Cai et al. developed a smart drug delivery system with an acid‐sensitive group that could respond to internal stimuli efficiently.[71] For instance, a pH‐responsive en‐srNP with pH‐cleavage amide bond and pH sponge PDEA was demonstrated to be size/charge changeable in an acidic environment.[16] Through exploration of metabolism, distribution, and decomposition of the en‐srNPs at cellular and animal levels, such nano‐system showed great potential for synergistic photodynamic and PD‐L1 immunotherapy due to improved cancer penetration. This evidence concerns the gene CD274 and cancer.