decrease with increasing CrEL-paclitaxel dose.
Conclusions
Compared with CrEL-paclitaxel, nab-paclitaxel demonstrated more efficient transport across endothelial cells, greater penetration and cytotoxic induction in xenograft tumors, and enhanced extravascular distribution in patients that are attributed to carrier-mediated transport. These observations are consistent with the distinct clinical efficacy and toxicity profile of nab-paclitaxel.
Electronic supplementary material
The online version of this article (doi:10.1007/s00280-015-2833-5) contains supplementary material, which is available to authorized users.
doi:10.1007/s00280-015-2833-5
PMCID: PMC4768222  PMID: 26231955
Taxane; Nanoparticle; Albumin; nab-paclitaxel; Cremophor EL
15.  Assessing the effectiveness and safety of liposomal paclitaxel in combination with cisplatin as first-line chemotherapy for patients with advanced NSCLC with regional lymph-node metastasis: study protocol for a randomized controlled trial (PLC-GC trial) 
Trials  2013;14:45.
Background
Lung cancer is still the leading cause of cancer-related mortality worldwide. Around 80 to 85% of lung cancers are non-small cell lung cancer (NSCLC). Regional lymphatic metastasis is a frequent occurrence in NSCLC, and the extent of lymphatic dissemination significantly determines the prognosis of patients with NSCLC. Hence, identification of alternative treatments for these patients should be considered a priority. Liposomal paclitaxel is a new formulation composed of paclitaxel and liposomes, with favorable pharmacokinetic properties. In particular, it produces dramatically higher drug concentrations in the lymph nodes than occurs with the current formulations of paclitaxel, thus we believe that patients with NSCLC with regional lymphatic metastasis may benefit from this new drug. Cisplatin-based doublet chemotherapy is recommended as the first-line treatment for patients with advanced NSCLC. We have designed a trial to assess whether first-line chemotherapy using liposomal paclitaxel combined with cisplatin (LP regimen) is superior to gemcitabine combined with cisplatin (GP regimen) in efficacy (both short-term and long-term efficacy) and safety (adverse events; AEs).
Method/Design
This is a prospective, open-label, controlled randomized clinical trial (RCT) to assess the therapeutic effects and safety of liposomal paclitaxel. The study aims to enroll 126 patients, who will be randomly allocated to one of the two treatment groups (LP and GP), with 63 patients in each group. Patients will receive four to six cycles of the assigned chemotherapy, and primary outcome will be assessed every two cycles. Patients will be recommended for surgery if the tumor becomes resectable. All participants will be followed up for at least 12 months. The objective response rate (ORR), changes in regional lymphatic metastasis (including number and size) and TNM (tumor, node, metastasis) staging will be the primary outcome measures. Progression-free survival, objective survival, median survival time, 1-year survival rate, toxicity, and time to disease progression will be the secondary outcome measures.
Conclusions
A systematic search has indicated that this proposed study will be the first RCT to evaluate whether liposomal paclitaxel plus cisplatin will have beneficial effects, compared with gemcitabine plus cisplatin, on enhancing ORR, changing TNM staging, improving long-term survival, and reducing the frequency of AEs for patients with NSCLC with regional lymphatic metastasis.
