Therapeutic Co-targeting of WEE1 and ATM Downregulates PD-L1 Expression in Pancreatic Cancer

PURPOSE: Pancreatic cancer (PC) is one of the most lethal cancers worldwide, but there are currently no effective treatments. The DNA damage response (DDR) is under investigation for the development of novel anti-cancer drugs. Since DNA repair pathway alterations have been found frequently in PC, the purpose of this study was to test the DDR-targeting strategy in PC using WEE1 and ATM inhibitors. MATERIALS AND METHODS: We performed in vitro experiments using a total of ten human PC cell lines to evaluate antitumor effect of AZD1775 (WEE1 inhibitor) alone or combination with AZD0156 (ATM inhibitor). We established Capan-1–mouse model for in vivo experiments to confirm our findings. RESULTS: In our research, we found that WEE1 inhibitor (AZD1775) as single agent showed anti-tumor effects in PC cells, however, targeting WEE1 upregulated p-ATM level. Here, we observed that co-targeting of WEE1 and ATM acted synergistically to reduce cell proliferation and migration, and to induce DNA damage in vitro. Notably, inhibition of WEE1 or WEE1/ATM downregulated programmed cell death ligand 1 expression by blocking glycogen synthase kinase-3β serine 9 phosphorylation and decrease of CMTM6 expression. In Capan-1 mouse xenograft model, AZD1775 plus AZD0156 (ATM inhibitor) treatment reduced tumor growth and downregulated tumor expression of programmed cell death ligand 1, CMTM6, CD163, and CXCR2, all of which contribute to tumor immune evasion. CONCLUSION: Dual blockade of WEE1 and ATM might be a potential therapeutic strategy for PC. Taken toget