Selective apoptosis of tumor-associated platelets boosts the anti-metastatic potency of PD-1 blockade therapy.

Despite the transformative impact of programmed cell death protein-1 (PD-1) blockade therapy on metastatic/advanced solid tumor treatment, its efficacy is hindered by a limited response rate. Platelets play a pivotal role in tumor metastasis by shielding circulating tumor cells and secreting immunosuppressive factors. We here demonstrate that selectively inducing apoptosis in tumor-associated platelets (TAPs) using ABT-737-loaded nanoparticles (cyclic arginine-glycine-aspartate containing peptide-modified ABT-737-loaded nanoparticles [cRGD-NP@A]) enhances the anti-metastatic efficacy of the anti-PD-1 antibody (aPD-1). cRGD-NP@A specifically binds to TAPs, disrupting platelet-tumor cell interactions and exposing tumor cells to immune surveillance in vivo. Combined with aPD-1, cRGD-NP@A substantially augments immune activation and reduces TAP-derived immunosuppressive factors, notably transforming growth factor β1 (TGF-β1), consequently improving anti-metastatic outcomes across multiple metastasis-bearing animal models without observable adverse effects. Our study underscores the importance of depleting TAPs to enhance PD-1 blockade therapy, presenting a promising strategy to improve response rates and clinical outcomes for patients with metastatic cancer.