PD-L1 Antibody [28-8] IHC staining examples

Different PD-L1 expression in human lung cancer

In the CheckMate-057 clinical study, researchers classified PD-L1 expression according to prespecified levels; more than 1%, more than 5%, and more than 10% for preplanned efficacy analysis. With OS as the primary endpoint, they compare Nivolumab’s efficacy with Docetaxel’s in patients with non-squamous NSCLC. The study showed that the OS time was longer with Nivolumab than with Docetaxel. The prespecified PD-L1 expression level cut-offs have similar predictive utility to identify non-squamous NSCLC patients who would benefit from Nivolumab.

Figures 1 to 5 show the IHC results of recombinant anti-PL1 antibody [28-8] staining PD-L1 in human lung cancer tissues with different expression levels.

Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Figure 1. Human lung cancer tissue PD-L1 antibody [28-8] IHC staining,（less than 1.0% expression Figure 2. Human lung cancer tissue PD-L1 antibody [28-8] IHC staining,（1% - 4.9% expression Figure 3. Human lung cancer tissue PD-L1 antibody [28-8] IHC staining,（5% - 9.9% expression Figure 4. Human lung cancer tissue PD-L1 antibody [28-8] IHC staining, 10%-49.9% expression Figure 5. Human lung cancer tissue PD-L1 antibody [28-8] IHC staining,（more than 50% expression

According to the NMPA Technical Review Guideline JSZ1800126, specific sequences and guidelines are followed when using the PD-L1 IHC 28-8 pharmDx kit from Dako to evaluate the slides21. They are summarized below:

1. Evaluate hematoxylin and eosin (H&E) staining of consecutive slides of the same tissue block to make sure the tissue sample is complete, well preserved, and needed to validate tumor indications.

2. Evaluate negative and positive control tissue for stain quality control to ensure that all reagents are working properly.

3. Evaluate two positive tissue controls. Select the control tissue from fresh biopsy/surgical specimens with the same tumor indication as the patient specimen. Fix, process, and embed the control tissue in the same way as the patient’s specimen as soon as possible.

Stain positive control tissue slides with PD-L1 IHC 28-8 pharmDx kit and with negative control reagents to monitor appropriate tissue handling and reagents.

4. Evaluate two negative tissue controls. Select the control tissue from fresh biopsy/surgical specimens with the same tumor indication as the patient’s specimen. Fix, process, and embed the control tissue in the same way as the patient specimen as soon as possible. Stain negative control tissue slides with PD-L1 IHC 28-8 pharmDx kit and with negative control reagents to monitor appropriate tissue handling and reagents.

5. Evaluate negative control reagent staining of patient tissue slides to help interpret the specific staining pattern of the antigen.

6. Evaluate the specific staining pattern of the antigen with the PD-L1 primary antibody.

The requirements for scoring stained slides are as follows21:

1. Evaluate all of the viable tumor cells on the PD-L1 stained slide. For a specimen to considered adequate for PD-L1 evaluation to determine the percentage of stained tumor cells, a minimum of 100 viable tumor cells must be present. For non-squamous NSCLC specimens, record the percentage of viable tumor cells showing circular and/or partial linear membrane staning at any intensity.

2. Exclude cytoplasmic staining, immune cells, necrotic cells, normal cells, and carcinoma in situ from scoring.

3. Determine the percentage of stained tumor cells in the entire sample, with the numerator as the number of stained viable tumor cells stained and the denominator as the number of viable tumor cells in the sample.

4. As for non-squamous NSCLC, set 1% PD-L1 expression as threshold.

While earlier studies have reported PD-L1 expression in a small subset of macrophage-like cells in human tonsil, placenta, lung, and liver4,5, a more detailed summary of normal tissue reactivity is provided in the NMPA Technical Review Guideline JSZ1800126 for the PD-L1 IHC assay kit .

A total of 30 normal tissues were tested in this study. Bone marrow cells in the adrenal gland, megakaryocytes, renal tubular epithelial cells, follicular macrophages, pancreatic epithelial cells (mainly islet cells), parathyroid cells, splenic sinuses cells, thymus bone marrow epithelium, supraorbital foramen, and tonsillar growth centers (immune cells) display membrane staining. Cytoplasmic staining can be observed in some tissue cells21 .

Figures 6 and 7 show IHC images of recombinant anti-PD-L1antibody [28-8] staining PD-L1 in human tonsil and placental tissues.

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Figure 6. Human tonsil tissue PD-L1 antibody [28-8] IHC staining Figure 7. Human placental tissue PD-L1 antibody [28-8] IHC staining

PD-L1 IHC staining of human cancer tissue

PD-L1 expression is heterogeneous in different cancers or patients with the same cancer. Figures 8 and 9 show IHC images of recombinant anti-PD-L1 antibody [28-8] staining PD-L1 in human cervical and gastric cancer tissues.

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Figure 8. Human cervical cancer tissue PD-L1 antibody [28-8] IHC staining Figure 9. Human gastric cancer tissue PD-L1 antibody [28-8] IHC staining