On November 6, 2024 Precision Biologics, Inc. reported that affinity maturation and characterization of its novel anti-core 2 O-glycan monoclonal antibody PB-223, will be presented in a poster at the Society for Immunotherapy of Cancer (SITC) (Free SITC Whitepaper) 39th Annual Meeting on November 7-8, 2024, George R. Brown Convention Center, Houston, Texas (Press release, Precision Biologics, NOV 6, 2024, View Source [SID1234647862]), USA, Poster title: Affinity Maturation and Characterization of a Novel O-glycan Epitope Targeting Anti-Human Carcinoma Monoclonal Antibody (mAb) PB-223

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Presentation of the poster will be made in person on the following dates and locations:

November 7th, 2024: SITC (Free SITC Whitepaper) Immune Engineering Workshop, 3.10 p.m-5 p.m. CST, George R. Brown Convention Center, Level 3 – Grand Ballroom AB, Houston, Texas, USA
November 8th, 2024: Poster Session Immuno-Engineering, abstract number 1101, 12:15–1:45 p.m. CST and 5:30-7 p.m. CST, George R. Brown Convention Center, Level 1-Exhibit Halls A B, Houston, Texas, USA
BACKGROUND:

PB-223 is an innovative mAb developed through immune engineering from the chimeric IgG1 NEO-102 (Ensituximab). It targets a unique core 2 O-glycan (variant of MUC5AC),

Preclinical and clinical data showed that NEO-102 specifically binds to and kills colorectal and pancreatic cancer cells through ADCC. NEO-102 did not bind to healthy tissues. In a phase 2 study, NEO-102 showed promising results in heavily pretreated patients with advanced, refractory metastatic colorectal cancer.

In general, the efficacy of using a monoclonal antibody as a single agent in cancer immunotherapy can be impaired not only by the resistance of cancer cells in the tumor microenvironment (TME), but also by a low binding affinity to target antigens expressed on cancer cells.

One strategy to improve the therapeutic efficacy of monoclonal antibodies is to enhance their binding affinity to target antigens.
STUDY PRESENTED AT SITC (Free SITC Whitepaper) 2024:

The objective of this study was to enhance the binding affinity of NEO-102 to its target antigen. By engineering the VH and VL sequences of NEO-102 through Fast Screening for Expression Biophysical Properties and Affinity (FASEA), while maintaining the binding specificity to the target antigen, allowed us to develop a new clone with a lower KD and markedly improved characteristics. This new biologic asset developed by affinity maturation was given the name PB-223.
Binding kinetics of PB-223 and NEO-102 to the target antigen were compared by ELISA. Results show that PB-223 has a KD of 4.5-fold less than NEO-102, suggesting a higher affinity for the target antigen by PB-223 compared to NEO-102.
The binding affinity of PB-223 and NEO-102 to various human tumor cell lines was also evaluated by flow cytometry. Flow cytometry analysis showed that PB-223 not only has markedly enhanced comparative binding to colorectal and pancreatic cancer cell lines recognized by NEO-102, but that PB-223 is also able to bind to many additional tumor cell lines that were not recognized by NEO-102.
Further study by O-glycan array analysis showed that 1) PB-223 binds specifically to core-2 O-glycans, and that 2) core 2 O-glycans recognized by PB-223 are expressed on tumor cell lines positive for PB-223 binding in flow cytometry.
Immunohistochemistry (IHC) analysis performed on human tumor tissues shows that PB-223 does not bind to healthy tissues. IHC analysis also shows that PB-223, in addition to binding to both colorectal cancer and pancreatic cancer, it also binds to additional tumor tissues not reactive with NEO-102, including triple negative breast cancer, prostate cancer, kidney cancer, head and neck cancer, liver cancer, and bladder cancer.
In addition, this study demonstrated that PB-223 is internalized into human cancer cell lines expressing core 2 O-glycans.
Findings from this study suggest that PB-223 has a strong binding affinity for human cancers expressing core 2 O-glycans and that PB-223 may be a potential candidate for the development of antibody-drug conjugates (ADC) for treatment of various human carcinomas.