Trial registration
http://www.chictr.org Identifier: ChiCTR-TRC-12602105
doi:10.1186/1745-6215-14-45
PMCID: PMC3599280  PMID: 23413951
Liposomal paclitaxel; Cisplatin; Gemcitabine; Regional lymph node metastasis; Trials
16.  Update on taxane development: new analogs and new formulations 
The taxanes (paclitaxel and docetaxel) represent an important class of antineoplastic agents that interfere with microtubule function leading to altered mitosis and cellular death. Paclitaxel (Taxol®) was originally extracted from a yew tree (Taxus spp., Taxaceae) a small slow-growing evergreen, coniferous tree. Due to the initial scarcity of paclitaxel, docetaxel (Taxotere®) a semisynthetic analog of paclitaxel produced from the needles of European yew tree, Taxus baccata was developed. Docetaxel differs from paclitaxel in two positions in its chemical structure and this small alteration makes it more water soluble. Today, paclitaxel and docetaxel are widely prescribed antineoplastic agents for a broad range of malignancies including lung cancer, breast cancer, prostate cancer, Kaposi’s sarcoma, squamous cell carcinoma of the head and neck, gastric cancer, esophageal cancer, bladder cancer, and other carcinomas. Although very active clinically, paclitaxel and docetaxel have several clinical problems including poor drug solubility, serious dose-limiting toxicities such as myelosuppression, peripheral sensory neuropathy, allergic reactions, and eventual development of drug resistance. A number of these side effects have been associated with the solvents used for dilution of these antineoplastic agents: Cremophor EL for paclitaxel and polysorbate 80 for docetaxel. In addition, reports have linked these solvents to the alterations in paclitaxel and docetaxel pharmacokinetic profiles. In this review, we provide preclinical and clinical data on several novel taxanes formulations and analogs which are currently US Food and Drug Administration (FDA)-approved or in clinical development in various solid tumor malignancies. Of the new taxanes nab-paclitaxel and cabazitaxel have enjoyed clinical success and are FDA-approved; while many of the other compounds described in this review are unlikely to be further developed for clinical use in daily practice. Furthermore, the successful clinical emergence of novel nontaxane microtubule-targeting chemotherapy agents such as epothilones and eribulin is liable to further restrict the development of novel taxanes.
doi:10.2147/DDDT.S28997
PMCID: PMC3523563  PMID: 23251087
taxane(s); novel taxanes; taxane analogs; new taxane formulations; new antimicrotubule agents
17.  Effects of Jia-Wei-Xiao-Yao-San on the Peripheral and Lymphatic Pharmacokinetics of Paclitaxel in Rats 
Paclitaxel is effective against breast cancer. The herbal medicine, Jia-Wei-Xiao-Yao-San (JWXYS), is the most frequent prescription used to relieve the symptoms of breast cancer treatments. The aim of the study was to investigate the herb-drug interaction effects of a herbal medicine on the distribution of paclitaxel to lymph. A validated ultraperformance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) method was used to determine the paclitaxel levels in rat plasma and lymph after intravenous infusion of paclitaxel alone with or without 7 days of JWXYS pretreatment. The pharmacokinetic results indicate that paclitaxel concentrations in plasma exceeded those in lymph by approximately 3.6-fold. The biodistribution of paclitaxel from plasma to lymph was 39 ± 5%; however, this increased to 45 ± 4% with JWXYS pretreatment. With JWXYS pretreatment, the AUC and Cmax of paclitaxel in plasma were significantly reduced by approximately 1.5-fold, compared to paclitaxel alone. Additionally, JWXYS decreased the AUC and Cmax of paclitaxel in lymph. However, the lymph absorption rate of paclitaxel with or without JWXYS pretreatment was not significantly changed (27 ± 3 and 30 ± 2%, resp.). Our findings demonstrate that when paclitaxel is prescribed concurrently with herbal medicine, monitoring of the blood pharmacokinetics of paclitaxel is recommended.
doi:10.1155/2016/5614747
PMCID: PMC4802034  PMID: 27057200
18.  A population pharmacokinetic model for paclitaxel in the presence of a novel P-gp modulator, Zosuquidar Trihydrochloride (LY335979) 
Aims
To develop a population pharmacokinetic model for paclitaxel in the presence of a MDR modulator, zosuquidar 3HCl.
Methods
The population approach was used (implemented with NONMEM) to analyse paclitaxel pharmacokinetic data from 43 patients who received a 3-h intravenous infusion of paclitaxel (175 mg m−2 or 225 mg m−2) alone in cycle 2 or concomitantly with the oral administration of zosuquidar 3HCl in cycle 1.
