Abstract
Despite recent advances in the use of immunotherapy, only a minority of patients with small cell lung cancer (SCLC) respond to immune checkpoint blockade (ICB). Here, we show that targeting the DNA damage response (DDR) proteins PARP and checkpoint kinase 1 (CHK1) significantly increased protein and surface expression of PD-L1. PARP or CHK1 inhibition remarkably potentiated the antitumor effect of PD-L1 blockade and augmented cytotoxic T-cell infiltration in multiple immunocompetent SCLC in vivo models. CD8+ T-cell depletion reversed the antitumor effect, demonstrating the role of CD8+ T cells in combined DDR–PD-L1 blockade in SCLC. We further demonstrate that DDR inhibition activated the STING/TBK1/IRF3 innate immune pathway, leading to increased levels of chemokines such as CXCL10 and CCL5 that induced activation and function of cytotoxic T lymphocytes. Knockdown of cGAS and STING successfully reversed the antitumor effect of combined inhibition of DDR and PD-L1. Our results define previously unrecognized innate immune pathway–mediated immunomodulatory functions of DDR proteins and provide a rationale for combining PARP/CHK1 inhibitors and immunotherapies in SCLC.
Original language | English (US) |
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Pages (from-to) | 646-661 |
Number of pages | 16 |
Journal | Cancer discovery |
Volume | 9 |
Issue number | 5 |
DOIs | |
State | Published - May 2019 |
ASJC Scopus subject areas
- Oncology
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