Development of Lectikines for Immunotherapy Against Ovarian Cancer – PI: Nobuyuki Matoba

The goal of this project is to create a novel immunotherapeutic drug candidate against ovarian cancer (OVCA). OVCA is the leading cause of death from gynecological malignancy in the United States, with poor survival rates due to late diagnosis and chemo-resistant, fatal recurrent disease after the first-line debulking surgery and chemotherapies. Immune checkpoint inhibitors have thus far failed to show any significant clinical benefit due to highly immunosuppressive tumor microenvironment and poor infiltration of T cells. Thus, the development of effective OVCA immunotherapy requires novel strategies. To address this problem, the proposed project led by Dr. Matoba (biopharmaceutical scientist, PI), in close collaboration with Drs. Yaddanapudi (tumor immunologist, co-I) and Kakar (ovarian cancer research expert, co-I), will create novel immunotherapeutic proteins based on Avaren lectin. It is a small recombinant lectin originally engineered in the PI’s laboratory as an antiviral agent based on its ability to selectively recognize high-mannose glycans overexpressed on the surface of enveloped viruses. A fusion protein consisting of Avaren lectin and human IgG1 Fc (AvFc) was previously shown to exhibit potent anti-HIV and anti-HCV activities without toxicity in in vitro and in vivo animal models. Meanwhile, growingevidence suggests that the aberrant accumulation of high-mannose glycans also occurs in the cell surface glycome of various malignancies, including OVCA. In fact, our preliminary data show that AvFc efficiently binds to OVCA but not to adjacent normal tissues. Furthermore, AvFc elicits potent antibody-dependent cell-mediated cytotoxicity (ADCC) against OVCA cell lines. Based on these data, we hypothesize that immunostimulatory variants of Avaren lectin will exhibit potent immunotherapeutic activity by transforming OVCA to more immunoactive tumors. Specifically, we will engineer translational fusion proteins consisting of Avaren lectin and an antitumor cytokine (“lectikines”). In Aim 1, we will generate lectikines by fusing IL-2 to AvFc and TNF to Avaren monomer, which will be produced in Nicotiana benthamiana plants using a transient overexpression system. After thorough purification, we will assess their molecular properties, high-mannose-binding affinity and cytokine functions in a battery of biochemical, biophysical and cell-based assays. In Aim 2, we will evaluate the therapeutic effects of lectikines in a syngeneic, orthotopic murine OVCA model using the ID8 cell line inoculated into the peritoneal cavity of immunocompetent C57bl/6 mice. Disease progression will be monitored through abdomen circumference, body weight and live animal bioluminescence imaging. Immunophenotyping of peritoneal cells will be performed by flow cytometry. We anticipate that lectikines will elicit significant efficacy through increased immune activation in the tumor microenvironment. Successful completion of this pilot project will establish an initial POC for a first-in-class OVCA immunotherapy and generate compelling preliminary data in a future R01 application for further investigation and optimization of MOA of top candidate lectikines.