Table 5.
Studies of PD-1/PD-L1 expression in OS.
| Study | Samples | Detection techniques | Positive Expression of PD-1/PD-L1 | Clinical guide |
|---|---|---|---|---|
| Chen et al. (2020) (139) | 15 OS patients | IHC | Biopsy samples (PD-1 47% and PD-L1 53%); none in resections; metastases samples (PD-1 40% and PD-L1 47%) | Assessment of PD-1/PD-L1 in biopsy or metastatic specimens have clinical value in predicting therapeutic response. |
| Torabi et al. (2017) (144) | OS samples | Western blot | Positive PD-L1 expression | — |
| qRT-PCR | More content of PD-1 mRNA | — | ||
| 26 OS samples | IHC | PD-1 detected in all tissue samples | — | |
| Costa Arantes et al. (2017) (145) | 9 oral OS patients of 13 | IHC | High positive expression of PD-L1 | No significant correlation of PD-L1 gene expression with clinicopathologic features. |
| Sundara et al. (2017) (146) | 85 samples | IHC | Positive rate of PD-L1 is 27.8% | Higher expression of PD-L1 was detected in metastatic lesions (48%) |
| Koirala et al. (2016) (147) | Cell lines | Western blot | Positive rate of PD-L1 is 40% | Primary OS tumor expressing PD-L1 were more likely to contain cells that express PD-1. |
| qRT-PCR | Positive rate of PD-L1 mRNA is 75% within 21 cell lines | — | ||
| 107 tissue samples | IHC, flow cytometry | Positive rate of PD-L1 mRNA is 67% within tumor specimens | Expression level of PD-L1 is connected with the presence of T cells, DCs and NK cells. | |
| Western blot | Positive rate of PD-L1 is 30% within patient samples | — | ||
| Lussier et al. (2015) (148) | 16 patients | IHC | Positive rate of PD-L1 is 75% within the metastatic OS | Metastatic tumors can tolerize infiltrating T cells within TME by PD-L1 interactions |
| Chowdhury et al. (2015) (149) | 15 OS patients of 115 pediatric tumors | IHC | Positive rate of PD-L1 expression is 47% among OS patients | Patients expressing PD-L1 showed distinctly better survival |
| Zheng et al. (2015) (150) | 56 OS patients | IHC, flow cytometry | High expression level of PD-1 is detected in peripheral CD4+ and CD8+ T cell within OS patients | PD-1 is involved in tumor progression. |
| Shen et al. (2014) (151) | OS cell lines | qRT-PCR, IHC, flow cytometry |
There is slightly higher PD-L1 expression of drug-resistant variants OS cell lines in comparison with that in parental cell lines | — |
| 38 patients with OS | qRT-PCR, IHC, flow cytometry | High PD-L1 expression level (23.7%) | — | |
| Intermediate PD-L1 expression level (50%) | Median survival time is 89 months at low levels of PD-L1 but is only 28 months at high levels of PD-L1. | |||
| Low PD-L1 expression level (10.5%) | PD-L1 expression is distinctly related to TIL expression. | |||
| Negative PD-L1 expression level | Pulmonary metastatic cases showed higher PD-L1 expression than that of the non-pulmonary metastatic lesions. |
*OS, osteosarcoma; PD-1, programmed cell death receptor-1; PD-L1, Programmed cell death receptor-1 ligand-1; IHC, immunohistochemistry; qRT-PCR, quantitative real time polymerase chain reaction; DCs, dendritic cells; NK cells, natural killer cells; TME, tumor microenvironment; TILs, Tumor-infiltrating lymphocytes.