Mitochondria Energy Metabolism Depression as Novel Adjuvant to Sensitize Radiotherapy and Inhibit Radiation Induced‐Pulmonary Fibrosis

Abstract Currently, the typical combination therapy of programmed death ligand‐1 (PD‐L1) antibodies with radiotherapy (RT) still exhibits impaired immunogenic antitumor response in clinical due to lessened DNA damage and acquired immune tolerance via the upregulation of some other immune checkpoint inhibitors. Apart from this, such combination therapy may raise the occurrence rate of radiation‐induced lung fibrosis (RIPF) due to enhanced systemic inflammation, leading to the ultimate death of cancer patients (average survival time of about 3 years). Therefore, it is newly revealed that mitochondria energy metabolism regulation can be used as a novel effective PD‐L1 and transforming growth factor‐β (TGF‐β) dual‐downregulation method. Following this, IR‐TAM is prepared by conjugating mitochondria‐targeted heptamethine cyanine dye IR‐68 with oxidative phosphorylation (OXPHOS) inhibitor Tamoxifen (TAM), which then self‐assembled with albumin (Alb) to form IR‐TAM@Alb nanoparticles. By doing this, tumor‐targeting IR‐TAM@Alb nanoparticle effectively reversed tumor hypoxia and depressed PD‐L1 and TGF‐β expression to sensitize RT. Meanwhile, due to the capacity of heptamethine cyanine dye in targeting RIPF and the function of TAM in depressing TGF‐β, IR‐TAM@Alb also ameliorated fibrosis development induced by RT.