MMP9 and neoplasm: This study also showed that combined treatment with an anti-MMP-9 antibody and immune checkpoint inhibitor (ICI) targeting programmed cell death-ligand 1 (PD-L1), improved anti-tumor immune response to anti-PD-L1 by increasing the levels of T-helper cell 1 type cytokines and infiltration of effector/memory T cells into tumors.