Efficacy and Safety of Iparomlimab, an Anti-PD-1 Antibody, in Patients with Advanced Solid Tumors: A Phase 1c Study

Iparomlimab (QL1604) is a humanized immunoglobulin G4 mAb against programmed cell death protein 1 (PD-1). Here, we report the preliminary efficacy, safety, pharmacokinetics, and immunogenicity of iparomlimab in patients with advanced solid tumors.

In this open-label, phase 1c study, patients with advanced or metastatic solid tumors, either failed or had no standard therapies available, were enrolled and received intravenous iparomlimab at 3 mg/kg once every 3 weeks. The primary efficacy endpoint was the objective response rate (ORR) assessed by the investigator per Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1.

Between July 20, 2020, and September 6, 2021, 71 patients were enrolled and received at least one dose of iparomlimab. The ORR was 9.9% (7/71) and disease control rate was 36.6% (26/71). Median duration of response of all responders was 10.7 months [95% confidence interval (CI), 1.4-not estimable]. Additionally, the median time to progression, progression-free survival, and overall survival were 1.4 months (95% CI, 1.4-2.8), 1.4 months (95% CI, 1.4-2.7), and 9.7 months (95% CI, 7.2-15.3), respectively. A total of 52 (73.2%) patients experienced treatment-related adverse events (TRAEs) (grade ≥ 3, 19.7%). The most common TRAE (≥ 10%) was anemia (18.3%). A total of 20 (28.2%) experienced immune-related adverse events (grade ≥ 3, 7.0%). TRAEs leading to discontinuation of study drug occurred in 4 (5.6%) patients, including immune-mediated myocarditis (2 patients), Guillain-Barré syndrome (1 patient), and diarrhea (1 patient).

Iparomlimab showed preliminary clinical activity and had a manageable safety profile in patients with advanced solid tumors. These results support further investigation of iparomlimab as monotherapy or in combination therapy in advanced solid tumors.

ClinicalTrials.gov identifier, NCT05801094. Retrospectively registered in 2023-03-24.