Enzyme-activatable polymer–drug conjugate augments tumour penetration and treatment efficacy


A tumour microenvironment imposes barriers to the passive diffusion of molecules, which renders tumour penetration an unresolved obstacle to an effective anticancer drug delivery. Here, we present a γ-glutamyl transpeptidase-responsive camptothecin–polymer conjugate that actively infiltrates throughout the tumour tissue through transcytosis. When the conjugate passes on the luminal endothelial cells of the tumour blood vessels or extravasates into the tumour interstitium, the overexpressed γ-glutamyl transpeptidase on the cell membrane cleaves the γ-glutamyl moieties of the conjugate to generate positively charged primary amines. The resulting cationic conjugate undergoes caveolae-mediated endocytosis and transcytosis, which enables transendothelial and transcellular transport and a relatively uniform distribution throughout the tumour. The conjugate showed a potent antitumour activity in mouse models that led to the eradication of small solid tumours (~100 mm3) and regression of large established tumours with clinically relevant sizes (~500 mm3), and significantly extended the survival of orthotopic pancreatic tumour-bearing mice compared to that with the first-line chemotherapeutic drug gemcitabine.

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Fig. 1: Scheme and characterization of the enzyme-activatable polymer–drug nanomedicine.
Fig. 2: The cell cytotoxicity assays of polymer-drug conjugates.
Fig. 3: In vitro penetration of polymer–drug conjugates in HepG2 tumour spheroids.
Fig. 4: Blood clearance, biodistribution and tumour penetration of polymer–drug conjugates in HepG2-tumour-bearing mice.
Fig. 5: Antitumour efficacy of polymer–drug conjugates against subcutaneous HepG2 tumours.
Fig. 6: Antitumour activity of polymer–drug conjugates against orthotopic pancreatic tumours.

Data availability

The authors declare that all data generated or analysed during this study are available in this published article and its supplementary information files or from the corresponding author upon request.


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We thank the National Natural Science Foundation of China (U1501243, 51833008, 51390481 and 51522304), National Basic Research Program of China (2014CB931900), the National Key Research and Development Program (2016YFA0200301), the Experimental Technology Research Program of Zhejiang University (SYB201605) and the Alfred P. Sloan Foundation for financial support.

Author information

Y.S. and Z.G. supervised the project and wrote the manuscript with Q.Z. and R.M.; Q.Z., C.X., S.S. and J.X. performed all the experiments; J.W., Q.Y., Z.Gan and R.M. re-evaluated the anticancer activity; Y.P. and X.L. instructed the bioassays; J.T. and Z.Z. instructed the synthesis.

Correspondence to Zhen Gu or Youqing Shen.

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Z.G. is a scientific co-founder of ZenCapsule, Inc. All the authors declare no conflicting interests.

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Supplementary Methods, Supplementary Figs. 1–30, Supplementary Table. 1 and 2, and Supplementary references.

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