They bind to cell surface receptors that are upregulated by mutant RAS and exhibit potent antitumor activity, demonstrating their efficacy in targeting undruggable proteins outside the cell.645–649 P1C1TM is a p53-specific TCR-like antibody, which has been verified by Wang’s group to be suitable for promoting drug delivery into tumor cells with p53 mutation via ADCs.608 TfR1, an antigen previously considered undruggable, is highly expressed in both tumor cells and normal cells and participate in cellular iron transport. This evidence concerns the gene TFRC and neoplasm.