ATR-mediated CD47 and PD-L1 up-regulation restricts radiotherapy-induced immune priming and abscopal responses in colorectal cancer

Rodney Cheng En Hsieh, Sunil Krishnan, Ren Chin Wu, Akash R. Boda, Arthur Liu, Michelle Winkler, Wen Hao Hsu, Steven Hsesheng Lin, Mien Chie Hung, Li Chuan Chan, Krithikaa Rajkumar Bhanu, Anupallavi Srinivasamani, Ricardo Alexandre De Azevedo, Yung Chih Chou, Ronald A. DePinho, Matthew Gubin, Eduardo Vilar, Chao Hsien Chen, Ravaen Slay, Priyamvada JayaprakashShweta Mahendra Hegde, Genevieve Hartley, Spencer T. Lea, Rishika Prasad, Brittany Morrow, Coline Agnes Couillault, Madeline Steiner, Chun Chieh Wang, Bhanu Prasad Venkatesulu, Cullen Taniguchi, Yon Son Betty Kim, Junjie Chen, Nils Petter Rudqvist, Michael A. Curran

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Radiotherapy (RT) of colorectal cancer (CRC) can prime adaptive immunity against tumor-associated antigen (TAA)-expressing CRC cells systemically. However, abscopal tumor remissions are extremely rare, and the postirradiation immune escape mechanisms in CRC remain elusive. Here, we found that irradiated CRC cells used ATR-mediated DNA repair signaling pathway to up-regulate both CD47 and PD-L1, which through engagement of SIRPα and PD-1, respectively, prevented phagocytosis by antigen-presenting cells and thereby limited TAA cross-presentation and innate immune activation. This postirradiation CD47 and PD-L1 up-regulation was observed across various human solid tumor cells. Concordantly, rectal cancer patients with poor responses to neoadjuvant RT exhibited significantly elevated postirradiation CD47 levels. The combination of RT, anti-SIRPα, and anti-PD-1 reversed adaptive immune resistance and drove efficient TAA cross-presentation, resulting in robust TAA-specific CD8 T cell priming, functional activation of T effectors, and increased T cell clonality and clonal diversity. We observed significantly higher complete response rates to RT/anti-SIRPα/anti-PD-1 in both irradiated and abscopal tumors and prolonged survival in three distinct murine CRC models, including a cecal orthotopic model. The efficacy of triple combination therapy was STING dependent as knockout animals lost most benefit of adding anti-SIRPα and anti-PD-1 to RT. Despite activation across the myeloid stroma, the enhanced dendritic cell function accounts for most improvements in CD8 T cell priming. These data suggest ATR-mediated CD47 and PD-L1 up-regulation as a key mechanism restraining radiation-induced immune priming. RT combined with SIRPα and PD-1 blockade promotes robust antitumor immune priming, leading to systemic tumor regressions.

Original languageEnglish (US)
Article numbereabl9330
JournalScience Immunology
Issue number72
StatePublished - May 2022

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology


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