Patient Scenario: A 44-Year-Old Woman With Metastatic TNBC

Transcript:

Aditya Bardia, MD, MPH: Let's talk about a case scenario of premenopausal 44 year old female presents with a palpable lump in the left breast. Has a diagnostic mammogram which reveals a 2.8 cm lesion in the left breast and left axillary lymph node involvement. Given the concern for higher stage disease, the patient has prestaging cat scans which unfortunately also shows a couple of lesions in the liver. The patient has ultrasound guided core biopsy of the liver lesion which confirms the presence of invasive breast cancer, triple negative. ERPR HER2 negative with INC zero. The patient has initial tumor analysis, and the tumor is positive for PD-L1 expression. Patient has germ line testing done and there's no detectable germ line BRCA mutation. This patient essentially has metastatic triple negative breast cancer, and the question is what should be the next best treatment option for this patient with metastatic TNBC that is PD-L1 positive, and the patient does not have detectable germ line BRCA mutation.

For a patient with metastatic triple negative breast cancer there are 2 biomarkers that need to be evaluated in everyone. The first is PD-L1 status because that's actionable. If positive, the patient should be treated with therapy. The second is assessment of germ line BRCA mutation because if present that patient is a candidate for treatment with a PARP inhibitor. Nowadays, there are other biomarkers that should also be considered, an example being the HER2 status. If a patient has what is called HER2 low breast cancer, meaning that if you look at HER2 expression by INC it's 1+ 2+, that patient could also be a candidate for treatment with trastuzumab dioxetane in the second line plus setting. That's another biomarker that should be evaluated.

For a patient with metastatic TNBC, systemic therapy is the main state of management. The first line for a patient like this who has PD-L1 positive metastatic TNBC would be chemotherapy plus immunotherapy, and you would continue that until this disease progression or an acceptable toxicity. The question often comes up if the breast tumor should also be removed. This patient who has de nevo metastatic TNBC and has the breast tumor as well, whether that should be surgically removed. This was evaluated in a large cooperative group trial, an ECOG trial. Essentially, there was no improvement in survival with the removal of the breast tumor. If anything, there was a hint toward worse survival in patients with triple negative breast cancer. We would not recommend that the breast tumor should be routinely removed, rather the focus should be on systemic treatment so that you can control the disease.

Transcript edited for clarity.