(M1530-01-01) Modification of Paclitaxel Nanocrystals by Hydroxypropyl-Beta-Cyclodextrin to Improve Their Release Characteristics, Safety, and Efficacy

Purpose: Paclitaxel is a hydrophobic chemotherapeutic agent with high cytotoxicity used in the treatment of many serious cancers. Many attempts were made to enhance its activity and reduce the side effects, of which, preparation as nanocrystals was one of the most successful approaches. The study aimed at designing novel Paclitaxel nanocrystals coated with the biocompatible and biodegradable Hydroxypropyl-Beta-Cyclodextrin (HPβCD). HPβCD was chosen given that it is been used to improve the physicochemical properties and the bioavailability of hydrophobic medications. Also, previous studies showed that HPβCD seems to improve the efficacy of anticancer agents.

Methods: Paclitaxel nanocrystals were prepared by the anti-solvent method followed by homogenization. Then, the surface of the prepared nanocrystals was coated using HPβCD by suspending the prepared nanocrystals in HPβCD solution with agitation. The coated and uncoated nanocrystals were both characterized in terms of size, polydispersity index, charge, morphology, and stability. Moreover, the nanocrystals were investigated using Powder X-Ray Diffraction (PXRD), Differential Scanning Calorimeter (DSC), and Fourier Transform Infrared Spectroscopy (FTIR). The in vitro drug release from the nanocrystals was performed under conditions similar to the IV route of administration. Furthermore, the tendency of the nanocrystals to induce hemolysis was investigated. The efficacy and safety of the prepared nanocrystals were also evaluated in vitro using MDA-MB-231 cancer cell line and the normal Vero cell line, respectively.

Results: It was found that the size of uncoated nanocrystals was about 241.4 nm with a polydispersity index less than 0.2 and zeta potential of about -22.6. While the size of the HPβCD coated Nanocrystals was about 310.5 nm with a polydispersity index close to 0.2 and zeta potential of about -16.4 mV. The increase in the size, PDI, and zeta potential is explained by the coat formation around paclitaxel nanocrystals. Additionally, the results of PXRD, FTIR, and DSC testing can be explained by the coat formation on the surface of the nanocrystals too. The SEM images showed that both the uncoated nanocrystals and the coated nanocrystals have rod-like shape structures. Moreover, HPβCD coated nanocrystals had significantly superior in vitro drug release than both the uncoated nanocrystals and the drug powder. Interestingly, the hemolytic assay showed that HPβCD coated nanocrystals have a safer profile than uncoated nanocrystals. Cytotoxicity studies on cancer cell lines showed that both uncoated nanocrystals and HPβCD coated nanocrystals can cause a similar trend of growth inhibition or cytotoxicity on MDA-MB-231 cancer cells. On the other hand, the results of Vero cells showed that the coated nanocrystals showed a superior safety profile over the uncoated nanocrystals as Vero cells represent a normal cell line. The marketed paclitaxel product showed higher toxicity against the Vero cell line as the concentration increased.

Conclusion: Surface modification of paclitaxel nanocrystal with HPβCD improves the drug nanocrystal physicochemical properties, especially drug release, enhances its safety profile, and provides a product that is as effective as the uncoated product.

References: Yamaguchi R , Perkins G , Hirota K, Targeting cholesterol with β-cyclodextrin sensitizes cancer cells for apoptosis , FEBS Lett. 2015 Dec 21;589 (24 Pt B):4097-105.

Yokoo M, Kubota Y, Motoyama K, Higashi T, Taniyoshi M, Tokumaru H, et al. 2-Hydroxypropyl-β-cyclodextrin acts as a novel anticancer agent. PloS one. 2015;10(11): e0141946.

Acknowledgements: The authors would like to thank the Deanship of Research for funding this research Project


SEM Images Showing the Morphology of (A) Uncoated Paclitaxel Nanocrystals (B) HPβCD Coated Paclitaxel Nanocrystals


The In Vitro Drug Release Profile for Paclitaxel Drug (PTX), Paclitaxel Nanocrystals (PTX-NCs), and HPβCD Coated Paclitaxel Nanocrystals (HPβCD-PTX-NCs) in PBS. pH = 7.4 at 37oC.


The Viability of the Vero Cells after 24 h Exposure to Different Concentrations (1-1*10^6 ng/ml) of Paclitaxel in the Prepared Nanocrystals and Taxol. NC: Paclitaxel Nanocrystals, HPβCD-NC: HPβCD Coated Paclitaxel Nanocrystals, Taxol: The marketed Paclitaxel Product