Your medical history will be reviewed to confirm that you have an advanced solid tumor that expresses the CA19-9 tumor marker. CA19-9 is a protein found on the surface of certain cancer cells.

Your tumor type will be confirmed through previous tissue analysis. Eligible tumor types include pancreatic cancer, bile duct cancer, bladder cancer, colorectal cancer, esophagogastric junction cancer, endometrial cancer, and ovarian cancer.

Your disease will be measured using imaging scans to establish a baseline according to RECIST 1.1 criteria, which is a standard method for measuring tumor size. If you have ovarian cancer, different measurement criteria will be used.

Blood tests and other assessments will be performed to check your organ function, blood cell counts, and blood clotting ability to ensure they meet the required levels for participation.

Your life expectancy will be assessed and must be at least 3 months.

You will receive BNT329, which is an investigational drug designed to target cancer cells that express the CA19-9 marker.

BNT329 will be given to you through an intravenous infusion, which means it will be administered directly into your vein over a period of time.

The dose of BNT329 you receive will depend on which part of the trial you are enrolled in. The trial is designed to test different dose levels to find the safest and most effective amount.

The frequency and duration of treatment will be determined by the specific protocol for your dose level and will continue as long as the treatment is considered safe and potentially beneficial for you.

Throughout the trial, you will be closely monitored for any adverse events, which are unwanted or harmful effects that may occur during treatment.

Special attention will be paid to dose-limiting toxicities, which are serious side effects that may require adjustment or stopping of your treatment.

Your treatment may be interrupted, the dose may be reduced, or treatment may be stopped entirely if you experience significant side effects.

Blood samples will be taken at regular intervals to measure the levels of the drug in your bloodstream and to assess how your body processes the medication.

Tests will also be conducted to check if your body develops an immune response to the drug, known as anti-drug antibodies.

Regular imaging scans will be performed to measure changes in your tumor size and to determine how your cancer is responding to treatment.

Your response will be classified as complete response (tumor disappears completely), partial response (tumor shrinks), stable disease (tumor stays the same size for at least 6 weeks), or progressive disease (tumor grows).

The duration of your response, if one occurs, will be tracked from the time your tumor first responds until the time it grows again or until death from any cause.

Your overall disease control will be assessed, which includes whether your tumor shrinks, disappears, or remains stable during treatment.

You will continue receiving BNT329 as long as the treatment is safe for you and your disease does not progress.

If your tumor grows despite treatment, if you experience unacceptable side effects, or if you decide to withdraw from the trial, your treatment will be stopped.

The trial is expected to continue until 2030, though your individual participation duration will depend on how you respond to treatment and whether you continue to meet the criteria for ongoing participation.