Abstract 5600: Glycopeptides promote anti-cancer immune response against solid tumors

Only a fraction of patients benefits from immune checkpoint inhibitors (ICI). Tumor cells exhibit a distinct glycosylation pattern and supplementation of glycans has the potential to promote response and overcome resistance to ICI, thus addressing an urgent clinical need. Using a subcutaneous tumor mouse model, we investigated whether two glycopeptide-based test items reduce tumor burden when orally administered alone or in combination with ICI. C57/BL6 mice were supplemented with 3% GNU-201 (n=10) or 3% GNU-101 (n=10) in the drinking water starting 14 days prior to tumor cell injection (d-14), while control mice (n=10) received normal drinking water. On day 0, all mice were injected subcutaneously with YUMM1.7 melanoma cells in each flank. On days 6, 9 and 12, mice in each group received anti-PD1 antibody or an isotype control. Tumor size was measured every 3rd day. On day 15, the mice were sacrificed to analyze tumor weight and tumor infiltrating immune cells. 16S rDNA sequencing of fecal samples was performed on days -14, 0 and 14. GNU-201 and GNU-101 supplementation was well tolerated, no difference in water consumption and no abnormal behavior were detected that would indicate adverse effects of the products. While anti-PD1 on its own had no effect on tumor growth, we observed reduced tumor growth in the GNU-201+anti-PD1, GNU-101 and GNU-101+anti-PD1-treated groups, resulting in a significantly reduced tumor volume in these three groups on day 15. Administration of the two test items had a clear effect on anti-tumor T cell responses. In combination with anti-PD1, GNU-201 promoted the overall abundance of T cells, and among those the proportion of CD8+ T cells and IFNγ producing CD4+ T cells. Even in absence of anti-PD1, GNU-201 promoted the number of IFNγ+ CD8+ T cells, indicating that GNU-201 did not only promote tumor infiltration but also activation of CD8+ T cells, which are known to directly kill tumor cells. Finally, GNU-201+anti-PD1 resulted in significantly increased levels of Perforin and TNFα producing CD8+ T cells. With GNU-101 there was a trend towards elevated numbers of T cells and TNFα+ CD4 T cells. In mice that received GNU-101 with anti-PD1, we observed significantly elevated levels of TNFα+ CD8+ T cells and a trend towards higher numbers of IFNγ+ CD8+ T cells. GNU-201 and GNU-101 induced a significant modulation of the gut microbiota. In particular, the products promoted the growth of Akkermansia spp., a genus previously associated with anti-tumor immunity. In conclusion, GNU-201 and GNU-101 are both able to boost an anti-tumor immune response upon PD1 inhibition and GNU-101 shows moderate anti-tumor effects on its own. The response is linked with tumor-infiltration and activation of T cells and seems to be associated with changes in the gut microbiome. This study highlights a potential therapeutic role for glycopeptides in boosting anti-tumor immunity in response to ICI therapy. Citation Format: Marianne R. Spalinger, Romain Wyss, Sara Vidal, Yong Miao, Michael Scharl, Yemi Adesokan. Glycopeptides promote anti-cancer immune response against solid tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5600.