New frontiers in polymeric nanomedicine for cancer therapy

1. IntroductionCancer treatment still wrestles with a narrow therapeutic window, systemic toxicities, and heterogeneous drug exposure in solid tumors. Polymeric nanoparticles (PNPs)—built from degradable backbones such as PLGA, PEG-block copolymers, and natural polysaccharides—aim to widen this window by improving solubility and stability of payloads, prolonging systemic circulation, increasing tumor accumulation, and enabling on-demand release via endogenous (pH, redox, enzyme) or exogenous (light, heat, ultrasound, electric/magnetic field) triggers (Chang et al., 2021; Darge et al., 2024; Li et al., 2022; Yu et al., 2020; Ulkoski et al., 2019; Dennahy et al., 2022).Beyond single-agent chemotherapy, PNPs now support combination regimens (chemo–immuno, chemo–photo, drug–gene) and theranostics that pair treatment with imaging to guide dosing and patient selection (Jiang et al., 2024; Mamuti et al., 2021; Zhang et al., 2023; Haidar et al., 2025). Parallel advances in tumor model fidelity (3D, organoids, murine “avatars”) and image-guided delivery are clarifying when and where nanomedicines succeed in vivo, and why they sometimes fail (Zhang et al., 2025; Jiang et al., 2021; Achterberg et al., 2021; Austria Jr et al., 2025). This review synthesizes design rules and translational lessons, centering on developments from the last five years.