Selection of threose nucleic acid aptamers to block PD-1/PD-L1 interaction for cancer immunotherapy

Threose nucleic acid (TNA) aptamers were selected in vitro to bind PD-L1 protein and inhibit its interaction with PD-1. These biologically stable TNA aptamers bound target proteins with nanomolar affinities, and effectively blocked PD-1/PD-L1 interaction in vitro . After injection into a colon cancer xenograft mouse model, the TNA aptamer N5 was specifically accumulated at the tumour site, and significantly inhibited tumour growth in vivo . In vitro selected threose nucleic acid (TNA) aptamers blocked PD-1/PD-L1 interaction and significantly inhibited tumour growth in xenograft mouse model.