Abstract 4695: Effect of fully human anti-PTGFRN antibody drug conjugate on head neck cancer cells and patient derived xenografts

Abstract Prostaglandin F2 Receptor Negative regulator, or PTGFRN, also known as FPRP is a 175 kDa transmembrane protein associated with metastatic characteristics of certain cancer types and a member of the tetraspanin family. PTGFRN expression is undetectable to low in normal tissues whereas it is elevated in several cancers such as head and neck, mesothelioma and medulloblastoma. PTGFRN has also been reported to be upregulated in many different types of cancer, increasingly so in metastatic cancer cells, compared to their non-metastatic counterparts PTGFRN expression has been reported to be a poor prognostic factor for glioblastoma making it a potential novel cancer therapeutic target. We have previously shown that PTGFRN is an internalizable cell surface protein making it suitable for targeting by antibody drug conjugate (ADC). We have developed fully human monoclonal antibodies to PTGFRN by immunizing humanized transgenic TC mice with human PTGFRN. Within 60 days from the start of immunization we were able to select several fully human anti-PTGFRN monoclonal antibodies that were examined by several functional assays that included flow binding, internalization, affinity determination and cell killing as antibody drug conjugates. Several monoclonal antibodies were selected and evaluated for their ability to inhibit tumor formation in several cancers. Selected antibodies were then conjugated to duocarmycin by a cleavable linker. The present study proposed to examine the effect of one such anti-PTGFRN ADC on head and neck cancer cell lines and patient derived xenografts that had been analyzed for their PTGFRN expression by western blot analysis using anti-PTGFRN antibody. Cells lines and PDX that were positive for PTGFRN expression were used to examine the effect of anti-PTGFRN ADC on their in vitro and in vivo proliferation. The data show that anti-PTGFRN ADC inhibits tumor formation in a dose-dependent fashion. These data also establish PTGFRN as cancer druggable target and the selected fully human anti-PTGFRN antibody as an attractive antibody for the development of new antibody drug conjugate in Oncology. These data also emphasize the potential of humanized transgenic TC mice for the development of fully human monoclonal antibodies, thus bypassing the need for humanization and affinity maturation required by other humanized mice or phase display. Citation Format: Jorge Marquez, Jianping Dong, Mitsuo Oshimura, Jun Hayashi, Ginette Serrero. Effect of fully human anti-PTGFRN antibody drug conjugate on head neck cancer cells and patient derived xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4695.