China-based Harbour Biomed (HKG: 2142) has announced the publication of results from a Phase Ib clinical study of its CTLA-4 antibody porustobart (HBM4003) in combination with Junshi Biosciences’ (HKG: 1877, SHA: 688180) PD-1 inhibitor toripalimab for the treatment of hepatocellular carcinoma (HCC) at the American Society of Clinical Oncology (ASCO) annual meeting.
Study Design and Patient Treatment
The open-label Phase Ib dosage expansion study aimed to assess the safety, tolerability, pharmacokinetic (PK)/pharmacodynamic (PD) characteristics, and preliminary efficacy of the combination therapy in advanced HCC and other solid tumors. Previously treated liver cancer patients (n=28) received porustobart 0.45mg/kg and toripalimab 240mg every three weeks in both cohort 1 and cohort 2. As of December 9, 2022, 28 patients had received study drug treatment with a median follow-up of 3.6 months.
Preliminary Efficacy and Safety Data
The combination of HBM4003 and toripalimab demonstrated good anti-tumor activity and acceptable safety, along with favorable PK/PD characteristics. While progression-free survival (PFS) or overall survival (OS) data has not yet matured, the objective response rate (ORR) and disease control rate (DCR) in cohort 1 were 46.7% and 73.3%, respectively. In cohort 2, the ORR and DCR were 9.1% and 54.5%, respectively. Treatment-related adverse events (TRAEs) were reported by 89.3% of patients, with 39.3% reporting level 3 TRAEs. No level 4 or level 5 TRAEs were reported, indicating the safety profile was acceptable.
Porustobart’s Unique Design
Porustobart is a fully human anti-CTLA-4 monoclonal heavy chain-only antibody (HCAb) generated on the Harbour Mice platform. It is designed to enhance the efficacy and reduce the toxicity associated with early-generation CTLA-4 antibodies.-Fineline Info & Tech
