Self-illuminating liposome-derived in situ triggerable photodynamic therapy combining radionuclide therapy for synergistic treatment of lung cancer

The persistent high prevalence and poor survival outcomes of lung cancer underscore the urgent need for innovative therapeutic modalities. Here, we present a novel multifunctional delivery platform for the synergistic treatment of lung malignancies, combining in situ-triggerable photodynamic therapy (PDT) with radiotherapy. The new platform CLL was developed by loading a new reactive oxygen species (ROS)-triggerable photosensitizer, luminol-conjugated chlorin e6 (Ce6), into liposomes. CLL can be activated through the bioluminescence resonance energy transfer effect under oxidative stress, thereby producing singlet oxygen for targeted tumor treatment without external irradiation. In vitro studies showed significant cytotoxic effects of CLL in both 4T1 and A549 tumor cells. Furthermore, a PDT-radiopharmaceutical combination nanotherapy CLL-¹⁷⁷Lu was engineered by incorporating the radionuclide ¹⁷⁷Lu into CLL. CLL-¹⁷⁷Lu demonstrated synergistic antitumor effects in 4T1 and A549 tumor cells, as well as in mouse models of 4T1 breast cancer lung metastasis or A549 tumor xenografts. Mechanistically, CLL-¹⁷⁷Lu can induce singlet oxygen/ROS generation, enhance tumor cell apoptosis, and promote M1 macrophage-mediated immunotherapy. Preliminary assessments showed a favorable profile for CLL-¹⁷⁷Lu, highlighting its potential as a promising nanotherapy for cancer treatment. Additionally, CLL can serve as a versatile platform for delivering a range of therapies to achieve synergistic antitumor effects.