Atezolizumab — Drug Monograph

Brand names: Tecentriq

Drug class: Checkpoint Inhibitor

Mechanism of Action

Engineered humanized anti-PD-L1 IgG1 monoclonal antibody (Fc region engineered to eliminate ADCC/CDC). Blocks PD-L1 binding to both PD-1 and CD80 (B7-1). By blocking PD-L1 directly on the tumor cell (rather than PD-1 on the T cell), atezolizumab theoretically allows PD-L2/PD-1 signaling to remain partially intact, which may preserve peripheral tolerance and reduce autoimmune toxicity compared to PD-1 inhibitors.

FDA Indications

• NSCLC — first-line (with bevacizumab, paclitaxel, and carboplatin); first-line monotherapy (PD-L1 high, EGFR/ALK wild-type); second-line after platinum failure
• SCLC — first-line (with carboplatin and etoposide)
• Hepatocellular carcinoma — first-line (with bevacizumab)
• Alveolar soft part sarcoma — previously treated
• TNBC — PD-L1 positive (SP142 assay IC ≥1%), first-line locally advanced/metastatic (with nab-paclitaxel)

Common Side Effects

• Fatigue
• Decreased appetite
• Nausea
• Rash
• Hypothyroidism
• Urinary tract infections

Clinical Pearl

PD-L1 testing for atezolizumab in TNBC uses the SP142 assay (immune cell staining, IC ≥1%), which is different from the 22C3 assay used for pembrolizumab (CPS ≥10). These PD-L1 assays are NOT interchangeable — use the companion diagnostic for the specific drug. Immune-related adverse event (irAE) management follows the standardized ASCO/NCCN/SITC grade-based ladder: Grade 1 — generally continue therapy with close monitoring and symptomatic care (exception: hold even radiographic-only Grade 1…

Related Therapies & Mechanisms

• Pembrolizumab (Keytruda) — Checkpoint Inhibitor · HCC
• Durvalumab (Imfinzi) — Checkpoint Inhibitor · HCC
• Nivolumab (Opdivo) — Checkpoint Inhibitor · HCC
• Carboplatin (Paraplatin) — Breast