Pharmacokinetics and safety of LEAD-452, an EGFR-specific 4-1BB-agon-istic trimerbody in non-human primates

LEAD-452 is a humanized bispecific EGFR-targeted 4-1BB-agonistic trimerbody with a unique trimeric configuration compared to other 4-1BB-specific antibodies that are currently in development. Indeed, enhanced tumor- specific costimulation and very remarkable safety and efficacy profiles have been observed in mouse models. Here, we conducted for the first time a preclinical pharmacokinetic and toxicity study in non-human primates (NHP) (Macaca fascicularis). LEAD-452 exhibits comparable binding affinity for human and macaque targets, indicating its pharmacological significance for safety testing across species. The NHP were administered LEAD- 452 in a series of ascending doses, ranging from 0.1 mg/kg to 10 mg/kg, and repeated doses up to 20 mg/kg. The administration of LEAD-452 was found to be clinically well tolerated, with no major related adverse effects observed. Furthermore, there have been no reported cases of liver toxicity, thrombocytopenia, and neutropenia, which are commonly associated with treatments using conventional anti-4-1BB IgG-based antibodies. In addition, neither IgM nor IgG-based anti-drug antibodies were detected in serum samples from NHP during the study, regardless of the dose of LEAD-452 administered. These results support the clinical development of LEAD-452 for the treatment of solid tumors.