Results
The structural pharmacokinetic model for paclitaxel, accounting for the Cremophor EL™ impact, was a three-compartment model with a nonlinear model for paclitaxel plasma clearance (CL), involving a linear decrease in this parameter during the infusion and a sigmoidal increase with time after the infusion. The final model described the effect of Zosuquidar 3HCl on paclitaxel CL by a categorical relationship. A 25% decrease in paclitaxel CL was observed, corresponding to an 1.3-fold increase in paclitaxel AUC (from 14829 µg l−1 h to 19115 µg l−1 h following paclitaxel 175 mg m−2) when zosuquidar Cmax was greater than 350 µg l−1. This cut-off concentration closely corresponded to the IC50 of a sigmoidal Emax relationship (328 µg l−1). A standard dose of 175 mg m−2 of paclitaxel could be safely combined with doses of zosuquidar 3HCl resulting in plasma concentrations known, from previous studies, to result in maximal P-gp inhibition.
Conclusions
This analysis provides a model which accurately characterized the increase in paclitaxel exposure, which is most likely to be due to P-gp inhibition in the bile canaliculi, in the presence of zosuquidar 3HCl (Cmax > 350 µg l−1) and is predictive of paclitaxel pharmacokinetics following a 3 h infusion. Hence the model could be useful in guiding therapy for paclitaxel alone and also for paclitaxel administered concomitantly with a P-gp inhibitor, and in designing further clinical trials.
doi:10.1046/j.1365-2125.2003.01826.x
PMCID: PMC1884334  PMID: 12848775
paclitaxel; P-glycoprotein modulator; population pharmacokinetics; Zosuquidar 3HCl
19.  Liposomal cisplatin combined with paclitaxel versus cisplatin and paclitaxel in non-small-cell lung cancer: a randomized phase III multicenter trial 
Annals of Oncology  2010;21(11):2227-2232.
Background: Liposomal cisplatin is a new formulation developed to reduce the systemic toxicity of cisplatin while simultaneously improving the targeting of the drug to the primary tumor and to metastases by increasing circulation time in the body fluids and tissues. The primary objectives were to determine nephrotoxicity, gastrointestinal side-effects, peripheral neuropathy and hematological toxicity and secondary objectives were to determine the response rate, time to tumor progression (TTP) and survival.
Patients and methods: Two hundred and thirty-six chemotherapy-naive patients with inoperable non-small-cell lung cancer were randomly allocated to receive either 200 mg/m2 of liposomal cisplatin and 135 mg/m2 paclitaxel (arm A) or 75 mg/m2 cisplatin and 135 mg/m2 paclitaxel (arm B), once every 2 weeks on an outpatient basis. Two hundred and twenty-nine patients were assessable for toxicity, response rate and survival. Nine treatment cycles were planned.
Results: Arm A patients showed statistically significant lower nephrotoxicity, grade 3 and 4 leucopenia, grade 2 and 3 neuropathy, nausea, vomiting and fatigue. There was no significant difference in median and overall survival and TTP between the two arms; median survival was 9 and 10 months in arms A and B, respectively, and TTP was 6.5 and 6 months in arms A and B, respectively.
Conclusions: Liposomal cisplatin in combination with paclitaxel has been shown to be much less toxic than the original cisplatin combined with paclitaxel. Nephrotoxicity in particular was negligible after liposomal cisplatin administration. TTP and survival were similar in both treatment arms.
doi:10.1093/annonc/mdq234
PMCID: PMC2962260  PMID: 20439345
liposomal cisplatin; NSCLC
20.  Correlation between radioactivity and chemotherapeutics of the 111In-VNB-liposome in pharmacokinetics and biodistribution in rats 
Background
The combination of a radioisotope with a chemotherapeutic agent in a liposomal carrier (ie, Indium-111-labeled polyethylene glycol pegylated liposomal vinorelbine, [111In-VNB-liposome]) has been reported to show better therapeutic efficiency in tumor growth suppression. Nevertheless, the challenge remains as to whether this therapeutic effect is attributable to the combination of a radioisotope with chemotherapeutics. The goal of this study was to investigate the pharmacokinetics, biodistribution, and correlation of Indium-111 radioactivity and vinorelbine concentration in the 111In-VNB-liposome.
