Creating an improved oncolytic virus through directed evolution and virus-driven expression of a cancer-targeting peptid - Project Summary/Abstract. The current treatment regimen for glioblastoma, surgical resection followed by radiation and chemotherapy, increases median survival from 12.1 to only 14.6 months. Generating effective therapies against glioblastoma is difficult because treatments must: 1) gain access to the brain and target tumor cells without damaging healthy cells, 2) target spread out cells since glioblastoma is not contained within a defined mass like other cancers, and 3) trigger the host’s immune response to overcome immune suppression mediated by glioblastoma cells, including highly invasive and resistant glioblastoma stem cells (GSCs). Neurotropic oncolytic viruses (NOVs) are a promising treatment option since they cross the BBB and preferentially target rapidly dividing cancer cells throughout the brain while stimulating host immune responses to target the tumor. OVs can also be engineered to produce foreign proteins to augment the vector’s killing capacity. Thus, NOVs overcome many of the limitations of other glioblastoma treatment options. Semliki Forest virus (SFV) is a potent and safe NOV, but there are limitations in its effectiveness since some glioblastoma cells are refractory to SFV infection, resulting in incomplete tumor removal. Our long-term objective is to create virus-based therapies that reduce human disease burden. This proposal aims to enhance SFV’s therapeutic efficacy against glioblastoma using directed evolution and virus-mediated delivery of a potent anti-GSC peptide. Our preliminary data show that we can effectively adapt a virus to a new environment using directed evolution, and we have also created highly safe vaccine candidates that express cytokines. Finally, we have developed a highly effective GSC-targeting peptide, generated SFV expressing the peptide, and showed it has more potent killing activity against glioblastoma cells while being safe in healthy cells. We hypothesize that more potent, yet still safe, oncolytic SFV vectors can be generated using directed evolution and virus-driven expression of cancer-targeting peptides. We will test our hypothesis using rigorous molecular virology, ex vivo, and in vivo methods and a multidisciplinary team of experts in virology, immunology, and oncology. In Aim 1, we will use directed evolution in 3D glioblastoma organoids to select for a glioblastoma-adapted virus. The outcome of this aim will be a glioblastoma-adapted virus, which we expect will improve disease outcomes and have minimal adverse effects. In Aim 2, we will test SFV- expressing a potent GSC-targeting peptide in relevant in vivo and ex vivo models. The outcome of this aim will be a virus targeting GSCs and differentiated glioblastoma cells. Impact: These studies will develop two novel strategies to create more potent OVs. Completing these high-risk, high-reward studies will lay the groundwork for studies aimed at clinical testing of NOVs to treat all types of cancer in humans and will launch an exciting research direction in the lab of a productive young investigator with a drive to improve cancer treatment outcomes.
