TFRC and cancer: Indeed, this strategy, named PEGylation, has been extensivelyemployed to improve systemic circulation time and decrease immunogenicity,thus increasing the efficiency of drug and gene delivery to targetcells and tissues.17,18 However, it has also been reportedthat PEGylation may interfere with the intrinsic ability ofHFn to recognize TfR1 and target cancer cells.19 As a consequence, it has become necessary to introducefurther adaptations to the classic PEGylation strategies.