Methods
The VNB-liposome and 111In-VNB-liposome were administered to rats. Blood, liver, and spleen tissue were collected to determine the distribution profile of the 111In-VNB-liposome. A liquid chromatography tandem mass spectrometry system and gamma counter were used to analyze the concentration of vinorelbine and radioactivity of Indium-111.
Results
High uptake of the 111In-VNB-liposome in the liver and spleen demonstrated the properties of a nanosized drug delivery system. Linear regression showed a good correlation (r = 0.97) between Indium-111 radioactivity and vinorelbine concentration in the plasma of rats administered the 111In-VNB-liposome.
Conclusion
A significant positive correlation between the pharmacokinetics and biodistribution of 111Indium radioactivity and vinorelbine in blood, spleen, and liver was found following administration of the 111In-VNB-liposome. The liposome efficiently encapsulated both vinorelbine and Indium-111, and showed a similar concentration-radioactivity time profile, indicating the correlation between chemotherapy and radiotherapy could be identical in the liposomal formulation.
doi:10.2147/IJN.S28279
PMCID: PMC3282608  PMID: 22359447
Indium-111; vinorelbine; liposome; pharmacokinetics; radiochemotherapy
21.  Targeted delivery of albumin bound paclitaxel in the treatment of advanced breast cancer 
OncoTargets and therapy  2009;2:179-188.
Taxanes are chemotherapeutic agents with a large spectrum of antitumor activity when used as monotherapy or in combination regimens. Paclitaxel and docetaxel have poor solubility and require a complex solvent system for their commercial formulation, Cremophor EL® (CrEL) and Tween 80® respectively. Both these biological surfactants have recently been implicated as contributing not only to the hypersensitivity reactions, but also to the degree of peripheral neurotoxicity and myelosuppression, and may antagonize the cytotoxicity. Nab-paclitaxel, or nanoparticle albumin-bound paclitaxel (ABI-007; Abraxane®), is a novel formulation of paclitaxel that does not employ the CrEL solvent system. Nab-paclitaxel demonstrates greater efficacy and a favorable safety profile compared with standard paclitaxel in patients with advanced disease (breast cancer, non-small cell lung cancer, melanoma, ovarian cancer). Clinical studies in breast cancer have shown that nab-paclitaxel is significantly more effective than standard paclitaxel in terms of overall objective response rate (ORR) and time to progression. Nab-paclitaxel in combination with gemcitabine, capecitabine or bevacizumab has been shown to be very active in patients with advanced breast cancer. An economic analysis showed that nab-paclitaxel would be an economically reasonable alternative to docetaxel or standard paclitaxel in metastatic breast cancer. Favorable tumor ORR and manageable toxicities have been reported for nab-paclitaxel as monotherapy or in combination treatment in advanced breast cancer.
PMCID: PMC2886338  PMID: 20616905
breast cancer; nab-paclitaxel; chemotherapy
22.  A Pharmacodynamic Study of the P-glycoprotein Antagonist CBT-1® in Combination With Paclitaxel in Solid Tumors 
The Oncologist  2012;17(4):512.
Background:
This pharmacodynamic trial evaluated the effect of CBT-1® on efflux by the ATP binding cassette (ABC) multidrug transporter P-glycoprotein (Pgp/MDR1/ABCB1) in normal human cells and tissues. CBT-1® is an orally administered bisbenzylisoquinoline Pgp inhibitor being evaluated clinically. Laboratory studies showed potent and durable inhibition of Pgp, and in phase I studies CBT-1® did not alter the pharmacokinetics of paclitaxel or doxorubicin.
Methods:
CBT-1® was dosed at 500 mg/m2 for 7 days; a 3-hour infusion of paclitaxel at 135 mg/m2 was administered on day 6. Peripheral blood mononuclear cells (PBMCs) were obtained prior to CBT-1® administration and on day 6 prior to the paclitaxel infusion. 99mTc-sestamibi imaging was performed on the same schedule. The area under the concentration–time curve from 0–3 hours (AUC0–3) was determined for 99mTc-sestamibi.
