SY12-2 PD-L1 testing in breast cancer

Two kinds of immune checkpoint inhibitor, atezolizumab and pembrolizumab, have been used for treatment of unresectable locally advanced or metastatic triple-negative breast cancers showing PD-L1-positive. Although both drugs acquire PD-L1 testing before administration, those companion diagnostics and assessment methods differ. Ventana PD-L1 SP142 assay is the only companion diagnostics for atezolizumab. Its primary antibody clone is an anti-PD-L1 rabbit monoclonal antibody, SP142, and it binds to the intracytoplasmic domain of PD-L1.