Purple Biotech Reports Positive New Preclinical Data Demonstrating Multi-Arm Anti-Tumor Activity Across Two CAPTN-3 Tri-Specific Antibodies at ESMO Immuno-Oncology Congress 2025

Data demonstrates the significant and sustained tumor regression achieved by the CAPTN-3 platform across two distinct tri-specific antibodies, IM1240 and IM1305, targeting different tumor antigens

Transcriptomic analysis across ~11,000 TCGA samples shows NKG2A expression is strongly associated with tumor expression of 5T4 or TROP2, supporting inclusion of the NKG2A arm in CAPTN-3 designs

NKG2A arm significantly contributes to IM1240 anti-cancer immune activity in PD1-resistant patient-derived explants

REHOVOT, Israel, Dec. 11, 2025 (GLOBE NEWSWIRE) -- Purple Biotech Ltd. (“Purple Biotech” or the “Company”) (NASDAQ/TASE: PPBT), a clinical-stage company developing first-in-class therapies that seek to overcome tumor immune evasion and drug resistance, today reported positive new preclinical data from its CAPTN-3 tri-specific antibody platform presented at the ESMO Immuno-Oncology (ESMO IO) Congress 2025. The data presented was generated in collaboration with the laboratory of Dr. Amir Horowitz of the Tisch Cancer Institute at the Icahn School of Medicine at Mount Sinai.

These new preclinical data successfully demonstrates that two CAPTN-3 tri-specific antibodies, IM1240 (capped-CD3×5T4×NKG2A) and IM1305 (capped-CD3×TROP2×NKG2A), 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 indicate that the CAPTN-3 architecture can generate potent multi-arm activity beyond a single target, supporting the platform’s potential applicability across a range of solid tumors. The CAPTN-3 platform is designed to unite three functional mechanisms—T-cell engagement and activation, enhanced by NKG2A-mediated innate and adaptive immune activation, and tumor-antigen targeting—into a single tri-specific molecule intended to coordinate a synergistic immune response.

“Immune failure is one of the biggest obstacles in treating solid tumors, and CAPTN-3 was built to address that challenge,” said Gil Efron, Chief Executive Officer of Purple Biotech. “The data we presented at ESMO IO shows that IM1240 can activate an immune response even in tumors that no longer respond to PD-1 therapy, and that each component of the molecule contributes to its overall effect. At the same time, the introduction of IM1305 demonstrates how CAPTN-3 can be adapted to different tumor targets, underscoring the versatility and scalability of the platform. These findings support our development roadmap as we prepare for anticipated key milestones in 2026 and advance CAPTN-3 toward IND-enabling studies.”