In vivo Discovery of Targets for Cancer Immunotherapy
See manuscript in Nature (Feb 2014)
Recent work has shown that T cells play a central role in controlling tumor growth. Clinical trials have demonstrated that antibodies targeting two inhibitory receptors on the surface of T cells –CTLA-4 and PD-1 – can induce durable responses in a subset of cancer patients despite metastatic spread. We have recently developed a novel approach for in vivo discovery of genes that inhibit T cell function in the tumor microenvironment. In a normal immune response, T cells proliferate extensively following antigen recognition, but this physiological response is severely blunted by multiple immunosuppressive mechanisms in tumor micro-environments. We reasoned that shRNAs targeting critical negative regulators in T cells can restore their proliferative response to tumor antigen recognition.
We infect CD8 T cells with pool shRNA libraries and transfer these T cells into tumor-bearing mice. One week later, T cells are isolated to quantify the representation of shRNAs in tumors and control tissues by deep sequencing. We have discovered a large number of genes that inhibit T cell function in the tumor microenvironment. We now investigate the molecular mechanisms by which these genes constrain T cell function in tumors and use these insights to develop novel T cell-based therapeutic approaches.
See manuscript in Nature (Feb 2014)
Recent work has shown that T cells play a central role in controlling tumor growth. Clinical trials have demonstrated that antibodies targeting two inhibitory receptors on the surface of T cells –CTLA-4 and PD-1 – can induce durable responses in a subset of cancer patients despite metastatic spread. We have recently developed a novel approach for in vivo discovery of genes that inhibit T cell function in the tumor microenvironment. In a normal immune response, T cells proliferate extensively following antigen recognition, but this physiological response is severely blunted by multiple immunosuppressive mechanisms in tumor micro-environments. We reasoned that shRNAs targeting critical negative regulators in T cells can restore their proliferative response to tumor antigen recognition.
We infect CD8 T cells with pool shRNA libraries and transfer these T cells into tumor-bearing mice. One week later, T cells are isolated to quantify the representation of shRNAs in tumors and control tissues by deep sequencing. We have discovered a large number of genes that inhibit T cell function in the tumor microenvironment. We now investigate the molecular mechanisms by which these genes constrain T cell function in tumors and use these insights to develop novel T cell-based therapeutic approaches.
|
In vivo shRNA screen for discovery of negative regulators of T cell function in tumors. A. T cells are infected with pooled shRNA libraries in a lentiviral vector and injected into mice bearing B16-Ova melanomas. B. shRNAs that target key negative regulators enable substantial T cell expansion in tumors in response to tumor antigen recognition. C. Deep sequencing of the shRNA cassette from purified T cells provides a quantitative representation of all shRNAs in the pool across different tissues. shRNAs that enable T cell proliferation in tumors are substantially enriched because the lentiviral vector has integrated into the genome of the T cells.
|
Zhou, P., Shaffer, D. R., Alvarez Arias, D. A., Nakazaki, Y., Pos, W., Torres, A. J., Cremasco, V., Dougan, S. K., Cowley, G. S., Elpek, K., Brogdon, J., Lamb, J., Turley, S. J., Ploegh, H. L., Root, D. E., Love, J. C., Dranoff, G., Hacohen, N., Cantor, H., and Wucherpfennig, K. W. (2014) In vivo discovery of immunotherapy targets in the tumour microenvironment, Nature 506, 52-57.