Targeting DNA Damage Response Promotes Antitumor Immunity through STING-Mediated T-cell Activation in Small Cell Lung...

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Limited response rates to immune checkpoint blockade (ICB) in small cell lung cancer (SCLC).
• Need for novel therapeutic strategies to enhance immunotherapy efficacy in SCLC.

Purpose of the Study:

• To investigate the potential of targeting DNA damage response (DDR) proteins, PARP and CHK1, in combination with PD-L1 blockade for SCLC treatment.
• To elucidate the underlying mechanisms of DDR inhibition-mediated immune modulation in SCLC.

Main Methods:

• Utilized immunocompetent SCLC in vivo models.
• Administered PARP or CHK1 inhibitors in combination with PD-L1 blockade.
• Assessed PD-L1 expression, cytotoxic T-cell infiltration, and innate immune pathway activation (STING/TBK1/IRF3).

Main Results:

• PARP or CHK1 inhibition significantly increased PD-L1 expression and potentiated the antitumor effects of PD-L1 blockade.
• Combined inhibition augmented CD8+ T-cell infiltration, which was crucial for the observed antitumor response.
• DDR inhibition activated the STING/TBK1/IRF3 pathway, increasing chemokines that enhanced cytotoxic T-lymphocyte function.

Conclusions:

• Targeting DDR proteins (PARP/CHK1) in combination with ICB offers a promising therapeutic strategy for SCLC.
• DDR inhibitors modulate the tumor microenvironment by activating innate immune pathways, enhancing adaptive anti-tumor immunity.
• This study provides a strong rationale for clinical trials combining DDR inhibitors and immunotherapy in SCLC patients.