Atezolizumab is an antibody inhibitor, a humanized monoclonal antibody, IgG1, which targets PD-L1 and blocks the interaction of PD-L1 with PD-1. Atezolizumab has antitumor activity and promotes T-cells to attack tumor cells.

Objective: Determine the binding of [111In]PD-L1-mAb to tumor cell lines. Cells: NCI-H2444（Lung Cancer cell line）, MDAMB231（Breast Cancer cell line）,etc. Concentrations: 1 μCi/100μl. Incubation Time: 1 h. Method: Incubating 1 μCi of [111In]PD-L1-mAb with 1×106cells (in triplicate for each cell line) for 1h at 37°C. PD-L1 blocking was performed by adding a 10-fold molar equivalent excess of the non-labeled mAb. After incubation, cells were washed three times with cold PBS prior to counting on an automated gamma counter.