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Scoring system of PD-L1 22C3 immunohistochemistry assay. At least 100 viable tumor cells were evaluated to judge PD-L1 immunohistochemistry positivity. PD-L1 positivity was defined as staining of the tumor cell membrane excluding cytoplasmic staining. All slides were evaluated at magnifications of 10×, 20×, and 40×. Each representative image demonstrated <1% positivity (A), 1–49% positivity (B), and >50% positivity (C). TPS, tumor proportion score.
