[P006] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P03-354] Novel Peptide Binders for the Early Detection of Epithelial Ovarian Cancer in E. coli

○Surya S Nair¹, Guhan Jayaraman², Narayanan M S², Mayilvahanan Bose² (1. Doctoral student (India), 2. Professor (India))

Keywords:

novel peptides,phage display,peptides,novel antibodies,diagnostic kit,epithelial ovarian cancer,early diagnosis,bacterial expression,large scale production

Epithelial ovarian cancer (EOC) remains one of the most lethal gynaecological malignancies due to the absence of reliable tools for early detection. The commonly used biomarker CA125 lacks sufficient sensitivity and specificity for early-stage diagnosis, highlighting the need for improved diagnostic strategies based on robust biomarker recognition systems. Proteomic profiling of plasma samples from EOC patients identified several differentially expressed proteins associated with disease progression. A customized quantibody array screening of 21 candidate biomarkers revealed significant up-regulation of CA125 (MUC16 SEA domain), Adipsin (CFD), and IGFBP2 in EOC patient samples compared with healthy controls. These observations were further validated by enzyme-linked immunosorbent assay (ELISA), confirming their potential utility as diagnostic targets. To develop selective recognition molecules, computationally designed single-chain variable fragments (scFvs) were engineered against the CA125 SEA domain antigen. Experimental validation confirmed functional scFv–antigen interaction, with the scFv paratope recognizing conserved structural features within the SEA5 domain. Structural analysis suggests that binding involves a hybrid conformational-linear epitope, where disulfide-stabilized loops and surface exposed motifs remain accessible even under partially denaturing conditions. This interaction supports stable antigen recognition in sandwich ELISA formats and provides a framework for further engineering to enhance binding affinity and specificity. Complementing the scFv platform, phage display technology was used to identify peptide binders targeting Adipsin (CFD) and IGFBP2. Compared with conventional antibodies, peptide binders offer several advantages, including small molecular size, improved thermal stability, minimal aggregation, and reduced background signal in immunoassays. These peptides can be produced either through chemical synthesis or recombinant expression in Escherichia coli, enabling rapid and cost-effective large-scale production using simple affinity purification strategies. Unlike scFvs, which require correct folding of immunoglobulin variable domains for functionality, peptide binders can recognize both conformational and linear epitopes across native and denatured antigen states. This property enables their application across diverse diagnostic platforms, including ELISA, Western blotting, lateral flow assays, and immunofluorescence. Future work will focus on clinical validation of this integrated scFv–peptide detection system using ovarian cancer cell line models and patient-derived plasma and tissue samples. The longterm goal is to develop a low-cost multiplex diagnostic platform for early-stage EOC detection that is suitable for large-scale screening and point-of-care applications.