Peptides as multifunctional players in cancer therapy

Peptides exhibit lower affinity and a shorter half-life in the body than antibodies. Conversely, peptides demonstrate higher efficiency in tissue penetration and cell internalization than antibodies. Regardless of the pros and cons of peptides, they have been used as tumor-homing ligands for delivering carriers (such as nanoparticles, extracellular vesicles, and cells) and cargoes (such as cytotoxic peptides and radioisotopes) to tumors. Additionally, tumor-homing peptides have been conjugated with cargoes such as small-molecule or chemotherapeutic drugs via linkers to synthesize peptide–drug conjugates. In addition, peptides selectively bind to cell surface receptors and proteins, such as immune checkpoints, receptor kinases, and hormone receptors, subsequently blocking their biological activity or serving as hormone analogs. Furthermore, peptides internalized into cells bind to intracellular proteins and interfere with protein–protein interactions. Thus, peptides demonstrate great application potential as multifunctional players in cancer therapy. Cancer treatment: peptides offer options for targeted therapeutic delivery Targeted drug delivery systems using tiny, non-toxic guiding molecules could transform cancer treatment and reduce chemotherapy resistance. Peptides are small molecules consisting of two or more amino acids. While they degrade quickly in the body, they show promise as guiding molecules for targeted drug delivery, with deep tissue penetration and low toxicity. Byungheon Lee at Kyungpook National University in Daegu, South Korea, and co-workers reviewed progress into novel therapeutic systems that use ‘tumour-homing’ peptides to target solid tumours. Adding peptides to nanoparticles that carry chemotherapy drugs enhances their penetration and accumulation in target tumours. Peptide-assisted delivery can also reduce the major adverse effects of chemotherapy, and appear to be widely tolerated in the body, even in the brain. Peptides that bind to and inhibit surface receptor proteins on tumour cells could also block cancer progression.