## First-Line Systemic Therapy for Advanced/Unresectable SCC **Key Point:** Cemiplimab, a PD-1 inhibitor, is the FDA-approved and preferred systemic agent for advanced cutaneous squamous cell carcinoma (CSCC) and is now the standard of care for unresectable or metastatic disease. ### Mechanism of Action Cemiplimab blocks programmed death receptor-1 (PD-1), restoring T-cell-mediated anti-tumor immunity. SCC tumors frequently express PD-L1, making them responsive to checkpoint inhibition. ### Clinical Evidence - **EMPOWER-CSCC-1 trial**: Cemiplimab demonstrated superior overall response rate (~50%) and durable responses in advanced CSCC compared to chemotherapy. - Approved by FDA in September 2018 for locally advanced or metastatic CSCC. - Now recommended as first-line systemic therapy by NCCN and ESMO guidelines for unresectable disease. ### Comparison of Systemic Options | Agent | Indication | Response Rate | Status | |-------|-----------|---------------|--------| | **Cemiplimab** | Advanced/metastatic CSCC | ~50% | **First-line, preferred** | | 5-Fluorouracil | Adjuvant (high-risk), palliative | Variable | Second-line, older standard | | Imiquimod | Early/in situ SCC, superficial | ~80% (topical) | Topical only, not systemic | | Methotrexate | Palliative, rare | Poor | Rarely used, historical | **High-Yield:** Cemiplimab is now the standard of care for unresectable or metastatic cutaneous SCC — this represents a paradigm shift from cytotoxic chemotherapy. **Clinical Pearl:** Patients with advanced SCC often have immunosuppression (organ transplant, chronic lymphocytic leukemia, or age-related immune decline), yet checkpoint inhibitors remain effective and are preferred over traditional chemotherapy. **Warning:** Do not confuse topical therapies (imiquimod, 5-FU) with systemic therapy. Imiquimod is excellent for early/superficial lesions but has no role in advanced disease.
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