Advancing immunotherapy in triple negative breast Cancer: A novel multimodal theranostic nanoplatform integrating synergetic ferroptosis and photothermal therapy

Triple negative breast cancer (TNBC) is a subtype of breast cancer with high invasiveness and the worst prognosis. Immunotherapy has demonstrated significant potential in its treatment. However, the response rate remains unsatisfactory. In this work, we prepared multifunctional theranostic nanoplatforms (P-R@P/U-V) with synergetic ferroptosis and photothermal therapy (PTT) in improving TNBC tumor microenvironment for improving local treatment in situ, and synergistic anti-programmed cell death-ligand 1 (PD-L1) immunotherapy to prevent distant metastasis. With P-R@P/U-V, real-time monitoring of the specific distribution in tumors is possible due to the greatly improved ultrasound imaging (US), photoacoustic imaging (PAI), and magnetic resonance imaging (MRI) capabilities. Moreover, P-R@P/U-V has excellent photothermal conversion ability. Whereas PTT killed TNBC cells after laser irradiation, the liquid-gas phase transition not only improved US but also triggered controllable release of RSL3 in situ, enhancing ferroptosis of TNBC cells. Besides, the release of tumor-associated antigens (TAAs) increased via PTT and ferroptosis, strongly stimulating T cell activation, dendritic cell maturation, and anti-tumor cytokine secretion. The lung metastases of TNBC were significantly inhibited following the combined use of P-R@P/U-V and PD-L1 inhibitors. The multimodal and multifunctional nanoplatforms demonstrated excellent effects in early diagnosis and synergistic treatment of TNBC. This represents a novel strategy based on local treatment for additional enhanced anti-PD-L1 immunotherapy, with high clinical application prospects.