Purple Biotech’s antibody platform shows anti-tumor activity

Purple Biotech (PPBT) reported positive new preclinical data from its CAPTN-3 tri-specific antibody platform presented at the ESMO Immuno-Oncology Congress 2025. These new preclinical data demonstrates that two CAPTN-3 tri-specific antibodies, IM1240 and IM1305, each achieve strong anti-tumor activity across different tumor antigens. IM1240 has also shown anti-tumor activity in models resistant to prior PD1 therapy. These results support the platform’s potential applicability across a range of solid tumors. The company’s lead CAPTN-3 program, IM1240, demonstrated significant anti-tumor activity in three PD1-resistant ex-vivo models, including new results in HNSCC patient-derived biopsies. In these studies, IM1240 induced tumor cell apoptosis, with anti-tumor activity dependent on both CD3 and NKG2A arms. The company’s new TROP2-targeting candidate, IM1305, further validates the adaptability of the CAPTN-3 platform and demonstrated high-affinity binding to both TROP2 and NKG2A. Potent PBMC-mediated tumor cell killing was observed at low concentrations across multiple tumor types, including triple-negative breast, gastric, pancreatic, and head and neck cancers. In humanized triple-negative breast cancer mouse models, IM1305 induced sustained tumor regression at low doses.