Pembrolizumab is a type of medication known as an immunotherapy. It works by helping your immune system fight cancer cells. In this trial, pembrolizumab is used to treat patients with a specific type of breast cancer that cannot be removed by surgery or has spread to other parts of the body. The goal is to see if pembrolizumab can help shrink the cancer or stop it from growing.

Olaparib is a medication that targets cancer cells with certain genetic mutations. It works by blocking a protein that cancer cells need to repair themselves, which can lead to the death of these cells. In this trial, olaparib is used alongside pembrolizumab to treat patients with breast cancer who have specific genetic mutations. The aim is to determine if the combination of these two medications is effective in treating the cancer.

HER2-negative breast cancer with homologous recombination deficiency – This type of breast cancer lacks the human epidermal growth factor receptor 2 (HER2) protein, which is often involved in the growth of cancer cells. It is characterized by a deficiency in the homologous recombination repair pathway, which is crucial for repairing DNA double-strand breaks. The disease can progress from localized tumors to more advanced stages, where it becomes unresectable or metastatic, meaning it cannot be surgically removed and may spread to other parts of the body. The presence of specific genetic mutations, such as those in BRCA1/2, ATM, and other related genes, can influence the progression and behavior of the cancer. As the disease advances, it may lead to increased tumor size and the involvement of additional tissues or organs. The progression is often monitored through imaging and clinical evaluations to assess changes in tumor size and spread.