Regulating A Tumor-Specific Cell Surface Glycopeptide Epitope For Precision Immuno-Oncology

Unlike ‘liquid’ leukemias and lymphomas, most solid tumors are extremely difficult to target immunologically with antibody-based therapeutics. In an effort to overcome this limitation, we identified a novel peptidoglycan on the surface of aggressive solid tumor cells that are present in multiple cancer types. These include breast, ovarian, bladder, colorectal and oral squamous carcinomas as well as glioblastomas. Molecularly, this peptidoglycan is found on the extracellular domain of the cell surface mucin ‘podocalyxin’. Biologically, the emergence of the podocalyxin peptidoglycan is exquisitely tumor-specific and we have demonstrated that it can be successfully targeted immunologically in pre-clinical solid tumor assays in a manner that spares normal cells and tissues. This has been achieved using an antibody drug conjugate against the podocalyxin peptidoglycan that we have developed.

In this project, we will first use genome-wide editing screens to identify regulators of the tumor-specific podocalyxin peptidoglycan using CRISPR Cas9 technology. In preliminary proof-of-principle experiments we have identified twelve potential regulators from four different functionally-clustered intracellular signaling complexes. We will next manipulate such regulators, both genetically and pharmacologically with small molecule inhibitors, to precisely tailor the immuno-oncologic targeting of aggressive podocalyxin peptidoglycan-positive solid tumors. Finally, we will take a glyco-proteomic approach to identify additional tumor-specific peptidoglycans that can also be targeted immunologically. The overarching goal of this project is to develop a pipeline of novel antibody-based immuno-therapeutics that can be used to treat multiple aggressive solid cancers with precision and minimal side effects given that they will, by design, spare normal cells and tissues.