Dual targeting of TGF-beta and PD-L1 inhibits tumor growth in TGF-beta/PD-L1 driven colorectal cancer

Immunosuppressive factors within the tumor microenvironment (TME), for example TGF-β, constitute a crucial hindrance to im-munotherapeutic approaches in the management of colorectal cancer (CRC). Furthermore, immune checkpoints (e.g., PD-L1) inhibit T cell proliferation and activation. To cope with the inhibitory effect of immune checkpoints, the therapeutic value of dual targeting of the PD-L1 and TGF-β pathways using M7824 plus 5-FU in CRC has been evaluated. Integrative-systems biology approaches and RNAseq were used to assess the differential level of genes associated in 88 metastatic-CRC patients. The level of PD-L1 and TGF-β was evaluated in a validation cohort. The anti-proliferative, migratory, and apoptotic effects of PD-L1/TGF-β inhibitor, M7824, was assessed by MTT, wound-healing assay, and flow cytometry. Anti-tumor activity was assessed in a xenograft model, followed by biochemical studies and histological staining, and gene/protein expression analyses by RT-PCR and ELISA/IHC. The result of DEGs analysis showed that there were 1268 upregulated and 1074 downregulated genes in CRC patients. PD-L1 and TGF-β were found to be among the top-scoring genes and dysregulated pathways associated with CRC, and this was validated in 92 CRC patients. Targeting of PD-L1-TGF-β inhibited cell growth and migration, associated with modulation of CyclinD1 and MMP9. Furthermore, M7824 inhibited tumor growth via targeting TGF-β and PD-L1 pathways, resulting in modulation of inflammatory response and fibrosis via TNF-/IL6/CD4-8 and COL1A1/1A2, respectively. In conclusion, our data indicate that co-targeting the PD-L1 and TGF-β pathways increased the effect of 5-FU and reduced the tumor growth in PD-L1/TGF-β expressing tumors, providing a new therapeutic option in the treatment of CRC.