Tasrif Pharmaceutical Secures Second U.S. Patent for CD155-Targeting Antibodies as Anti-TIGIT Field Contracts
Key Insights
Tasrif Pharmaceutical (search) has been granted its second U.S. patent covering humanized monoclonal antibodies targeting CD155 (search), expanding IP protection around lead candidate TSRF-786C IgG4 (S241P).
The patent strengthens Tasrif's position as multiple anti-TIGIT (search) receptor-blocking programs from Roche, Merck (search), Arcus, and BeiGene (search) have been discontinued following Phase III failures.
Preclinical data for TSRF-786C show sub-nanomolar CD155 (search) binding affinity, target specificity, low predicted immunogenicity, and cross-reactivity with non-human primate CD155.
New York-based Tasrif Pharmaceutical, LLC has been granted its second U.S. patent covering humanized monoclonal antibodies and antigen-binding fragments targeting CD155 (search), the poliovirus receptor (PVR), the company announced on July 29, 2026. The newly issued patent, together with Tasrif's foundational first U.S. patent, now protects a proprietary panel of humanized monoclonal antibodies including the lead candidate TSRF-786C IgG4 (S241P). National phase applications originating from Tasrif's PCT international filing remain pending in Japan, Europe, Canada, Australia, and China.
The patent expansion arrives at a pivotal moment for the CD155 (search)/TIGIT (search) immune checkpoint axis. Anti-TIGIT receptor-blocking strategies from Roche, Merck (search), Arcus Biosciences, and BeiGene (search) (now BeOne Medicines) have all been discontinued following Phase III failures, leaving ligand-blocking approaches—those targeting CD155 rather than the TIGIT receptor—among the remaining strategies being explored on this pathway.
TSRF-786C: Preclinical Profile and Engineering
TSRF-786C is a humanized monoclonal antibody developed using Abzena's Composite Human Antibody (CHAb) platform. The IgG4 isotype was deliberately selected to minimize Fc-mediated effector function, and the S241P hinge mutation eliminates Fab-arm exchange—the in vivo dissociation of IgG4 heavy chains that can generate monovalent or adventitiously bispecific molecules. The newly issued patent identifies the stabilized IgG4 S241P format among its protected embodiments.
Preclinical characterization, disclosed through company press releases, demonstrates sub-nanomolar binding affinity for CD155 (search) as confirmed by Surface Plasmon Resonance (SPR). Target specificity was validated through the Retrogenix Cell Microarray Platform Assay, and low predicted immunogenicity was demonstrated via Abzena's EpiScreen DC T-cell assay. TSRF-786C also showed a favorable profile on Cytokine Release Assay (CRA) and exhibited excellent thermostability and freeze-thaw resilience. Critically, the antibody demonstrates robust cross-reactivity with non-human primate (NHP) CD155, supporting planned IND-enabling safety and toxicology studies.
Preclinical Efficacy and Mechanism of Action
In pilot studies using humanized mouse models of pancreatic and lung cancer (search), TSRF-786C successfully modulated the PVR (CD155 (search))–DNAM-1 (CD226) (search) immune axis. Treatment yielded a statistically significant increase in the percentage of CD226 (DNAM-1) positive T cells—both CD4 and CD8—within the lung tumor microenvironment, as well as a statistically significant increase in the percentage of CD226-positive tumor-infiltrating Natural Killer (NK) cells in the pancreatic tumor microenvironment.
Notably, TSRF-786C did not alter local PD-1 (search) expression, providing a strong rationale for combination strategies with anti-PD-1 therapies. Tasrif is also leveraging its patented CD155 (search)-binding platform to engineer next-generation modalities, including antibody-drug conjugates (ADCs), bispecifics, T-cell engagers, CAR-T, and CAR-NK cell therapies.
CNS Malignancy Strategy
To address central nervous system malignancies, Tasrif evaluated its CD155 (search) targeting platform in a syngeneic GL261 glioblastoma (search) mouse model using a surrogate anti-mouse CD155 antibody. The study confirmed in vivo target engagement and tumor-specific accumulation within GL261 brain tumors. Building on this proof-of-concept, the company is advancing brain-penetrating bispecific antibodies—comprising humanized Anti-CD155 × Anti-Transferrin Receptor (Anti-CD155 × Anti-TfR)—specifically engineered to cross the blood-brain barrier for CNS indications.
Competitive Landscape
Among the closest clinical comparators is NTX-1088, developed by Israel-based Nectin Therapeutics (search), which also targets CD155 (search) and reported encouraging Phase I combination data with pembrolizumab at ASCO 2026, including the first clinical demonstration of restored DNAM-1 expression on peripheral immune cells. AstraZeneca's rilvegostomig (AZD2936), a bispecific simultaneously blocking PD-1 (search) and TIGIT (search), remains the most advanced active program on the broader axis and is currently in Phase III across multiple solid tumor indications.
Tasrif remains a preclinical-stage company, and no IND application or clinical trial registration has been publicly identified for TSRF-786C. The expanded patent estate positions the company to advance or partner its CD155 (search) platform as ligand-blocking approaches continue to attract interest following the setbacks across anti-TIGIT (search) programs.