Cemiplimab — Drug Monograph
Brand names: Libtayo
Drug class: Checkpoint Inhibitor
Mechanism of Action
Human IgG4 monoclonal antibody targeting PD-1 (programmed death-1). Blocks PD-1 interaction with its ligands PD-L1 and PD-L2, restoring T cell-mediated anti-tumor immunity. Cemiplimab has no Fc-mediated effector function (IgG4 class), minimizing risk of T-cell depletion via ADCC.
FDA Indications
- Cutaneous squamous cell carcinoma (cSCC) — locally advanced or metastatic not eligible for curative surgery or radiation
- Basal cell carcinoma (BCC) — locally advanced or metastatic after progression on or intolerance to hedgehog pathway inhibitor (HHI)
- Non-small cell lung cancer (NSCLC) — first-line, PD-L1 ≥50%, no EGFR/ALK alterations (monotherapy); first-line in combination with platinum-based chemotherapy regardless of PD-L1
- Cervical cancer — first-line persistent, recurrent, or metastatic (with chemotherapy ± bevacizumab)
Common Side Effects
- Fatigue
- Rash
- Diarrhea
- Musculoskeletal pain
- Pruritus
- Nausea
- Hypothyroidism
- Constipation
Clinical Pearl
Cemiplimab was the first PD-1 inhibitor approved for cSCC and remains the only FDA-approved systemic therapy for advanced BCC in patients who progressed on hedgehog pathway inhibitors (vismodegib/sonidegib). In cSCC, ORR is approximately 46% with durable responses — remarkable for a historically chemo-resistant cancer. Unlike melanoma and NSCLC, PD-L1 testing is not required for cSCC or BCC indications. Immune-related adverse event (irAE) management follows the standardized ASCO/NCCN/SITC…
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