PSB205 is a first-in-class, bifunctional therapy composed of a precisely defined mixture of unique anti-PD-1 and anti-CTLA-4 monoclonal antibodies, co-produced from a single cell line using our proprietary MabPair technology. Unlike conventional bispecifics, MabPair products allow tight control of the component ratio, while enabling independent engineering of each antibody to optimize target coverage, effector function, pharmacokinetics, and exposure. The CTLA-4 component is intentionally engineered with a shorter half-life to help mitigate known toxicities associated with CTLA-4 blockade. In preclinical tumor models, PSB205 demonstrated superior antitumor activity compared with either checkpoint inhibitor alone, supporting the potential for robust combination efficacy with improved tolerability.
Clinical development began with Phase 1 studies in refractory solid tumors conducted in China and the United States (NCT03986606), followed by multiple Phase 2 studies across multiple tumor types—including a hepatocellular carcinoma study in which PSB205 showed superior efficacy without increased overall toxicity versus PD-1 monotherapy (ASCO 2023). PSB205 is currently being evaluated in six ongoing pivotal Phase 3 trials in China across NSCLC, cervical cancer, hepatocellular carcinoma, and metastatic colorectal cancer.
Regulatory status: Based on strong Phase 2 results, PSB205 (QL1706) received NMPA approval in 2024 for the treatment of metastatic cervical cancer in China.
