TIGIT checkpoint inhibitor (GigaGen)

Tiragolumab, an anti-TIGIT antibody with an active IgG1κ Fc, demonstrated improved outcomes in the phase 2 CITYSCAPE trial (ClinicalTrials.gov: NCT03563716) when combined with atezolizumab (anti-PD-L1) versus atezolizumab alone1. However, there remains little consensus on the mechanism(s) of response with this combination2. Here we find that a high baseline of intratumoural macrophages and regulatory T cells is associated with better outcomes in patients treated with atezolizumab plus tiragolumab but not with atezolizumab alone. Serum sample analysis revealed that macrophage activation is associated with a clinical benefit in patients who received the combination treatment. In mouse tumour models, tiragolumab surrogate antibodies inflamed tumour-associated macrophages, monocytes and dendritic cells through Fcγ receptors (FcγR), in turn driving anti-tumour CD8+ T cells from an exhausted effector-like state to a more memory-like state. These results reveal a mechanism of action through which TIGIT checkpoint inhibitors can remodel immunosuppressive tumour microenvironments, and suggest that FcγR engagement is an important consideration in anti-TIGIT antibody development.

Both preclinical and clinical studies have extensively proven the effectiveness of TIGIT inhibitors in tumor immunotherapy. However, it has been discovered that the presence of CD226 on tumor-infiltrating lymphocytes is crucial for the effectiveness of both anti-TIGIT therapy alone and when combined with anti-PD-1 therapy for tumors. In our investigation, we observed that cordycepin therapy significantly augmented the expression of the Cd226 gene. As a result, it was hypothesized that cordycepin therapy could enhance the effectiveness of anti-TIGIT therapy. By employing single-cell RNA sequencing analysis of immune cells in the MC38 tumor model, we discovered that cordycepin combined with anti-TIGIT therapy led to a significant increase in the proportion of NK cells within the tumor immune microenvironment. This increased NK cell activity and decreased the expression of inhibitory receptors and exhaustion marker genes. In the combination therapy group, CD8⁺ T cells had lower exhaustion state scores and increased cytotoxicity, indicating a better immune response. The combination therapy group increased DCs in the tumor immune microenvironment and promoted cellular interaction with CD4⁺ T cell and CD8⁺ T cell populations while decreasing Treg cell interactions. In conclusion, cordycepin with anti-TIGIT therapy in colon cancer could reshape the tumor immune microenvironment and have notable anticancer effects.