Study of Resistance Mechanisms in Breast Cancer Treatments Including HER2, HR, and Triple Negative Types Using Tumor Tissue and Blood Samples

What this Trial Is About

Researchers are studying mechanisms of resistance to breast cancer therapies in participants with HER2 positive, hormone receptor positive, or triple negative breast cancer. The study focuses on understanding how tumors and blood samples change when the cancer progresses or recurs during treatment. It is a Phase 4 interventional trial designed to investigate these resistance processes in multiple patient cohorts. Participants will be assigned to different groups based on whether they have newly appearing or recurrent metastatic lesions or tumors that continue to grow while on anti-cancer therapy. Tumor tissue and blood samples will be collected during procedures such as biopsies. These samples will be analyzed for changes in HER2 protein and gene levels, estrogen receptor protein levels, genes linked to CDK46 and endocrine resistance, and immune markers like PD-L1 and tumor-infiltrating lymphocytes. Participants will undergo tumor tissue sampling and blood draws when disease progression or recurrence occurs. Researchers will monitor changes from baseline in various proteins, gene copy numbers, and immune features over periods of at least six months or less depending on the cohort. The study will last until September 2026, with ongoing assessments to evaluate resistance mechanisms and disease progression markers. Safety and the ability to complete study procedures will be carefully monitored.

A Study to Investigate Mechanisms of Resistance to Breast Cancer Therapies