PSB205 is a first-in-class bifunctional product that contains a mixture of unique anti-PD-1 and anti-CTLA-4 monoclonal antibodies produced by a single cell line via the company’s proprietary MabPairTM technology. MabPair products offer many advantages over bispecific antibodies. The relative ratio of the two antibodies in the MabPair can be well controlled, and each antibody is individually engineered for optimal target coverage, effector function, pharmacokinetics and exposure. The anti-CTLA-4 component of the MabPair is designed with a shorter half-life than currently available anti-CTLA-4 antibodies in an effort to reduce known side effects associated with CTLA-4 blockade. Preclinical studies with PSB205 demonstrated superior efficacy in tumor models compared to either checkpoint inhibitor alone. PSB205 represents a potentially best-in-class immuno-oncology product that promises to exhibit robust combination activity while being significantly more tolerable to patients than currently approved anti-PD-1/anti-CTLA-4 combinations. Parallel Phase 1 studies in a broad range of refractory solid tumors are currently ongoing in China and the United States (www.clinicaltrials.gov; NCT03986606). The first release of clinical data from one of these studies was presented in a poster at AACR 2021.
Filled vial of PSB205, ready for study.