Improved effectiveness of nanoparticle albumin-bound (nab) paclitaxel versus polysorbate-based docetaxel in multiple xenografts as a function of HER2 and SPARC status.
ABSTRACT Nanoparticle albumin-bound (nab)-paclitaxel (Abraxane) is an albumin-bound 130-nm particle form of paclitaxel that demonstrated higher efficacy and was well tolerated compared with solvent-based paclitaxel (Taxol) and docetaxel (Taxotere) in clinical trials for metastatic breast cancer. Nab-paclitaxel enhances tumor targeting through gp60 and caveolae-mediated endothelial transcytosis and the association with the albumin-binding protein SPARC (secreted protein, acidic and rich in cysteine) in the tumor microenvironment. The overexpression of human epidermal growth factor receptor-2 (HER2) in breast cancer has been shown to correlate with resistance to paclitaxel. To evaluate the importance of HER2 and SPARC status in determining the relative efficacy of nab-paclitaxel compared with polysorbate-based docetaxel, nude mice bearing six different human tumor xenografts were treated with nab-paclitaxel (MX-1: 15 mg/kg, once a week for 3 weeks; LX-1, MDA-MB-231/HER2+, PC3, and HT29: 50 and 120 mg/kg, every 4 days three times ; MDA-MB-231: 120 and 180 mg/kg, every 4 days three times) and polysorbate-based docetaxel (15 mg/kg). HER2 and SPARC status were analyzed by RT-PCR and immunohistochemical staining. MDA-MB-231 and MX-1 breast and LX-1 lung cancers were HER2 negative and low in SPARC expression. Nab-paclitaxel at submaximum-tolerated dosage was significantly more effective than polysorbate-based docetaxel at its maximum-tolerated dosage in these three HER2-negative tumors. The HER2-positive tumors had variable SPARC expression, with MDA-MB-231/HER2+ <PC3 <HT29. In these HER2-positive tumors, nab-paclitaxel was equal to or better than polysorbate-based docetaxel in tumors with medium to high SPARC levels (PC3 and HT29), but not in MDA-MB-231/HER2+ tumors with low SPARC expression. These results demonstrated that the relative efficacy of nab-paclitaxel was significantly higher compared with polysorbate-based docetaxel in HER2-negative tumors (three of three) and in HER2-positive tumors with high levels of SPARC. HER2 and SPARC expression may be useful biomarkers in determining antitumor effectiveness for taxanes.
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ABSTRACT: Solubilization of highly hydrophobic drugs with carriers that are non-toxic, non-immunogenic and well-defined remains a major obstacle in pharmaceutical sciences. Well-defined amphiphilic di- and triblock copolymers based on poly(2-oxazolines) were prepared and used for the solubilization of Paclitaxel (PTX) and other water-insoluble drugs. Probing the polymer micelles in water with the fluorescence probe pyrene, an unusual high polar microenvironment of the probe was observed. This coincides with an extraordinary large loading capacity for PTX of 45 wt.% active drug in the formulation as well as high water solubility of the resulting formulation. Physicochemical properties of the formulations, ease of preparation and stability upon lyophilization, low toxicity and immunogenicity suggest that poly(2-oxazoline)s are promising candidates for the delivery of highly challenging drugs. Furthermore, we demonstrate that PTX is fully active and provides superior tumor inhibition as compared to the commercial micellar formulation.Biomaterials 03/2010; 31(18):4972-9. DOI:10.1016/j.biomaterials.2010.02.057 · 8.31 Impact Factor
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ABSTRACT: Because liver involvement in patients with metastatic cancer has limited options and poor outcomes, we conducted a phase I study to determine the safety, activity, and pharmacokinetic characteristics of hepatic arterial infusion of nanoparticle albumin-bound paclitaxel (HAI nab-paclitaxel). Cohorts of three patients having predominant hepatic metastases received HAI nab-paclitaxel at three dose levels (180, 220, and 260 mg/m(2), respectively) infused for more than 1 hour every 3 weeks (3 + 3 design). Some patients participated in comparative pharmacokinetic studies (i.v. vs. HAI), receiving their first course i.v., to determine peak concentrations and effect of first-pass hepatic extraction compared with subsequent courses administered by HAI. The highest dose level was expanded to determine the safety and activity of HAI nab-paclitaxel. Thirty-eight patients were treated. There were no dose-limiting toxicities at doses up to 260 mg/m(2). Common adverse events included alopecia, fatigue, myelosuppresion, nausea, and vomiting. Three patients had stable disease for 4 or more months and 2 patients (1 of 12 with breast cancer and 1 of 1 with cervical cancer) achieved a partial response lasting for 5 and 15 months, respectively. Peak concentrations were lower (∼50%) with greater hepatic extraction of drug (∼42%) following HAI than i.v. infusion based on area under the curve comparison of drug exposure. HAI nab-paclitaxel showed partial hepatic extraction. At doses 260 mg/m(2) or less given for 1 hour every 3 weeks, the treatment was well-tolerated and showed activity in advanced cancer patients with predominant liver metastases.Molecular Cancer Therapeutics 05/2011; 10(7):1300-7. DOI:10.1158/1535-7163.MCT-11-0259 · 6.11 Impact Factor
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ABSTRACT: Pancreatic ductal adenocarcinomas are characterized by the desmoplastic reaction, a dense fibrous stroma that has been shown to be supportive of tumor cell growth, invasion, and metastasis, and has been associated with resistance to chemotherapy and reduced patient survival. Here, we investigated targeted depletion of stroma for pancreatic cancer therapy via taxane nanoparticles. Cellax-DTX polymer is a conjugate of docetaxel (DTX), polyethylene glycol (PEG), and acetylated carboxymethylcellulose, a construct which condenses into well-defined 120nm particles in aqueous solution, and is suitable for intravenous injection. We examined Cellax-DTX treatment effects in highly stromal primary patient-derived pancreatic cancer xenografts and in a metastatic PAN02 mouse model of pancreatic cancer, focussing on specific cellular interactions in the stroma, pancreatic tumor growth and metastasis. Greater than 90% of Cellax-DTX particles accumulate in smooth muscle actin (SMA) positive cancer-associated fibroblasts which results in long-term depletion of this stromal cell population, an effect not observed with Nab-paclitaxel (Nab-PTX). The reduction in stromal density leads to a >10-fold increase in tumor perfusion, reduced tumor weight and a reduction in metastasis. Consentingly, Cellax-DTX treatment increased survival when compared to treatment with gemcitabine or Nab-PTX in a metastatic PAN02 mouse model. Cellax-DTX nanoparticles interact with the tumor-associated stroma, selectively interacting with and depleting SMA positive cells and macrophage, effects which are associated with significant changes in tumor progression and metastasis. Copyright © 2015. Published by Elsevier B.V.Journal of Controlled Release 03/2015; 206. DOI:10.1016/j.jconrel.2015.03.023 · 7.26 Impact Factor