Poly Ethylene Glycol (PEG)‐Based Hydrogels for Drug Delivery in Cancer Therapy: A Comprehensive Review

Hydrogel‐based drug delivery systems (DDSs) can leverage therapeutically beneficial outcomes in cancer therapy. In this domain, polyethylene glycol (PEG) has become increasingly popular as a biomedical polymer and has found clinical use. Owing to their excellent biocompatibility, facile modifiability, and high drug encapsulation rate, PEG hydrogels have shown great promise as drug delivery platforms. Here, the progress in emerging novel designs of PEG‐hydrogels as DDSs for anti‐cancer therapy is reviewed and discussed, focusing on underpinning multiscale release mechanisms categorized under stimuli‐responsive and non‐responsive drug release. The responsive drug delivery approaches are discussed, and the underpinning release mechanisms are elucidated, covering the systems functioning based on either exogenous stimuli‐response, such as photo‐ and magnetic‐sensitive PEG hydrogels, or endogenous stimuli‐response, such as enzyme‐, pH‐, reduction‐, and temperature‐sensitive PEG hydrogels. Special attention is paid to the commercial potential of PEG‐based hydrogels in cancer therapy, highlighting the limitations that need to be addressed in future research for their clinical translation. This article systematically and critically reviews the progress in the fabrication, characterization, and application of Poly Ethylene Glycol (PEG)‐based hydrogels for drug delivery in cancer therapy. The article sheds light on the design criteria that are important in regulating the on‐demand release of anti‐cancer drugs from PEG hydrogels in response to various stimuli. Special emphasis is placed on the commercial viability of these hydrogels, while also highlighting the critical limitations that must be overcome in future research for successful clinical translation.