S-1 and Oxaliplatin (SOX) Plus Sintilimab in the Locally Advanced Esophagogastric Junction Adenocarcinoma

"Drug: Oxaliplatin Oxaliplatin: 130mg/m2，iv drip for 2h，d1, q3w~Drug: S-1 S-1: 40\~60mg Bid，d1\~14, q3w"

"Drug: Sintilimab Sintilimab, recombinant humanized anti-PD-1 monoclonal antibody for injection; 200mg ivdrip, d1, q3w.~Other Name: PD-1 antibody~Drug: Oxaliplatin Oxaliplatin: 130mg/m2，iv drip for 2h，d1, q3w~Drug: S-1 S-1: 40\~60mg Bid，d1\~14, q3w"