pH‐Triggered Transformable Peptide Nanocarriers Extend Drug Retention for Breast Cancer Combination Therapy

Increasing the penetration and accumulation of antitumor drugs at the tumor site are crucial in chemotherapy. Smaller drug‐loaded nanoparticles (NPs) typically exhibit increased tumor penetration and more effective permeation through the nuclear membrane, whereas larger drug‐loaded NPs show extended retention at the tumor site. In addition, cancer stem cells (CSCs) have unlimited proliferative potential and are crucial for the onset, progression, and metastasis of cancer. Therefore, a drug‐loaded amphiphilic peptide, DDP‐ and ATRA‐loaded Pep1 (DA/Pep1), is designed that self‐assembles into spherical NPs upon the encapsulation of cis‐diamminedichloroplatinum (DDP) and all‐transretinoic acid (ATRA). In an acidic environment, DA/Pep1 transforms into aggregates containing sheet‐like structures, which significantly increases drug accumulation at the tumor site, thereby increasing antitumor effects and inhibiting metastasis. Moreover, although DDP treatment can increase the number of CSCs present, ATRA can induce the differentiation of CSCs in breast cancer to increase the therapeutic effect of DDP. In conclusion, this peptide nanodelivery system that transforms in response to the acidic tumor microenvironment is an extremely promising nanoplatform that suggests a new idea for the combined treatment of tumors. After the encapsulation of cis‐diamminedichloroplatinum and all‐transretinoic acid, an amphiphilic peptide self‐assembles to form spherical nanoparticles, which target acidic fibroblast growth factor and form sheet‐like aggregates in the slightly acidic environment. This transformation increases drug accumulation at the tumor site and prolongs drug retention, thereby increasing antitumor efficacy and the inhibition of lung metastasis.