80P - Safety, preliminary efficacy, and pharmacokinetics of HLX26 plus serplulimab in advanced solid tumours: An open-label, dose-escalation phase I study

Background

HLX26 is a novel humanised anti-lymphocyte activation gene-3 monoclonal antibody. This study aimed to evaluate the safety, preliminary efficacy, and pharmacokinetics of HLX26 plus serplulimab (a novel programmed cell death-1 inhibitor) in patients with advanced solid tumours.

Methods

This was a single-centre, open-label, dose-escalation phase 1 study. Patients with histologically or cytologically confirmed advanced/metastatic solid tumours that had failed or could not receive standard therapies were enrolled and received intravenous HLX26 at three dose levels (500, 800, 1600 mg) plus serplulimab (300 mg) Q3W, following a “3+3” design. The primary endpoint was dose-limiting toxicity (DLT) and the maximum tolerated dose (MTD) within three weeks after the first administration of HLX26 (i.e. the DLT observation period). Secondary endpoints included safety, preliminary efficacy, pharmacokinetics, and immunogenicity.

Results

As of 19 July 2023, 9 patients with primary stage IV non-small cell lung cancer (n=4, 44.4%), small cell lung cancer (n=2, 22.2%), gastric cancer (n=1, 11.1%), cervical cancer (n=1, 11.1%), or endometrial cancer (n=1, 11.1%) were enrolled and received HLX26 at 500 mg (n=3), 800 mg (n=3), or 1600 mg (n=3), in combination with 300 mg serplulimab. The median age was 66 years, and 6 (66.7%) patients were male. All patients experienced treatment-emergent adverse events (TEAEs); all TEAEs that occurred during the DLT observation period were grade 1 or 2. One patient in the 800 mg group reported grades 3 or 4 drug-related asthenia, pain, and neutrophil count decreased. No DLT was reported and the MTD was not determined yet. Among the 8 efficacy evaluable patients, none had achieved complete or partial response; 3 (37.5%) patients (one in each group) had a best overall response of stable disease.

Conclusions

No new safety signals were observed for the different doses of HLX26 in combination with serplulimab. HLX26 plus serplulimab was safe and well tolerated in patients with advanced solid tumours who had failed or could not receive standard therapies.

Clinical trial identification

NCT05400265 (released on 1 June 2022).

Editorial acknowledgement

Editorial assistance was provided by Zhi Hao Kwok, Shiqi Zhong, and Chen Hu of Shanghai Henlius Biotech, Inc.

Legal entity responsible for the study

Shanghai Henlius Biotech, Inc.

Funding

Shanghai Henlius Biotech, Inc.

Disclosure

H. Li, W. Kang, J. Li, Q. Wang, J. Zhu: Financial Interests, Personal, Full or part-time Employment: Shanghai Henlius Biotech, Inc. All other authors have declared no conflicts of interest.