Safety and efficacy of anti-EGFR monoclonal antibody (SCT200) as second-line therapy in advanced esophageal squamous cell carcinoma

Abstract

Objective: The mainstay treatment of esophageal squamous cell carcinoma (ESCC) involves chemotherapy and immunotherapy.However, alternative therapies are required for patients who are refractory or intolerant to existing therapies. Methods: In this single-arm, multicenter, open-label phase Ib study, 30 patients received an intravenous infusion of SCT200, an antiepidermalgrowth factor receptor (EGFR) monoclonal antibody, 6.0 mg/kg once a week for 6 weeks, followed by 8.0 mg/kg once every2 weeks until disease progression or intolerable toxicity. The primary endpoint was the objective response rate (ORR). The secondaryendpoints were progression-free survival (PFS), overall survival (OS), and safety. Results: Thirty patients were enrolled between July 2018 and May 2019. The ORR was 16.7% (95% CI: 5.6%–34.7%). The medianPFS and OS were 3.1 months (95% CI: 1.5–4.3) and 6.8 months (95% CI: 4.7–10.1), respectively. A numerical difference without anystatistical significance in ORR was observed in patients with different EGFR expressions (= 50%: 25.0% vs. < 50%: 0%, P = 0.140)or TP53 mutation abundance (< 10%: 23.8% vs. = 10%: 0%, P = 0.286). Improved median PFS (3.4 vs. 1.4 months, P = 0.006) andOS (8.0 vs. 4.2 months, P = 0.027) were associated with TP53 mutation abundance of < 10%. The most common treatment-relatedadverse events of grade 3 or 4 (occurring in = 2 patients) were hypomagnesemia [7 (23.3%)] and rash [2 (6.7%)]. No treatmentrelateddeath occurred. Conclusions: SCT200 monotherapy as the second- or further-line treatment for advanced ESCC showed favorable efficacy, with anacceptable safety profile. TP53 mutation abundance might serve as a potential predictive biomarker.