Tumor sample collection and immunohistochemical staining
TGF-β1, tumor, Tumor
TUMOR, TUMOR
Tumor samples were collected before the initiation of treatment using formalin-fixed paraffin-embedded (FFPE) tissues at the patient’s discretion. If the tumor content of the sample was estimated to be ≥40% on pathologic examination, IHC was used to detect the expression of PD-L1 and TGF-β1 in FFPE sections. (TGF-β; clonePD00-17, Cat#HA721143; HVABIO; Hangzhou, China); (PD-L1; clone 22C3, Cat#A1645; ABclonal; Wuhan, China). PD-L1 tumor expression was determined by IHC performed at a central laboratory (22C3clone, Cell Signaling Technology, Shanghai, China) and calculated as a combined positive score (TPS, defined as the number of PD-L1 staining tumor cells out of the total number of tumor cells, multiplied by 100). TGF-β1 was centrally detected by IHC (PD00-17 clone, Cell Signaling Technology) and presented as histochemical score (H-score, defined and calculated as the product of the intensity score and proportion) in extracellular matrix and immune cells. Immunostaining results were interpreted by two senior pathologists (SKK and SDY). We also used Image-Pro Plus (version 6.0; Media Cybernetics, Inc., Rockville, MD, USA) to analyze the results.