Lignin-assisted construction of sub-10 nm supramolecular self-assembly for photothermal immunotherapy and potentiating anti-PD-1 therapy against primary and distant breast tumors

Photothermal therapy (PTT) has brought hope for cancer treatments, with hyperthermia-induced immunogenic cell death (ICD), which is a critical part of therapeutically induced antitumor immune responses. Limited immune stimulation response in PTT is the primary reason for incomplete tumor ablation, therefore demonstrating urgent requirements for ICD amplifier. Herein, a sub-10 nm supramolecular nanoassembly was formed by co-assembly of clinically approved aluminum adjuvant and commonly used indocyanine green (ICG) under the assistance of lignosulfonate (LS, a green and sustainable multifunctional lignin derivative) for localized photothermal-immunotherapy of breast cancer. The overall results revealed that LS-Al-ICG is capable of inducing amplified ICD, efficiently eliciting solid immune responses through dendritic cells (DCs) activation and cytotoxic T-cell responses initiation for tumor killing. Moreover, anti-PD-1 therapy blocked the PD-1 pathway and led to remarkable anti-tumor efficacy against laser-irradiated primary tumors and distant tumors by potentiating systemic tumor specific T cell immunity. The results of this study demonstrate a handy and extensible approach for engineering green natural lignin nanoparticles for cancer immunotherapy, which shows promise for delivering other therapeutics in biomedical applications.