Fgl2 neutralizing therapy for inducing tumor specific brain resident immune memory against CNS tumor relapse

Our goal in this application is to test the hypothesis that neutralizing the newly identified immune-suppressive regulator fibrinogen-like protein 2 (Fgl2) in glioblastoma (GBM) following standard care chemotherapy will trigger tumor-specific resident memory T cells in the brain (bTrm cells), which allows immunological clearance of gliomas within the central nervous system and prevention of GBM recurrence. This hypothesis was raised based on our recently published papers and newly established preliminary data. In brief, we have discovered that Fgl2 is highly expressed in GBM tissues (Yan et al, JNCI, 2015) and can transform low-grade brain tumors to GBM (Latha et al, JNCI, 2018). Knockout of Fgl2 in tumor cells completely eliminates tumor progression in the brains of immune-competent mice but not in immune-deficient mice (Yan et al, Nat Commun, 2019). Our unpublished preliminary data have shown that neutralizing Fgl2 via administering T cells armed with a membrane-anchored anti-Fgl2 scFv induces bTrm cells that reject intracranial tumor cell challenge directly or after intracranial transplantation into naïve mice (see preliminary data section); the same mice are unable to reject tumors from peripheral tissue challenge. To test our central hypothesis, the following aims are proposed: Aim 1: Determine how T-aFgl2– neutralizing T-cell therapy induces bTrm cells in brains; Aim 2: Optimize the T-aFgl2–neutralizing cell therapy and develop a next-generation T-aFgl2 cell therapy for boosting safety and therapeutic efficacy. Impact: This study will yield a therapeutic candidate—an Fgl2-neutralizing cell therapy that may permanently prevent tumor recurrence—the key deadly cause of GBM patient death. Considering that Fgl2 can be detected in almost all GBMs, with most having very high levels, this candidate therapeutic will be important. This study will also further mechanistically elucidate how Fgl2-neutralizing cell therapy induces bTrm cells and how we can make additional improvements to move this therapy into the next phase. Ultimately, this novel field will transform the treatment of GBM.