An epidemiologic study on PD-L1 expression combined with clinical observation in the Chinese MIUBC patients. - POLARIS

The Primary Objective of this observational study is to investigate the prevalence of high PD-L1 expression in Chinese MIUBC patients.

The primary objective of this observational study is: •To investigate the prevalence of high PD-L1 expression in Chinese MIUBC patients. High PD-L1 expression is defined as ≥25% tumor cell membrane positivity for PD-L1 at any intensity above background staining as noted on the corresponding negative control OR ≥25% tumor associated immune cell positivity for PD-L1 at any intensity above background staining as noted on the corresponding negative control. Note: PD-L1 High (>=25% tumor cell membrane positivity for PD-L1 or 1) IF IC area >1%: >=25% tumor associated immune cell positivity for PD-L1; 2) If IC area=1%: 100% tumor associated immune cell positivity for PD-L1). PD-L1 Low if criteria not met for PD-L1 High. The second objectives of this observational study are: •To investigate the PD-L1 expression profile in TC or IC in Chinese MIUBC patients. •To assess the concordance of PD-L1 testing results generated from the hospital labs with those from the central lab. •To observe the initial treatment pattern for MIUBC patients in usual clinical practice in China. •To observe 2-year OS of the Chinese MIUBC patients. The exploratory objectives of this observational study are: •To explore the relationship between the demographic characteristics and expression of PD-L1 and other exploratory biomarkers including immune cell (IC) subset CD8+ T cells and tumor mutation burden (TMB). •To explore the relationship between OS and the demographic characteristics as well as the expression of biomarkers. •To explore the relationship between PD-L1 and TMB, PD-L1 and CD8 positive T cell respectively.