In vivo discovery of immunotherapy targets in the tumour microenvironment

• Published in: Nature (London) Vol. 506; no. 7486; pp. 52 - 57
• Main Authors: Zhou, Penghui, Shaffer, Donald R., Alvarez Arias, Diana A., Nakazaki, Yukoh, Pos, Wouter, Torres, Alexis J., Cremasco, Viviana, Dougan, Stephanie K., Cowley, Glenn S., Elpek, Kutlu, Brogdon, Jennifer, Lamb, John, Turley, Shannon J., Ploegh, Hidde L., Root, David E., Love, J. Christopher, Dranoff, Glenn, Hacohen, Nir, Cantor, Harvey, Wucherpfennig, Kai W.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06.02.2014; Nature Publishing Group
• Subjects: 38/22; 38/23; 38/39; 38/61; 38/89; 631/250/251/1574; Animals; Antigens, Neoplasm - immunology; Apoptosis - immunology; CD4-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - cytology; CD8-Positive T-Lymphocytes - immunology; CD8-Positive T-Lymphocytes - secretion; Cell growth; Cell Proliferation; Cytokines - immunology; Cytokines - secretion; Cytotoxicity; Female; Gene Knockdown Techniques; Gene targeting; Genes; Genetic research; High-Throughput Nucleotide Sequencing; Humanities and Social Sciences; Immune response; Immune system; Immunotherapy; Immunotherapy - methods; Infections; Kinases; Lymphocytes; Lymphocytes, Tumor-Infiltrating - cytology; Lymphocytes, Tumor-Infiltrating - immunology; Lymphocytes, Tumor-Infiltrating - metabolism; Lymphocytes, Tumor-Infiltrating - secretion; Medical prognosis; Melanoma; Melanoma, Experimental - immunology; Mice; Mice, Inbred C57BL; Microenvironments; Molecular Targeted Therapy; multidisciplinary; Physiological aspects; Protein Phosphatase 2 - deficiency; Protein Phosphatase 2 - genetics; Protein Phosphatase 2 - metabolism; Reproducibility of Results; RNA, Small Interfering - genetics; Rodents; Science; Spleen; T cell receptors; T cells; Tumor Microenvironment - immunology; Tumors
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature12988

Recent clinical trials showed that targeting of inhibitory receptors on T cells induces durable responses in a subset of cancer patients, despite advanced disease. However, the regulatory switches controlling T-cell function in immunosuppressive tumours are not well understood. Here we show that such inhibitory mechanisms can be systematically discovered in the tumour microenvironment. We devised an in vivo pooled short hairpin RNA (shRNA) screen in which shRNAs targeting negative regulators became highly enriched in murine tumours by releasing a block on T-cell proliferation upon tumour antigen recognition. Such shRNAs were identified by deep sequencing of the shRNA cassette from T cells infiltrating tumour or control tissues. One of the target genes was Ppp2r2d , a regulatory subunit of the PP2A phosphatase family. In tumours, Ppp2r2d knockdown inhibited T-cell apoptosis and enhanced T-cell proliferation as well as cytokine production. Key regulators of immune function can therefore be discovered in relevant tissue microenvironments. A short hairpin RNA screen to identify genes that modify the action of tumour-infiltrating CD8 T cells in tumour-bearing mice pinpointed the phosphatase subunit Ppp2r2d as a new target for tumour therapy; knockdown of Ppp2r2d in T cells enabled their accumulation in tumours and significantly delayed tumour growth. New targets for cancer immunotherapy Immunotherapy is an important area of cancer research, and recent work has shown that targeting inhibitory receptors on T cells can result in clinical benefit in patients with advanced cancers. A major problem in the field is the difficulty of finding potential targets. Here Kai Wucherpfennig and colleagues show that in vivo discovery of therapeutic targets is a practical proposition by using short hairpin RNA (shRNA) screening to identify genes that modify the action of tumour-infiltrating CD8 T cells in tumour-bearing mice. They identify the regulatory phosphatase Ppp2r2d as a target and show that knockdown of Ppp2r2d in T cells enabled their accumulation in tumours and significantly delayed tumour growth.