Results:
Twelve patients were planned and enrolled. Toxicities were minimal and related to paclitaxel (grade 3 or 4 neutropenia in 18% of cycles). Rhodamine efflux from CD56+ PBMCs was a statistically significant 51%–100% lower (p < .0001) with CBT-1®. Among 10 patients who completed imaging, the 99mTc-sestamibi AUC0–3 for liver (normalized to the AUC0–3 of the heart) increased from 34.7% to 100.8% (median, 71.9%; p < .0001) after CBT-1® administration. Lung uptake was not changed.
Conclusion:
CBT-1® is able to inhibit Pgp-mediated efflux from PBMCs and normal liver to a degree observed with Pgp inhibitors studied in earlier clinical trials. Combined with its ease of administration and lack of toxicity, the data showing inhibition of normal tissue Pgp support further studies with CBT-1® to evaluate its ability to modulate drug uptake in tumor tissue.
Discussion:
Although overexpression of ABCB1 and other ABC transporters has been linked with poor outcome following chemotherapy efforts to negate that through pharmacologic inhibition have generally failed. This is thought to be a result of several factors, including (a) failure to select patients with tumors in which ABCB1 is a dominant resistance mechanism; (b) inhibitors that were not potent, or that impaired drug clearance; and (c) the existence of other mechanisms of drug resistance, including other ABC transporters. Although an animal model for Pgp has been lacking, recent studies have exploited a Brca1−/−; p53−/− mouse model of hereditary breast cancer that develops sporadic tumors similar to cancers in women harboring BRCA1 mutations. Treatment with doxorubicin, docetaxel, or the poly(ADP-ribose) polymerase inhibitor olaparib brings about shrinkage, but resistance eventually emerges. Overexpression of the Abcb1a gene, the mouse ortholog of human ABCB1, has been shown to be a mechanism of resistance in a subset of these tumors. Treating mice with resistant tumors with olaparib plus the Pgp inhibitor tariquidar resensitized the tumors to olaparib. Although results in this animal model support a new look at Pgp as a target, in this era of “targeted therapies,” trial designs that directly assess modulation of drug uptake, including quantitative nuclear imaging, should be pursued before clinical efficacy assessments are undertaken. Such assessment should be performed with compounds that inhibit tissue Pgp without altering the pharmacokinetics of chemotherapeutic agents. This pharmacodynamic study demonstrated that CBT-1®, inhibits Pgp-mediated efflux from PBMCs and normal liver.
doi:10.1634/theoncologist.2012-0080
PMCID: PMC3336838  PMID: 22416063
23.  Randomized crossover pharmacokinetic study of solvent-based paclitaxel and nab-paclitaxel 
Purpose:
Abraxane (ABI-007) is a 130 nm albumin-bound (nab™) particle formulation of paclitaxel, devoid of any additional excipients. We hypothesized that this change in formulation alters the systemic disposition of paclitaxel compared with conventional solvent-based formulations (sb-paclitaxel, Taxol®), and leads to improved tolerability of the drug.
Patients and Methods:
Patients with malignant solid tumors were randomized to receive the recommended single agent dose of nab-paclitaxel (260 mg/m2 as a 30 minute infusion) or sb-paclitaxel (175 mg/m2 as a 3 hour infusion). Following cycle 1, patients crossed over to the alternate treatment. Pharmacokinetic studies were carried out for the first cycle of sb-paclitaxel and the first two cycles of nab-paclitaxel.
Results:
Seventeen patients were treated, with 14 receiving at least one cycle each of nab-paclitaxel and sb-paclitaxel. No change in nab-paclitaxel pharmacokinetics was found between the first and second cycles (P =0.95), suggesting limited intrasubject variability. Total drug exposure was comparable between the two formulations (P= 0.55) despite the dose difference. However, exposure to unbound paclitaxel was significantly higher following nab-paclitaxel administration, due to the increased free fraction (0.063 ± 0.021 vs 0.024 ± 0.009, P <0.001).
