This study is designed to assess the levels of drug exposure following treatment with tislelizumab administered as a subcutaneous (SC) injection compared to intravenous infusion (IV) as first-line therapy in adults with gastric or gastroesophageal junction (GEJ) that is locally advanced and cannot be surgically removed or has spread from the stomach to other areas of the body. Approximately 351 patients will be participating in this study. The study is composed of a screening period, a treatment period, and a follow-up period.

Our company, previously known as BeiGene, is now officially BeOne Medicines. Because some of our older studies were sponsored under the name BeiGene, you may see both names used for this study on this website.

Inclusion Criteria:

• Histologically confirmed, locally advanced unresectable or metastatic gastric/ gastroesophageal junction (GEJ) adenocarcinoma.
• No previous systemic therapy for locally advanced unresectable or metastatic gastric/GEJ cancer.
• At least 1 measurable or nonmeasurable lesion per RECIST v1.1 as determined by investigator assessment.
• Must be able to provide tumor tissues for biomarker assessment.
• Eastern Cooperative Oncology Group (ECOG) Performance Status score ≤ 1.
• Adequate organ function.
• Women of childbearing potential must be willing to use a highly effective method of birth control for the duration of the study and ≥ 120 days after the last dose of tislelizumab.
• Non-sterile males must be willing to use a highly effective method of birth control for the duration of the study and for ≥ 120 days after the last dose of tislelizumab.

Exclusion Criteria:

• Squamous cell or undifferentiated or other histological type gastric cancer (GC)
• Active leptomeningeal disease or uncontrolled brain metastasis. Patients with equivocal findings or with confirmed brain metastases are eligible for enrollment provided that they are asymptomatic and radiologically stable without the need for corticosteroid treatment for ≥ 4 weeks before randomization.
• Diagnosis with gastric or GEJ adenocarcinoma with positive human epidermal growth factor receptor 2 (HER2).
• Active autoimmune diseases or history of autoimmune diseases that may relapse.
• Uncontrollable pleural effusion, pericardial effusion, or ascites requiring frequent drainage (at least once a week) and/or diuretics within 7 days prior to randomization

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

BeOne shares data on completed studies responsibly and provides qualified scientific and medical researchers access to data and supporting documentation for clinical trials in dossiers for medicines and indications after submission and approval in the United States, China, and Europe. Clinical trials supporting subsequent local approvals, new indications, or combination products are eligible for sharing once corresponding regulatory approvals are achieved.

BeOne shares data only when permitted by applicable data privacy and security laws and regulations, when it is feasible to do so without compromising the privacy of study participants, and other considerations.

Qualified researchers with appropriate competencies who are engaged in novel scientific research may submit a request for participant-level data with a research proposal for BeOne review. Research teams must include a biostatistician and sign a Data Sharing Agreement prior to receiving access to clinical trial data.

See plan description

See plan description