Table 2. Evaluation of human PD-L1 by immunohistochemistry (IHC) in the selected studies.
| Ref | Type of cancer | PD-L1 + Tumor (%) | Antibody (Clone) | Cutoff for overexpression |
|---|---|---|---|---|
| Boorjian, S. A et al.(2008)[22] | Bladder cancer | 12.40% | 5H1 | Positive: ≥5% tumor cells were positive for PD-L1 staining. |
| Chen, L., et al. (2014)[23] | Esophageal cancer | 82.80% | NBP1-03220 | IHC, presence of PD-L1 staining. |
| Chen, X. L et al.(2009)[12] | Pancreatic carcinoma | 45.00% | 2H11 | Positive: ≥10% tumor cells were positive for PD-L1 staining. |
| Chen, Y. B., et al. (2012)[24] | Lung cancer | 57.50% | 236A/E7 | IHC, IRS≥3 points, IRS = SI (staining intensity) × PP (percentage of positive cells). SI was determined as: 0, negative; 1, weak; 2, moderate; and 3, strong. PP was defined as: 0, negative; 1, 1–10% positive cells; 2, 11–50% positive cells; 3, 51–80% positive cells; and 4, more than 80% positive cells. IRS ≥ 3 points was regarded as PD-L1 positive expression. |
| Cho, Y. A et al.(2011)[25] | Oral squamous cell carcinoma | 87.00% | ab82059 | IHC, SID score; The proportion of stained cells in each field was assessed as: 0, no stained cells; 1, <25% stained cells; 2, 25–50% stained cells; and 3, >50% stained cells. Staining intensity was graded as: 0, negative staining; 1, light staining; 2, moderate staining; and 3, intense staining. A staining-intensity-distribution (SID) score was computed for each sample as follows: the score of the proportion of stained cells for each field was multiplied by the score of the staining intensity in that field to provide a SID score for the field. The mean of the five fields was the final SID score for the sample. |
| Gao, Q et al.(2009)[13] | Hepatocellular carcinoma | 25.00% | MIH1 | Positive: ≥75%; Three images of representative fields were captured under a Leica CCD camera DFC420 connected to a Leica DM IRE2 microscope (Leica Microsystems Imaging Solutions) at a magnification of 200 and saved as TIFF files using the Leica QWin Plus version 3 software. Images were analyzed with Image-Pro Plus version 6.2 software (Media Cybernetics) using a special function called measurement of integrated absorbance, which evaluate both the area and the intensity of the positive staining. With this function, integrated absorbance of all the positive staining of PD-Ls in each photograph was measured and its ratio to total area of each photograph was calculated as PD-Ls density. The average integrated absorbance value (integrated absorbance/total area) on each slide (three images) was used to represent a particular sample. |
| Geng, Y., et al. (2014)[26] | Gastric cancer | 65.00% | 2H11 | IHC, IRS≥3, The intensity (I) of staining was graded on a scale of 0–3+, with 0 representing no detectable staining and 3+ representing the strongest staining. Four strongest staining regions were randomly selected under a 409 field. In each of the four regions, the rate of positive cell staining (R) under a 400 × field was calculated. R was defined as: 0, no staining; 1, ≤10% tumor cells with staining; 2, 11–50% tumor cells with staining; 3, 51–75% tumor cells with staining; and 4, >75% tumor cells with staining. Samples with scores<3 were considered as the negative and with scores ≥3 were considered as the positive. Histochemistry score = I × R. |
