A Study of DKN-01 in Combination With Tislelizumab ± Chemotherapy in Patients With Gastric or Gastroesophageal Cancer

This is a Phase 2 open-label, multicenter study to be conducted concurrently in 3 Parts (Parts A, B, and C). Approximately 232 patients aged 18 years or older with inoperable, histologically confirmed locally advanced or metastatic Gastric or Gastroesophageal Junction (G/GEJ) adenocarcinoma with measurable disease (RECIST v1.1) requiring therapy will be enrolled in the study. Part A and B are designed to evaluate safety, tolerability, and efficacy of the combination therapy of intravenous (IV) DKN-01 and tislelizumab ± CAPOX in G/GEJ adenocarcinoma patients. Treatment continues in repeating 21-day cycles until patient meets criteria for discontinuation or is no longer deriving clinical benefit. Two doses of DKN-01 will be evaluated in Part B (Part B1 and Part B2). Part C is the open-label, randomized, controlled, 2-arm portion of the study to evaluate the efficacy and safety of tislelizumab + chemotherapy regimen (CAPOX or mFOLFOX6) ± DKN-01 in adult patients with inoperable, histologically confirmed locally advanced or metastatic G/GEJ adenocarcinoma with measurable disease (RECIST v1.1) requiring therapy. Approximately 160 patients will be randomized in a 1:1 ratio to receive either DKN-01 in combination with tislelizumab and chemotherapy regimen (CAPOX or mFOLFOX6) (n=80) or tislelizumab in combination with chemotherapy regimen (CAPOX or mFOLFOX6) (n=80).