Abstract 2289: Evaluation of novel genetically engineered anti-MUC16 antibody for therapeutic targeting in pancreatic cancer

Introduction: MUC16, the largest membrane glycoprotein, is not only important for protection under normal physiological conditions, but also contributes to disease progression and metastasis in various malignancies. TCGA analysis along with clinicopathologic data validate the association of aberrant MUC16 overexpression with poor prognosis in pancreatic cancer. Research from different groups and our lab has demonstrated the contribution of surface tethered MUC16 in tumorigenesis and metastasis. Further, in a recent study MUC16 was identified as a neoantigen associated with long-term pancreatic cancer survivors, which further supports its utility as a therapeutic target. With this in mind, we have recently generated a panel of monoclonal antibodies against tumorigenic carboxy terminal (CT) portion of MUC16. Method: We characterized anti-MUC16 mAbs in different pancreatic cancer cell lines and selected mAb5E6 for further engineering as therapeutic entity. We constructed novel chimeric mAb by grafting mouse heavy and light chain variable fragment (Fv) region on constant portion of human heavy (FcH ) and light (FcL) chain under IL-2 secretion system followed by their co transfection in CHO-K1 cells. These chimeric antibodies were characterized for their binding in different assays and evaluated for functional activity. Results and summary: Anti-MUC16 mAb 5E6 recognized different molecular weight forms of MUC16 in several pancreatic cancer cell lines and successfully inhibited the invasion (45%) and migration (62%) of MUC16 CT transfected MiaPaca cells in in vitro assays. Therefore, we engineered this antibody for therapeutic targeting. Chimeric antibody purified from culture supernatant recognized both recombinant and endogenous MUC16 in different binding assays. Interestingly, chimeric mAb 5E6 displayed better affinity (50nM) than its parent murine version (478nM) and recognized different forms of endogenous MUC16. Chimeric mAb5E6 decreased the colony formation ability (50%) and migration (~40%) of MUC16 expressing pancreatic cancer cell lines. Besides, chimeric mAb 5E6 treated pancreatic cancer cells showed reduction in FAK and Akt signaling associated with tumorigenesis and migration. Of importance, the chimeric antibody was internalized by MUC16 expressing pancreatic cancer cells and localized in the lysosomes in both time and temperature dependent manner which suggest their implication for payload delivery. Conclusions: Genetically engineered anti-MUC16 a