Serological markers associated with response and adverse events in patients of esophageal squamous carcinoma with toripalimab combined with nab-paclitaxel and S-1 as neoadjuvant therapy.

e16017 Background: Immune checkpoint inhibitor (ICI) combined with chemotherapy as a neoadjuvant therapy has been applied to the treatment of patients with esophageal squamous carcinoma (ESCC), however, there were a limited number of predictive biomarkers for response and adverse events. Methods: 60 patients diagnosed with ESCC and considered propable for surgical treatment were enrolled from October 2019 to September 2020 in the first medical center of Chinese PLA General Hospital and received Toripalimab combined with nab-Paclitaxel and S-1 as neoadjuvant therapy. Serum samples were collected at baseline and performed with 92 proteins using proximity extension assay technology. Results: In total, 50 patients were examined, and 3 patients did not pass quality control. Patients with IFN-Y-L, LAMP3-L and Gal.1-H at baseline were associated with longer overall survival. Furthermore, 21 proteins were found to be significantly lower in patients with severe side effects than in patients without serious adverse events. Conclusions: Our study found that serum levels of several proteins were associated with clinical benefit and severe side effects, and these proteins may be useful biomarkers for predicting response and severe side effects in ESCC treated with ICI and chemotherapy.