Interleukin-6 as a predictive factor of pathological response to FLOT regimen systemic treatment in locally advanced gastroesophageal junction (GEJ) or gastric cancer (GC) patients

Background: Perioperative treatment is a gold standard in locally advanced gastric cancer or GEJ cancer in western population. Unfortunately, the response rate after neoadjuvant chemotherapy (NAC) remains limited. Moreover, there are currently no biomarkers enabling an individual prediction of therapeutic efficacy. The aim of this study was identification of serum biomarkers of early response to NAC. Methods: We conducted this prospective study in the MSCNRIO, in Warsaw, Poland. A total of 71 patients and 15 healthy volunteers signed informed consent. Complete blood count, blood chemical tests, carcinoembryonic antigen (CEA) carcinoma antigen 125 (CA125), carcinoma an-tigen 19.9 (CA19.9), d-dimer, fibrinogen (F) were measured at baseline and before every cycle. Circulating tumour cells (CTCs) and interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10) were measured in a pilot group of 40 patients at baseline and before cycle two (C2) and cycle three (C3). Results: Of all the measured parameters, only IL-6 serum level was statistically significant. The IL-6 level before C2 of chemotherapy was significantly decreased in complete pathological re-sponse (pCR) vs non-pCR group (3.71 pg/mL vs 7.63 pg/mL, p=0,004). In all patients with IL-6 levels below 5.0 pg/mL in C2, tumour regression TRG1a/1b according to Becker classification and ypN0 were detected in postoperative histopathological specimens. The IL-6 level before C1 of chemotherapy was significantly elevated in ypN+ vs ypN0 (7.69 pg/mL vs 2.89 pg/mL, p=0.022). Conclusions: The trial showed that elevated level of IL-6 prior to treatment and C2 might be a predictor of pathologic response to NAC.