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Home > A. Molecular pathology > Targeted therapy > Therapeutical antibodies > atezolizumab


Wednesday 16 March 2016


Definition: Atezolizumab (also known as MPDL3280A) is a fully humanized, engineered monoclonal antibody of IgG1 isotype against the protein programmed cell death ligand 1 (PD-L1). It is currently in clinical trials as an immunotherapy for several types of solid tumors.

Atezolizumab blocks the interaction of PD-L1 with PD-1 and B7.1. PD-L1 can be highly expressed on certain tumors, which is thought to be a mechanism that leads to reduced activation of immune cells (cytotoxic T-cells in particular) that might otherwise recognize and attack the cancer. Inhibition of PD-L1 by atezolizumab can remove this inhibitor effect on T-cell activation, and thereby engender an effective anti-tumor response.

This one of several ways to block inhibitory signals related to T-cell activation, a more general strategy known as "immune checkpoint inhibition." For some cancers (notably bladder) the probability of benefit is related to PD-L1 expression, but most cancers with PD-L1 expression still do not respond, and many (about 15%) without PD-L1 expression do respond, and therefore it is clear that there is much to learn about how these drugs work, and how to predict which patients will benefit.

It has been approved for treatment of several cancers :
- melanoma,
- breast cancer,
- non-small-cell lung carcinoma,
- bladder cancer ( urothelial carcinoma )
- renal cell carcinoma.

See also

- PD-1 and PD-L1 system