The broad, long-term objectives of our research are: i) to develop and optimize cellular immunotherapy approaches for the treatment of brain tumors;and ii) to gain a better understanding of the mechanisms of immune responses generated by cell-based strategies targeting central nervous system (CNS) neoplasms. Toward these goals, we have actively explored permutations of local adoptive immunotherapy for human malignant gliomas with autologous and allogeneic effector cells. We have achieved both pre-clinical and clinical success with adoptive transfer of intracavitary alloreactive cytotoxic T lymphocytes (aCTL), which are sensitized to the tumor host's human leukocyte antigens (HLA). HLA antigens expressed on the patient's lymphocytes are also on brain tumor cells but not on normal brain cells such as neurons and glia. Thus, the tumor-bearing host's own HLA offers a means for targeted selective glioma cell kill by CTL sensitized to them.
Aim 1 of this study is to assess the safety and feasibility of intratumoral delivery of aCTL/IL-2 in recurrent glioma patients. A Phase I clinical study will involve treatment with alloreactive CTL over ten months. The immune treatment will be administered only after the patients have failed standard radiation and chemotherapy for malignant glioma. Data relative to the clinical toxicity as observed in Aim 1 will be correlated with laboratory studies conducted in parallel.
Aim 2 of the laboratory studies will determine molecular/cellular and functional characteristics of the donor aCTL infusates that may influence the clinical toxicity/response. To this end we will determine the cytotoxicity of the aCTL to relevant target, perform phenotypic analyses and determine the fold-increase in the cytotoxic T cell phenotype producing IFN-? upon exposure to relevant target cells.
Aim 3 of the laboratory studies will determine the reaction of the patient's endogenous immune cells to the treatment by assessing the ability of patient peripheral blood mononuclear cells pre- and post-treatment to secret Th1 and Th2 cytokines when stimulated with relevant targets. We will also assess local CNS host anti-tumor immune responses by analyzing cells and cytokines within the resection cavities at specific times after the aCTL have been infused. Thus, this is a truly bi-directional clinical project that is directly related to our long-term objectives stated above.
The primary objective of our research is to train immune cells from healthy donors that are manipulated outside the body with various growth factors to recognize proteins on the surfaces of brain tumor cells that are not on normal brain cells. The immune cells are termed alloreactive cytotoxic T lymphocytes (aCTL) because they are sensitized to the tumor host's human leukocyte antigens (HLA). The immune treatment will be administered only after the patients have failed standard radiation and chemotherapy. The trained immune cells will be adoptively transferred into the surgically-resected tumor beds of patients diagnosed with malignant brain tumors. Data relative to the clinical toxicity and patient response to the treatment will be correlated with laboratory studies designed to determine if the antitumor effects are due alone to the immune cells given, or whether they also activate the patient's own immune system. This immunotherapy approach will help us gain a better understanding of the mechanisms of immune responses generated by cell-based strategies targeting tumors located in the central nervous system (CNS).
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