Anti-tumor activity and trafficking of self, tumor-specific T cells against tumors located in the brain

Abstract

It is commonly believed that T cells have difficulty reaching tumors located in the brain due to the presumed "immune privilege" of the central nervous system (CNS). Therefore, we studied the biodistribution and antitumor activity of adoptively transferred T cells specific for an endogenous tumor-associated antigen (TAA), gp100, expressed by tumors implanted in the brain. Mice with preestablished intracranial (i.c.) tumors underwent total body irradiation (TBI) to induce transient lymphopenia, followed by the adoptive transfer of gp100 25-33 -specific CD8 + T cells (Pmel-1). Pmel-1 cells were transduced to express the bioluminescent imaging (BLI) gene luciferase. After adoptive transfer, recipient mice were vaccinated with hgp100 25-33 peptidepulsed dendritic cells (hgp100 25-33 /DC) and systemic interleukin 2 (IL-2). This treatment regimen resulted in significant reduction in tumor size and extended survival. Imaging of T cell trafficking demonstrated early accumulation of transduced T cells in lymph nodes draining the hgp100 25-33 /DC vaccination sites, the spleen and the cervical lymph nodes draining the CNS tumor. Subsequently, transduced T cells accumulated in the bone marrow and brain tumor. BLI could also detect significant differences in NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript the expansion of gp100-specific CD8 + T cells in the treatment group compared with mice that did not receive either DC vaccination or IL-2. These differences in BLI correlated with the differences seen both in survival and tumor infiltrating lymphocytes (TIL). These studies demonstrate that peripheral tolerance to endogenous TAA can be overcome to treat tumors in the brain and suggest a novel trafficking paradigm for the homing of tumor-specific T cells that target CNS tumors.

Kinetic phases of distribution and tumor targeting by T cell receptor engineered lymphocytes inducing robust antitumor responses

“…The 2A self-cleaving sequences were inserted between the transgenes by overlap PCR (12, 13). The whole construct was then inserted into a self-inactivating third generation lentiviral vector (21) or a retroviral vector derived from a murine stem cell virus (pMSCV) backbone (22) containing a 5′ long terminal repeat-driven truncated version of the sr39tk (15) fused with enhanced green fluorescent protein (eGFP), or a firefly luciferase gene (14). (R&D Systems) and ELISPOT assays as described (26).…”

“…BLI was performed with a Xenogen IVIS 200 Imaging System (Xenogen/Caliper Life Sciences) as previously described (14).…”

“…The 2A sequences allow the stoichiometric expression of several transgenes under a single promoter in a reasonably sized gene transfer vector (12,13), which are key features for the success of this approach. The reporter genes were luciferase for bioluminescence imaging (BLI) and an optimized herpes simplex virus 1 thymidine kinase (HSV1-tk) termed sr39tk for microPET imaging (14,15). Transduction of cells with viral supernatants efficiently induced the expression of both alpha and beta TCR chains with more than 90% cleavage efficiency mediated by the 2A sequences as assessed by immunoblotting (Fig.…”

Immune Infiltration of Spontaneous Mouse Astrocytomas Is Dominated by Immunosuppressive Cells from Early Stages of Tumor Development

“…However, afferent immunity and cell-transported antigen egress from the brain might still be impaired (11). Nevertheless, in inflammatory or tumoral situations, T cells are eventually activated, induced to proliferate, and imprinted with the necessary adhesion molecules that facilitate their migration to the brain (12)(13)(14)(15)(16).…”

Glioma Grade Is Associated with the Accumulation and Activity of Cells Bearing M2 Monocyte Markers

“…While CNS tissues are normally immunologically privileged, the diminished barrier function of the tumor vasculature in glioblastoma multiformes may be expected to facilitate immune cell entry into the tumor parenchyma, and a number of studies have documented the presence of immune cells, both lymphocytes and macrophages, in tumor tissues (11,12). However, many of these cells do not appear to have antitumor activity (13,14) and, on the basis of the factors they produce, may be more likely to contribute to tumor progression.…”