Cathepsin B-responsive and gadolinium-labeled branched glycopolymer-PTX conjugate-derived nanotheranostics for cancer treatment

Multi-modal therapeutics are emerging for simultaneous diagnosis and treatment of cancer.Polymeric carriers are often employed for loading multiple drugs due to their versatility and controlled release of these drugs in response to a tumor specific microenvironment.A theranostic nanomedicine was designed and prepared by complexing a small gadolinium chelate,conjugating a chemotherapeutic drug PTX through a cathepsin B-responsive linker and covalently bonding a fluorescent probe pheophorbide a(Ppa)with a branched glycopolymer.The branched prodrug-based nanosystem was degradable in the tumor microenvironment with overexpressed cathepsin B,and PTX was simultaneously released to exert its therapeutic effect.The theranostic nanomedicine,branched glycopolymer-PTX-DOTA-Gd,had an extended circulation time,enhanced accumulation in tumors,and excellent biocompatibility with significantly reduced gadolinium ion(Gd3+)retention after 96 h post-injection.Enhanced imaging contrast up to 24 h post-injection and excellent antitumor efficacy with a tumor inhibition rate more than 90%were achieved from glycopolymer-PTX-DOTA-Gd without obvious systematic toxicity.This branched polymeric prodrug-based nanomedicine is very promising for safe and effective diagnosis and treatment of cancer.

Polysaccharide-based nanomedicines for cancer immunotherapy:A review

Cancer immunotherapy is an effective antitumor approach through activating immune systems to eradicate tumors by immunotherapeutics.However,direct administration of“naked”immunotherapeutic agents(such as nucleic acids,cytokines,adjuvants or antigens without delivery vehicles)often results in:(1)an unsatisfactory efficacy due to suboptimal pharmacokinetics;(2)strong toxic and side effects due to low targeting(or off-target)efficiency.To overcome these shortcomings,a series of polysaccharide-based nanoparticles have been developed to carry immunotherapeutics to enhance antitumor immune responses with reduced toxicity and side effects.Polysaccharides are a family of natural polymers that hold unique physicochemical and biological properties,as they could interact with immune system to stimulate an enhanced immune response.Their structures offer versatility in synthesizing multifunctional nanocomposites,which could be chemically modified to achieve high stability and bioavailability for delivering therapeutics into tumor tissues.This review aims to highlight recent advances in polysaccharide-based nanomedicines for cancer immunotherapy and propose new perspectives on the use of polysaccharide-based immunotherapeutics.