Neoadjuvant Apatinib Combined With Sintilimab and Perioperative SOX Versus Neoadjuvant Sintilimab Combined With Perioperative SOX for Intestinal Type of Locally Advanced Gastric/Gastroesophageal Junction Adenocarcinoma

Sintilimab: 200mg, iv, day 1 Oxaliplatin: 130 mg/m², iv, day 1 S-1: 40-60 mg/m², po, day 1-14 (BSA \< 1.25 m², 40 mg bid, 1.25 m² ≤ BSA \< 1.5 m², 50 mg bid, BSA ≥ 1.5 m², 60 mg bid) Apatinib: 250mg, po, day1-21, for 3 cycles preoperatively

Sintilimab: 200mg, iv, day 1 Oxaliplatin: 130 mg/m², iv, day 1 S-1: 40-60 mg/m², po, day 1-14 (BSA \< 1.25 m², 40 mg bid, 1.25 m² ≤ BSA \< 1.5 m², 50 mg bid, BSA ≥ 1.5 m², 60 mg bid)