Brief Report: Ivonescimab Combined With Etoposide Plus Carboplatin as First-Line Treatment for Extensive-Stage SCLC: Results of a Phase 1b Clinical Trial

Introduction

Ivonescimab is a humanized IgG1 bispecific anti–programmed cell death protein 1/vascular endothelial growth factor antibody. This study aimed to evaluate the safety and tolerance of ivonescimab combined with etoposide and carboplatin as first-line treatment in patients with extensive-stage SCLC and to explore the primary efficacy of this regimen.

Methods

Eligible patients received intravenous ivonescimab 3 mg/kg, 10 mg/kg, or 20 mg/kg every 3 weeks combined with etoposide and carboplatin for up to four cycles, followed by ivonescimab as maintenance. The primary end points were safety and objective response rate (ORR).

Results

Between April 23, 2021, and December 2, 2021, 35 patients were enrolled. At data cutoff (October 25, 2023), the median follow-up was 13.3 (range: 0.3–28.5) months. For all patients, the confirmed ORR and disease control rate were 80% and 91.4%, respectively. The ORR was 66.7%, 90.9%, and 76.2% at the dose of 3 mg/kg, 10 mg/kg, and 20 mg/kg, respectively. Grade more than or equal to 3 treatment-related adverse events (TRAEs) were observed in 21 patients (60%), and the most frequent toxicities were decreased neutrophil count (n = 8, 22.9%), decreased white blood cell count (n = 5, 14.3%), and anemia (n = 5, 14.3%). Grade more than or equal to 3 TRAEs occurred in 66.7%, 54.5%, and 61.9% of patients in 3, 10, and 20 mg/kg groups, respectively. TRAEs leading to death were reported in two patients (5.7%). Immune-related adverse events, most of them grade 1 or 2, occurred in 14 patients (40.0%).

Conclusions

Ivonescimab in combination with etoposide and carboplatin was well tolerated and found to have promising antitumor activity in extensive-stage SCLC.