Malignant gliomas are lethal due to their Ioco-regionally invasive growth and the limited capacity of conventional treatment moralities to eradicate this dispersed population of tumor cells within the central nervous system (CNS). T lymphocytes can migrate extensively in the CNS and adoptive therapy with tumor-specific cytotoxic T lymphocytes (CTL's) can eradicate intracranially implanted glioma in a variety of animal model systems. To date, this approach has made limited progress towards clinical application, due in part, to the paucity of molecularly-defined glioma antigens for T-cell targeting, and, the appreciation that these tumors frequently express low levels of MHC class I, thereby limiting tumor recognition by CD8+ CTL. In order to circumvent these obstacles, we have developed a T-cell genetic modification strategy by which CTL's are engineered to express a chimeric immunoreceptor for re-directing their antigen specificity to tumor cells of high grade glioma. This was accomplished by constructing the IL13(E13Y)-zetakine for targeting IL-13Ralpha2, a consistently expressed specific cell-surface marker of malignant glia, in an MHC independent manner. Ex vivo expanded IL13(E13Y)- zetakine+ CTL's retain IL13Ralpha-specific anti-glioma cytolytic activity as well as chimeric immunoreceptor regulated Tc1 cytokine secretion and proliferation in vitro, and, mediate the in vivo regression of established human glioblastoma xenografts.
Specific Aim 1 will evaluate the feasibility and safety of infusing autologous IL13(E13Y)-zetakine+/HyTK+ CTL clones into glioma resection cavities. Anti-tumor activity of the adoptively transferred clones, as well as, CNS reactive changes resulting from T-cell infusions will be studied by routine gadoteridol enhanced T1-/T2-weighted and FLAIR magnetic resonance (MR) pulse sequences. Correlative imaging and laboratory studies are proposed in Specific Aim 2 to study T1-weighted 3D spoiled gradient-recalled echo MR pulse sequences, multi-voxel 1H-MR spectroscopy (mvMRS), and 18F-fluro-2-deoxy-D-glucose(FDG) and 18FHBG PET for their capacity to more accurately delineate tumor responses and T-cell distribution/persistence within the CNS. Serially collected resection cavity CSF samples will be analyzed using cytokine bead arrays to identify surrogate glioma-derived cytokine markers of microscopic tumor burden. The studies proposed in Specific Aim 3 will focus on delineating the survival and retention of effector function of clones retrieved from resection cavity CSF specimens, and, determine the frequency of systemic immune responses against the zetakine and HyTK transgenes in this patient population. These data will form the basis for designing Phase I/II trials using enhanced T-cell dosing schedules, imaging techniques, and surrogate marker endpoints.
