On the origin of the low immunogenicity and biosafety of a neutralα-helical polypeptide as an alternative to polyethylene glycol

Poly(ethylene glycol)(PEG)is a prominent synthetic polymer widely used in biomedicine.Despite its notable success,recent clinical evidence highlights concerns regarding the immunogenicity and adverse effects associated with PEG in PEGylated proteins and lipid nanoparticles.Previous studies have found a neutral helical polypeptide poly(γ-(2-(2-(2-methoxyethoxy)ethoxy)ethyl L-glutamate),namely L-P(EG3Glu),as a potential alternative to PEG,displaying lower immunogenicity.To comprehensively assess the immunogenicity,distribution,degradation,and biosafety of L-P(EG3Glu),herein,we employ assays including enzyme-linked immunosorbent assay,positron emission tomography-computed tomography,and fluorescent resonance energy transfer.Our investigations involve in vivo immune responses,biodistribution,and macrophage activation of interferon(IFN)conjugates tethered with helical L-P(EG3Glu)(L20k-IFN),random-coiled DL-P(EG3Glu)(DL20k-IFN),and PEG(PEG20k-IFN).Key findings encompass:minimal anti-IFN and anti-polymer antibodies elicited by L20k-IFN;length-dependent affinity of PEG to anti-PEG antibodies;accelerated clearance of DL20k-IFN and PEG20k-IFN linked to anti-IFN and anti-polymer IgG;complement activation for DL20k-IFN and PEG20k-IFN but not L20k-IFN;differential clearance with L20k-IFN kidney-based,and DL20k-IFN/PEG20k-IFN accumulation mainly in liver/spleen;enhanced macrophage activation by DL20k-IFN and PEG20k-IFN;L-P(EG3Glu)resistance to proteolysis;and safer repeated administrations of L-P(EG3Glu)in rats.Overall,this study offers comprehensive insights into the lower immunogenicity of L-P(EG3Glu)compared to DL-P(EG3Glu)and PEG,supporting its potential clinical use in protein conjugation and nanomedicines.

Gadolinium Neutron Capture Reaction-Induced Nucleodynamic Therapy Potentiates Antitumor Immunity

A nuclear reaction-induced dynamic therapy,denoted as nucleodynamic therapy(NDT),has been invented that triggers immunogenic cell death and successfully treats metastatic tumors due to its unexpected abscopal effect.Gadolinium neutron capture therapy(GdNCT)is binary radiotherapy based on a localized nuclear reaction that produces high-energy radiations(e.g.,Auger electrons,γ-rays,etc.)in cancer cells when^(157Gd)is irradiated with thermal neutrons.Yet,its clinical application has been postponed due to the poor ability of Auger electrons andγ-rays to kill cells.Here,we engineered a^(157Gd)-porphyrin framework that synergizes GdNCT and dynamic therapy to efficiently produce both•OH and immunogenic 1O2 in cancer cells,thereby provoking a strong antitumor immune response.This study unveils the fact and mechanism that NDT heats tumor immunity.Another unexpected finding is that the Auger electron can be the most effective energy-transfer medium for radiation-induced activation of nanomedicines because its nanoscale trajectory perfectlymatches the size of nanomaterials.Inmouse tumormodels,NDT causes nearly complete regression of both primary and distant tumor grafts.Thus,this^(157Gd)-porphyrin framework radioenhancer endows GdNCT with the exotic function of triggering dynamic therapy;its applicationmay expand in clinics as a new radiotherapy modality that utilizes GdNCT to provoke whole-body antitumor immune response for treating metastases,which are responsible for 90%of all cancer deaths.