| Hamanishi, J et al.(2007)[27] | Ovarian cancer | 68.60% | 27A2 | Positive: H-score ≥ 2; The expression of PD-L1 was evaluated according to the intensity of the staining and scored as follows: 0, negative; 1, very weak expression; 2, moderate expression; and 3, stronger expression. Cases with scores 0 and 1 were defined as the low-expression group, and cases with scores 2 and 3 were the high-expression group. |
| Hino, R et al.(2010)[5] | Melanoma | 57.60% | 27A2 | RD value ≥90, Digital image analysis |
| Hou, J. et al.(2014)[28] | Gastric cancer | 63.10% | ab82059 | Positive: ≥10% tumor cells were postive for PD-L1 staining. |
| Karim, R et al.(2009)[29] | Cervical carcinoma | 19.00% | 5H1 | IHC, presence of PD-L1 staining. |
| Konishi, J et al.(2004)[8] | Lung cancer | 50.00% | MIH1 | Positive: ≥11% tumor cells were postive for PD-L1 staining. |
| Liu, Y et al.(2013)[30] | Glioblastoma | 35.29% | NR | IHC≥10 cells/field tumor cells were postive for PD-L1 staining |
| Loos, M et al.(2011)[31] | Esophageal cancer | 73.30% | NR | IHC; H-score ≥ 4; Scores were given separately for the stained area and for the intensity of staining. Quantification was made as follows: 33% of the cancer cells or less, 1; more than 33% to 66% of the cancer cells, 2; and more than 66% of the cancer cells, 3. Intensity of staining was stated as absent or weak, 1; moderate, 2; and strong, 3. Each section had a final grade that derived from the multiplication of the area and intensity scores. |
| Mansfield, A. S., et al.(2014)[32] | Malignant mesotheliomas | 40.00% | 5H1 | Positive: ≥5% tumor cells were postive for PD-L1 staining. |
| Mu, C. Y et al.(2011)[9] | Lung cancer | 53.21% | Primary antibody | Positive: H-score ≥ median value; PD-L1 proteins were quantified using a visual grading system based on the extent of staining (by percentage of positive tumor cells graded on a scale of 0–3: 0 = none, 1 = 1–10%, 2 = 11–50%, 3 = 51–100%) and the intensity of staining (graded on a scale of 0–3: 0 = no staining, 1 = weak staining, 2 = moderate staining, 3 = strong staining). A semi-quantitative H-score was obtained by multiplying the grades of extent and intensity of staining. The median value of all the H-scores was chosen as the cutoff value for dividing the expression of proteins into high and low. |
| Nakanishi, J et al(2007)[33] | Bladder cancer | 70.77% | MIH1 | Positive: ≥12.2% tumor cells were postive for PD-L1 staining. |
| Ohigashi, Y et al.(2005)[34] | Esophageal cancer | 43.90% | MIH1 | Positive: ≥10% tumor cells were postive for PD-L1 staining. |
| Shi, S. J. et al.(2013)[7] | Colorectal cancer | 44.80% | ab58810 | IHC, presence of PD-L1 staining. |
| Taube, J. M et al.(2012)[6] | Melanoma | 38.00% | 5H1 | Positive: ≥5% tumor cells were postive for PD-L1 staining. |
| Ukpo, O. C et al.(2013)[35] | Oral squamous cell carcinoma | 46.40% | 5H1 | Positive: ≥5% tumor cells were postive for PD-L1 staining. |
| Velcheti, V et al.(2014)[11] | Lung cancer | 86.00% | 5H1 | NR |
| Wang, Y et al.(2009)[36] | Bladder cancer | 76.00% | NR | Positive: >10% tumor cells were postive for PD-L1 staining. |
| Wu, C et al.(2006)[37] | Gastric cancer | 72.00% | 2H11 | IHC, presence of PD-L1 staining. |
| Wu, K et al.(2009)[15] | Hepatocellular carcinoma | 42.20% | MIH1 | NR |
| Xylinas, E et al.(2014)[38] | Bladder cancer | 49.30% | 5H1 | NR |
| Yang, C. Y et al.(2014)[10] | Lung cancer | 25.00% | NR | IHC ≥5% tumor cells were postive for PD-L1 staining |
| Zhu, J., et al. (2014)[39] | Colorectal cancer | 39.90% | 2H11 | NR |
NR: Not reported.