STA551 + atezolizumab

STA551 + atezolizumab is a combination of two immunotherapeutic monoclonal antibodies investigated for the treatment of advanced or metastatic solid tumors. **STA551** is a novel anti-CD137 (4-1BB; TNFRSF9) agonistic antibody designed to activate selectively in the tumor microenvironment, exploiting the high extracellular ATP levels characteristic of solid tumors. This selectivity aims to boost anti-tumor immunity while minimizing systemic immune-related toxicities. **Atezolizumab** is a humanized IgG1 monoclonal antibody targeting PD-L1 (programmed death-ligand 1), blocking its interaction with PD-1 and B7.1 receptors, thereby enhancing T-cell immune responses against cancer cells. The rationale for the combination is to synergistically enhance antitumor T cell activity—STA551 stimulates T cell costimulation via CD137 in tumors, while atezolizumab relieves immunosuppression via checkpoint inhibition. The combination is under study via intravenous administration in a dose-escalation phase Ia/Ib clinical trial in patients with locally advanced or metastatic solid tumors[1][3].

Brand names

Tecentriq

Other names

RG7446RG-7446RG 7446