Conclusion:
This study demonstrates that paclitaxel disposition is subject to considerable variability depending on the formulation used. Since systemic exposure to unbound paclitaxel is likely a driving force behind tumoral uptake, these findings explain, at least in part, previous observations that the administration of nab-paclitaxel is associated with augmented antitumor efficacy as compared with solvent-based paclitaxel.
doi:10.1158/1078-0432.CCR-07-4592
PMCID: PMC2661025  PMID: 18594000
24.  Design and characterization of anionic PEGylated liposomal formulation loaded with paclitax for ovarian cancer 
Journal of Pharmacy & Bioallied Sciences  2012;4(Suppl 1):S17-S18.
Despite its strong antitumor activity, paclitaxel (Taxol®) has limited clinical applications due to its low aqueous solubility and hypersensitivity caused by cremophor EL and ethanol which is the vehicle used in the current commercial product. In an attempt to develop a pharmaceutically acceptable formulation that could replace Taxol®, we have prepared PEGylated liposomes containing paclitaxel to improve its solubility and physicochemical stability. Its percent drug entrapment (PDE), mean particle size, zeta potential and in vitro release profile were determined. The optimized PEGylated liposomes provided high percent entrapment efficiency (64.29%) and mean particle size of 228.6 nm. The electroflocculation method showed 5 mol% of DSPE-mPEG2000 was required to obtain maximum stability for PEGylated liposome. In vitro release data showed its long circulating characteristic. Paclitaxel loaded PEGylated liposomes can be considered a promising long circulating paclitaxel delivery with absence of side effects related to Taxol®.
doi:10.4103/0975-7406.94122
PMCID: PMC3467822  PMID: 23066189
Antitumor activity; electroflocculation; in vitro release; thin film hydration
25.  Targeted Delivery of Doxorubicin by Folic Acid-Decorated Dual Functional Nanocarrier 
Molecular Pharmaceutics  2014;11(11):4164-4178.
Doxorubicin (DOX) is one of the most commonly used antineoplastic agents, but its clinical application is oftentimes coupled with severe side effects. Selective delivery of DOX to tumors via nanosized drug carrier represents an attractive approach to this problem. Previously, we developed a dual functional nanomicellar carrier, PEG5K-embelin2 (PEG5K-EB2), which was able to deliver paclitaxel (PTX) selectively to tumors and to achieve an enhanced therapeutic effect. In the present study, we examined the utility of PEG5K-EB2 to deliver DOX to tumors. In addition, folic acid (FA) was coupled to the surface of the PEG5K-EB2 micelles (FA-PEG5K-EB2) to further improve the selective targetability of the system. DOX-loaded PEG5K-EB2 micelles were uniformly spherical particles with a diameter of approximately 20 nm. Incorporation of FA had minimal effect on the size of the particles. The DOX loading efficiency was as high as 91.7% and 93.5% for PEG5K-EB2 and FA-PEG5K-EB2, respectively. DOX formulated in PEG5K-EB2 micelles (with or without FA decoration) demonstrated sustained kinetics of DOX release compared to free DOX. FA-PEG5K-EB2 significantly facilitated the intracellular uptake of DOX over free DOX and PEGylated liposomal DOX (Doxil) in breast cancer cells, 4T1.2, and drug resistant cells, NCI/ADR-RES. P-gp ATPase assay showed that PEG5K-EB2 significantly inhibited the function of the P-gp efflux pump. The maximum tolerated dose of DOX-loaded PEG5K-EB2 micelles was 15 mg/kg in mice, which was 1.5-fold greater than that for free DOX. Pharmacokinetics (PK) and biodistribution studies showed that both types of DOX-loaded micelles, especially FA-PEG5K-EB2, were able to significantly prolong the blood circulation time of DOX and facilitate its preferential accumulation at the tumor tissue. Finally, DOX/PEG5K-EB2 mixed micelles demonstrated significantly enhanced tumor growth inhibitory effect with minimal toxicity in comparison to free DOX and Doxil and the antitumor activity was further enhanced after the decoration by folic acid. Our data suggest that FA-PEG5K-EB2 micelles represent a promising DOX delivery system that warrants more study in the future.
doi:10.1021/mp500389v
PMCID: PMC4224520  PMID: 25265550
doxorubicin; targeted delivery; folic acid; nanomicelles; multidrug resistance; antitumor activity

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