Study to Evaluate the Efficacy and Safety of Andecaliximab Combined With Nivolumab Versus Nivolumab Alone in Adults With Unresectable or Recurrent Gastric or Gastroesophageal Junction Adenocarcinoma

Key Inclusion Criteria:

Histologically confirmed inoperable locally advanced or metastatic adenocarcinoma of the stomach or GEJ which have progressed on at least 1 prior systemic therapy or line of treatment for unresectable/metastatic disease
Eastern Cooperative Oncology Group (ECOG) performance score of ≤ 1
Measurable disease according to Response Criteria in Solid Tumors (RECIST) v1.1
Tumor sites that can be accessed for repeat biopsies
Archival tumor tissue, preferably obtained from the most recent available biopsy; there must be adequate tissue for a Cochran-Mantel Haenszel (CMH) test stratified by programmed death ligand 1 (immunotherapy-drugs-are-boosting-survival/" >PD-L1) stratification test, as assessed by central pathologist
Individuals not receiving anticoagulant medication must have an international normalized ratio (INR) ≤ 1.5 and activated partial thromboplastin (aPTT) ≤ 1.5 x upper limit of normal (ULN)
Required baseline laboratory data as outlined in protocol

Key Exclusion Criteria:

Individuals who have received only neoadjuvant or adjuvant therapy for gastric adenocarcinoma
Radiotherapy within 28 days of randomization
Uncontrolled intercurrent illness as outlined in protocol
History of a concurrent or second malignancy except for those outlined in protocol
Major surgery, within 28 days of first dose of study drug
Known positive status for human immunodeficiency virus (HIV)
Known acute or chronic-active infection with hepatitis B virus (HBV) or hepatitis C virus (HCV)
Chronic daily treatment with oral corticosteroids (dose of > 10 mg/day prednisone equivalent) or other immunosuppressive medications within 14 days of randomization
Known or suspected central nervous system metastases
Documented myocardial infarction or unstable/uncontrolled cardiac disease within 6 months of randomization
Serious systemic fungal, bacterial, viral, or other infection that is not controlled or requires intravenous antibiotics
Current or history of pneumonitis or interstitial lung disease
Active known or suspected autoimmune disease with exceptions noted in protocol.
History of bone marrow, stem cell, or allogenic organ transplantation

NOTE: Other protocol defined Inclusion/ Exclusion criteria may apply.