IL-1 and IL-6 as predictors of ypN and early response to neoadjuvant chemotherapy in patients with locally advanced GC and GEJ cancer.

454 Background: Perioperative chemotherapy remains a standard of care in locally advanced gastric cancer. About 10-15% patients do not respond to such therapy and there are currently no biomarkers which could be used to predict early response to the neoadjuvant treatment. Methods: This prospective biomarker study aimed at identification of serum biomarkers of early response to neoadjuvant chemotherapy. Here we report only the results for serum cytokine assessments. It was an academic, nonrandomized, prospective study, conducted in MSCNRIO. Between January 2018 and November 2019 we analysed 42 patients aged 30-77 (median 63 years, 52.5% male and 47.5% female) with histologically confirmed GC or GEJ cancer qualified by MDT for perioperative FLOT. Exclusion criteria were: inflammatory and autoimmune diseases, other cancers, chronic steroid and immunosuppressive therapy. Blood sample was collected a.c. prior to the administration of cycle one (C1), two (C2) and three (C3) FLOT regimen. Serum levels of IL-1β and IL-6 were measured twice using ELISA. Results: All patients with pre-treatment IL-1β levels above 0.5 ng/ml on the postoperative histopathological report had positive lymph nodes (ypN+). There was a statistically significant difference in the level of IL-1β in the blood serum of patients before the start of treatment in the subgroups ypN0 vs ypN+ vs unresectable tumor (p = 0.003), ypN0 vs ypN+ (p = 0.002) as well as ypN+ vs unresectable tumor (p = 0.075). There was a trend for change in IL-1β level between cycles C1 and C3 in the ypN0 vs ypN+ subgroups (p = 0.056). The difference in IL-1β level before C1 between the groups TGR-G1-2/ypN0 vs TGR-G1-2/ypN+ vs TGR-G3/ypN0 vs TGR-G3/ypN+ was statistically significant (p = 0.017). The difference in IL-6 level between C3 and C1 in the subgroups TGR-G1-2/ypN0 vs TGR-G1-2 / ypN + vs TGR-G3 / ypN0 vs TGR-G3 / ypN + vs unresectable tumor was statistically significant (p = 0.009). Among the analyzed factors, only the difference in serum IL-6 level between C3 and C1 may be a predictor of ypN+ response to preoperative FLOT regimen. Among ypN0 patients, 76% had an IL-6 difference between C3 and C1> 1.1, i.e. C3 greater than C1 by at least 1.1 (specificity), and among ypN+ patients 83% had an IL-6 difference between C3 and C1 <1.1 (specificity). Conclusions: Low IL-1β levels before starting treatment is a prognostic factor while an early decrease in IL-6 could be considered a predictive marker of response to FLOT.