A study comparing injection under the skin versus infusion into the vein of tislelizumab with chemotherapy for patients with advanced gastric or gastroesophageal junction cancer

Treatment assignment

Upon joining the study, you will be randomly assigned to one of two treatment groups. This means that neither you nor your doctor will choose which group you are in.

One group will receive tislelizumab as a subcutaneous injection, which means the medication will be injected under the skin. The other group will receive tislelizumab as an intravenous infusion, which means the medication will be given directly into a vein over a period of time.

Both groups will also receive chemotherapy in combination with tislelizumab.

Treatment cycles

The treatment will be given in cycles. Each cycle lasts 21 days (3 weeks).

On Day 1 of each cycle, you will receive tislelizumab either as a subcutaneous injection or as an intravenous infusion, depending on which group you were assigned to.

You will also receive chemotherapy according to the schedule determined by your treatment plan.

This treatment pattern will continue for multiple cycles as long as the treatment is working and you are not experiencing unacceptable side effects.

Monitoring and assessments

Throughout the study, your health will be monitored regularly to check how the treatment is affecting you and whether it is working.

Blood samples will be taken at specific times to measure the levels of tislelizumab in your body. One important measurement will be taken before your dose on Day 1 of Cycle 5.

Your tumor will be assessed using imaging scans to see if it is responding to the treatment. These assessments will follow standard guidelines called RECIST version 1.1, which is a set of rules used to measure tumor response.

You will need to provide tumor tissue samples for laboratory testing to help understand how the treatment works.

Safety monitoring

Your doctor will monitor you for any side effects or adverse events throughout the study. This includes both mild and serious side effects.

Any side effects will be recorded and assessed for their severity, when they occur, and whether they are related to the study treatment.

Tests will be performed to check your organ function, including your liver, kidneys, and blood cells, to ensure your body is tolerating the treatment.

Blood tests will also be done to check if your body has developed any antidrug antibodies, which are proteins your immune system might make in response to tislelizumab.

Birth control requirements

If you are a woman who can become pregnant, you must use a highly effective method of birth control throughout the entire study period.

You must continue using birth control for at least 120 days after receiving your last dose of tislelizumab.

If you are a male who is not sterile, you must also use a highly effective method of birth control during the study and for at least 120 days after your last dose of tislelizumab.

Study duration

The length of time you will receive treatment depends on how well the treatment is working for you and how well you are tolerating it.

Even after your treatment ends, you will continue to be followed for safety monitoring and to assess long-term outcomes.

The overall study is expected to continue until approximately April 2028, though your individual participation may be shorter or longer depending on your specific situation.