An Open Label Phase 2 Study to Evaluate the Safety and Efficacy of Lenvatinib With Pembrolizumab or Lenvatinib, Pembrolizumab and FLOT in the Neoadjuvant / Adjuvant Treatment for Patients With Gastric Cancer

This study is an open label phase 2 study to evaluate the safety and efficacy of Lenvatinib with Pembrolizumab or Lenvatinib, Pembrolizumab and FLOT in the neoadjuvant / adjuvant treatment for Patients with Gastric Cancer.

Inclusion Criteria: 1. Have gastric and gastroesophageal junction adenocarcinoma 2. Untreated and cT2-4 and/or cN+ without evidence of metastatic disease 3. Patients at least 20 years of age on the day of providing consent. 4. Patients with a performance status of 0 or 1 on the Eastern Cooperative Oncology Group. 5. Patients with adequate organ function at the time of enrollment as defined below: * Neutrophil count ≥1500mm3 * Platelet count ≥10 × 100,000/mm3 * Hemoglobin (Hb) ≥ 9.0 g/dL, * Total bilirubin ≤1.5 mg/dL * AST (GOT) and ALT (GPT) ≤ 100 IU/L * Creatinine ≤1.5 mg/dL * Urinary protein : It satisfies one of the following (if any of the inspection criteria are satisfied, other examination may not be carried out) (i) urinary protein (test paper method) is 2+ or less (ii) Urine Protein Creatinine (UPC) ratio \