Lack of effective targeted therapy in metastatic esophageal squamous cell carcinoma (ESCC) underscores the urgent need for identifying new treatment approaches for this challenging disease. We sought to assess the addition of cetuximab to paclitaxel-cisplatin chemotherapy for first-line treatment in patients with metastatic ESCC. In this randomized, multicenter, open-label, phase II clinical trial, patients were randomized to receive paclitaxel-cisplatin (TP) (paclitaxel [175 mg/m(2) intravenously (i.v.) on day 1 of every 3-week cycle] and cisplatin [75 mg/m(2) i.v. on day 1 of every 3-week cycle]) and TP plus cetuximab (CTP) (cetuximab, 400 mg/m(2) v. on day 1 of week 1, followed by 250 mg/m(2) weekly), respectively. Targeted next-generation sequencing (NGS) was performed on 89 tumor samples for biomarker exploration. The primary endpoint was progression-free survival (PFS) in the intention-to-treat population. With a median follow-up of 22.6 months, median PFS was 5.7 months (95% confidence interval [CI]: 4.8-7.0) in patients administered CTP versus 4.2 months (95% CI: 3.0-5.3) in the TP group (hazard ratio [HR] = 0.61; 95% CI: 0.40-0.93; p = 0.02). Median overall survival was 11.5 months (95% CI: 7.9-13.1) in the CTP group and 10.5 months (95% CI: 9.0-13.2) in the TP arm (HR = 0.98; 95% CI: 0.67 1.44; p = 0.91). The most common reported greater than or equal to grade 3 adverse events were neutropenia (35.2% versus 22.4%) and leukopenia (25.4% versus 13.2%). In patients with epidermal growth factor receptor (EGFR) amplification tumors (15.7%), PFS was improved with CTP compared with TP treatment (HR = 0.11; 95% CI: 0.01-0.98; p = 0.018). First-line CTP significantly improves PFS, with a manageable safety profile in patients with metastatic ESCC.