The addition of RANKL/RANK blockade to immune checkpoint inhibitors (ICIs) such as anti-PD-1/PD-L1 and anti-CTLA4 antibodies is associated with increased anti-tumor immunity in mice.
Interestingly, the combination treatment of VPA and anti-PD-L1 antibody activated IRF1/IRF8 transcriptional axis in MDSCs leading to blockade of their immunosuppressive function by downregulating the expression of IL-10, IL-6, and ARG1 while re-activating CD8<sup>+</sup> T-cells for the production of TNFα to further enhance anti-tumor immunity.
These findings suggest MUC1 is a critical regulator of PD-L1 expression via its effects on microRNA levels and represents a potential therapeutic target to enhance anti-tumor immunity.
From these data, we infer that MACC1 regulates PDL1 expression and tumor immunity through the c-Met/AKT/mTOR pathway in GC cells and suggest that MACC1 may be a therapeutic target for GC immunotherapy.
The TIME (Tumor Immunity in the MicroEnvironment) classification based on tumor <i>CD274</i> (<i>PDCD1</i> ligand 1, PD-L1) expression and tumor-infiltrating lymphocytes (TIL) has been proposed to predict response to immunotherapy.
In the present studies, we examined the effects of chemopreventive agents, paclitaxel, etoposide and 5-fluorouracil, on the surface expression of programmed death-1-ligand 1 (PD-L1), a negative regulator of T cell anti-tumor immunity.
In contrast with this positive regulation of TAM recruitment, we found no evidence of a direct effect of ERK1/2 signaling on two other important aspects of TAM regulation by GBM cells: (1) the expression of the immune checkpoint ligands PD-L1 and PD-L2, expressed at high mRNA levels in GBM compared with other solid tumors; (2) the production of the tumor metabolite lactate recently reported to dampen tumor immunity by interacting with the receptor GPR65 present on the surface of TAM.
Moreover, the antitumor effect of AdSOCS-1 was significantly attenuated by PD-L1 Fc-fusion protein administration <i>in vivo</i>, suggesting that the effect of AdSOCS-1 is mainly attributable to enhancement of tumor immunity.
This study highlights the importance of PD-L1 expression, as primarily a signature of reacting efficiency of pre-existing anti-tumor immunity, in balancing the tumor microenvironment.
Our study identifies LSD1 as a potent inhibitor of anti-tumor immunity and responsiveness to immunotherapy and suggests LSD1 inhibition combined with PD-(L)1 blockade as a novel cancer treatment strategy.
Our study identifies VGLL4 as an important regulator of PD-L1 expression and highlights a central role of VGLL4 and YAP in the regulation of tumor immunity.
Experiments using bone marrow (BM) chimeric mice, generated by transferring PD-L1-KO BM cells into wild-type mice or vice versa, further suggested that PD-L1 expressed on BM-derived hematopoietic cells mediates the suppressive effects on anti-tumor immunity.
Engagement of programmed death-ligand 1 (PD-L1) with its receptor programmed death 1 (PD-1) on T cells has been speculated to play a major role in suppressing the immune system, which helps tumor cells evade anti-tumor immunity.