MMP2 and neoplasm: Apart from pH‐responsive nanoparticles, MMP‐2‐sensitive nanoparticles were developed to enable tumor‐specific PDT‐triggered T‐cell activation.[50] Elevated MMP‐2 expression was reported in various cancer tissues, primarily driven by the imbalance between MMP‐2 and their natural inhibitors.[51] Wang et al. developed MMP‐2‐sensitive nanoparticles to enable tumor‐specific delivery of anti‐PD‐L1 antibodies (Figure2A).