Prospectively Predict the Immunotherapy Response of Gastric Cancer Based on Circulating Exosomal LncRNA-GC1 Biopsy

"Collect peripheral blood sample of 80 gastric cancer patients pre-treatment. Blood samples will be transferred to central lab to detect circulating exosomal lncRNA-GC1. Tumor response evaluation will be performed after two cycles of immunotherapy by CT/MRI based on RECIST.~Clinical data, including tumor stage, metastastic organ, regimen, objective response, progression free survival, overall survival, etc, will be collected according to study protocol."