A Study to Evaluate the Adverse Events, Efficacy, and Optimal Dose of Intravenous (IV) ABBV-400 in Combination With IV Fluorouracil, Leucovorin, and Budigalimab in Adult Participants With Locally Advanced Unresectable or Metastatic Gastric, Gastroesophageal Junction, or Esophageal Adenocarcinoma

City of Hope National Medical Center /ID# 268690, Duarte, California, United States

City of Hope - Orange County Lennar Foundation Cancer Center /ID# 272630, Irvine, California, United States

UCLA - Santa Monica /ID# 270024, Santa Monica, California, United States

AdventHealth Orlando /ID# 268561, Orlando, Florida, United States

City Of Hope - Atlanta. /ID# 280646, Newnan, Georgia, United States

Hattiesburg Clinic /ID# 268572, Hattiesburg, Mississippi, United States

Duke University Medical Center /ID# 268186, Durham, North Carolina, United States

Millennium Research & Clinical Development /ID# 268540, Houston, Texas, United States

Algemeen Ziekenhuis klina /ID# 268754, Brasschaat, Antwerpen, Belgium

Universitair Ziekenhuis Leuven /ID# 269957, Leuven, Vlaams-Brabant, Belgium

CHU de Liege /ID# 270223, Liège, Belgium

Princess Margaret Cancer Centre /ID# 268277, Toronto, Ontario, Canada

Centre Hospitalier de l'Universite de Montreal (CHUM) /ID# 268763, Montreal, Quebec, Canada

Jewish General Hospital /ID# 268413, Montreal, Quebec, Canada

Beijing Cancer Hospital /ID# 268455, Beijing, Beijing Municipality, China

Cancer Hospital Chinese Academy of Medical Sciences(Langfang) /ID# 277479, Langfang, Hebei, China

Harbin Medical University Cancer Hospital /ID# 268452, Harbin, Heilongjiang, China

Union Hospital - Tongji Medical College /ID# 268796, Wuhan, Hubei, China

The first Affiliated Hospital, Zhejiang University School of Medicine. /ID# 268782, Hangzhou, Zhejiang, China

Universitaetsklinikum Freiburg /ID# 270407, Freiburg im Breisgau, Baden-Wurttemberg, Germany

TUM Klinikum rechts der Isar /ID# 267792, Munich, Bavaria, Germany

Krankenhaus Nordwest /ID# 268462, Frankfurt am Main, Hesse, Germany

Universitaetsklinikum Leipzig /ID# 270432, Leipzig, Saxony, Germany

Haematologisch-Onkologische Praxis Eppendorf /ID# 268024, Hamburg, Germany

Meir Medical Center /ID# 267998, Kfar Saba, Central District, Israel

Soroka Medical Center /ID# 268301, Beersheba, Southern District, Israel

Tel Aviv Sourasky Medical Center /ID# 267755, Tel Aviv, Tel Aviv, Israel

Shaare Zedek Medical Center /ID# 267752, Jerusalem, Israel

Hadassah Medical Center-Hebrew University /ID# 267753, Jerusalem, Israel

Aichi Cancer Center /ID# 268124, Nagoya, Aichi-ken, Japan

National Cancer Center Hospital East /ID# 268083, Kashiwa-shi, Chiba, Japan

Shizuoka Cancer Center /ID# 268123, Sunto-gun, Shizuoka, Japan

National Cancer Center Hospital /ID# 268648, Chuo-Ku, Tokyo, Japan

The Cancer Institute Hospital Of JFCR /ID# 268656, Koto-ku, Tokyo, Japan

Pan American Center for Oncology Trials /ID# 268833, Rio Piedras, Puerto Rico

Hospital Universitario de Navarra /ID# 270119, Pamplona, Navarre, Spain

Hospital General Universitario Gregorio Maranon /ID# 270037, Madrid, Spain

Complexo Hospitalario Universitario de Ourense /ID# 270042, Ourense, Spain

Hospital Clinico Universitario de Valencia /ID# 270040, Valencia, Spain

Kaohsiung Medical University Chung-Ho Memorial Hospital /ID# 267672, Kaohsiung City, Taiwan

China Medical University Hospital /ID# 267667, Taichung, Taiwan

National Cheng Kung University Hospital /ID# 267669, Tainan, Taiwan

National Taiwan University Hospital /ID# 267666, Taipei, Taiwan

Taipei Veterans General Hospital /ID# 267664, Taipei, Taiwan

Linkou Chang Gung Memorial Hospital /ID# 267668, Taoyuan City, Taiwan

Barts Health NHS Trust /ID# 270796, London, Greater London, United Kingdom

Oxford University Hospital NHS Trust /ID# 274614, Oxford, Oxfordshire, United Kingdom

Queen Elizabeth Hospital Birmingham /ID# 271199, Birmingham, United Kingdom

NHS Tayside Health Board /ID# 270799, Dundee, United Kingdom