25Transcriptome profiling identifies TIGIT and PD-1 co-expression in the immunosuppressive environment in cholangiocarcinoma
Lara Heij, Sikander Hayat, Konrad Reichel, Sidrah Maryam, Juan Garcia Vallejo, Danny Jonigk, Mark Kuehnel, Lueong Smiths, J Hammons, Gregory Lesinski, Ulf NeumannAbstract
Background
Checkpoint blockade in cholangiocarcinoma (CCA) is promising; however, little is known about the poor response. We investigated the single-cell and spatial immune environment in combination with checkpoint expression in CCA.
Methods
Checkpoint molecules (PD-1, PD-L 1, PD-l2, LAG-3, ICOS, TIGIT, TIM-3, and CTLA-4), macrophages (CD68), and T cells (CD4 and CDS) were assessed by multiplex immunofluorescence (mlF) (n = 50). We investigated the transcriptomic profile using the NanoString Cancer Progression Panel on selected TIGIT high and low samples (n = 12). Validation was performed by mlF (n = 24). Furthermore, we identified an immune profile with co-expression ofTIGIT and PD-1 in our Cytometry-Time-Of-Flight (CyTOF) cohort in 50% (n = 16). By snRNA sequencing (n = 6), we investigated cell-cell interactions and crosstalk mechanisms. The mouse model demonstrated representative immune cell populations, although dual blockade therapy (anti-TIGIT and PD-1) did not reach significance.
Results
The expression of checkpoint molecules TIGIT, CTLA-4, and LAG-3 alone and in combination with other checkpoint molecules was more abundant in the tumor than in normal tissue (CD4 and CDS TIGIT p < 0.0001, CD4 and CDS CTLA-4, p < 0.0001 and p < 0.001, respectively, and CDS LAG-3 p < 0.05). MMP2 and MMP14 genes were differentially expressed in patients with high TIGIT expression. PD-1 and TIGIT dual expression on CD4 and CDS cells are common in CCA.
Conclusion
The immune environment in CCA is characterized by the expression of multiple checkpoints, demonstrating the complexity of ICI treatment. High TIGIT expression drives an immunosuppressive environment by modulating the extracellular matrix. These findings suggest that CCA is unlikely to respond optimally to PD-1 monotherapy and support TIGIT as a promising target for combination immunotherapeutic strategies. Our cohort identified 50% of patients with high levels of dual checkpoint expression, stratifying a subgroup likely to respond to dual blockade therapy.