The lack of effective glioblastoma treatments remains a significant health problem and highlights the need for novel and innovative approaches. Immunotherapy is an appealing strategy because of the potential ability for immune cells to traffic to and destroy infiltrating tumor cells. For the past decade, our group and others have been testing active vaccination strategies, such as dendritic cells pulsed with tumor lysates or synthetic peptides to induce antitumor immunity in glioblastoma patients. However, our data, and that of other immunotherapeutic strategies for patients with cancer, suggest that the vast majority of tumor-specific T cells induced by this personalized, patient-specific immunotherapy do NOT recognize well-characterized, known antigens. In order to design the most effective immunotherapeutic strategies for glioblastoma, we believe that it is critical to understand which antigens tumor-specific T cells recognize in this disease. Recent information suggests that patients mounting immune responses after immunotherapy can recognize novel neoantigens created by tumor-specific mutations. Our hypothesis is that glioblastoma patients treated with autologous tumor lysate-pulsed DC vaccination will mount anti-tumor immune responses against specific mutations in their individual tumor. Furthermore, we hypothesize that patients with extended survival will have mounted more diverse anti-tumor immune responses to such neoantigens. To test this, we propose to perform exome sequencing on patient tumor specimens to identify nonsynonymous mutations in glioblastoma patients treated with DC vaccination. We will then screen and identify candidate epitopes for glioma-specific T cell recognition, and finally evaluate which neoepitope- specific T cells are preferentially expanded following autologous tumor lysate-pulsed DC vaccination. We will also design a set of parallel pre-clinical studies in our orthotopic murine glioma model. We will characterize nonsynonymous mutations in two murine glioma cell lines, and subsequently identify dominant neoantigens recognized by murine glioma-specific T cells. To expand this, we will then vaccinate mice with identified glioma-specific neoantigens and evaluate which antigens confer effective anti-tumor immunity to mice bearing intracranial gliomas. This project could potentially be transformative, as a better understanding of the relevant neoantigens in malignant glioma could dramatically alter immunotherapy for this deadly disease. The studies proposed herein could have important implications for the development of personalized cancer vaccines in glioblastoma patients.

Public Health Relevance

The prognosis of glioblastoma patients is among the worst of all cancers. The studies proposed herein are designed to test whether patients and animals specifically mount anti-tumor immune response directed to neoantigens created from somatic mutations present in their brain tumor. We also believe that autologous tumor lysate-pulsed dendritic cell vaccination may actually expand these specific types of T lymphocytes. The proposed studies outline a straightforward, novel method to identify individualized immunotherapeutic targets for glioblastoma patients. If successful, this would represent a new paradigm for personalized immunotherapy, which can integrated into the current care of patients who suffer from a lack of effective therapeutic options.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21CA186004-01A1
Application #
8814995
Study Section
Special Emphasis Panel (ZCA1-RTRB-Z (O1))
Program Officer
Welch, Anthony R
Project Start
2015-01-16
Project End
2016-12-31
Budget Start
2015-01-16
Budget End
2015-12-31
Support Year
1
Fiscal Year
2015
Total Cost
$180,105
Indirect Cost
$48,735
Name
University of California Los Angeles
Department
Neurosurgery
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
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Antonios, Joseph P; Soto, Horacio; Everson, Richard G et al. (2017) Immunosuppressive tumor-infiltrating myeloid cells mediate adaptive immune resistance via a PD-1/PD-L1 mechanism in glioblastoma. Neuro Oncol 19:796-807
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