PD-1 (Programmed death-1) is mainly expressed on the surface of T cells and primary B cells. The two PD-1 ligands, PD-L1 and PD-L2, are widely expressed on antigen-presenting cells (APCs). PD-1 interacts with its ligands and plays an important role in the negative regulation of the immune response. PD-L1 protein expression is detected in many human tumor tissues. PD-L1 expression in tumor cells could be induced by the microenvironment of tumor cells. PD-L1 expression is favorable for tumorigenesis and growth, for induction of anti-tumor T Cell Apoptosis, and for escaping responses by the immune system. Inhibition of PD-1 binding to its ligand can result in tumor cells that are exposed to the killing version of the immune system, and thus is a target for cancer treatments.
PD-L1 (Programmed cell death ligand-1), also known as B7-H1 and CD274, is mainly expressed in antigen-presenting cells (APCs) and activated T cells, and is one of the two ligands of PD-1. The interaction between PD1 and PD-L1 plays an important role in the negative regulation of the immune response. PD-L1 is highly expressed in a variety of solid tumors. PD-1 and PD-L1 interactions can reduce T Cell Activation and promote tumor immune escape. The PD-1/PD-L1 signaling pathway can be blocked and antitumor immune response can be restored by using by anti-PD-1 or anti-PD-L1 antibodies to block the binding of PD1 to PD-L1.
Gene targeting strategy for B-hPD-1/hPD-L1 mice. The exon 2 of mouse PD-1 gene that encode the extracellular domain was replaced by human PD-1 exon 2 in B-hPD-1/hPD-L1 mice. The exon 3 of mouse Pdl1 gene that encode the extracellular domain was replaced by human PD-L1 exon 3 in B-hPD-1/hPD-L1 mice. This double knock-in model, was developed by breeding the B-hPD-1 mice and the B-hPD-L1 mice.
mRNA Expression Analysis
RT-PCR analysis of the B-hPD-1/hPD-L1 humanized mice. The splenocytes of the B-hPD-1/hPD-L1 homozygous mice showed expression of human PD-1 and PD-L1 mRNA but not mouse PD-1 and PD-L1 mRNA.
Protein Expression Analysis
Splenocytes from both wild type (WT) C57BL/6 and homozygous B-hPD-1/hPD-L1 mice were analyzed by flow cytometry. Mouse PD-1+ and PD-L1+ T cells were detectable in the WT C57BL/6 mice, while human PD-1 and PD-L1+ T cells were detectable in the homozygous B-hPD-1/hPD-L1 mice.
Human PD-L1 (Tecentriq) mAb Efficacy Evaluation (MC38-hPD-L1 Cell Line)
Murine colon cancer MC38-hPD-L1 cells were subcutaneously implanted into homozygous B-hPD-1/hPD-L1 mice. Mice were grouped when the tumor size was approximately 150±50 mm3 (n=5). High dose of human PD-L1 antibody Tecentriq significantly inhibited tumor growth, confirming that the B-hPD-1/hPD-L1 mouse model is a powerful tool for in vivo PD-L1 antibody pharmacological efficacy study. (A) Tumor average volume ± SEM, (B) Mice average weight ± SEM.
Combination therapy of PD-1 Ab and PD-L1 Ab
Antitumor activity of anti-human PD-1 antibody pembrolizumab combined with anti-human PD-L1 antibody atezolizumab in B-hPD-1/hPD-L1 mice. (A) Pembrolizumab combined with atezolizumab inhibited MC38-hPD-L1 tumor growth in B-hPD-1/hPD-L1 mice. Murine colon cancer MC38-hPD-L1 cells (5×105) were subcutaneously implanted into homozygous B-hPD-1/hPD-L1 mice mice (female, 5-7 weeks old, n=6). Mice were grouped when tumor volume reached approximately 150 mm3, at which time they were treated with Pembrolizumab and atezolizumab with doses and schedules indicated in panel. (B) Body weight changes during treatment. As shown in panel A, pembrolizumab alone gives anti-tumor effect, low dose of pembrolizumab combination of atezolizumab did not show significant difference compared with atezolizumab alone at tested condition. Values are expressed as mean ± SEM.
Combination Therapy of PD-1 (Keytruda) mAb and PD-L1 (Tecentriq) mAb
Murine colon cancer MC38-hPD-L1 cells were subcutaneously implanted into homozygous B-hPD-1/hPD-L1 mice. Mice were grouped when the tumor size was approximately 150±50 mm3 (n=6). Anti-hPD-1 antibody Keytruda, anti-hPD-L1 antibody Tecentriq and Combination of anti-hPD-1 antibody Keytruda and anti-hPD-L1 antibody Tecentriq all show significant inhibitory effects. (A) Tumor average volume ± SEM, (B) Mice average weight ± SEM.
- Journal of Biomedical Science (2017) 24:26
- PLoS ONE 12(4): e0176822. Doi: 10.1371/journal.pone.0176822
- NATURE COMMUNICATIONS 7:13354 doi: 10.1038/ncomms13354