550 PD-1-mediated inhibition is critical to the development and maintenance of high affinity stem-like CD8+ T cells in the tumor draining lymph node

• DOI: 10.1136/jitc-2024-sitc2024.0550
• Publication Date: 2024-11-05T14:58:58Z
• Authors: Jyh Liang Hor; Edward Schrom; Abigail Wong-Rolle; Luke Vistain; Wanjing Shang; Qiang Dong; Chen Zhao; Chengcheng Jin; Ronald Germain

<h3>Background</h3> Stem-like CD8+ T cells constitute a subset of activated cytotoxic with high proliferative potential critical for successful checkpoint immunotherapy.¹ Emerging evidence suggests that tumor-draining lymph nodes (tdLN) can serve as reservoirs support the generation TCF-1+ stem-like continuously replenish tumor sites to sustain ongoing anti-tumor activity and responsiveness therapy.^{2 3} However, how retain their stemness in highly antigenic inflammatory tdLN microenvironment, especially those highest affinity presented antigen, has not been determined. <h3>Methods</h3> OVA-expressing mouse Kras/p53 adenocarcinoma were intradermally implanted into mice. Optically cleared harvested late immune response (Days 4–8+ post-tumor initiation) analyzed an advanced multiplexed 3D tissue microscopy technique enables single-cell level quantification cell functional states <i>in situ</i>. Antigen-specific polyclonal also tracked using tetramer staining via flow cytometry from animals treated anti-PD-L1/2 or anti-PD-1 therapies. <h3>Results</h3> identified PD-1+ SLAMF6-hi is uniquely retained tdLN, forms distinct niches cross-presenting XCR1+ dendritic (cDC1) engages prolonged antigen stimulation beyond initial priming phase. <i>In vivo</i> ablation cDC1 during stage significantly reduced expansion, suggesting presentation sustains mode lymphocyte proliferation retains stemness. These clones comprise antigen-specific population, measured binding normalized TCR expression, indicating likely promote expansion evolution over time. Co-localization PD-1 molecules ligands at T-DC interface inhibitory pathway restrains effector differentiation through attenuating TCR-dependent signaling on competition by cDC1. blockade led loss thus highlighting central role maintenance population. <h3>Conclusions</h3> Our findings reveal unexpected relationship between ligand recognition, negative feedback regulatory loops, across space Importantly, these raise clinical question whether use therapy provides short-term effects expense long-term precursors, which subsequently diminishes treatment efficacy. <h3>Acknowledgements</h3> This work was supported Division Intramural Research NIAID, NIH Program Center Cancer NCI, NIH. We would like thank Tsuneyasu Kaisho (RIKEN Allergy Immunology) providing transgenic strains this study. <h3>References</h3> Zehn D, Thimme R, Lugli E, de Almeida GP, Oxenius A. 'Stem-like' precursors are fount persistent responses. <i>Nat Immunol</i> 2022 Jun;<b>23</b>(6):836–847. Connolly KA, Kuchroo M, Venkat A, Khatun Wang J, William I, Hornick NI, Fitzgerald BL, Damo Kasmani MY, Cui C, Fagerberg Monroy Hutchins Cheung JF, Foster GG, Mariuzza DL, Nader Zhao H, W, Krishnaswamy S, Joshi NS. A reservoir node preserves antitumor response. <i>Sci 2021 Oct;<b>6</b>(64):eabg7836. Schenkel JM, Herbst RH, Canner Li Hillman Shanahan SL, Gibbons G, Smith OC, Kim JY, Westcott P, Hwang WL, Freed-Pastor WA, Eng Cuoco MS, Rogers Park JK, Burger ML, Rozenblatt-Rosen O, Cong L, Pauken KE, Regev Jacks T. Conventional type I maintain tumor-antigen specific nodes. <i>Immunity</i> Oct 12;<b>54</b>(10):2338–2353.e6.