PEG-polyaminoacid based micelles for controlled release of doxorubicin: Rational design, safety and efficacy study

Silvia Brunato; Francesca Mastrotto; Federica Bellato; Chiara Bastiancich; Alessandra Travanut; Mariangela Garofalo; Giuseppe Mantovani; Cameron Alexander; Veronique Preat; Stefano Salmaso; Paolo Caliceti

doi:10.1016/j.jconrel.2021.05.010

PEG-polyaminoacid based micelles for controlled release of doxorubicin: Rational design, safety and efficacy study

J Control Release. 2021 Jul 10:335:21-37. doi: 10.1016/j.jconrel.2021.05.010. Epub 2021 May 11.

Affiliations

¹ Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via F. Marzolo 5, 35131 Padova, Italy.
² Université catholique de Louvain, Louvain Drug Research Institute, Advanced Drug Delivery and Biomaterials, Avenue Mounier 73, 1200 Brussels, Belgium.
³ Molecular Therapeutics and Formulations Division, School of Pharmacy, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
⁴ Department of Pharmaceutical and Pharmacological Sciences, University of Padova, via F. Marzolo 5, 35131 Padova, Italy. Electronic address: stefano.salmaso@unipd.it.

PMID: 33989691
DOI: 10.1016/j.jconrel.2021.05.010

Abstract

A library of amphiphilic monomethoxypolyethylene glycol (mPEG) terminating polyaminoacid co-polymers able to self-assemble into colloidal systems was screened for the delivery and controlled release of doxorubicin (Doxo). mPEG-Glu/Leu random co-polymers were generated by Ring Opening Polymerization from 5 kDa mPEG-NH₂ macroinitiator using 16:0:1, 8:8:1, 6:10:1, 4:12:1 γ-benzyl glutamic acid carboxy anhydride monomer/leucine N-carboxy anhydride monomer/PEG molar ratios. Glutamic acid was selected for chemical conjugation of Doxo, while leucine units were introduced in the composition of the polyaminoacid block as spacer between adjacent glutamic repeating units to minimize the steric hindrance that could impede the Doxo conjugation and to promote the polymer self-assembly by virtue of the aminoacid hydrophobicity. The benzyl ester protecting the γ-carboxyl group of glutamic acid was quantitatively displaced with hydrazine to yield mPEG_5kDa-b-(hydGlu_m-r-Leu_n). Doxo was conjugated to the diblock co-polymers through pH-sensitive hydrazone bond. The Doxo derivatized co-polymers obtained with a 16:0:1, 8:8:1, 6:10:1 Glu/Leu/PEG ratios self-assembled into 30-40 nm spherical nanoparticles with neutral zeta-potential and CMC in the range of 4-7 μM. At pH 5.5, mimicking endosome environment, the carriers containing leucine showed a faster Doxo release than at pH 7.4, mimicking the blood conditions. Doxo-loaded colloidal formulations showed a dose dependent cytotoxicity on two cancer cell lines, CT26 murine colorectal carcinoma and 4T1 murine mammary carcinoma with IC₅₀ slightly higher than those of free Doxo. The carrier assembled with the polymer containing 6:10:1 hydGlu/Leu/PEG molar ratio {mPEG_5kDa-b-[(Doxo-hydGlu)₆-r-Leu₁₀]} was selected for subsequent in vitro and in vivo investigations. Confocal imaging on CT26 cell line showed that intracellular fate of the carrier involves a lysosomal trafficking pathway. The intratumor or intravenous injection to CT26 and 4T1 subcutaneous tumor bearing mice yielded higher antitumor activity compared to free Doxo. Furthermore, mPEG_5kDa-b-[(Doxo-hydGlu)₆-r-Leu₁₀] displayed a better safety profile when compared to commercially available Caelyx®.

Keywords: Controlled release; Doxorubicin; Polyaminoacids; Polymeric micelles; pH-sensitive drug carriers.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Delayed-Action Preparations
Doxorubicin
Drug Carriers*
Hydrogen-Ion Concentration
Mice
Micelles*
Polyethylene Glycols
Polymers

Substances

Delayed-Action Preparations
Drug Carriers
Micelles
Polymers
Polyethylene Glycols
Doxorubicin