A Clinical Study of Patritumab Deruxtecan to Treat Breast Cancer (MK-1022-016)

To join this study, you must have advanced breast cancer that is hormone receptor-positive (HR+) and HER2-negative (HER2-). This means your cancer cannot be removed by surgery because it has grown too much locally, or it has spread to other parts of your body. Your cancer must have been confirmed to have these specific features by tests, including looking at levels of another protein called HER3.

You must have already received certain treatments for your advanced breast cancer. Specifically, your cancer must have grown or come back after you had an earlier type of hormone therapy combined with a CDK4/6 inhibitor. This could have happened either during your first treatment for advanced cancer, or within two years of finishing a similar treatment after earlier surgery.

Other important requirements include being at least 18 years old, having cancer that can be measured, and generally being well enough to take part. There are also specific medical conditions, like certain other cancers or not being able to receive further hormone-based treatment, that would prevent you from joining.

Taking part in this study would involve regular hospital visits for assessments and to receive the study medication. You would receive either the new drug, patritumab deruxtecan, or one of the standard treatments for your condition. This would be decided randomly, like flipping a coin. You would have blood tests, scans, and physical examinations to closely monitor your health and how the treatment is working. We cannot provide a total duration, but you would continue treatment and monitoring for as long as it is safe and beneficial for you, or until the study requires follow-up. Detailed information on visits and assessments would be given by the study team.