Tasrif Pharmaceutical Granted Second U.S. Patent for CD155-Targeting Antibody Developed with Abzena’s Humanization & Immunogenicity Platforms

Key Takeaways:

• IP expansion: Second U.S. patent broadens coverage of Tasrif’s humanized anti-CD155 (PVR) antibody panel, including lead candidate TSRF-786C. National-phase filings pending in JP, EP, CA, AU, CN.
• Two modality tracks: TSRF-786C for systemic cancers (sub-nanomolar affinity, NHP cross-reactivity, heading toward IND-enabling tox) and an Anti-CD155 × Anti-TfR bispecific for CNS/BBB penetration (proof-of-concept via surrogate antibody in a glioblastoma mouse model, not TSRF-786C itself).
• Abzena platforms de-risked the developability of the candidate: CHAb was used for humanization (generating the IgG4 S241P sequence), and EpiScreen (in vitro DC T-cell assay) confirmed low immunogenicity risk — sequence design and immunogenicity deselection at different optimization stages, not one combined readout.
• Mechanistic, not efficacy, data: In mouse tumor models, TSRF-786C increased CD226(DNAM-1)+ T cells and NK cells in the TME without altering PD-1 expression — rationale for anti-PD-1 combos, but no tumor growth/survival data reported.

On July 29, 2026, Abzen’s customer Tasrif Pharmaceutical, LLC announced the grant of its second U.S. Patent, expanding its intellectual property targeting the Poliovirus Receptor (CD155/PVR). Together with Tasrif’s foundational issued U.S. patent, this expanded portfolio covers a proprietary panel of humanized monoclonal antibodies and antigen-binding fragments, including the lead candidate, TSRF-786C IgG4 (S241P), humanized using Abzena’s Composite Human Antibody™ (CHAb) platform. Tasrif is also leveraging its patented CD155-binding platform to engineer next-generation modalities, including Antibody-Drug Conjugates (ADCs), Bispecifics, T-cell engagers, CAR-T, and CAR-NK cell therapies. National Phase patent applications originating from Tasrif’s PCT international application are currently pending in Japan, Europe, Canada, Australia, and China.

To address central nervous system (CNS) malignancies, Tasrif evaluated its CD155 targeting platform in a syngeneic GL261 glioblastoma 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, Tasrif 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.

For systemic cancer indications, lead candidate TSRF-786C exhibits sub-nanomolar binding affinity for CD155, as confirmed by Surface Plasmon Resonance (SPR). Selection of TSRF-786C was validated through extensive preclinical profiling, demonstrating precise target specificity via the Retrogenix® Cell Microarray Platform Assay, low immunogenicity via Abzena’s EpiScreen® DC T-cell assay, a favorable profile on Cytokine Release Assay (CRA), and excellent thermostability and freeze-thaw resilience. Crucially, TSRF-786C demonstrates robust cross-reactivity with non-human primate (NHP) CD155, enabling planned IND-enabling safety and toxicology studies.

In pilot studies using humanized mouse models of pancreatic and lung cancer, TSRF-786C successfully modulated the key PVR (CD155)–DNAM-1 (CD226) immune axis. Treatment with TSRF-786C 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 (DNAM-1) positive tumor-infiltrating Natural Killer (NK) cells in the pancreatic tumor microenvironment. Notably, TSRF-786C did not alter local PD-1 expression, thus providing a strong rationale for combination strategies with anti-PD-1 therapies. These data support the ongoing preclinical development of TSRF-786C, with IND-enabling safety and toxicology evaluations for systemic cancers.

About TSRF-786C IgG4 (S241P)

TSRF-786C IgG4 (S241P) is a humanized monoclonal antibody currently under preclinical development for the treatment of cancers that express CD155.

About Tasrif Pharmaceutical, LLC

Tasrif Pharmaceutical, LLC is a preclinical-stage biopharmaceutical company incorporated in New York. Tasrif’s mission is to improve and prolong the lives of cancer patients. Learn more about Tasrif Pharmaceuticals.