DNA damage response (DDR) deficiency has emerged as a prominent determinant of tumor immunogenicity. This study aimed to construct a DDR-related immune activation (DRIA) signature and evaluate the predictive accuracy of the DRIA signature for response to immune checkpoint inhibitor (ICI) therapy in gastrointestinal (GI) cancer.

A DRIA signature was established based on two previously reported DNA damage immune response assays. Clinical and gene expression data from two published GI cancer cohorts were used to assess and validate the association between the DRIA score and response to ICI therapy. The predictive accuracy of the DRIA score was validated based on one ICI-treated melanoma and three pan-cancer published cohorts.

The DRIA signature includes three genes (CXCL10, IDO1, and IFI44L). In the discovery cancer cohort, DRIA-high patients with gastric cancer achieved a higher response rate to ICI therapy than DRIA-low patients (81.8% vs. 8.8%; P < 0.001), and the predictive accuracy of the DRIA score [area under the receiver operating characteristic curve (AUC) = 0.845] was superior to the predictive accuracy of PD-L1 expression, tumor mutational burden, microsatellite instability, and Epstein–Barr virus status. The validation cohort demonstrated that the DRIA score identified responders with microsatellite-stable colorectal and pancreatic adenocarcinoma who received dual PD-1 and CTLA-4 blockade with radiation therapy. Furthermore, the predictive performance of the DRIA score was shown to be robust through an extended validation in melanoma, urothelial cancer, and pan-cancer.

The DRIA signature has superior and robust predictive accuracy for the efficacy of ICI therapy in GI cancer and pan-cancer, indicating that the DRIA signature may serve as a powerful biomarker for guiding ICI therapy decisions.

The systemic inflammation index and body mass index (BMI) are easily accessible markers that can predict mortality. However, the prognostic value of the combined use of these two markers remains unclear. The goal of this study was therefore to evaluate the association of these markers with outcomes based on a large cohort of patients with gastric cancer.

A total of 2,542 consecutive patients undergoing radical surgery for gastric or gastroesophageal junction adenocarcinoma between 2009 and 2014 were included. Systemic inflammation was quantified by the preoperative neutrophil-to-lymphocyte ratio (NLR). High systemic inflammation was defined as NLR ≥ 3, and underweight was defined as BMI < 18.5 kg/m².

Among 2,542 patients, NLR ≥ 3 and underweight were common [627 (25%) and 349 (14%), respectively]. In the entire cohort, NLR ≥ 3 or underweight independently predicted overall survival (OS) [hazard ratio (HR): 1.236, 95% confidence interval (95% CI): 1.069–1.430; and HR: 1.600, 95% CI: 1.350–1.897, respectively] and recurrence-free survival (RFS) (HR: 1.230, 95% CI: 1.054–1.434; and HR: 1.658, 95% CI: 1.389–1.979, respectively). Patients with both NLR ≥ 3 and underweight (vs. neither) had much worse OS (HR: 2.445, 95% CI: 1.853–3.225) and RFS (HR: 2.405, 95% CI: 1.802–3.209). Furthermore, we observed similar results in subgroup analyses according to pathological stage, age, and postoperative chemotherapy.

Our results showed that preoperative elevated NLR and decreased BMI had a significant negative effect on survival. Underweight combined with severe inflammation could enhance prognostication. Taking active therapeutic measures to reduce inflammation and increase nutrition may help improve outcomes.