Tasrif Pharmaceutical Secures Second U.S. Patent for CD155-Targeting Antibody Developed with Abzena’s Humanisation Technology

Tasrif Pharmaceutical, LLC has announced the grant of its second United States patent, further expanding its intellectual property portfolio focused on the Poliovirus Receptor (CD155/PVR). This new patent complements Tasrif’s foundational U.S. patent and collectively covers a proprietary panel of humanised monoclonal antibodies and antigen-binding fragments. Central to this portfolio is TSRF-786C IgG4 (S241P), a lead candidate humanised using Abzena’s Composite Human Antibody™ (CHAb) platform.

Leveraging its patented CD155-binding platform, Tasrif is developing a range of next-generation modalities, including Antibody-Drug Conjugates (ADCs), bispecific antibodies, T-cell engagers, CAR-T, and CAR-NK cell therapies. The company has also filed national phase patent applications derived from its PCT international application in key jurisdictions such as 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 tumour-specific accumulation within GL261 brain tumours. Building on this proof-of-concept, Tasrif is advancing brain-penetrating bispecific antibodies composed of humanised Anti-CD155 × Anti-Transferrin Receptor (Anti-CD155 × Anti-TfR) constructs. These bispecifics are specifically engineered to cross the blood-brain barrier, targeting CNS indications.

For systemic cancer therapies, TSRF-786C exhibits sub-nanomolar binding affinity for CD155, as demonstrated by Surface Plasmon Resonance (SPR) analysis. The selection of TSRF-786C was validated through comprehensive preclinical profiling, including precise target specificity confirmed by the Retrogenix® Cell Microarray Platform Assay. The candidate also showed low immunogenicity in Abzena’s EpiScreen® DC T-cell assay, a favourable cytokine release profile, and excellent thermostability and freeze-thaw resilience.

Importantly, TSRF-786C demonstrates robust cross-reactivity with non-human primate (NHP) CD155, facilitating planned Investigational New Drug (IND)-enabling safety and toxicology studies.

In pilot studies using humanised mouse models of pancreatic and lung cancer, TSRF-786C effectively modulated the PVR (CD155)–DNAM-1 (CD226) immune axis. Treatment resulted in a statistically significant increase in the percentage of CD226-positive T cells (both CD4 and CD8) within the lung tumour microenvironment. Similarly, there was a significant increase in CD226-positive tumour-infiltrating Natural Killer (NK) cells in the pancreatic tumour microenvironment. Notably, TSRF-786C did not alter local PD-1 expression, supporting potential combination strategies with anti-PD-1 therapies.

These preclinical data underpin the ongoing development of TSRF-786C, with IND-enabling safety and toxicology evaluations underway for systemic cancer indications.

The collaboration between Tasrif and Abzena highlights the integration of advanced antibody humanisation and immunogenicity platforms to accelerate the development of innovative immuno-oncology therapeutics. Tasrif’s expanding patent estate and promising preclinical results position the company at the forefront of CD155-targeted cancer therapies with potential applications across CNS and systemic malignancies.