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.
