A phase 2 study of HLX07 as monotherapy or combination therapy in patients with locally advanced, unresectable, or metastatic esophageal squamous cell carcinoma.

Abstract

4029 Background: Esophageal cancer is one of the most common cancers worldwide with esophageal squamous cell carcinoma (ESCC) being the predominant histological subtype. Most patients are diagnosed at the advanced stage, and the prognosis remains poor. About 40–84% of ESCC cases showed overexpression of EGFR which was related to shorter overall survival and disease-free survival, indicating that treatment targeting EGFR could be a new strategy. This study aimed to evaluate the efficacy and safety of HLX07, a novel recombinant humanized anti-EGFR monoclonal antibody (mAb), as monotherapy or combination therapy in patients with locally advanced, unresectable/metastatic ESCC. Methods: In this open-label, multicenter phase 2 study, patients aged 18–75 years with histologically or cytologically confirmed locally advanced, unresectable/metastatic ESCC or esophageal adenosquamous carcinoma were enrolled. Patients with no prior systemic antitumor therapy were assigned to group A and given HLX07 1000 mg plus serplulimab 200 mg (anti-PD-1 mAb) and chemotherapy (5-FU 2400 mg/m2 + cisplatin 50 mg/m2), Q2W IV. Patients who had failed first-line immuno-chemotherapy combination or at least two lines of other systemic antitumor therapy were assigned to group B and given HLX07 monotherapy (1000 mg Q2W IV). The primary endpoints were objective response rate (ORR) and progression-free survival (PFS) assessed by an independent radiological review committee and investigators per RECIST v1.1. Secondary endpoints included other efficacy measures, safety, pharmacokinetics, immunogenicity, and biomarker explorations. Results: As of February 4, 2023, 49 patients were enrolled in group A (n=30) and group B (n=19), with a median age of 64.5 and 59.0 years, respectively. 26 (86.7%) patients in group A and all patients in group B were male. The median follow-up duration was 2.9 months, and the preliminary efficacy was presented. Among the 42 efficacy evaluable patients (29 in group A and 13 in group B), investigator-assessed ORRs were 55.2% (95% CI 35.7–73.6%) and 23.1% (95% CI 5.0–53.8%) in the respective groups. Investigator-assessed median PFSs were not reached in group A and 1.5 months (95% CI 1.2–not evaluable) in group B. 15 (50.0%) patients in group A and 5 (26.3%) in group B had grade ≥3 treatment-emergent adverse events (AEs). AEs of special interest were observed in 16 (53.3%) and 11 (57.9%) patients, respectively, most commonly rash (43.3% vs 47.4%) and hypomagnesemia (33.3% vs 36.8%). No drug-related death was reported. Conclusions: The encouraging antitumor activity and manageable safety profile support further development of HLX07 as a new treatment option for patients with advanced ESCC, both in first-line and late-line settings. Clinical trial information: NCT05221658 .