| First Author | Snook JP | Year | 2020 |
| Journal | Cancer Immunol Res | Volume | 8 |
| Issue | 4 | Pages | 506-517 |
| PubMed ID | 32075800 | Mgi Jnum | J:298427 |
| Mgi Id | MGI:6480104 | Doi | 10.1158/2326-6066.CIR-19-0690 |
| Citation | Snook JP, et al. (2020) Inhibition of SHP-1 Expands the Repertoire of Antitumor T Cells Available to Respond to Immune Checkpoint Blockade. Cancer Immunol Res 8(4):506-517 |
| abstractText | The presence and activity of CD8(+) T cells within the tumor microenvironment are essential for the control of tumor growth. Utilizing B16-F10 melanoma tumors that express altered peptide ligands of chicken ovalbumin, OVA257-264, we measured high- and low-affinity OVA-specific responses following adoptive transfer of OT-I CD8(+) T cell into mice subsequently challenged with tumors. T-cell receptor (TCR) affinity positively correlated with the frequency of OT-I tumor-infiltrating lymphocytes (TIL). Differences in TCR affinity inversely corresponded to in vivo tumor growth rate. Blockade of the PD-1 and CTLA-4 checkpoints preferentially increased the frequency and antitumor function of TIL responding to high-affinity antigens, while failing to enhance the antitumor activity of low-affinity T cells. To determine whether lowering the TCR activation threshold could enhance the breadth and magnitude of the antitumor T-cell response, we inhibited Src homology region 2 domain-containing phosphatase 1 (SHP-1) in OT-I T cells prior to tumor antigen exposure. SHP-1 knockdown increased the cytokine-producing potential of high- and low-affinity T cells but failed to enhance control of tumor growth. In contrast, when SHP-1 knockdown of OT-I T cells was combined with immunotherapy, we observed a significant and long-lasting suppression of tumor growth mediated by low-affinity T cells. We conclude that lowering the TCR activation threshold by targeting SHP-1 expands the repertoire of T cells available to respond to conventional checkpoint blockade, leading to enhanced control of tumor growth. |
