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Modulation of Drug Resistance in Ovarian Adenocarcinoma by Enhancing Intracellular Ceramide Using Tamoxifen-Loaded Biodegradable Polymeric Nanoparticles

Authors' Affiliations: ¹ Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University; ² Department of Hematology and Oncology, Massachusetts General Hospital, Boston, Massachusetts

Requests for reprints: Mansoor M. Amiji, Department of Pharmaceutical Sciences, School of Pharmacy, Northeastern University, 360 Huntington Avenue, Boston MA 02115. Phone: 617-373-3137; Fax: 617-373-8886; E-mail: m.amiji{at}neu.edu.

Purpose: To modulate intracellular ceramide levels and lower the apoptotic threshold in multidrug-resistant ovarian adenocarcinoma, we have examined the efficacy and preliminary safety of tamoxifen coadministration with paclitaxel in biodegradable poly(ethylene oxide)–modified poly(epsilon-caprolactone) (PEO-PCL) nanoparticles.

Experimental Design: In vitro cytotoxicity and proapoptotic activity of paclitaxel and tamoxifen, either as single agent or in combination, was examined in wild-type (SKOV3) and MDR-1–positive (SKOV3_TR) human ovarian adenocarcinoma cells. Subcutaneous SKOV3 and SKOV3_TR xenografts were established in female nu/nu mice, and this model was used to evaluate the antitumor efficacy and preliminary safety. Paclitaxel (20 mg/kg) and tamoxifen (70 mg/kg) were administered i.v. either as a single agent or in combination in aqueous solution and in PEO-PCL nanoparticles.

Results: In vitro cytotoxicity results showed that administration of paclitaxel and tamoxifen in combination lowered the IC₅₀ of paclitaxel by 10-fold in SKOV3 cells and by >3-fold in SKOV3_TR cells. The combination paclitaxel/tamoxifen co-therapy showed even more pronounced effect when administered in nanoparticle formulations. Upon i.v. administration of paclitaxel/tamoxifen combination in PEO-PCL nanoparticle formulations, significant enhancement in antitumor efficacy was observed. Furthermore, the combination paclitaxel/tamoxifen therapy did not induce any acute toxicity as measured by body weight changes, blood cell counts, and hepatotoxicity.

Conclusions: The results of this study show that combination of paclitaxel and tamoxifen in biodegradable PEO-PCL nanoparticles can serve as an effective clinically translatable strategy to overcome multidrug resistance in ovarian cancer.