Your tissue sample will be analyzed in a central laboratory to check the level of a protein called CLDN1 in your tumor cells. This sample should be collected within 180 days before joining the study, unless taking a new sample would be unsafe for you. If a new sample cannot be obtained, an older tissue sample may be used, preferably collected before your most recent cancer treatment started.

You will undergo screening tests within 14 days before receiving the first dose of the study medication. These tests will check your blood counts, liver function, kidney function, and other organ systems to ensure your body can handle the treatment.

Your tumor will be measured using imaging scans to establish a baseline according to RECIST 1.1, which is a standard method for measuring tumors in clinical studies.

Your overall health and ability to carry out daily activities will be assessed using the ECOG performance status scale, which ranges from 0 to 5, with lower numbers indicating better function.

If you are a woman of childbearing potential, you will have a pregnancy test within 72 hours before receiving the first dose of the study medication.

An electrocardiogram (a test that records the electrical activity of your heart) will be performed, and your vital signs will be measured.

You will receive ALE.P03, which is the study medication being tested. This medication is an antibody-drug conjugate that targets the CLDN1 protein on tumor cells.

The medication will be given to you through an intravenous infusion, which means it will be delivered directly into your vein through a needle or catheter.

The medication comes as a powder for solution for infusion, which will be prepared by the study staff before being given to you.

The dose you receive will depend on which phase of the study you are in. During Phase I, different doses are being tested to find the safest and most effective dose. During Phase II, you will receive the dose that was determined to be most appropriate in Phase I.

The frequency and duration of your infusions will be determined by the study protocol and the phase you are participating in. Your treatment will continue in cycles, with specific intervals between doses.

Throughout your participation, you will be monitored closely for any side effects or adverse events. This includes both mild and serious adverse events that may occur.

Blood samples will be taken regularly to check your blood counts, liver function, kidney function, and other laboratory values to ensure the medication is not causing harmful changes in your body.

Your vital signs, such as blood pressure, heart rate, and temperature, will be measured at each visit.

Electrocardiograms will be performed periodically to monitor your heart function.

Blood samples will be collected to measure the level of ALE.P03 in your bloodstream. This helps determine how your body processes the medication. Specific measurements include how much medication is in your blood at different times and how long it stays in your system.

Blood samples will also be taken to check if your body develops antibodies against the study medication, which is called immunogenicity testing.

At regular intervals during the study, you will have imaging scans to measure your tumor and see how it is responding to the treatment.

The response of your tumor will be evaluated using RECIST 1.1 criteria, which is a standardized way to determine if the tumor has shrunk, stayed the same size, or grown.

The study will track several outcomes, including the objective response rate (the percentage of patients whose tumors shrink significantly), duration of response (how long the tumor shrinkage lasts), and disease control rate (the percentage of patients whose disease does not get worse).

Your progression-free survival will be measured, which is the length of time during and after treatment that your disease does not get worse.

Your overall survival will also be tracked throughout the study and follow-up period.

Your treatment may be interrupted or the dose may be adjusted if you experience certain side effects. The study will track these dose interruptions and changes in dose intensity.

You will continue receiving the study medication as long as your disease is not getting worse and you are not experiencing unacceptable side effects.

If you are in Phase I of the study, the study team will be carefully watching for dose-limiting toxicities, which are serious side effects that occur at a specific dose level and help determine the safest dose to use.

If you are a woman of childbearing potential, you must use two methods of birth control throughout the study and for 180 days after receiving your last dose of the study medication.

If you are a male patient, you must use an adequate method of contraception and not donate sperm starting from your first dose through 90 days after your last dose of the study medication.

After you stop receiving the study medication, you will continue to be monitored for side effects and long-term outcomes.

Follow-up assessments will continue to track your survival and disease status.

The study is expected to continue until approximately September 2029, though your individual participation length may vary depending on how your disease responds to treatment and whether you experience side effects.