Effectiveness and toxicity of cetuximab with concurrent RT in locally advanced cutaneous squamous cell skin cancer: a case series

Background: Treatment for locally advanced cutaneous squamous cell cancers (laCSCC) remains poorly defined. Most laCSCC tumors express high levels of epidermal growth factor receptors (EGFR). Cetuximab has activity in other EGFR expressing cancers and enhances the effectiveness of radiotherapy. Methods: A retrospective review of institutional data identified eighteen patients with laCSCC treated with cetuximab induction and concurrent radiotherapy. The loading dose of cetuximab was 400 mg/m² IV. Subsequent weekly doses of 250 mg/m² IV were infused throughout the period of radiation. The treatment doses ranged from 4500–7000 cGy, with a dose fraction of 200-250 cGy. Results: The objective response rate was 83.2% with 55.5% complete responses and 27.7% partial responses. Median progression-free survival was 21.6 months. Progression-free survival was 61% at 1 year and 40% at 2 years. With longer follow-up, some patients developed a local recurrence (16.7%), distant metastases (11.1%) or a second primary cancer (16.3%). Cetuximab was well tolerated, with 68.4% patients experienced only mild acneiform skin rash or fatigue (Grade 1 or 2). Radiotherapy produced expected side effects (skin erythema, moist desquamation, mucositis). Discussion: Cetuximab plus radiotherapy represents an active and tolerable treatment option for laCSCC, including patients with contraindications for checkpoint inhibitor therapy.