Thermo‐pH‐Sensitive Polypeptides Boost Protein Drug's Tumor Permeation and Pharmacology

Abstract Proteins are typically subject to poor stability, short half‐life, and poor cell and tissue permeability, which restrict their wide applications as drugs for disease treatment. Current protein modification techniques mostly focus on improving the stability and half‐life of proteins, but hardly solve their poor cell and tissue permeability. To address this issue, the study innovatively designs thermo‐pH‐sensitive elastin‐like polypeptides to modify proteins, named ELP(HX)_n in which histidine (H) and any amino acid except proline (X) are guest amino acids in the polypeptides and n is the total number of the guest amino acids. H in ELP(HX)_n can be protonated under acidic conditions. To prove the concept, an important protein drug of L‐asparaginase (ASP) is genetically fused to ELP(HV)₆₀ to generate ASP‐ELP(HV)₆₀. Compared with ASP and PEGylated ASP, ASP‐ELP(HV)₆₀ exhibits not only elevated stability and extended half‐life but also enhanced tumor cell and tissue penetration, resulting in improved antitumor efficacy. These findings demonstrate that ELP(HX)_n fusion is a novel and general protein modification method to overcome the intrinsic limitations of proteins as therapeutics, rendering it feasible to design intelligent protein therapeutics, especially for efficient tumor therapy.