STING1 and neoplasm: We recently found that treatment efficacy with olaparib was reduced when the histologically same tumor was treated in an immunocompromised host (Pantelidou et al., 2019) or when cytotoxic T cells were depleted and that PARPi-induced activation of the STING pathway in tumor cells ultimately led to the engagement of cytotoxic T cells (Pantelidou et al., 2019).